Ran out of time to get an update on here yesterday - so have that one prior to today's (rather lengthy) update. I'm going to split these into separate posts for the sake of my own sanity.
-- -- --
Didn't get a whole lot done at the weekend because the weather was being so incredibly erratic on Saturday, and the moment I stepped outside when I was available it immediately started raining. Sunday I was mostly busy so only had a few minutes really spare. Nevertheless I was determined to get something done, however small.
Previously we identified this connection between the vehicle and engine sides of the ignition system which I filed under "could be better" when I looked at it.
This clearly wasn't going to be great in a relatively exposed location long term. Especially when two wires pulled out of the crimp terminals pulling the supposedly removable parts apart.
Before and after showing me in the process of switching this out for a more suitable connector for use buried down in the bottom of the engine bay.
There are some areas where it's easy to argue that little progress has been made in the last 40 years or so...but I'd absolutely argue that properly waterproof connectors like these really have been a vast improvement over their predecessors.
Should be a fit and forget solution, but also still allows the wiring to be disconnected without having to open up the points compartment to disconnect things to allow the fan belt to be changed.
The wiring has also been secured to keep it well clear of the fan belt.
Speaking of the points compartment - you all knew I wasn't going to be able to leave it with that bit of red heat shrink sticking out of it didn't you?
Added a bit of additional black tubing to both provide a bit of additional protection to the wiring and to make it look a bit tidier.
Hardly ground breaking work, but I'm glad I was able to at least tick something off the to do list.
-- -- --
-- -- --
Things escalated somewhat this afternoon!
Main mission for the day was to get a look at the rings to confirm they were all present and correct, and generally to look for any further signs of damage. My intention was also to pull the jug of number 2 (I'm numbering the cylinders 1 at the crank pulley end, and 2 at the flywheel end for clarity), to see if I could see any further bits of metal floating around in the case.
Step 1 was simple but awkward. Removing this lot.
Awkward because I had to remove it as one assembly because there's no way to get a (non stubby) wrench on the inboard bolt without first removing the starter motor...and just pulling it off in one piece seemed like less hassle. That heat exchanger is surprisingly heavy but it came off without too much hassle once I figured exactly which way we needed to twist and slide things to fit the manifold between the front valance and the starter motor. If you have a stubby 17mm wrench you could probably do it, but that's not something I have.
I was quite surprised looking inside the big metal assembly which is labelled as a silencer for the heater air supply to find that rather than just being a big box, it is in fact as the name suggests a proper silencer.
I'd expected at best for there to be some metal ribbing in there to help cut down reflected sound, but no...proper padding and everything. Again, surprising areas of attention to detail on a car that people by and large tend to dismiss as being chucked together without a care in the world.
Having the manifold out of the way revealed instantly where a good deal of the oily gunge in the engine bay had come from. Cylinder number 1 had completely blown its exhaust manifold gasket at the top, and number 2 had been fitted with completely the wrong gasket at some point which didn't even come close to actually sealing.
The rings on number 2 were indeed present and what I could see though the exhaust port looked in decent shape. However you can see from this angle what an absolute beating the piston crown took from that bit of metal.
You can clearly see how it's caused the edge of the piston to be mushroomed outwards - I'm pretty sure that this would have caused me issues if I'd left it - while it ran with the engine cold, once it warmed up and things expanded a bit that might be a different story.
Looking at number 1 things started to immediately ring far more alarm bells. For a start the piston skirt looked like this.
That's not just oily dirt - the surface is as deeply ridged there as a ploughed field. This is Not Good.
Even worse, when the piston was lowered there was also clear evidence of it having also ingested foreign matter, albeit less dramatically than number 2.
The head was pulled then to inspect and confirm that theory - and yes, there is definitely evidence of there having been something bouncing around in that combustion chamber - albeit whatever it was has long vanished down the exhaust in this case.
Number 2 is at the top, 1 at the bottom.
Don't read into the surface rust too much - that's likely it having taken a bit of water on when I pressure washed the engine, so I'm to blame for that.
While this piston crown hasn't taken anywhere near the battering that number 2 did there clearly has been something bouncing around in here.
That piston crown was pristine and damage free when I had the head off back in February to change the head gasket.
