Hi, a new member here with a question!

I have an old S40, 1.8 – 98 which has done just less than 50k miles. I recently had it fully serviced and as I drove home from the garage the engine started to produce a strange sound. I took it back to the garage but obviously they can’t reproduce the problem…

When the engine is cold everything is fine and it runs like a dream but after 5-10min when the engine goes above 80c the noise starts. The noise is there if the engine is running at 2100RPM or if I put some load on the car, for example if I try to accelerate fast from 20mph in 3rd gear. Apart from those two scenarios it runs really smooth. I can reproduce this 100% of the time.

The noise it self is fairly loud (if I turn up the music I can till hear it). It sounds a little bit like small explosions or like a hot rod car.

My first thought was that it is misfiring, maybe a vacuum leak or something but the check engine light doesn’t come on which I think it would if it was misfiring?

Any ideas about what it might be?

Thank you

 

Welcome aboard.

If the problem wasn't there before you had it serviced the garage must have done something wrong. If they can't reproduce the problem but you can, I suggest that you take the car back and take the service manager out for a test drive.

If they broke it they should fix it.