welding project Juular's Scandi Noir. Volvo C70, 240 &122. Earth day.

[juular]

Nearly there.

Block didn't look too pleased about being left out in the open, but that was sorted with an abrasive pad. Also drained the oil and coolant.

Gasket.

Heed on and torqued then angle tightened.

I seem to have lost one of the exhaust gaskets, and I need to try and compress then timing belt tensioner to refit it, so I did everything else I could then called it a day.

Can't feel my toes now.

[juular]

This is so close to being pushed into the canal.

Thats with the new valve installed.

There's almost nothing left except taking that piston out.

 

[juular]

I have sorted the 240 problem by once again pretending I don't own it.

On to the stalwart C70 which I forgot needed an MOT until the last moment.

This car has been giving such little trouble I had to check what the previous MOT said.

The steering rack play comes up every year, and it changes from steering rack to inner tie rods to one of the track rod ends depending on where I take it for MOT.  The car has the tightest steering of any car I own so I think there's nothing actually wrong there. Maybe the rack adjuster needs tightened a bit, but for now I'll ignore it.

The sills were easy enough to sort. In fact I'm a bit annoyed they even made an advisory as there's nothing wrong with them. Simply, a tyre fitter has managed to fold over both seams of the sill.  But then this is the same place that failed a spotless 240 for DANGEROUS CORROSION because a rubber grommet was missing.

Fixing that is just a case of straightening the seams with mole grips. Done.

Last thing to sort was the small matter of the tailpipe having fallen off. Since there's no backbox on these it wasn't a big deal but I thought it was worth fixing.

I fixed this by HAMMERING A BIGGER EXHAUST OVER IT.

No, really, I found a bit of spare pipe that was marginally bigger than the exhaust and fit perfectly without evening having to cut it. And I just hammered it on.

Let's see how that goes.

Ah.

Note how the steering rack play has switched to a track rod end this time, right as expected.

They've done their time I suppose. Pair of new springs £35 and half an hour of work.

I'm annoyed about the suspension arm advisories as I replaced them this time last year. 5 year warranty apparently. I'll test that!

Anyway, good to get another year out of this beast, because I absolutely love it. No sign of anything major on the horizon either. Brilliant car.

[juular]

Right. The 240. I checked and it's still there. Damn.

Mulling over what could possibly be wrong with it, I have absolutely eliminated ignition, unmetered air, and fuelling, and have eliminated the other 3 cylinders. The only thing left is compression on #3.

Compression on #3 when tested with a gauge shows it being a maximum of 5% and a minimum of 0% down over the others depending on the phase of the moon.  I suspect a standard compression test isn't telling the whole story, but I don't have the kit to do a leakdown or dynamic compression test.

Basically, it's got to be the compression ring, right? It's either stuck or broken. The car was originally stood for over 10 years which does tie in with this theory.

My first attempt at trying to sort this without dismantling the engine is to throw some special sauce down the spark plug hole and leave it for a week. In this case, a 50:50 mix of Acetone and ATF.

Place your bets now!!

[Talbot]

It'll either make it a bit better (gummed/siezed ring) or worse (broken ring)

There's so little left that this can be!!

[juular]

Whatever bet you placed, I reckon you're wrong.

Cranked the starter with the plug out to blow the fluid out of the cylinder, then drained the remnants from the oil pan. Refilled the oil and started it.

#3 is now giving good compression which is a massive improvement. So I was right in that it had a stuck ring.

..but!

#4 is now not firing at all. 

WTF?

4 gave a solid 175psi compression on the last test.

It's getting fuel and spark.

Answers on a postcard.

 

[EyesWeldedShut]

1 minute ago, juular said:

Answers on a postcard.

Cracked the insulator on the spark plug and it's tracking to earth when it's in the head but looking good when it's out and earthed?

[juular]

2 hours ago, EyesWeldedShut said:

Cracked the insulator on the spark plug and it's tracking to earth when it's in the head but looking good when it's out and earthed?

Very reasonable shout.

[juular]

Wait a second...

No, really, @MrsJuular noticed that the Volvo branded spark plugs (which weren't cheap) looked like they were held together with glue.

