Zel's Motoring Adventures...Peugeot, Renault, Rover, Trabant, Invacar & A Sinclair C5 - 29/06 - Instrument Panel Repairs Done...

[Zelandeth]

A lot of good and useful information here. 

The single biggest headache it looks like I face regarding just buying a load of parts, stripping down and rebuilding this unit is the damage to the valve port faces.  Photos don't really show quite how rough they are.  Machining out that damage (assuming there's not already enough material missing to render that impossible) isn't a job that I know of anyone kitted out to deal with.  It was definitely something that concerned me when I saw the state of them, and a couple of people in different places have also raised red flags with that damage.  So we need to add crank case to the shopping list. 

I have taken the belt drive off and spun the engine over and the bottom end is definitely grumbly.  There's also a distinct tight spot which comes around every few revolutions.  That actually ties in with a noise the engine has always made which was definitely engine speed related, but had always sounded more like something associated with the fan or alternator.  It was engine speed related, but wasn't as quick as once per revolution.    Not exactly sure what's causing it - but it definitely shouldn't do that.

Currently scoping out a couple of possible engine options in the UK to just see where it leads.  One of them was removed from the car in "good running condition" when they took things apart to do the always popular Wartburg swap, so depending on the associated price tag that might be a decent option.  I'm not really expecting a good candidate to turn up, but it's an avenue which I think is at least worth investigating.  Yes it's entirely likely that anything I pick up is going to need something doing to it, which is why the price tag will be a big factor in anything that's an unknown.  It needs to be cheap enough that I'm not going to be overly bothered if it turned out to be a total loss as I know I'm rolling the dice there.

Given that the valves are held against that surface under spring tension it does look like the case on these engines is always going to be somewhat vulnerable to damage in the case of contamination getting in there.

I certainly can't really see me looking to move the car on in the near term.  It puts a big smile on my face, doesn't take up much space and has generally proven so far to be pleasingly easy to work on. 

Looking at how I worded things earlier as well I think I need to clarify that I don't think the prices Trabantwelt are asking for the full rebuild kit nor the ready to go engines they're offering are unreasonable.  The fact that they're offering that level of support for a car that's not seen production for 34 years and has a relatively niche appeal is pretty incredible, and while they're not cheap that is just par for the course if you're doing something like rebuilding an engine - and you're always going to pay a bit of a premium for that degree of convenience. 

The first results in a (very) quick Googling for a re manufactured A-Series immediately turned up results of £2500+ for a 998cc engine sans gearbox, which makes the prices for TW's engines look pretty attractive.  Yes I know there's more work involved in rebuilding a four stroke engine - but conversely some of that work is less specialised (read: Crankshaft overhaul on a two stroke) and it's definitely a wider market, so I don't think it's an entirely unfair comparison in all honesty.

So watch this space.  I'm going to give it a few days to see if anything turns up before we make a definite call on the way we're going.

 

This afternoon I decided to have a look into seeing if we could do something about the oil leak on the Rover.  It's kind of hard to tell exactly where it's coming from but all evidence suggests the join between the oil pump body and filter housing.  The vast majority of the oil seeming to run down and drip off the bottom of the filter itself and the cap over the pressure relief valve.  Or it might be the filter bypass valve looking at the location...It's clearly a piston/spring type pressure regulating valve of some description.

This would be a lot less of a pain to deal with if Rover hadn't put this...thing...right in front of the oil filter.

Yes, that does get precisely as in the way as it looks like it will when changing the filter too.

You can see how many small bolts hold the assembly in place by looking at the replacement gasket.

I eventually figured out that a 3/8" wrench was a perfect fit on these - after spending a good 20 minutes digging through toolboxes while cursing the fact that Rover hadn't discovered the joys of the metric system in the early 70s.  Unfortunately that's about where the good news ended.  I cannot for the life of me figure out how to get a wrench on the "back" two bolts.  On in particular I can barely even touch between the amount of structural metalwork in the way and the oil pressure switch boss being in about the most unhelpful place imaginable in terms of trying to remove this assembly.

