I don't know if the emissions tests are different in other countries so I specified UK.

A garage just failed my girlfriends 1.4 Golf MK4 and said it was smoking bad, they tried sparks, cat, lambda, oil change and a couple of other common things, they say it's engine strip/replace time.

I read on more than one forum that the piston rings can go on these cars. Is that the most likely cause of the failure? The engine wasn't particularly well looked after before she has only had it a year.

1 Answer 1


A smoking engine is going to ensure an emission test failure pretty much anywhere these days...

Can you see the engine smoke when it's idling for a while and/or when you rev it?

Worn piston rings certainly would a good reason for a smoking engine, but it can also be something fairly simple like worn valve guides or worn valve guide seals. Either way you cannot determine this without stripping the engine.

I'd get a second opinion from another garage, preferably a VW specialist, before doing anything drastic, though. I'd also think that getting a remanufactured engine is probably cheaper than getting the existing engine rebuilt.

  • I would agree with you on 'getting a remanufactured engine is probably cheaper' if it wasn't for a friend of a friend who recently qualified as a mechanic and wants experience said he would strip the engine for not much money so I will have to check what 'not much money' means =)
    – Paul C
    Commented Aug 22, 2011 at 15:24
  • Stripping it is the cheap part :). Unless your friend has access to the necessary tools for machining the engine block, you'd still have to pay for that work and that's not that cheap at retail pricing. Same goes for the parts. OTOH if he's trying to do a really good job, having him rebuild the engine is probably going to result in an engine that's at least as good as a renman one, plus you've got the choice of parts quality that you don't get with a reman engine. Commented Aug 22, 2011 at 15:39
  • Interesting, out of interest could you clarify 'necessary tools for machining the engine block'
    – Paul C
    Commented Aug 22, 2011 at 15:47
  • 1
    If you need to rebore the cylinders or deck the engine block so it's true (if the gasket surface to the head is out of true), you'll need some pretty specialised machinery for that. These things are rather big and expensive. Depending on the state of the bores (if it was really the piston rings), just honing isn't going to clean up the cylinder bores, then you need to rebore, get oversized pistons etc. Same goes for the crank if that's been damaged/worn, you need specialised machinery to 'fix' the crank. That said, you/your friend can farm out that work. Commented Aug 22, 2011 at 19:48
  • I think she is giving up on the car, shame! Thank you very much for the advice anyway
    – Paul C
    Commented Aug 23, 2011 at 8:19

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .