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Zelandeth

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Zelandeth last won the day on February 25

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    Milton Keynes
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    Vintage technology restoration (if it's got valves, I'm interested), retro computing (Amiga and Acorn in particular), photography (film based generally), the Furry Fandom, vintage commercials...and whatever else I've inevitably forgotten.

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  1. Somewhat frustrating day here. Well on the Merc front anyway. I wanted to have a look at what the journals under the camshaft looked like. More for the sake of my curiousity and because everything at this stage is an education. Now this is where I fell into a trap that it sounds like many people working on these engines have. The only OHC engines with chains I've messed around with had tensioners which were either manually tensioned or ran off oil pressure. As the camshaft is keyed to the sprocket, provided I didn't let the chain go slack so it could slip at the bottom end it shouldn't be an issue. Yeah...oops. Turns out the timing chain tensioner on the M102 engine is near aerospace levels of over-engineered. Tensioning method number 1 is an oil pressure actuated plunger as I'm used to. Tensioning method number 2 is a spring based setup as a backup and to ensure it doesn't go slack when the engine isn't running. What's caught me out is number 3. There's also a ratchet mechanism which means that the tensioner can add tension to the chain as it wears, but there's no way for it to go the other way...the only way to reset the thing to take tension off is to completely dismantle the tensioner. Which involves quite a bit of faff. So I've now managed to move the car from "sick" to "non runner." I did have the sprocket tied up, but apparently I gave enough slack that it now won't go back on. Great. I have read up on how the tensioner works, but working through such a small gap looks like a right pain. Hopefully I can get back to where we started out again tomorrow. Oh, the camshaft bearing journals are scored to hell, exactly as expected. The transparency film I'd been waiting for to sort the dash on the BX arrived. Thankfully because I was working on a scan I had taken I knew the dimensions would be right when I printed it. Didn't look too bad at first glance. Though precisely as I expected opacity was clearly going to be a problem. I had expected this, so the solution was to print two layers which were just the colour filters, one that's just the frame mask and a final one with the legends and again the frame on it. As shown by the initial print from the other side that worked much better. Just holding them together by hand there, hence the registration errors. With everything back into the panel it looks far better than the blotchy, faded original ones. It's really hard to get an accurate photo of how it looks, but this is vaguely close. Colours are far more saturated in person. There is more of a hot spot than with the original filters but it's perfectly reasonable. The fact that I've got enough opacity is shown by the lack of bleed through on the left hand lamp unit. This is vastly overexposed because I was looking for evidence of light shining through where it shouldn't be. In reality this looks more like this. Might get that dropped back in tomorrow. LED illumination hasn't been done yet, but I've enough projects going on right now so could do with it back in the car!
  2. Note to whoever designed the timing chain tensioner used on the Mercedes M.102 engine: I hate you. What a bloody stupidly overcomplicated faff of a setup. Yes, it means there's double redundancy, but jeeez...if you've made it that complicated anyway would it have been too much to ask for some means to reset the damned thing without having to completely dismantle it?
  3. Is there an easy way to get the sump off? Looks like no. Mercedes simply didn't see any reason it would need to come off during routine maintenance. Not unreasonable to be honest...especially being an aluminium sump so it's not going to rust through. The expectation simply is that it doesn't need to come off unless you're doing a rebuild, and if so the engine would be out of the car. It seems like it is possible if you have it on an engine crane, undo all the engine mounts and lift it about as far as you can before the gearbox fouls on the bulkhead...but even then it's a fiddly swear fest of a job...and getting it back in is an order of magnitude worse. Plus by that point you're the best part of 3/4 of the way to having the engine out anyway... Need to have a think.
  4. Oooh...dibs if you decide you don't want it! I've been after something like that to tinker with and restore for years.
  5. Actually had a few consecutive hours available today so flipped a coin between pulling the alternator on the Jag (which has of course started working again) and delving into the diagnosis of what's going on with the Merc. Merc won. Step 1 I decided was to have a proper look at the camshaft. I knew a couple of lobes were badly scored but wanted to see what state the bearings were in - I had a feeling they were likely to be shot and haemorrhaging oil, hence the less than stellar pressure at a hot idle. Off we go again. Getting used to doing this now! Number 1 cam rocker assembly off revealed... An impressively scored up bearing with a lot of slack, which you can actually see looking closer. Don't think I need to get a Plastigauge out to confirm there's too much free play there. You can easily get a fingernail into the gap. The cam followers feature some epic scoring too. Number 2 was pretty similar, though with slightly more severe bearing scoring, cam followers were *slightly* less mangled. This was the first one where I couldn't remove all of the bolts from the rocker frame itself because of how much carbon buildup there is in the bolt holes! Number 3 however was where things got real exciting... The cam followers are utterly wrecked, both inlet and exhaust. That however pales into total insignificance compared to the state of the camshaft... Wait...that doesn't look right, let me move a bit to get a better look...wait...what the? Oh fluffing hell... Yep... pretty much the entire cam lobe of the number 3 inlet valve has been totally *obliterated.