It doesn't look like removing the filter will actually help the bolts that it looks like it interferes with in the photos are actually accessible - and the filter itself actually gives me something to hold on to while I'm trying to remove the thing from the car.

I did notice though that - even using a pretty stubby wrench as I was - that at least four of the bolts were not all that tight at all.  So nipped those up a little and ran the car for a while to see if it helped.  After 20 minutes or so (however long it took me to go over the seats with leather conditioner again), evidence suggested that it maybe had helped...We definitely didn't seem to have the regular drip or two every second off the bottom of the filter anyway.  We did still have a drip every ten seconds still coming off the bottom of the oil pressure relief valve housing.  Which when spraying the area down with brake clean (which was then immediately blown in my face courtesy of the cooling fan), looked like it might be seeping out around the cap over the valve - the copper washer there looking a bit mangled where I could see it.  So I figured I'd pull that and swap the copper washer and see if that improved things.

Rookie mistake.

First off - I should have checked that I had any replacements that were big enough.  I don't.  Also failed to realise that the washer is actually captive on the cap, though that could just be be that it's distorted and has become somewhat oval over the years.  It's clearly been on and off a few times from how badly scored the surface is.

Second big mistake - What removing this of course then did was allow all of the oil to drain out of the pump.  What don't Rover V8 oil pumps like doing?  Priming themselves!  So I likely now NEED to remove the housing from the pump so I can pack the blasted thing with petroleum jelly so the thing has any hope of actually pulling prime and supplying the engine with oil when I next start it. 

Was one of those moments where I realised that I'd done something really daft right about the moment I did it.  Getting that thing back in there with how much tension is on the spring by the way was also an absolute pig of a job.

So until I can figure out how to get that apart I've successfully immobilised not one but two of my cars, with the third boxed in between them.

I'll have another bash at it tomorrow.  Will try making up an adaptor to spin the pump with a drill and see if it will prime but I'm not holding my breath - and aside from cleaning the surfaces up and removing a couple of burrs on the copper washer I've not actually changed anything so I'm still expecting it to leak anyway.

So not a very successful afternoon today - but some days are just like that.

Definitely was missing the Trabant's ease of access to most things and the fact that it seems to use a total of about half a dozen sizes of metric fasteners throughout the whole car.

[TrabbieRonnie]

Well done Zel, and glad you like the wee Trab enough to persevere 👍

[GlenAnderson]

I was going to say that a Warburg engine in a Trabant is on my list of “things to do prior to packing in doing stupid things”…

[kevins]

When I had oil pump appart on my Range Rover It primed easily enough, I think there is still enough oil floating around inside for it to prime.

 

[Zelandeth]

3 hours ago, kevins said:

When I had oil pump appart on my Range Rover It primed easily enough, I think there is still enough oil floating around inside for it to prime.

 

Guess I'll investigate tomorrow then.  Just know it's something I've read about in many places that these engines can be really finicky about.  Not having much experience with them I'm just being a bit paranoid I suspect.

The question does still remain of how many laws of geometry I need to figure out how to suspend to get that pump/filter housing off to replace the gasket.  

4 hours ago, TrabbieRonnie said:

Well done Zel, and glad you like the wee Trab enough to persevere 👍

It really has been a car which has surprised me in that regard.  For all it has a plethora of flaws, it's just fun.  

The fact that it pretty much immediately became my go to for local runs more or less the moment it arrived here says a lot in that regard I think.  

[Zelandeth]

I saw a couple of people mentioning backfilling the pump via the oil pressure switch port.  So gave that a try.  This turned out to be a bit of a mistake as given how things are oriented you really can't get anything much in there, and also because it turned out to be a gigantic faff to get the bleeding thing back in again.  There's about room to get a skinny 10mm spanner in there, not the 24mm (or whatever the imperial equivalent is - 24mm fitted perfectly) that's needed.  So a lot of swearing was involved, but got there in the end.