Between having ascertained that there was absolutely more than one piece of debris involved and having seen damage to the skirt on number 1, pulling both jugs was now something that absolutely definitely had to happen. I'm definitely not the first person to be in here given that one of the nuts was 12mm rather than 13, and 2 of the 8 studs were missing washers below the nuts. This and the exhaust gasket choice makes me somewhat hesitant to trust the attention to detail of whoever last had the top end apart.
I started with number 2...For reasons I don't really know. That theme continues for the rest of this post.
There's no really *horrible* damage (save for what we already knew about), though there is definite signs of a lot of blow by.
Front:
Rear:
Cylinder as we saw when we looked in there the other day does indeed have a few scratches on it. I had an absolute nightmare of a time trying to get the camera to focus properly on this.
The pitting nearer to BDC I find quite interesting as that's the sort of damage I usually associate with rust pitting. Though I know nothing of the history of this engine, and the car did spend some period of time off the road so it may have wound up with a bunch of moisture in the cylinder(s) at some point.
Piston number 1 is rather more gruesome...Those of a mechanically squeamish nature may wish to turn away now.
Front:
Rear:
Ouch. It's hard to see in the photos, but there are honest *chunks* of piston material missing, particularly from in between the rings. That piston is absolutely definitely scrap.
Given the state of the piston, I'm honestly surprised the cylinder isn't worse. It's actually better than number 2 aside from the one scratch at around 8 o'clock which is just deep enough to feel. Which also makes me think that this overheating/seizure damage most likely isn't something that's happened recently, if it had I'd expect witness marks to still be more obvious. With the exception of the one scratch I'd be surprised if most of this doesn't clean up with a good honing - the camera as is often the case with things like this makes it look worse than it seems in person, and that one scratch just below the inlet port is the only one which fails the fingernail test.
What I don't know about either of these however is if they're still circular and straight - though given they're both damaged that's kind of academic, I'm just curious. We're definitely looking at the very least by this point at a pair of new jugs and pistons.
Then I spotted something poking out of the oily pool by where the base of number 2 cylinder sits.
What was fished out of that pool very clearly didn't belong there, nor was it as I had initially hoped a bit of gasket material or similar.
Unlike the previous bit of metal we found this one very clearly is absolutely definitely hardened steel. Even with a pair of pliers on both ends I can't bend it at all. So there's every possibility that this does indeed originate from a bearing somewhere within the engine. Assuming of course that it's not a free gift still in there from a previous failure - as we've seen clear evidence that somebody has been in here before, and that they've not maybe been as careful as we'd like.
The wrist pins were the next items to come out - albeit requiring a little persuasion. Thankfully I managed to avoid pinging any of the retaining clips off to bounce off the ISS, into my eyes, nor did I drop them into the crankcase. Again we're doing number 2 first before moving on to 1. Plenty of pitting visible. While *most* of it is actually where the race sits, there are a few bits which do extend into the bearing running surface. This also needs to be filed under B for bin.
I couldn't see any damage to the bearings themselves - but I was working in bright sunlight and with no magnification on hand so I don't think that means much. I think this was actually from the second cylinder - the photo is mainly to give the curious among you a look at what the bearings look like though, and they both looked in pretty much identical condition.
As was the case with the piston itself, the wrist pin from number 1 was in worse condition. There's both more pitting visible and it's definitely deeper.
Despite the pitting on the wrist pins, both of these bearings felt fine with everything able to move smoothly and no play in the load direction that I could detect by hand.
With the pistons out of the way and looking down into the crank case, there are definitely a few small "bits" in there, but no big chunks of metal that I can see.
That "blob" you can see roughly centre frame in the first image below just appears to be some oily gunk. I thought it might be a bit of metal but poking it with a screwdriver proved it to be liquid.
The most concerning thing I was able to find in this area by a purely visible inspection though was some absolutely horrible looking scoring on the area adjacent to the transfer ports where the disc valve runs. While I imagine a little surface scratching is inevitable here, I'm pretty sure it shouldn't look (and feel) like a brake disc that's been run with knackered pads for a couple of thousand miles.
