Zel's Fleet Blog - BX, Jag XJ-S, Sinclair C5, Mercedes 208D & 230TE, AC Model 70.

[CitroJim]

Oh Zel, sorry to hear Covid has got you... And may your recovery be quick and complete...

[mickthemaverick]

Me too that's a real pain Zel. Presumably it means another period of isolation this week?

[Zelandeth]

It is a pain in the behind. Based on the onset of symptoms being basically Thursday evening in theory I should be clear by the latter half of this week. Doesn't hurt to be safe though.

So this weekend I have achieved basically the sub total of nothing. I just haven't had the energy or brain power to really do anything useful, so I've just been working on digitising photos as that's something I can mostly do on autopilot more or less and could just dip in and out of.

It's hard to convey quite how much better the results with the new scanner are. Here's an example though. This is taken with the old Olympus OM-10 which has been one of my "daily driver" cameras for a couple of years now, on Fuji Velvia 100.

Not going to get much sharper than that. I'm really going to miss Velvia when my current stock is finished.

The scanner having actually decent dynamic range has proven really helpful in getting better results from black and white as well.

Velvia is very sharp and has virtually no grain. Delta 3200, not so much. My aim with that photo was always to try to recreate something that looked like it could have been seen in a motoring publication in the 60s - which I reckon I pulled off.

Hopefully tomorrow I'll be able to start getting towards doing something useful again...the to do list is getting a bit ridiculous.

[Gibbo2286]

On the photos subject, on the Birmingham history forum there are c couple of guys who fix up old photos sent in by the users, they get some very good results removing damage and even colourising old black and white.
Last week one of them said this when someone commented on the quality of the work:

"I just put the picture into a new AI app called BlurBuster, and used Descratch and Enhance and this was the result."

[Zelandeth]

On the photos subject, on the Birmingham history forum there are c couple of guys who fix up old photos sent in by the users, they get some very good results removing damage and even colourising old black and white.
Last week one of them said this when someone commented on the quality of the work:

"I just put the picture into a new AI app called BlurBuster, and used Descratch and Enhance and this was the result."

I wouldn't say no to a tool which actually did a halfway decent job of scratch removal to be honest. Touching them up on a complex frame can be incredibly tedious. Had one film which had clearly due to an equipment issue a single scratch that ran the whole way along it, just above centre frame. Probably took me an hour per frame give or take to touch that in, and is absolutely mind numbing at times.

-- -- --

Today I had enough energy to actually try to do *something* for an hour or so, so decided to go see if I could ascertain what had happened on the Trabant.

I'd seen evidence of something in the combustion chamber on number two looking through the plug hole, so off with the head.



Not unlike what I was expecting to see to be honest, and that definitely would explain the Unhappy Noises we encountered while driving. Something has obviously managed to get itself ingested by the cylinder.



This is evidently what was causing the lockup as once the head was removed the engine could be rotated normally. I was kind of expecting the jug to have been absolutely destroyed based on both what I heard and seeing the state of the top of the piston.



Evidently not. Yes there's a bit of wear there, but this doesn't look any worse than the other cylinder did when I changed the head gasket on that.

This is what is left of what was floating around in there.



Answers on a postcard as to what these bits of metal used to be? It's ferrous, but can be bent with pliers, so it doesn't seem to be hardened like I'd generally expect the rollers from a bearing to be.

The engine rotated just fine by hand, and spinning it over on the starter didn't result in any unusual noises. So I did the obvious thing, cleaned it up as best I could, threw a new head gasket on and bolted it back together.



Didn't sound odd with compression either...So I hooked the plugs up, turned fuel on and went for a start.



Sounds...Pretty much exactly like it did before to me! A little louder here because there's no cowling on obviously, but really doesn't seem any more rattly...in fact if anything less so. Goes without saying I only ran the engine for a minute or two tops like this so it didn't overheat.

My gut feeling is that piston needs to be changed no matter what our prognosis is, as the rough surface will cause hot spots. Probably likewise the head - though I'm willing to listen to experience from those who know these engines better on that.

This is where I had to leave it today as I was thoroughly out of energy by the time I'd got here, for all it was probably half an hour's work if that.

The next question of course is what's our next step?

Does that little bit of metal look like something that's been ingested by the engine from external possibly at some point in distant history? Or does it look like something that's escaped from the internals, and is likely to be the first bit of many if we let the engine run longer?

Basically...Do we stop here, or do we continue digging deeper? I'm inclined to pull at least one of the jugs and take a peek down into the crankcase and see if it's full of bits of metal. I do have all the gaskets necessary to put things back together after that.

Hmm...

[myglaren]

I wish I had saved them now but read recently of a couple of Briggs & Stratton motors, one a ride-on mower that 'sounded odd' but continued to be used until autumn whe the head was taken off the engine and there was a screw embedded in the piston crown. Abbrade flat, engine reconstructed and used for years after.
The other was low on power and seemed to be running on one cylinder only. A look in the crankcase showed nothing alarming but there was a mysterious twisty tube of some sort that was attributed to engine management or similar. Removing the cylinder head revealed a missing pushrod, preventing one of the valves (exhaust) opening. The twisty 'tube' turned out to be the ingested pushrod.
And having written that, on reflection, I thought that Briggs & Stratton engines were two-stroke.
Hmmm.

[xantia_v6]

All B&S engines I ever saw were 4-stroke.

I had a Honda engine that ingested a piece from the choke mechanism in the carburettor, resulting in a bent valve.