I was doing a (yet another) spark test with them all lying out on top of the engine block, except this time it was starting to get dark outside. This time I noticed how thin and crappy the spark looked, which prompted a closer look.

Ironically I bought these spark plugs last year to try and sort the running issues that were likely caused by the burned #3 valve which I have now fixed. I hadn't thought those "genuine Volvo" plugs would contribute their own issues.

So I chucked on an old set of NGK plugs I had lying in the boot, and...

 

Running perfectly!

MOT time now.

[danthecapriman]

Just caught up with this! Glad you’ve (hopefully!) got it cracked.

Those fake plugs are more common than you’d believe. I heard about these knock off plugs being about but thought nothing of it. Until I bought a set of allegedly Bosch plugs for my Capri. Of course they were absolute crap and worked if they felt like it. Showed them to someone I know who works in a garage and he immediately said they were cheap Chinese fakes. Apparently he’s had problems with them too.

[juular]

This is a good time to do what I was intending to and merge these threads together.  For reference here is the whole Amazon debacle.

To recap, I thought I'd sorted all of the running problems with the 240, and all I had to do was take it for an MOT when I felt like it.  

In early July, I felt like it, so I gave it a wash and booked it in. I only had one thing to fix, and that was one of the rear doors wouldn't unlock. That was just a seized central locking motor which demanded opening and staring at.

Literally just opened it, moved it around a few times, and then put it back on the car with nice new crimps and heatshrink.

 

Holy fuck.

Part of the problem here is that I keep going back to the same place that failed a newly restored car on having 'structural corrosion' because a grommet was missing from a hole. I only go there when my usual place is too busy, and in this case it was over two weeks for a test.

Yellow headlights were installed, but that's totally legal.  So that's bullshit right away.

The brakes, well it was only a couple of miles to the test centre and the car was lying over a year. So just needed a bit of anger applied.

The exhaust, again, bullshit. The exhaust is fairly new, and when I went under it with the car running and with my hand over the joins, there was absolutely no gas leaking.

The one I'm really fucked off with is the 'chassie leg slight fracture' which is absolute nonsense.  When I got under to look at it, all that had happened was a bit of the crappy Bilt Hamber epoxy paint had split and fallen off, which it does for fun, because it's shite.

So despite the dramatic fail sheet, I had the car back on the test ramp in a couple of hours.  Bit of foil tape round the exhaust joins as a token gesture. A few really hard stops got the brakes working lovely again.  I swapped the headlight bulbs, again a token gesture.  I also chucked a bit of underseal on the 'chassie leg fracture'.  Nipped up the water pump a tiny bit to stop the fluid leak, then stuck a number plate bulb in. 

Passed on an almost clean sheet, only the power steering leak as an advisory. That's so miniscule that it can get enthusiastically ignored.

The big problem was that on the way to the test centre it started misfiring again. 

FU. KING. HELL.

Again, to recap, I've been chasing this misfire for years.  The entire k-jet system has been eternally fettled with, almost entirely new fuel and ignition parts, every possible gasket and seal replaced, it's even had a new #3 intake valve.

At this point I wished I'd stayed in bed and left the 240 where it was.

Thinking ignition, I pulled the entire ignition system off the Amazon and installed it in the 240. Crazily, despite going from 1964 to 1988, it fits and works fine. But it didn't solve the misfire. 

Final roll of the dice was to pull off the K-Jet metering head and take it apart. 

Step 1: an uncontrolled explosion of springs and small parts.

I could only really find one thing wrong with the metering head and that's this O-ring which looked knackered, but on studying the schematics shouldn't even be there at all.

Regardless this was all cleaned up, and put back together with a new rebuild kit.

Sealed together with a very thin layer of permatex anaerobic gasket maker.

Back on the car, pressurised the system, no leaks. So all good on that front.  

Started the car. Ran like a bag of absolute shite, but that was somewhat to be expected because I'd had to remove the balance screws from the injector ports.  So I ran the injectors into bottles to measure the flow rates.

Well that's definitely not going to work!