Tool making time.

One Rover V8 oil pump priming tool.

Distributor marked up so I could get it back in the right place (I failed), pulled out of the way  and that attached to a drill used to spin the pump.  For reference, it goes clockwise.  At least in this application.

Glad I took that approach.  It took well over a minute with the drill running fairly quickly before it eventually took prime and started to generate pressure.  Cranking/running the engine for long enough to build that would have been extremely uncomfortable.

Getting the drive slot to go back into the bottom of the distributor shaft also caused a certain amount of swearing, as it can obviously only slot into place in two orientations and it turned out to need to be pretty precise.

Initial start up attempt revealed that I'd obviously not marked things as accurately as I'd hoped as it was instantly apparent that I had way way too much advance and the engine was trying to spin itself backwards while cranking.  I gave the distributor a highly technical twist of "about that much" in the appropriate direction and the car started as normal.

Have never been so happy to see a light go out and pressure register on a gauge.

I'll need to pull the timing light out at some point, as currently I've just set the timing purely by ear.  It seems happy enough at least.

Testing reveals...Our leak definitely appears to have been significantly improved though it's definitely still there.  As I kind of expected.

Of course it wouldn't be this car without it presenting at least one new fault during a run.

Outside:

Inside:

Left hand indicator light on the dash has failed.  Percussive maintenance failed to resolve this, so looks like I'll need to pull the panel apart to either sort the contact or change the lamp.  I have been wanting to investigate the totally non functional ammeter for a while now as well so not maybe the worst thing if I can do both of those things at the same time.

At least I've got back to where I was before I started messing with things yesterday!

Given how crap the access is I may well see if I can get a garage to take on the oil pump gasket replacement - I get the impression that having the car on a proper lift would make the job merely "fscking awkward" rather than being seemingly geometrically impossible as it looks while laying on the ground.  That said, will probably find that nobody wants to touch it because it's not routine servicing something less than ten years old...

[GlenAnderson]

24mm, 15/16” AF and 1/2” WW are all close enough to each other to be interchangeable.  

[Zelandeth]

12 minutes ago, GlenAnderson said:

24mm, 15/16” AF and 1/2” WW are all close enough to each other to be interchangeable.  

Sounds right.  I found a 15/16" socket but sadly there wasn't enough room to get a suitable driver in there.  So had to do it 1/3927420th of a rotation at a time with the spanner.

I hate imperial measurements.  I know you get used to certain things being certain sizes, but not just being able to know immediately that "oh, this is slightly too small, I need 'n'."  Is really annoying.  If 12mm is slightly too small, then I need 13mm...not having to do mental gymnastics while rummaging in the bottom of the toolbox.  It's not quite so bad if you're using sockets as they're all laid out in sequence - however that's not always going to be the case.

Disclaimer: I am dyslexic and really struggle with mental math at the best of times, likewise memorising numerical patterns - I still can't do any but the absolute most basic multiplication in my head to save my life - this was the bane of my bloody life in secondary school.  But this may be a major part of why it winds me up so much!

I keep meaning to get a complete set of new, matching spanners covering all the usual sizes you find on British cars and just label the damned things from 1 at the smallest and increment heading upwards, as that would likely vastly reduce the "rage digging" that goes on when I've found that 7/16" is slightly too small and I don't know what I'm looking for!

[High Jetter]

I get 24mm & 15/16 being roughly the same, a smidge under 1". How does that equate to 1/2” whit tho?

