Hello kind sirs, could anyone provide me with advice concerning oil blow back? The problem comes and goes as the oil comes back up through the engine to the air filter on occasions. Also, she backfires on a high rev or changing down of gears on occasion. Apparently the engine was refitted only a year ago just before I bought her (a '79 Bay). The mecanic's advice was to seek a new engine and I probably will do this but any other advice on this subject would be welcome! Thank you
find another mechanic, he's talking out of his arse! What engine is it? The oil comes through a crankcase breather, these engines need to breathe like this so they don't explode. Does it smoke? Is there oil leaking? Have you got the right amount of oil in (not too much) As for the backfire that is likely down to it needing a tune, or it could have loose hoses etc etc etc. Find a VW aircooled mechanic who knows what he is talking about and you can trust - or find a friend who has an engine the same as yours and knows how to keep his/her engine tuned. Buy some books Ditch your friendly mechanic. Most 'mechanics' know bugger all about aircooled engines, they hear one running rough or see an oil leak and the first thing they see is pound note signs... needs a new engine blah blah blah ;D
Thanks for your advice, clearly I would like to avoid having to get a new engine (a 1600 cc AS Code 215mm flywheel), I do trust this mechanic though as he has done work for me in the past. His point is that we could change the carb, change the oil and remount the engine but there's no guarantee that I wouldn't be back to see him in a year or so. Am considering all options here
sounds like it just needs a good service , valves adjusting , timing, plugs, points and a general service ! backfireing could be an exhaust leak somewhere . Not sure what changeing the carb and ?remounting? the engine would achieve you may trust your mechanic but does he/she really know there way round an aircooled ? . the breather does take the excess oil"fumes" back to the air filter to be filtered and then re-burnt through the carb ! Hence why the air filter needs to be cleaned or replaced from time to time or the oil changed in an oil bath filter
if you take the oil fill cap off with the engine running, what's the air flow out of it like... it should be a steady light blow, if it's more than that, then likely as not the rings are on their way out...
Cheers, it's not a steady light blow but the oil was coming out in spurts. Like I said however, the problem comes and goes. Recently I have'nt had any problem with blow back but I haven't been on long journeys either. The backfiring generally occurs on a change-down of gears when driving or if I rev the engine. Smell of petrol when sitting in the back.
could well be valve guides then... bit difficult to diagnose without doing a compression or leak down test
Sounds to me its not one fault but a culmination of faults your describing The smell of petrol is probably down to a fuel syastem breather hose so have a search for jokers thread on the matter Dont buy a new engine untill we have helped you through some simple fixes
