Hello,

We've recently experienced a problem when starting our 1997 Golf Mk3 Estate CL with a 1.8 ADZ engine. It doesn't get much use now as we have recently bought a Mk5 but it is a very useful load carrier so we've kept it as a second car. Initially I thought it was the technique my wife used but it has been happening to me as well now.

Basically, there has been a loud backfire when starting from cold accompanied by smoke from under the bonnet. It usually starts and runs normally on the second or third attempt but I decided the Christmas break was the opportunity to try and uncover the cause of the problem.

My father-in-law suggested it might be a sticking inlet valve and I had already decided it was probably time to replace the plugs and air filter so set to this morning to take a look at the air filter. Unfortunately, in moving the lid, which I had left connected to its hose and the inlet, caused the throttle body to come lose and I have found that the intermediate flang is broken. I hope that this may be the cause of the backfire but we'll see! Luckily, GSF had one in stock so I'm now ready to fit it.

One question, though, should I use anything, grease, silicon or vaseline etc, on the 'O' ring that seals onto the inlet manifold? On bikes I usually use something to seal O rings but wanted to check with some experts.

Thanks for your help

Mark