* I'm pretty certain this is the most mangled non-broken camshaft I have ever seen... it's *definitely* the worst I've ever seen on a running engine. Never mind one that seemed to be running quite happily aside from being a bit rattly. That's easily 5mm plus change of material that has been worn away. Number 4 also has quite a lip on the exhaust valve...which would have been impressive wear if we hadn't just seen the above photos. The followers on this one were probably the least badly deformed of the lot, though that's not saying much. Goes without saying that the whole camshaft assembly inboard of the timing sprocket is scrap metal. Well I don't think it is actually...this is more the sort of artefact that should be hung on the garage wall as a warning to future generations! I did start the engine up with the rocker cover off briefly simply because I wanted to confirm we did have good oil flow up there, as there's obviously a load of damage been caused by oil starvation or *severe* contamination. We do - in fact so much oil is gushing out from around the rear two and front bearing that it totally overwhems the drains in the respective areas of the head and starts flooding over the top of the head after the engine has been running for about five seconds. Probably why everything under the car looks like this. Definitely plenty of oil getting to the camshaft now... Though sadly too late, this hardware was mortally wounded years if not decades ago. There's like 1/8" of this gritty sludge just caked over everything. If you remember back to when I first set the valve clearances I checked and found that the spray bar which runs above the camshaft was about 70% clogged, with the front most jet being the only one that was working properly. This ties in with where the most damage seems to be...so I'm calling on oil starvation as the main cause. The lack of zinc additives in modern oils probably hasn't helped given the cam follower design. A separate additive will definitely be going in with the oil once this mess is sorted out. It's a bit hard to see, but in person you can make out glittery residue in the head valley around number 3 far more than anywhere else, which supports the thought that the mangled camshaft may be where a lot of the glitter I found in the oil had come from. So if the bottom end has survived, we might just get away with a head swap. Before going all the way down that lengthy road (being used to OHV engines a head swap on an OHC engine feels daunting!) I'd really like to take a look at the condition of the engine bottom end. Simple enough to get a quick health assessment done, drop sump, pop a couple of bearing caps off and see if we can see copper and if the crankshaft looks smoother than the surface of the moon. Simple enough. Oh. How the bleep do you get the sump off this thing? There's a stinking great cross member in the way. Sump appears to go back to about the red marker in this photo, a good foot or so behind the front of the aforementioned metalwork. Even if I could figure out how to get to the half dozen or so bolts buried above it and removed the engine mount attached to it... I'm not convinced I'd have enough clearance to pull it out. Think I need to go do some reading to figure out what really simple trick it is that I've missed...or getting the sump out will wind up with me 3/4 of the way down the road to removing the engine...by which point I may as well just take it out anyway! Feels like I must be missing something though given how serviceable most things on this car seem to be. I did wonder if the sump was split into a front and rear half, but if so I can't see the join. Definitely an instructive day...and kinds good news in a way. The camshaft being so chewed up to this extent definitely would have an impact on oil pressure I'd think and we've definitely found a likely cause for the glitter. It's just possible the bottom end might have survived... Either way I want to check the condition of it before going to the trouble and expense of a head swap. Plus given the amount of grime in and around the top end I fully expect the sump to be as bad or worse...and worry about the oil pickup strainer. Now I just need to figure out how the fluff to get the sump off! Simple right?
  6. "Just drop the sump" I said. Ah. It goes back to here... possibly further. Several bolts completely obscured by that cross member plus an engine mount attached to it. Yep... consulting a manual and may come back to it tomorrow... though unless I've missed something really obvious I can't see how this would come out without lifting the engine quite a ways. First job I've come up against on this car which has made me swear at it, so it was overdue I guess!
  7. This picture tells the story of this engine really. It's caked on about 1/8" thick everywhere under the rocker cover. We've always had acceptable oil pressure in the time I've had the car - I've started this investigation as I'd noticed a slight drop in the pressure at a hot idle - but it's worth noting that the spray bar that sits above the camshaft was about 70% clogged when I got the car. We've definitely got good flow there now but I think it was already mortally wounded years, if not decades ago. Oil is absolutely pouring out of the front and rearmost bearings on the camshaft. Not surprised...you generally shouldn't be able to stick a finger nail down between the shell it sits in and the bearing surface. There's at least 0.5mm of clearance there. The fact that there's enough clearance that significant varnish has built up on several of the bearing surfaces says a lot about how much clearance there is. Depending what I find when I pull a couple of caps off the bottom end we *might* get away with a head swap. Maybe. If we're really, really, really lucky.
  8. Reckon there's been a serious oil starvation issue at the top end and the engine being badly neglected. There's so much carbon buildup I can't pull the bolts out of the rocker assemblies in several cases. I'm hoping (read: praying) the bottom end of the engine is in better shape. Camshaft is "last in the circuit" as far as lubrication is concerned and I've never had an actual loss of oil pressure so there is some hope. I do have a good (as far as I know!) spare head at least...so that being scrap isn't a huge disaster. Pain yes, disaster, no.
  9. My approach would be: Soak in Plusgas or similar for as many days as possible beforehand and use an impact driver to remove them - the impact part there is critical as it really does help break things loose. Heaving on it with a whacking great breaker bar is far more likely to shear things off. If it doesn't pretty much immediately wind out, get heat involved.
  10. Wow...I think I have just uncovered the worst case of camshaft wear that I have ever seen...much less on a running engine. I give you the number 3 exhaust valve cam lobe in the engine of my Merc S123. That's a good 5mm of the camshaft lobe tip just outright missing. Edit: Derp... that's an intake valve. Oops.
  11. Yep, that's toast. Just have to hope the leak hasn't been going long enough to have eaten away the mating surface on the head too. Bit hard to tell if it's just the light, but looks like there might be signs of slight leakage from underneath number 2 as well.
  12. Zelandeth