[Noel Tidybeard]

you need a Metrinch socket set if you can find one for the right money

[LightBulbFun]

17 minutes ago, Noel Tidybeard said:

you need a Metrinch socket set if you can find one for the right money

Ditto, I got one a few years ago, based on recommendations from this very forum on how deal with the unique fastener situation that is the Model 70, (without having to get a 200 piece advanced Halford set that would be too heavy for my fragile arse to lug about anyhow)

and its worked very well so far for me   Invacar for scale!

well I have not really used the spanners side of things so I cant speak for those, but the socket side has worked very well, I usually just eyeball for the right size and if it does not fit, just go up or down a size and then ill quickly find something that fits snuggly and gets the job done  

[bobdisk]

@Zelandeth   Have you ever heard of an American tool called a "Tite Reach"  (American spelling!!) If you can get a socket (and its size adaptor) on your target , but not turn it, this tool works to turn the socket.

https://tite-reach.com/

 

[GlenAnderson]

11 hours ago, High Jetter said:

I get 24mm & 15/16 being roughly the same, a smidge under 1". How does that equate to 1/2” whit tho?

1/2” Whitworth is 23.4mm across the flats of the hexagon. 15/16” AF is 23.8mm across the flats. 
 

Whitworth sizes are based on the outside diameter of the thread. So a 1/2” Whitworth nut/bolt has a 1/2” thread, and you grab the spanner marked 1/2” to fasten it. The logic is fine when you think about it, and in some ways is more intuitive than the metric system where you need a 10mm spanner for an M6 fixing. 
 

Where things get a little more complicated is that BSF fine thread fixings used the next size down hexagons, and sometime around WW2 those slightly smaller sizes were standardised for the coarse Whitworth threads too. So a 1/2” Whitworth spanner is likely to be dual marked as 1/2”W-9/16”BS, and will actually have a 9/16” thread. You normally only encounter “proper” Whitworth fasteners if you work on pre-WW2 stuff, and even then only if everything is still original. 
 

The common spanner sizes on vehicles are 3/8” , 1/4” and 5/16”, which are the ones associated with 1/4”, 5/16” and 3/8” thread sizes. 
 

I get the frustration with the size increments being a bit of a challenge, but the more you use them, the easier it becomes to make the steps in your head. 
 

Admittedly, I have had forty years of practice, but I don’t find it difficult to eyeball the difference between a 5/16” UNF fitting, that needs a 1/2” AF spanner, an M8 one that needs a 13mm, and a 5/16” one that needs a 1/4”WW, even though they are only a few thou different (they’re actually 12.7mm, 13mm and 13.3mm respectively).

[Zelandeth]

8 hours ago, GlenAnderson said:

1/2” Whitworth is 23.4mm across the flats of the hexagon. 15/16” AF is 23.8mm across the flats. 
 

Whitworth sizes are based on the outside diameter of the thread. So a 1/2” Whitworth nut/bolt has a 1/2” thread, and you grab the spanner marked 1/2” to fasten it. The logic is fine when you think about it, and in some ways is more intuitive than the metric system where you need a 10mm spanner for an M6 fixing. 
 

Where things get a little more complicated is that BSF fine thread fixings used the next size down hexagons, and sometime around WW2 those slightly smaller sizes were standardised for the coarse Whitworth threads too. So a 1/2” Whitworth spanner is likely to be dual marked as 1/2”W-9/16”BS, and will actually have a 9/16” thread. You normally only encounter “proper” Whitworth fasteners if you work on pre-WW2 stuff, and even then only if everything is still original. 
 

The common spanner sizes on vehicles are 3/8” , 1/4” and 5/16”, which are the ones associated with 1/4”, 5/16” and 3/8” thread sizes. 
 

I get the frustration with the size increments being a bit of a challenge, but the more you use them, the easier it becomes to make the steps in your head. 
 

Admittedly, I have had forty years of practice, but I don’t find it difficult to eyeball the difference between a 5/16” UNF fitting, that needs a 1/2” AF spanner, an M8 one that needs a 13mm, and a 5/16” one that needs a 1/4”WW, even though they are only a few thou different (they’re actually 12.7mm, 13mm and 13.3mm respectively).

Thanks for that.  I'd often wondered what the logic behind some of them was.

Sockets I don't struggle with so much as I have a decent combination set, and all being in one box I can pretty easily just grab what I need visually.  It's just spanners where it bugs me.  Best thing I can probably do is to just grab "the usual suspects" and keep those separated on pegs on the wall like the 8-23mm metric range live on, rather than having to dig through the tool box every time.

Feels a bit strange this...feels like I'm actually bringing a bit of class to the car parks of the area using the Rover rather than dragging the tone down as often seems to be the case with my fleet!

Oil leak is definitely vastly reduced.  A drip or two a minute is on the "needs to be sorted but the car can be used" list.  Before I wasn't comfortable using it at all really out of concern for other road users, particularly those on two wheels.  Still going to try to get it booked in somewhere to get that sorted as soon as I can though.  Had another look at it today and I just can't see how you'd get to it.  Maybe if you jack the engine up a bit or maybe pull the radiator and grill and go in from the front?  Nah, someone with better tools and a proper lift can have the fun of this one.

Really do need to address the issue of the square tyres as well as they currently pretty much preclude exceeding about 50mph due to the amount of wobble that then starts happening.  That may have to wait until after we've sorted the Trabant's current engine issues though.

[Zelandeth]

Somewhat idiotically, I didn't make sure that the Rover was drowned in wax before the winter.  This was a mistake.

Likewise the Renault (which I do confess to having been kind of ignoring and hoping it will miraculously fix itself for a while) was even worse.

Spent a couple of hours trying to make things a little more presentable.

Of course something fell off the Rover.  Because Rover.

Looks like it was being held on by the world's smallest blob of super glue.  Will reattach that shortly.

Hopefully this will make the driveway look slightly more presentable in the eyes of our neighbours.

[LightBulbFun]

On 23/12/2021 at 19:56, Zelandeth said:

On 23/12/2021 at 19:01, LightBulbFun said:

of course this comes at the expense of lamp life, would be interesting to get some to directly take some measurements of tho! (anyone got a spare Ulbricht sphere? LOL)

Sadly not any more...I had got a pretty good setup which worked as a crude one in the flat in Aberdeen.  The (tiny en suite) bathroom was all white aside from a pale grey floor and I figured out that with a good light meter taking an indirect reading off the wall furthest from the light source and some maths from a known source I could get a pretty good relative reading - an arbitrary number which was easy enough to convert to lumens.  Obviously it depended on how close to the expected output the 40, 60, 100 and 200W incandescent lamps I used to create the reference curve were to their specified values in terms of giving an actual lumen output - but it worked well for comparing the relative output of two sources and tracking lumen depreciation over time.

well! if you dont mind a road trip to Belgium I know where you can get one or 2 FoC!  

 

[PhilA]

Re wrench sizes. I bought multicoloured ones. Yellow is smaller than blue. Orange is smaller than yellow. 

Etc. That might help some. 

RV8 pumps usually only fail to prime when they're totally empty. A small amount of residual oil and they normally manage unless they're really utterly dead. Looking at the pressure you got there I'd say yours is ok.

Good luck with the dash.

[Zelandeth]

Okay...driving the P6 through built up areas at low speeds with the windows down, the really deep burble just off idle definitely puts a grin on my face when it gets bounced back by surrounding buildings.

Of course because it's this car we couldn't have a journey without something new cropping up.  Today it was the temperature gauge deciding it wasn't going to join the party.

Perfect on a hot day!  Suffice to say this increased anxiety levels tenfold while driving.

Looks like we have an issue with the power supply to it as I'm only seeing 1.3V at the sensor.  Which I promptly broke the terminal off.

New one added... sadly hasn't fixed the gauge.

Not that I really expected it to given the voltage reading.  My guess is that the 5V regulator for the instrument panel (which I rebuilt using a solid state regulator) has died.  Usually this would be made obvious by the fuel gauge also dying, but as that doesn't work anyway it's harder to be certain.  Not going to have time to look into this today anyway.

Very exciting news to me though was that after having the enging idling for a couple of minutes while I fiddled with that was that I had no oil drips!

Coolant drips instead!  Which appears to actually be coming from around this top radiator hose.

