I give up! - advice on who can help - oil everywhere post rebuild

@Dave Goddard it seems you would benefit from having a book.
Simple things like Mike's advice above will save you compromising the good parts but you rely on knowing what needs asking and us second guessing what you might fall foul of - that's if you want the advice before rather than after when it's too late.
A good book is How to Rebuild Your Volkswagen Air-cooled Engine by Tom Wilson. Well... it's the only one AFAIK. It's basic stock engine building and parts ID and a must have really.

 

Its not the pump mike, its the cooler i need to get off to flush in case its got some Marmitee mixed up in there.

 

Thanks Zedders, I have a book similar which is a good one I think.

 

If your cooler is downstream of a filter its unlikely to have picked up junk. Any filter bypass valve relies on pressure drop across the filter, not absolute pressure only letting stuff past when an old filter is totally blocked to save the engine.

I drained the oil from my filter- I fitted an extra extender to make it possible to easily disconnect one hose, there was nothing visible in the cooler oil when my engine filled with shrapnel. All I did was clean the oil pump and replace the hose from pump out to filter in when I reused the oil cooler loop. I had driven it about half a mile with the engine in pieces so there was time for the oil to circulate after disintegration.

 

Makes sense Mike, guess as its almost impossible to get off i will do the same.
I have taken a new tack on the engine build, rather than a full strip i am going to replace all 4 barrels and pistons and see what happens. If it goes bang then i get an exchange engine, if all is well then happy days.

 

Have a look in the oil pump too? That's first thing in line for any bits that might have got past the mesh filter on the pickup. Nothing of note should have got past, but aluminium bits tend to stick to things like oil pump gears so worth a look? You should be able to do that without removing the pump.

 

Unless I’ve missed it somewhere in the 300+ posts you still don’t know what caused the piston to fail and if you simply replace the pistons and barrels you should do some checks so that if there is another failure it’s not just guessing what the fault might have been.

AA will tell you the ring gaps are correct but if you don’t measure them, you don’t know what the gaps are. AA will also tell you what the piston dish volume is but we know what they say for their type 4 pistons isn’t correct. Are they correct for the type 1 pistons?

You should measure the piston dish volume, combustion chamber volume and the deck height, then you can calculate the compression ratio. Cool Air sell a kit and I believe they will hire it for a few quid. https://www.coolairvw.co.uk/product/ac000137/

Good luck with the build.

 

Thanks guys, will take the oil pump face plate off and clean it out. I have a new gasket for thst coming. My plan now is to rebuild top end on 1641 for ease, speed and cost . If it goes pop then face up to costs for an exchange 1776.
In terms of cause i am working on the assumption that i either had a duff piston or the barrel filled with fuel, i cranked the engine and the pressure cracked the piston (to me the second seems unlikely but i cant deny i had continuous fuel stinks in the garage on the mech fuel pump which means its not inconceivable). The head looks good, no issues, the con rods feel good on the main bearings- no play and free moving on 1 and 2. Turning the engine over on the flywheel seems fine, no grinds just compression resistance and valve hisses so good there too.
I aim to change all 4 barrels and pistons and this time will check ring gap and deck height absolutely too. Should be done this weekend if parts arrive on time.

 

This book is quite fun.
It has suggestions for" Street" , " Hot Street" and "competition" engine builds.
Mostly unsuitable for a bus, one or two only good for about 10 seconds...




I built an engine using this and a video from The Engine Shop...(probably why it broke)

However if you want to know how to put together an engine that produces more than 300HP its in here...

 

So guys, i did the top end rebuild replaced all 4 barrels and pistons as the spare i was sent by the vw engine company was pretty much scrap and was maybe spare because it was unusable so had to shell out for a new complete set. The remaining three barrels and pistons were in good shape though with no signs of damage, and no barrel scoring etc i hope this points to a duff piston for the original fail. They were very black and sooty though from presumably the over fuelling.
There was no sign of damage to the bottom end discernable from anything that might have got in to the case, the conrods seem to turn free with no play, and the engine turns on the flywheel free and no rubbing sounds etc. This time i gapped the rings - last time i had prob wrongly assumed they were good from the factory. I took the advice on the oil pump and took the cover off and checked for debris also - nothing there which i guess is good. I bought a malpasi fuel pressure reg which is in and connected to the main fuel feed from the new elec fuel pump too. I have an in line removable fuel pressure gauge which i hope the plumb in tomorrow if the fuel lines i ordered arrive so i can be sure that side is ok too.
A mate helped tonight and after limited swearing due to my Marmitety trolley jack which doesnt hold pressure we got her up and the engine is back in.
Tomorrow i have ancillaries and stuff to fit and if the fuel stuff arrives i should be in a position to start her up.
For the moment i have bypassed the ool filter and cooler with a pipe going from out to in on the maxi 3 pump - i figure get it going first and then dtop the oil before plumbing that lot in if all is well.....or should i put that in the loop from the start...?

 

We have a hill near us must be a proper hill as camper struggles but we're nearer civilization as we have 5g

Sent from my Nokia 3.4 using Tapatalk

 

It'll be slightly quicker to build oil pressure on your initial start without the cooler but either way.

Did you measure your deck height?

 

Do you have any pictures of the broken piston?

 

Thanks for advice zedders. I didn't measure the deck height with any special gear but assumed maybe wrongly that going from 1600 to 1641 with identical cam and head would mean all was well as these are sold as slip in replacements. I did do a quick non scientific feeler gauge check with a straight edge across the barrel which from memory was 1.6mm. I think this means with my stock heads I may be on the low end rather than high on cr- would that be your take?

Piston pic I thought I posted before doc jon but will find pic tomorrow if not, along with other piston pics in case anyone is interested.

 

If your heads have a step in them then this is giving close to 3mm deck height .. at which point things happen.

You lose a bit of power as CR drops and maybe the flame front heats up the whole of the head and the top of the piston so it may run hotter.
Not that you can do anything about it unless the heads turn out to have Vege steel spacer rings ( machine step off and insert ring to improve old heads) . One of mine did, pulling out the rings to get the deck height back to nearer 1mm was noticeable on hills.

The larger deck height clearance is erring on the safe side- going the other way causes bigger problems as pistons hitting heads with thermal expansion and carbon buildup is not good.

 

Low compression runs hot and gutless.
High compression makes holes in your pistons.
Compression matters a lot more than a tight squishy deck.
If I had a type-1 stock cam I'd head for between 8:1 and 8.5:1.
7."something":1 will be poop.

 

'Slip in' means they fit without machining the heads or crankcase but they are not standard and all the usual fits and clearance checks should be carried out.

 

I did say he should measure the piston dish volume, combustion chamber volume and the deck height, then calculate the compression ratio.

 

He appears to be fixated on over-fuelling being the root of all his problems.

 

Sorry, you may well have done so and I've missed it. I was interested in how it looked out of the engine.