Club 80-90 Forums

hi dudes,
this is all new to me.
i hope you can help , i have a very smokey 1980 t25 2l Aircooled van.
it seems that petrol is getting into the engine oil ( making the oil very thin ) would any one know why . the petrol pump has bee replaced with an electric one done by last owner, could this be the problem ie pushing to much petrol through the carbs, or is it just worn carbs, is this a common fault?
hope you can help.
cheers...........................

Its all a bit new to me too, so Im no expert, but engines is engines and Ive stripped a few of them in me time

First of all, are you sure its petrol in the oil and not water? Petrol would be unusual, but water gets in there (if your van is liquid cooled) if your head gasket is leaking.

But if it is petrol...
It wont be the carbs, even if they are 'worn out' and chucking too much fuel into the cylinder it ought to stay there!

So Im guessing its either a cracked piston (but you'd probably know fairly quickly that its this as your engine self destructs) or a worn piston ring.
Im guessing a worn piston ring - the ring makes the piston/cyliner airtight, but if its worn then the high pressure in the cylinder may force petrol down into the crank

You need to take at least the head off to have a look at this, and probably the cylinders too, so not that easy a job if you're not that mechanically confident

Hopefully someone with more VW knowledge will come along now and suggest a more optimistic solution!

Sorry, just read the 'Aircooled' bit!

So its not water then!

Is th eoil level incresing ?, if so by how much?
normally worn rings cause oil burning as the pressure of the piston on the down stroke forces oil vapour up, petrol is lighter and would burn.

There needs to be access from fuel line to sump, usual through fuel pump , but you sem to have stopped that one.
so that's my guesses run out

Was the electric pump spliced into the line leaving the original mechanical one in place/connected up? (Have seen this before!) If so, the original could well be leaking ! Bypass or remove it.

Sorry to disagree with purplechugster but badly set up carbs can put excess petrol in ending up with petrol in the oil.

If it is the carbs, it won't necesarily happen when the engine is running but at rest. If the needle valve is stuck or the float height in the carb is incorrectly set, the carb will simply overflow petrol into the engine and even with brand new piston rings, it will seep slowly into the engine.

If you remove the aircleaner tubes from the tops of the carbs and look down the choke with a torch, you may see the petrol leaking in. Best done just after having run the engine.

Its not the only way that petrol can get into the engine oil but its a common one.

MG

Harlequin Syncro wrote:Sorry to disagree with purplechugster

Happy to be disagreed with!!

It's all a learning experience!

IF you are only driving slowly and mincing about then petrol vapour can get into the oil and condense making the oil a bit thinner. A good rag down the motorway usually sorts it out or you could change the oil and drive a bit harder.