Once everything is cooled down I'll pull it, make sure the surface is clean and maybe move the hose clip a little further along the stub.  That end tank has obviously seen "some repair work" in the past so I'll be making sure there's not a crack or other damage to the hose mating surface which would cause us issues.

There is a tiny weep from a porous spot you can see in the photo, I think this drip is totally separate to that though.

Did get a nice photo while out though.  Right up to the point I realised the bonnet wasn't fully latched.

Guess I'll need to snap that again then!

[beko1987]

I guess the pain with modern solid state stuff is a "bit" of it could have failed to one circuit but still be providing/leaking/shorting power to another? Whereas a proper unit would just fully die and kill everything the polite way

[Zelandeth]

4 hours ago, beko1987 said:

I guess the pain with modern solid state stuff is a "bit" of it could have failed to one circuit but still be providing/leaking/shorting power to another? Whereas a proper unit would just fully die and kill everything the polite way

Given I was measuring with a digital multimeter it could just be picking up residual from other systems - the signal lines for this run right by the alternator so could have been picking up all kinds of noise from there.

Will need to pull the panel out to investigate further.  May just be a cheap regulator being a cheap regulator.  Wonder if I might have been smart to put a couple of transient suppression caps on the input and output given how noisy the electrical environment in a car is.

Just a bit annoying that I have to pull the panel out to get to it.  Getting the speedometer drive reattached I seem to remember being a right pain.

[Zelandeth]

Of course this morning this warning light which has been MIA and was the other reason the dash needed to be opened up has self-healed itself.

Yep, that sounds about right.  Aren't intermittent faults fun?  I'll clean all the connections to the panel and lamp holders when I have it out anyway as we've clearly got at least one slightly dodgy contact going on.

[LightBulbFun]

15 hours ago, Zelandeth said:

Given I was measuring with a digital multimeter it could just be picking up residual from other systems - the signal lines for this run right by the alternator so could have been picking up all kinds of noise from there.

Will need to pull the panel out to investigate further.  May just be a cheap regulator being a cheap regulator.  Wonder if I might have been smart to put a couple of transient suppression caps on the input and output given how noisy the electrical environment in a car is.

Just a bit annoying that I have to pull the panel out to get to it.  Getting the speedometer drive reattached I seem to remember being a right pain.

 I seem to recall not sure if it was you here, or on @SiC's thread but someone got a modern replacement for the old thermal style regulator, and it literally was nothing more then a 7810 voltage regulator in a tin-can, which while I appreciated the simplicity  of it, did also seem a bit vulnerable to me, most basic regulator circuits do have some filter/smoothing caps on the input/output at least

[Zelandeth]

6 hours ago, LightBulbFun said:

 I seem to recall not sure if it was you here, or on @SiC's thread but someone got a modern replacement for the old thermal style regulator, and it literally was nothing more then a 7810 voltage regulator in a tin-can, which while I appreciated the simplicity  of it, did also seem a bit vulnerable to me, most basic regulator circuits do have some filter/smoothing caps on the input/output at least

I rebuilt mine by ripping the guts out and bolting a 7810 in the old case - having found photos online showing that's exactly what was in most of the ones you could buy for £30.

I've now pulled the panel back out of the car.

The offending module, which I have confirmed is providing precisely no volts out.

I will rebuild it with yet another 7810, but this time I'll slap a transient suppression cap on the input and output pins - I'm pulling numbers out of my backside somewhat, but I'm guessing 10uF of thereabouts should do the job.  Hopefully I won't just turn the entire circuit into a giant oscillator.

While I have the panel out I'm going to do a couple of jobs I really should have last time it was apart. 

[]  Drill out the one front panel screw which sheared off when I tried to take it apart. 

[] The vias through the PCB (you can see two below the regulator in the photo above) are particularly prone to making poor connections, especially if things have ever got damp - and there's PLENTY of evidence of this panel having spent a portion of its life in a swamp.  Assuming that I can get to both sides non-destructively I'll solder some bridging wires in so that the rivets are no longer an essential bit of the circuit.

