broke down...engine blown? UPDATED WITH PICS

[paulandchez]

Right folks, finally can update you on the engine issues. Unfortunately my bikes engine has recently gone too and that's my daily commuter so needed to sort that first.

Anyway, finally managed to drop the engine and begin stripping. First I started on the 1+2 cylinder side, and when I took the rocker cover off, this is what I found...


Now I tried refitting the cover without the gasket in as this was rock hard, and it wouldn't fit properly. One corner was stopping it from seating correctly. This cover is a replacement one I fitted not too long ago (non genuine VW one) so I might actually dig out my old one and see if that can be fettled to fit again (couldn't get a proper seal regardless of what I tried hence buying the new one). I'm thinking it couldn't have been like that from first fitting as oil would have been p1ssing out from the start wouldn't it?
Then I removed the head....and think I instantly found what my problem is...


As you can see, cylinder 2 has a bit of valve missing. Now my first question is would this be down to just a knackered valve or could some other problem cause it?
So....this is the barrels both with an amount of crap inside, but no apparent damage to the pistons...
Number 2

Number 1


However, after removing the barrels, cylinder 2 piston has a weird finish to the side of it. Is this the result of lack of oil, or some crap getting between it and the barrel?


The other side look ok...

Why are the threads on the plug wet though?


Again the top of the pistons had an amount of crap in though.



Final thing is the contents of the strainer....doesn't look good. The flat pits are actually bits of thin metal, like a shim or something.



So folks, I'm thinking get the heads refurbed (there's a place very local to me called Bannisters in bamber bridge I've been told he's very good) and without being an expert, I'm guessing I'll need at least one new piston. Am I going to need new barrel too for #2? And due to all that crap going round my engine, am I going to need to split the case and see if there is any more damage?

All help appreciated as always

[Paul Weeding]

Time for a full strip down dude... The whole engine needs to be checked...

[paulandchez]

Thanks Paul, thought that would be the answer. Any idea where the bits of "shim" might be from?

[BOXY]

Any photos from down the inlet tract?
Metal on top of the piston probably means something got sucked down from / through the carb, unless the metal is from the valve seat.

[AdrianC]

Smaller valve is the exhaust valve, yep? So it could just be that the seat's not been sealing perfectly for a while, mebbe a crack? So a minor blow's turned into a nibble out. If it was the inlet valve, FOD would be more likely.

[sarran1955]

Hello,

You have PM...

Cordialement,

[silverbullet]

Diagnosis is schoolboy stuff. Overheated cylinder #2 due to going lean on that one pot. Result: burnt exhaust valve and the piston has picked up on the barrel.
As for the crap on the oil strainer, is it hard or flexible? It looks plasticky to me but that might be the photo?
I would guess that the bearings will be distressed too. Full rebuild needed.

[Atomic]

That "shim" stuff in the sump is probably the remains of a big end bearing.

[paulandchez]

Those bits around the strainer are mainly thin metal pieces....and if I feel up inside the sump there's more!

Looks like there's only one way to find out though eh

[Paul Weeding]

That "shim" stuff in the sump is probably the remains of a big end bearing.

This is exactly what I was thinking

[Paul Weeding]

Looks like there's only one way to find out though eh

Afraid so dude... I've rebuilt quite a few type 4s now, and even the good ones require a fair bit of work/parts

[Sir Brixalot]

Sorry for your woes. Fascinating pics which give me a better idea of what's going on. I've had loads of rebuilds but never seen inside. Good luck with it

[mrhutch]

perfect Ian

Diagnosis is schoolboy stuff. Overheated cylinder #2 due to going lean on that one pot. Result: burnt exhaust valve and the piston has picked up on the barrel.
As for the crap on the oil strainer, is it hard or flexible? It looks plasticky to me but that might be the photo?
I would guess that the bearings will be distressed too. Full rebuild needed.

[paulandchez]

Well....think I may have figured out the problem.
Managed to finally split the case today. It became obvious that one of the big end bearings had gone. Holding the conrod, you could feel loads of free play vertically. So I took it all apart and found loads more bits of metal in the case. The rod that had gone has also turned black. The bits of bearing have made a mess of the rod plus the crank, and the bits have gone round the engine and badly scored the cam shaft too!
Pictures for you all to gaze at...and maybe offer me some help as to where to go from here, ie is anything reusable and where can I get the needed bits from:




















Also, is this normal for the inside of the case to be rough like this?


Thanks guys, all help appreciated

Paul

[silverbullet]

Oof! In reverse order:

Case roughness is typical die casting, nothing to fret over.
Cam bearing failure is due to lack of oil pressure and/or corrosive old oil.
Cam lobe scuffing is old age/high mileage/old oil again.
Rod is bin filler, crank might clean up with a grind but maybe easier to find another.

Big question: why no oil pressure? Its been driven to death, was oil pressure switch connected and bulb working? Did you drive on despite is being a bit "endy"? It must have been a right old knocker before it finally died...