With much twiddling of the individual port adjusters, I managed to get it on a low idle injection setting that put out equal amounts.

Put back together, the car fired up on a half turn and idled beautifully. It has never been so smooth!

This means that I can now in good faith and conscience dig out this and wheel it onto the stage.

 

Five minutes later...

I took the car a short drive and it broke down.

Thankfully I'd only got as far as the end of my street, so I was able to nurse it back to the drive via combination of coughing, spluttering, and bumping it on the starter. 

This time the cause was fairly straightforward, the main high pressure fuel pump had died.  So I parked it up and went to FOTU instead, which definitely wasn't a two day ordeal of about eighteen breakdowns and returning home on a truck.  Then I went on holiday, which definitely wasn't a two day ordeal of being stranded at the roadside with a fucked clutch.

Conclusion to follow.

[juular]

Conclusion, and to finally bring the 240 saga to an end, for now!

With the main fuel pump dead, I replaced it with a new aftermarket one (I'm in danger.gif), but in the process of doing so noticed that the old pump was absolutely rammed full of what looked like sand.  At this point I knew what had caused this, and sure enough when I pulled out the in-tank fuel sender and pump unit, the mesh prefilter was no longer attached. 

That was replaced with a new filter, and the fuel lines flushed out using the in-tank pump.

After the crud had been removed from the high pressure pump it actually ran perfectly without a single bit of noise or pressure loss, so that's a small bonus and I now have a spare I can carry in the boot.

Feeling hopeful, everything was put back together and I went for a drive.

Broke down again.

This time it was simple enough, the main fuel pump fuse had melted. Presumably it was already partially gone given the heat / current that must have been going through the blocked pump, not helped by the fusebox terminals being extremely dirty with huge resistance through them.

Cleaned the fuse box. Took it yet another drive. This time everything seemed to be working fine, but the performance was completely flat.  Going up a motorway slip road, I could barely reach 50mph by the top even with my foot on the floor in 3rd. 

This time I thought that maybe the K-jet pressures had all been thrown off by the new pump and the metering head rebuild. That would have various effects on the fuel mix at different times. So out comes the trusty OBD v0.00003 test kit.

This showed that everything was pretty much bang on, sadly.  The warm control pressure was maybe a tiny bit on the low side, but that would only cause the engine to run a tiny bit rich which is neither dangerous or likely to cause a total lack of grunt.  Regardless I set about fixing this by shimming the control pressure regulator with a copper washer which I had to keep filing down and refitting to get to the magic 3.5 bar of warm control pressure.  At this point the washer was so thin it was like paper, but it's just right.

Once again, no luck.  Slow as a week in Stranraer.

I thought perhaps it just needed a good run to flush any remaining crap out of the system. So I took it to a local car meet where I met up with @rml2345

Unfortunately after a good bit of shoe on the motorway it still wasn't happy. While it could maintain 70+ without too much effort, getting there was a slog, and in my memory this was always quite a quick car.

Yet more fettling occurred. I changed and gapped the plugs, replaced the coil lead, advanced the timing, even took the timing cover off to see if the belt had jumped a tooth. Nothing made the slightest difference. 

And then @rml2345 handed me a rusty metering head unit from an unknown source and in unknown condition. At this point I had nothing to lose, so I simply gave it a cursory skoosh through with brake cleaner and fitted it on the car.

And it ran perfectly.  Absolutely smooth at idle, and absolutely bags and bags of power, back to what I remember. No hiccups, no issues at all. 

So that's all it was. Presumably the metering head has been on its last legs for a very long time, as I remember the previous owner mentioning that the idle was always a bit choppy.  The thing that's annoying me the most about this is that I don't understand the problem. The old metering head looks fine to my eye, and it was carefully rebuilt with new parts. Pressures are all spot on.  Hazarding a guess, I have maybe put it back together very slightly out of alignment somehow, and have restricted the flow to the injectors.  No doubt I will take it apart again at some point just out of curiosity, but as it stands I'm most definitely just taking the win.

So now that particular part of the story has a happy ending, I don't plan to do huge amounts to the car except drive it. I'd really like to feel less bitter about all the time and heartache this thing has caused over the past year, and I think in a short amount of time I will remember why I kept it and put the time in.  I took it out on a long drive yesterday, it's such a big comfortable competent thing. The best way I can describe it is it's like driving a sledgehammer. It's chunky, torquey, tight and thunderous. 

I do have a few small niggles to sort, such as the bonnet which still sits high after the hinges bent. I suspect I'll have to take the hinge off and cut and re-weld it.

The other thing is the places where I've used that Bilt Hamber crap on the suspension and floor could really do with being tidied up before it ends up showing up on the MOT.  You wouldn't think this has had a recent strip down and repaint.

The boot floor is particularly bad given this was nice clean new steel and doesn't see any impact or dampness.

This is a nice way to segue into the Amazon by showing a photo of the underside after a year including a winter hammering through the salt.

This makes me feel vindicated that my much cheaper method of derusting and painting the underside is in a different league from all the expensive Bilt Hamber nonsense.

Anyway, this month is the first time all three Volvos have made it into working service at the same time and at the same place.

Which is an occasion I had to mark with a photo.

There is in fact not a lot to say about the Amazon at the moment. It has been a lot of fun to own.

It has suffered again from the issue where the crappy Simon's sports exhaust has been smashing into the rear axle despite being moved and re-clamped, and it has once again flattened the rear brake pipe.

Getting routine to replace this now, but I have rerouted it to the bottom of the axle tube.

There doesn't seem to be a way to stop this from happening, the exhaust is simply the wrong shape for the car. I'm not sure how it works at all on lowered cars.

I plan to take the Amazon to Cholmondeley next month, so I better get started on the cosmetics. 

First I tried to wipe all the fingerprints off it. Which just wiped yet more of the strange mustardy paint off, exposing random colours underneath.

Then I went all Vice Grip Garage.

 

This 'shine juice' actually has worked quite nicely, giving the car a bit of a satin glow and taking away the powdery look to the paint. It's not shiny, but it's kind of cool.

 

 

[danthecapriman]

Just caught up with this, I keep missing updates somehow!

 

Glad you seem to have sorted the 240, I’d be interested to see what you find with that original metering head. Seems very strange!  
Amazon looks fantastic too👍

Thats really not a good advert for the Bilt Hamber paint. Really poor. I’ve always used their wax and found that really good stuff though so I’m a bit surprised the paint seems to be such utter crap.

[chadders]

1 hour ago, danthecapriman said:

Just caught up with this, I keep missing updates somehow!

 

Glad you seem to have sorted the 240, I’d be interested to see what you find with that original metering head. Seems very strange!  
Amazon looks fantastic too👍

Thats really not a good advert for the Bilt Hamber paint. Really poor. I’ve always used their wax and found that really good stuff though so I’m a bit surprised the paint seems to be such utter crap.

I'm surprised as well as I've used it on a few of my cars with absolutely no issues and I live about 100 yards from the beach. It also does pretty well in independent tests as far as I recall.

[juular]

Not a huge amount to report, I just liked this photo.

I've been using it a fair bit by taking it to work a couple of days a week which is a 50 mile round trip. I've noticed it's been getting increasingly fumey in the car which turned out to be the valve cover gasket giving up, which explains both the migraines and the slight loss of oil over a few hundred miles.  The fact I actually had a spare makes me think I never changed it last time round when I meant to.

The other thing I noticed is that the nasty droning I'm getting at around 70mph may not be exhaust related, and might actually be from the larger air filters, which I installed at the same time as the exhaust.  I noticed that there's a distinct ringing sound that happens at the same time and I reckon it's the bonnet resonating with the intake pulses. 

The quick fix here would be to add mass to the bonnet as it's actually quite a lightweight single skin affair.  If anyone has successfully soundproofed a bonnet then feel free to advise.

[juular]

On 16/08/2024 at 12:28, danthecapriman said:

I’ve always used their wax and found that really good stuff though so I’m a bit surprised the paint seems to be such utter crap.

Their wax is actually very good, both the detailing kind and the underbody / cavity kind.

