M20B25 knocking sound!!!

Post Tue Dec 27, 2016 12:28 pm

So i have installed a new engine in my car after building it.. (was seen and heard running before removing from doner car)

Now that the engine is in my car it fires up staright away and all wireing is connected corerctly it makes a clicking/knocking sound when running.

The sound after investigating is not coming from the head or the block but it seems to be the loudest wen you put your ear to the top of the inlet manifold. Oil i circulating as it should and the engine runs well but sounds as if its on 5 cylinders..

Could this be injector related?
Has been fiited with new plugs etc

Any ideas what to check next? Before i startrd striping it down!!!

Will be doing a compresion test tommorw but im gutted right now!!

Any help please.....

Post Tue Dec 27, 2016 3:23 pm

After ensuring you have actually wired it all up correctly (are the spark plug leads in the correct firing order, and are the new spark plugs of the correct type and gapped properly?), I would check the valve/rocker arm clearances are correct:

http://www.e30zone.net/e30zonewiki/inde ... M20_engine

Post Tue Dec 27, 2016 5:45 pm

Gonna sound stupid, but it caught me out (and someone else on YouTube too), but have you checked the pulleys are all tight?

I'd left the bolts loose on the water pump pulley, couldn't pin down the noise, but found it a little loose. Once tightened: silence

Post Sat Dec 31, 2016 10:19 pm

Thanks guys will check all of these items...

Gona try to adjust tappets too!

After check the whole engine bay with a stethoscope iv narrowed the sound to be coming from the centre of the cam cover and the bmw logo on the inlet manifold.. these are the two loudest points when the knock ocours

The spark plugs if been supplier with from euro car parts are the kind with 4 prongs at the end where as the ones that came out where single prong... will this be a problem?

Leads are correct however i have used the following items from my 2.0 engine, will this cause isssues:

Ht leads and distributer
Engine loom and crank sensor and pulley?

Thanks and happy new year to you all