Hi we've got a 1998 turbo 2000 uk car thats done 87k. When you start the car from cold in the morning, there is a tapping noise from the engine that goes away when the engine is warm. It increases with engine revs. Any ideas? Is it a easy fix?
Thanks

 

probably piston slap

worry about it when it does it while warm


mine has always done it, and still does it today after a rebuild, the pistons were checked and i was told they were fine. so they were used again.

 

More than likely its the Hydraulic lifters..

Use a long screw driver held in a closed fist against your hear as a stethascope, push the end against the cam covers and have a good listen, if its lifters the sound should be right up above the top end.. Probably inlet lifters as they dont get as much oil as the exhaust ones.

If its the lifters dont worry about it, all cars with hydraulic lifters start doing this at a certain age and the Impreza is not really any different to any other car, other than being a flat four..

 

you could well notice a difference with an oil change,when did it last have one? did you use the correct grade oil?a lot of people think the correct grade of oil is not really important but it is.a search on here will give you all the answers you need as to grades and manufacurers.
hope this helps.

 

Hasn't the '98 got solid lifters, with over bucket shims ?


Mark.

 

Check the wastegate solenoid.. is it attached to the cars body ? and with rubber bushings attached ?

In New Age models this problem asually arises:

"the boost control solenoid starts cycling at anything over ~3% throttle. basically anything off idle.

in the cold the rubber bushings that isolate the solenoid from the chassis of the car get harder and conduct more acoustic energy as it cycles. this is heard in the cabin as a clicking/tapping/rapping/etc sound.

since the frequency of cycling is electronically determined by the ecu (and is fixed at some 15Hz or so) it will not change in relation to engine rpms."