[] See if the ammeter can be saved.  Hoping so as I'd really rather not have to pay for a replacement, but I know it not working will bug the hell out of me.

[] Clean all of the lamp holder contacts and inspect all the lamps to make sure I did replace any which looked tired (I'm 99% sure I did this already, but can't hurt to check).

[] See if I can clean the rust staining on the inside of the cover in the offside lower corner.

[] Have another shot at freeing off the trip counter reset cable - though I'm not holding out much hope there and am not going to waste too much time on it.

[] Grease the angle drive for the speedometer (again, pretty sure I did this already, but want to check).

[LightBulbFun]

2 hours ago, Zelandeth said:

I will rebuild it with yet another 7810, but this time I'll slap a transient suppression cap on the input and output pins - I'm pulling numbers out of my backside somewhat, but I'm guessing 10uF of thereabouts should do the job.  Hopefully I won't just turn the entire circuit into a giant oscillator.

from the venerable Afrotechmod's video on Voltage regulators

https://www.youtube.com/watch?v=GSzVs7_aW-Y

 

I also wonder if theres some way of adding some sort of output protection, do you know how much power the gauges draw? I cant imagine its all that much if its being powered from a linear regulator so im just thinking something like a resistor in line with the output so if something shorts out on the output rather then blow the regulator up, it just pulls the rail low and nothing happens?

[Zelandeth]

Update:

Dismantling has happened.  This has to be the easiest instrument panel to take apart I can remember pulling apart, I have to give it that.

  Found another reason these panels surely suffer connection issues.  I give you the interconnect method between what I'm referring to as the backplane and the gauge PCB.

Yep, a hole in the solder resist and two bits of PCB trace which are squeezed together. 

No, I'm sure that's not going to be prone to tarnishing after 49 years at all.  Need to see if there's something we can do to improve on that.

Ammeter was next to be investigated.  This turned out to be a purely physical problem.  

The electrical connections are fine, the coil is fine, and the pointer moves freely.  However the PCB is purely held in place by the terminals passing through it, and the grommits around them have shrunk, allowing it to drop by a millimetre plus change.  This has caused the armature to move too far away from the coil so it wasn't being affected by the magnetic field.  It should be sitting like this.

Araldite has been employed to ensure this stays where it should.

I'll make up a new voltage regulator in the morning.  

Regarding output protection, I'm not honestly sure.  They're thermal bimetallic type gauges, so probably more than moving coil/moving iron type ones.  Not actually sure of a number though.  

So my dining table has been left covered in bits of instrument panels.  Hopefully get that reassembled tomorrow.

Something I did discover was that the gauge faces in here *are* backlit.

I'd always thought that they looked far too evenly lit to be purely front/edge lit, but they didn't look like backlit instruments as the digits are all raised.

Turns out the faces are actually a good 1/4" thick block of acrylic with the block itself being edge lit.  The whole thing then acts as a giant light pipe through to the digits.

That must have been pretty advanced stuff in the early 70s.  Certainly a good deal brighter and more evenly lit than most panels of the time would have been.

[SiC]

I wouldn't worry too much about protecting the output of a 7810. They're pretty indestructible. It could have been transients on the input that killed it as it's probably not an automotive rated part. I'd be putting an automotive rated TVS diode on the input as a minimum really. Pretty sure these regs need 100nF on the output/input to ensure stability - check the datasheet. 

https://m.littelfuse.com/~/media/electronics/application_notes/littelfuse_tvs_diode_automotive_circuit_protection_using_automotive_tvs_diodes_application_note.pdf.pdf

 

 

[Zelandeth]

10 hours ago, SiC said:

I wouldn't worry too much about protecting the output of a 7810. They're pretty indestructible. It could have been transients on the input that killed it as it's probably not an automotive rated part. I'd be putting an automotive rated TVS diode on the input as a minimum really. Pretty sure these regs need 100nF on the output/input to ensure stability - check the datasheet. 

https://m.littelfuse.com/~/media/electronics/application_notes/littelfuse_tvs_diode_automotive_circuit_protection_using_automotive_tvs_diodes_application_note.pdf.pdf

 

 

I'll look to get something along those lines in stock for the future.  For now it's been stuffed back together with a new 7810 and an input cap.

