I'm feeling very stupid today - car help?

[aclivity]

My car is sick. It stopped working yesterday morning and I had to pinch my wife's car to get to work. The computer said there was a 'catalytic convertor fault' and then an 'antipollution fault', which also happened a couple of weeks ago and was fixed (or not, as it turns out) by a software download.

Anyway, it's in the garage today and they've said it needs new tappets.

What is a tappet? Is it garage talk for muppet, or 'problem exists between chair and steering wheel'? I thought tappets were something to do with old pushrod / rocker engines but I think my car is OHC for the exhaust valves, and unless the i in GTi means something else, it's also a duel injection. Thus it shouldn't HAVE pushrods / rockers?

So, for anyone out there who knows more than me about engines - which os probably everyone - what's a tappet and why would new ones help?

Andy

[MattS]

A tappet is the bit that taps the valve open and adjusts valve clearance. It is (usually) a small threaded stud which is locked into the valve rocker. The rocker is actuated directly by the camshaft on OHC engines.

Some DOHC engines avoid tappets by mounting the camshaft directly over the valves. A cap over the valve (bucket) holds a shim of metal under and the cam lobe hits the shim. Valve clearance is adjusted by swapping in thinner shims.

Mechanics sometimes say 'tappets' when they mean to say 'shims'.

It is a long time since I took an engine aprt though.

[Gunna Do]

Might be able to give you a bit off advice as well..

As Matt has explained very nicely what a tappet is, Ill do the catalytic converter.
I doubt there different from the ones over here in NZ.
A catalytic converter sits just below the exhaust manifold, and is a cyramic tuby thing encased by steel pipe, which your exhaust gases pass thru,It causes a secondary burning effect to minimise potental harmfull emissions and excess smoke.
It is located no where near the Tappets.
And as a Mechanic, albiet a Diesal Mechanic, I would be mildly concerened by anyone saying that the tappets need replacing, unless of course they are Hydrolic tappets. Then the clatter they would be making if they are not functioning correctly is very noisy, Is your engine very noisy????
and sometimes if your engine oil is low, then oil pressure is low and they will clatter,Do you have enough engine oil???
Still if your Comp is saying Catalytic converter, and they are saying tappets time to go to another mechanic. I wouldnt trust this one.
Or better yet ask for a more detailed diagnosis, he could have been treating you like a Numpty
Steve

[Andy Bloss]

Andy - give Malcolm a call, in addition to being your DO, he's also a car mechanic you know...

Even if he does have time to fix it, I'm sure he'd be able to help you understand exactly what the problem is.

ta

Andy

[aclivity]

Thanks for all the advice - thing is, the car is covered by a warranty (and I've heard from people who own the same model of car that they've had similar problems) so I'm just letting the dealer sort it out.

I just felt a little bit thick when my wife reported back what the mechanic had said and asked me what a tappet was!

Originally Posted by gunnado

I would be mildly concerened by anyone saying that the tappets need replacing, unless of course they are Hydrolic tappets. Then the clatter they would be making if they are not functioning correctly is very noisy, Is your engine very noisy????
and sometimes if your engine oil is low, then oil pressure is low and they will clatter,Do you have enough engine oil???

Doesn't seem particularly noisy to me, and the car has plenty of oil. I wouldn't know if it had hydraulic tappets - I'm fairly certain it has an overhead cam (but based on the fact that this little problem has highlighted that I know next to nothing about this engine, I'm going to treat myself to the haynes manual this week).

Originally Posted by bloss

give Malcolm a call, in addition to being your DO, he's also a car mechanic you know...

If I get chance I'll do that Andy - current work situation has stopped me being up at the club much for the last few weeks!

[Andy Phillips]

If it's new enough to have a warranty it almost certainly has hydralic adjustment.

But far more important, did you know the active component in Catalytic converters is platinum. Just yet more proof that running a car is a way to waste money.

Andrew