    Tyre quality

    Tyres are the single most important safety item on a car. With that in mind, I just don't see it being worth trying to save a few quid. That said, they do seem to perish a lot quicker than used to be the case - probably because of efforts to make the rubber less "sticky" to reduce rolling resistance and changes to manufacture processes to make them less environmentally harmful. Neither are necessarily bad things, but do have knock on effects.
  13. Actually saw another one of these today, over in Newport Pagnell on an X plate in a sort of blueish silver colour.
  14. Quick job to tidy up the BX dash completed, sanding back and repainting the speedometer pointer white. Which looks a good deal brighter back in the panel. Another bit of BX was obtained and fitted today too. That's right, she has a parcel shelf now. Yes it's black rather than beige, but it's less jarring than if it were blue or something like that. I'll take the wrong colour over "missing." Means the junk in the boot is less obvious! Small details yes. Though I still see it as important as the less things which are missing, the more likely my enthusiasm to keep pushing forward on getting the car sorted is to continue. Has it helped take the rate the thing hurls itself open at? Nope...it still wants to smash my teeth out! The Jag's alternator lately has been behaving itself - right up till this afternoon. I'll need to see if I can get the brush pack out with the alternator in situ (as I *really* don't want to have to mess about with the belt tensioners again). It doesn't actually look too hard to get at by the standards I'm used to on this car. I'm sure I'll end up swearing a lot at that power steering lines a lot though... From the symptoms I'm hoping it just needs a brush pack as I really could do without spending on a new alternator on this right now...
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