ClintUK

Just got a '97 UK Turbo and it's top, everyone should have one !

BUT odd tinkling / buzzing sound that I've been told may be knocking and I don't want to rebuild the engine in the 1st month ! Also looking on SIDC FAQ this may be nothing more than a cracked exhaust heatsheild. Any clues ?

Will find out about this knocklink thing everyones talking about and guess I should change the MAF as I bet it's never been done but in the meantime can I sleep peacefully or should I change the MAF tonight ?

scoobyslut

Can we have some clues as to when you hear this noise, like is it from cold starting. Is it when you switch off, can you hear it on tickover?

it all helps to answer your query.

ClintUK

1st time I noticed it was low revs, high gear, high load. Could be knocking huh. But I'm pretty sure I get the same noise coasting under engine braking, seems unlikely now.

But as I've not been playing with cars since I had a Mini I'm out of the game with moden stuff.

The car is warm or cold and I'm driving round town between 20 & 40mph.

Also changed to a K&N air filter and the old one was pretty oiled up - where's that come from

The_Judge

Depends what your old air filter was. If it was an OEM paper filter, you wouldn't expect it to be covered in oil... but if it was (for instance) an ITG, then it's also quite unusual for the filter to be covered in oil. Normally said oil can often be found in the bottom of the air box, or trying to make acquaintences with the MAF...

Joking aside, if it's your heat shield, it'll be fairly obvious, and will resonate at particular revs in particular gears, fairly consistently.

Do you have any other MAF related symptoms? For instance, dodgy idle (sometimes nearly stalling, bouncing up and down between 0 and 1000 rpm), hesitant "lumpy" full throttle acceleration... Might be worth doing a couple of quick checks. With a warm engine idling, pop the bonnet and disconnect the MAF. If the engine stalls, your MAF is probably OK. If there's no change in revs, your MAF's probably shot (or failing). The other test is to reset the ECU, as over time it may have learned its way around a failing MAF. By resetting the ECU, these learnt values will be lost, the idle will be awful, as will acceleration, exposing the knackered MAF. However, if resetting makes little or no difference to idle/acceleration, the MAF's probably OK. If you don't know how to reset the ECU, click here for info...

ClintUK

Filter was an IGT. With Dandilion seeds

Do not seem to have any other MAF type problems (thanks for the pointers) Idle is rock solid cold or hot and acceleration seems pretty smooth.

Will play with MAF as you suggest and see what happens, cheers.