Cylinder 2:
Cylinder 1:
Given there's a very narrow clearance there though and we know there's been foreign matter floating around in the crankcase, that damage probably isn't all that surprising. I don't know how critical the condition of that surface might be in terms of the engine being rebuildable though - that's part of the crankcase so not exactly easily replaceable. You'd probably have to TIG weld to build the surface back up then mill it back to the correct surface - which involves equipment many, many tens of thousands of pounds above my pay grade!
The last thing I could check without any further strip down and/or equipment I don't have on hand was to look for play in the big end bearings. In summary: Not good. There's what I would say is about 0.5mm of "vertical" play at the bottom of both con rods, and enough play that you can visibly "tilt" both rods left to right by a good distance which doesn't seem right. The bottom end also sounds quite grumbly if you spin the engine over by hand.
Apologies for the vertical video, I didn't think about that when I recorded this.
https://youtu.be/v2ToaoUOcvU
I am open to feedback from people who know these engines there - but the fact that I can twist/tilt the rods just seems off to me. I'd expect a needle bearing to allow straight side-to-side movement, but not for the lateral relationship to the crank to be changed - at least not that extremely.
So what next?
Given the damage we've found to both pistons, the scored/pitted cylinders, hardened metal debris and what to me seems like excessive play in the bottom end, just throwing this back together and crossing my fingers feels like I'm just asking for further trouble. Whether that be 5, 50 or 500 miles down the road, something is going to let go and it's most likely going to do it at the worst possible moment. I count myself very lucky that when the breakdown that kicked this all off happened that I was able to coast without any drama into a safe stopping location well clear of the road at the entrance to someone's driveway. If this had happened during probably 85% of my normal driving it would have been far more of a nuisance, given the plethora of 70mph dual carriageways with absolutely zero provision on them for safe stopping in Milton Keynes, odds are that's where it would have happened.
My hunch is that the 35K kilometres shown on the odometer in this car most likely is 135K. Which if the bottom end of this engine hasn't already been apart at some point is pretty impressive going for a little air cooled two stroke with its design roots in the 50s I'd think! Especially given that the general evidence in this car suggests that it's never really lived a pampered life either before or since its arrival in the UK.
This leaves me with three options I reckon.
[] Find a second hand replacement engine.
[] Buy a rebuild kit.
[] Buy a reconditioned engine.
The first option is obviously most likely to be the least painful to my bank balance. If I can find someone in the UK who has one they're willing to part with at a sensible price of course - and assuming that engine itself doesn't also need major work, otherwise we just end up straight back where we are now.
Trabantwelt do sell a "rebuild in a box" kit which most likely would contain everything we needed to get up and going again. Albeit not exactly cheap - and viability of this is assuming that that scoring we found by the disc valve ports isn't a show stopper.
Link.
Actually a little more as I'd need to factor in return shipping for the old core parts, though that's likely to be a drop in the ocean compared to the overall price tag in all honesty.
By far the biggest single cost in there is the crankshaft assembly which is €550 if you were to buy just that alone.
Though if we're already looking at a four digit price tag for this as it stands, do we just accept this is going to be expensive and order a whole engine off the shelf?
Link.
Don't honestly know how much I'd need to add on to that for shipping the core back to Germany, but I'm guessing most likely somewhere in the region of £100. Don't imagine postage for the new part here is exactly going to be cheap either.
Time to do some digging to see if I can find a serviceable spare in the same country first I think as that would definitely be the easy option, also time to get the lump currently in there pulled out - as whether it's getting rebuilt or replaced it needs to come out of the car to be worked on. I'd also like to examine the clutch as that has always been prone to a lot of judder - so I'd like to know if we need to look at ordering that as well.
Getting the engine stripped down that far took maybe an hour or so - and that included probably 20 or 30 minutes wrestling with the exhaust before it occurred to me to just remove the manifold and heat exchanger together as one assembly. Total tools involved: 10 (is just to remove the cowling), 13, 16 & 17mm sockets (x2 for the exhaust manifold-heat exchanger bolts as they're not captive), a ratchet flat blade screwdriver, needle nose pliers, a few rags and a couple of ziplock bags to put each cylinder's small components in. Can't really complain at that to basically have an engine half way stripped down. Actually quite enjoyable to do as well, even the brief bit of wrestling with the exhaust wasn't all that annoying all told.