On the plus side replacing it in future is a twenty minute job, whole panel doesn't need to come out to remove it (now I know where it is).  Just four screws and I can pull the panel forward enough to unplug the regulator.

Also electrically bridged these riveted connections.

Soldering isn't pretty, but it means that the rivets are no longer the sole means of getting power to/from the socket for the regulator.

All of the other contact pads were also given a good clean up - the scratching on a couple of them tells me I'm not the first to be in here.

Result?

We have a working temperature gauge again.  The ammeter also now moves - albeit what feels like fairly little.  It also still sits showing off charge when inactive - the needles on that and the oil pressure gauge have clearly been bent slightly at some point in the past, that's a job for another day.

I'll take that as a win for now - not having a temp gauge wasn't something I was willing to put up with.

For those of you who haven't seen this type of gauge movement before, here's all there is to it.

It is literally a heater coil wound around a bimetallic strip, with one end attached to the pivot for the pointer.  About as simple as you can get.  The big advantage of this setup is that it's inherently heavily damped.  They are a good deal more power hungry than moving coil or moving iron gauges though.

Spurred on by success here I decided to do a little more digging on the fuel gauge.  I knew I'd tested the gauge itself in isolation and had confirmed it worked, but I couldn't remember if I'd tested the wiring to it.  I had a hunch that this was likely the remains of the sender wiring in the boot.

Likely a victim of the wiring butchery which seemed to go hand in hand with the wiring in of the tow bar (masking tape is a good long term insulating material, right?) and the stereo goodness knows how many years ago.

Checking this with a meter revealed 10V there, and grounding it indeed resulted in the gauge springing to life.

So I just need to figure out where that wire actually should disappear under the car.  The sender did measure open when I originally checked I'm 90% sure, but I'll obviously need to hook this back up properly either way or the gauge won't work even once the sender is changed!  I did have a poke around underneath but couldn't immediately see where it went - though it's hard to see anything useful given there's a whole load of suspension and brakes in the way.  Car really needs to be up on ramps to see anything much at all.  That's a job for future me though.

[Zelandeth]

Much as I despise working under cars that are jacked up, no matter how many axle stands are involved, I really wanted to see if I could get the fuel gauge reconnected.  

Shoving my phone up into the vicinity revealed that the wiring was still connected to the sender.

That's looking pretty much straight up from just forward of the diff - front of the car is top of the frame.

I couldn't find any angle I could see this from in person.  From the back I could just about reach it with one hand while I was basically eating the cross bar on the rear suspension.  That's a definite downside of the Di Dion tube setup... it's in the way of things no matter which side you try to sneak up on what you're trying to work on.

Eventually I did spot where the end of the wiring was floating around.  This is looking towards the front of the car - offside rear wheel is to the right of the frame.

Trying to strip that back to clean wire and connecting new leads to it was precisely as much if a pain as you'd think given I was working with one hand essentially stretched out as far as I could reach up above my head.

Yes, I used Wago connectors.  This will be done "properly" at some point in the future when the car's on a life of proper ramps.  This is just wanting to get things hooked back up.

Turns out that I was correct about the pass through in the boot floor, this is where the wiring was meant to run through. However it does actually just go straight under the car, I originally thought it went into a box section.  

Wish I'd realised that sooner as it would have made my routing of the fuel return line far less of a pain!

As expected this hasn't actually restored function of the gauge - but the sender I was already pretty sure was knackered.

She is definitely running warm though.  Seems fine bumbling around at low speeds, but going anywhere north of 40 seems to soon see the gauge creeping up.  At idle it seems to creep up quicker than I'd really like.  

I chickened out when it got that far - next step there is to take some measurements and see if it's reading something resembling accurately I think.