Re the damage to the Trabant piston and head, I would just clean up the sharp edges with an emery disc on a Dremel.

[Michel]

I would just clean up the sharp edges with an emery disc on a Dremel.

My experience with 125 and 200cc 2-smoke motorbike engines says a big YES to this!

As for 4-strokes, I had a 250 single Suzuki GN250 that I utterly thrashed everywhere. It dropped a valve at speed and it got battered around the combustion chamber. It put a crack in the head which I had welded up, but the piston, despite some marking on the crown was absolutely fine.

[Zelandeth]

I do like the video of it idling happily there - less than 30 minutes of work after the engine being unable to complete a rotation.

Think my next steps with this will be as follows.

First up, do a compression test to confirm that both cylinders are (at least more or less) in spec, and are reasonably close to each other. Takes five minutes and very quickly should tell me if there's any critical damage to the rings that I can't see or if the jugs are more badly worn than I think. Not expecting this to show anything up really as the engine started easily and idled evenly, but while I've got things already in bits this is a good time to replace any parts that are obviously worn out.

Properly pressure wash the engine. It's a disgusting slime ball which makes it unpleasant to work on. It also can't be helping cooling. If I'm going to be opening up the crankcase I'd really rather it be as clean as possible first to minimise the odds of dropping grime in there.

Pull the jugs and go magnet fishing. I don't think you can really see much with the jugs removed as there will be a load of crankshaft in the way. However I'm hoping that by wiggling a magnet on a stick down in there if there's any further ferrous debris floating around in the crankcase I can extract it before it eventually finds its way into the cylinders. The only way to really go better than that would be to remove the engine and shake it upside down and see what falls out or to split the case. The potential for there to still be more bits in there is probably my single biggest concern at the moment.

With the jugs removed this will also allow me to inspect the condition of the bearings at both ends of the con rods for excess play and to properly assess the condition of the rings and pistons. Plus will allow me to try to smooth out things on the damaged piston crown a bit. Getting to the edges would be really difficult with it in situ.

Then chuck it back together and see what happens I guess!

[bobins]

Would an el-cheapo phone mounted endoscope be any use in the crankcase to observe (or not) the carnage ? Is there enough room to snake one in ?

[Hell Razor5543]

I have got a Wi-Fi endoscope, which is fairly good (but with a short focal length). I picked it up at a boot sale for £10. It has a couple of 'tools' that screw onto the end, including a small magnet and a small hook.

[MattBLancs]

Hopefully tomorrow I'll be able to start getting towards doing something useful again...the to do list is getting a bit ridiculous.

Ah, the trick is not to limit yourself to just one list! There's 5 lists on my fridge at present! (House, garden, more than one on the cars, household "online jobs" to do - shop around for house insurance, that sort of thing)

Problem is keep finding myself completing other "off list" tasks instead

[MattBLancs]

Pleasing Trabant investigation progress, looking much less of a disaster zone than I'd have expected from description of the failure. Also surprised how insignificant those pieces look given enough to lock the engine up!

Think I'd get Dremel type sanding flap disk and clean up as best you can piston face and inside of cylinder head. Don't think it'd remove enough material to meaningfully change the compression ratio - guess pretty low to start with? Guess you could get the mating face faced off on a mill to restore it as an alternative?

[Zelandeth]

Pleasing Trabant investigation progress, looking much less of a disaster zone than I'd have expected from description of the failure. Also surprised how insignificant those pieces look given enough to lock the engine up!

Think I'd get Dremel type sanding flap disk and clean up as best you can piston face and inside of cylinder head. Don't think it'd remove enough material to meaningfully change the compression ratio - guess pretty low to start with? Guess you could get the mating face faced off on a mill to restore it as an alternative?

There's only really a couple of significant gouges in the head, and I scratched off the little bit of metal "peeled" out when they were made before cleaning the mating surface and bolting it back on before that test start video. That ring around the combustion chamber is what really should make the primary seal, so I do question if whoever was in here last cleaned it up properly as that one was clearly leaning heavily on the gasket itself and basically waiting to blow like the other one did a while ago. I'd just never had the time to get back in here to swap the second one too.

Not surprising it locked things up really when you look at where the metal was sitting. The crown of the piston at TDC is virtually touching the step on the inside of the head around the edges, so anything sitting in there will jam things up. I suspect when the engine was running there was enough gas movement to encourage it into the central combustion chamber or to just brute force the piston over TDC, but once it was stopped it settled right at the edge and required more force than I could (or was willing to) apply to turn it by hand. I never tried it on the starter after it was turned off during the breakdown until after I'd cleared the cylinder out. I suspect that would have been able to turn it - though having said that, the starter motor is physically nearly the same size as the engine!

I'll clean up the worst bits on the piston when it's next apart, but it's one of those cases where I think the photos actually make it look worse than it does in person. The vast majority of the damage is small pits down into the piston rather than metal that's been dished upwards. Also helpfully, the vast majority of the damage is around the edges rather than the centre, which is the bit which is exposed to the full violence of the combustion event.

Stock compression ratio is apparently 7.8:1, so not particularly high. Admittedly, still higher than the 6.7:1 that's standard on the Steyr-Puch unit in the Invacar!

[MattBLancs]

Interesting stuff, I'd not thought about it being caught round the perimeter, makes perfect sense that!

Wow the invacar ratio is low! Guess that's aiming at use of two star which is very low octane, isn't it?