I have no idea why my experience with the paint was so poor, but I do know others personally who have had the same problem with it. And yet others swear by it, and independent tests sing its praises.

I've heard similar things about POR-15 for example. Many swear by it and others say it just falls off in big sheets or rusts through from behind in days.

Presumably there is one variable in the equation which is messing everything up. On the other hand, ease of use and repeatability of results is surely a big part of a product's value.

[danthecapriman]

32 minutes ago, juular said:

Their wax is actually very good, both the detailing kind and the underbody / cavity kind.

I have no idea why my experience with the paint was so poor, but I do know others personally who have had the same problem with it. And yet others swear by it, and independent tests sing its praises.

I've heard similar things about POR-15 for example. Many swear by it and others say it just falls off in big sheets or rusts through from behind in days.

Presumably there is one variable in the equation which is messing everything up. On the other hand, ease of use and repeatability of results is surely a big part of a product's value.

I’ve had mixed results with POR-15. On most things I’ve used it on it’s worked and lasted very well. Yet on a few other things, even different parts on the same car, it’s started rusting through. My Capri fuel tank was one such part. The tank is fine, it just had a few areas of surface rust, followed the POR-15 instructions to the letter yet within months there were tiny rust speckles coming through. Suspension arms, springs etc however no such problems! Weird.

[Dyslexic Viking]

4 hours ago, danthecapriman said:

My Capri fuel tank was one such part. The tank is fine, it just had a few areas of surface rust, followed the POR-15 instructions to the letter yet within months there were tiny rust speckles coming through. Suspension arms, springs etc however no such problems! Weird.

Could there have been active rust on the inside of the tank that spread through to the outside and caused it to rust again?

[danthecapriman]

4 minutes ago, Dyslexic Viking said:

Could there have been active rust on the inside of the tank that spread through to the outside and caused it to rust again?

The inside of the tank is absolutely pristine. There wasn’t even much sediment in it. With the sender out and looking in with a torch it’s all shiny bright metal still. 
I think it’s the surface rust that was on the outside already coming back through the POR-15. Despite it being labelled as for going over surface rust. Everything was cleaned as the instructions said and applied the way it said. Unless maybe I brushed the paint on too thinly?? Perhaps it’s supposed to be left on in a thick coat.

[Dyslexic Viking]

2 hours ago, danthecapriman said:

Unless maybe I brushed the paint on too thinly?? Perhaps it’s supposed to be left on in a thick coat.

I don't know enough to comment on that. But it's strange that it started rusting again, that's for sure.

[danthecapriman]

54 minutes ago, Dyslexic Viking said:

I don't know enough to comment on that. But it's strange that it started rusting again, that's for sure.

I’ll get a photo of it when I next go out to the garage. 
It’s not hideously ugly but you can just about make loads of little brown rust freckles all over it. It’s disappointing really as that paint isn’t exactly cheap! 
Luckily on mine it’s right under the car so you can’t really see it but still… maybe one day I’ll drag the tank out again, wire wheel it back to bare metal and re-do it.

[Dyslexic Viking]

35 minutes ago, danthecapriman said:

maybe one day I’ll drag the tank out again, wire wheel it back to bare metal and re-do it.

I think it's worth trying and maybe paint even more layers than last time? 

[juular]

Cholmondeley festival of 1000 cars is at the weekend, and I'm weighing up my transport options.  I originally wanted to take the Amazon, but I had a bit of bother with the alternator last week. What, not the third aftermarket alternator in less than a year? Never?! It may well be difficult to believe but yes, I noticed that on a quick throttle-off, the lights would dim and almost go out completely.  Sounds to me like the regulator pack is fried.    I'm also a little bored of the droning noise from the sports exhaust, and although I have some plans to sort that, I don't think I will manage to get round to it in time.

So at this point it's looking like the 240 may be the weapon of choice, which I am secretly enjoying the thought of.  It's been laid up for so long with issues that I am just starting to really enjoy it again, like a second or third honeymoon phase. It also hasn't had a chance to go to any of the car shows for the past couple of years purely because of last minute issues or long standing temper tantrums. So the thought of sinking into those nice comfy heated seats and listening to that viscous fan thrum its way down the M6 sounds like just what I need.

I do have a few things I want to do to it beforehand, but thankfully those are just cosmetic annoyances. So, it's arts and crafts time.

First of all, I was sick of looking at its wonky bonnet which from the front onwards looks like the car has a slightly surprised expression. To recap, @MrsJuular used all of her might to shut the bonnet last year when the hinges were a bit sticky, and instead bent the bonnet and folded the hinges in half. 

To recap.

Despite the hinges being mostly hammered back into shape, the left side of the bonnet always sat stupidly high and I'd had enough. Time to get angry.

I took about 10mm out of the main hinge upright section and welded it back together.

Not too bad a result at all.

It's still a little high at the back, but that's more of an issue of the bonnet itself being slightly bent.

In penance I got @MrsJuular started on the task of removing the safety stripe from the front of the car.  Love it or hate it, the stripe was starting to disintegrate and just looked silly.

Next up is sorting the rather ugly looking sills. I painted these in Bilt Hamber's finest rust encouragement liquid and predictably, they rusted.

First step was to get into the corners with phosphoric acid and a wire brush to clean up and inhibit the surface rust where it was breaking out.

Then a quick coat of industrial jet black paint.  I don't have enough blue rattle can left to make these the right colour, but that can be done in the future.

So, destriped and sills painted, I think it looks a bit cleaner now.

 

All of this took a bit less time than anticipated so I turned attention to the Amazon, which got a similar sill cleanup.

I've also started taking steps to sort out the annoying exhaust drone.  I picked up one of these decibel killers from the same manufacturer as the exhaust itself. It just hammers into a straight section and acts a bit like a hemholtz resonator in that it bounces soundwaves back up the pipe. Whether it actually works or whether it just reduces power, I will find out soon enough.

 

 

Finally, I remembered that a previous owner had neatly cut some accurate holes for speakers in the rear parcel shelf using a machete / axe/ JCB, so I set about making panels to patch these up, which should hopefully help with the noise issues.

 

 

Next up, I'm going to see if I can get a replacement alternator in a decent timeframe, and give the wheels a quick coat of black. If I take a mad notion, the Amazon might go to Chodmolondonleley instead.

 

[Supernaut]

I can't say I've heard many positive things about that style of decibel killer.

Hence I'm waiting for a standard rear section for the BMW to arrive.

 

I'm curious how you get on with it. If it does work I'll likely be kicking myself.

[mat_the_cat]

8 hours ago, juular said:

If I take a mad notion, the Amazon might go to Chodmolondonleley instead.

Given your recent terrible luck, is it worth taking both to maximise your chances of getting there?

[juular]

16 hours ago, Supernaut said:

I can't say I've heard many positive things about that style of decibel killer.

Hence I'm waiting for a standard rear section for the BMW to arrive.

 

I'm curious how you get on with it. If it does work I'll likely be kicking myself.

My thinking was, it was only eight quid. If it doesn't work the alternative is £85 worth of extra silencers so it's worth a try in the meantime.

[juular]

12 hours ago, mat_the_cat said:

Given your recent terrible luck, is it worth taking both to maximise your chances of getting there?

"Unlimited callouts" it says on the policy. I appear to be testing this.

Sorry everyone for next year's policy increase. I'm averaging one breakdown a month at the moment, all >150 miles recovery.

[juular]

The 240 made it to Cholmondeley without issue, in fact it was such a nice change to take a car that didn't always feel in imminent danger of shitting itself.

It has been pressed into use as my daily for quite a while now as I'm still tinkering with the Amazon to try and make it a bit quieter, and my Trafic properly let the side down by breaking down twice hundreds of miles from home.  The more I delve into small niggles with the Trafic I realise it's needing a good overhaul, and unfortunately to do the smallest thing on that the whole front end has to come off. I have tried to make it Someone Else's Problem but nobody wants to take on the work, so I guess that's my winter project.

In the meantime one small hiccup happened with the 240.

I first noticed that I was crunching into gear quite a lot which was a bit of a mystery as I've always got on well with the 240 gearbox. Then one morning I noticed the biting point was on the floor.

The slave cylinder hasn't completely gone, but there was no fluid left in the reservoir and there was a bit of a jelly like substance at the end of the piston which is definitely congealed brake fluid. 

It's so easy to change on this car, you just loosen the circlip and give it a tap and out it drops. So no point messing around, I've ordered another one for 40 quid.

Despite the Amazon being a work in progress at the moment I have been taking it short drives. At the weekend it got to meet some other Swedish pig iron at a car meet in Falkirk.

It always gets more attention than the trailer queens which is odd. I do eventually want to paint it though, as I'd actually rather it was a bit more anonymous, and I'd like it to have at least some value in the future.

[juular]

New slave cylinder arrived.

 

 

Dead easy to swap on these as it's held on with a single circlip into the gearbox bracket. 

Then a simple bleed and it's back to having a normal biting point.

These old things are so nice to work on!

[juular]

Some more Amazon tinkering. It's getting to the stage where most of the work I'm doing on the fleet is the sort of under-the-bonnet things you'd dabble with on a Sunday afternoon, which I'm really grateful for after what feels like a year of having to rebuild engines and tearing suspension apart.

Last month I thought I had problems with yet another aftermarket alternator, but it turns out I might have been a bit hasty to blame that. 

To recap I was having some problems with glitchy electrics as throttle was applied / taken off. The last job I did to diagnose this was to steal the alternator out of @MrsJuulars Toledo while it was having its head gasket replaced. I checked that it was charging and drove around, but mostly in the daytime where I didn't notice things like pulsing headlights.

Recently I went a longer drive with @captain_70s to rake around some antiques.

Never had any problems in the 50-odd miles to the destination, but as it started to get dark on the way back, I noticed that the lights were still flickering as I came off the throttle, and that it was starting to misfire during the electrical glitches.  Very weird!

So for me that ruled out the alternator as the source of the problem. I spent a day going round the engine bay and interior electrics with a multimeter checking everything I could think of. 

Here followed a fair bit of head scratching, as I ruled out wire by wire that everything was connected properly and that there weren't any strange resistances showing on any of the new wiring I'd put in earlier this year.   

HT leads? Maybe one of them has broken down and is arcing off the block (or another cable) causing pulses in the voltage.

Alternator cable? Pulled that off and checked it, it was showing 0 ohms even when twisted and moved around. Mental note made to replace it in the future anyway.

Then I did another bit of diagnosis of which the results made no sense. I unplugged the alternator and the problem persisted. So it wasn't to do with the charging circuit at all.

Then one more test which made even less sense. I turned the engine off,  tapped the accelerator pedal, and the problem was still there! I could see the headlights pulsing against the garden gate, only when barely touching the pedal (like 0.0001% throttle application).  I also noticed the fuel and temperature gauges bouncing at the same time.

The problem has to be the throttle linkages somehow. Initially I thought perhaps the linkages were disturbing a wire or causing something to short circuit, but there was nothing at all in the way.  Then I spotted this.

There isn't anything wrong with this throttle linkage, but it struck me that all of the links are metal, and that they are quite chunky.  I also noticed that with the throttle snapping closed (where the problem occurs) the linkage would be coming to rest against the stop on the valve cover, at which point it would be providing quite a substantial ground path between the engine and body.

When rebuilding the car I installed a pair of 16mm2 ground cables between the battery negative and the engine block, but it's possible the throttle linkage is still acting as the path of least resistance when the throttle snaps shut, causing an arc and the subsequent electrical problems.

I then remembered that I removed the gearbox to chassis earth strap when I was welding, and I never put it back because I had to replace the bit of the chassis where it bolted in.  So it looks like I'll have to find a way to improve the grounding of the engine block, probably by adding chunky cables until the problem goes away..

In the meantime since the weather was dry I did another job I've been meaning to do for a while.

Wheels jet-washed and scrubbed with acid.

Then a coat of rattle can.

 

Then the chrome trims replaced.

 

I quite like it.