cant diagnose engine fault

[westie88 0]

:banghead: iI over-reved my engine causing it to imeadiatly to lose power.theres no smoke and starts okay,idles a little rough but backfires through the intake when reved.

at 1st i thought it was a head gasket or valve related but there seems to be no mechanical fault and theres no water surging in the radiator.

im thinking it could be timing related or an intake leak. the timing can not be adjusted manualy as it is motronic .

is there a common fault relating to censors or the computer ? any other suggestions?arrrrrgh!

[smokenbaby 0]

did you over rev on down change or did you just rev to redline. If you over revved on down change then there is every likelyhood that the timing belt (m20 motor) or chain (e36 and newer) has jumped a tooth.

[westie88 0]

its an auto so it poped when i hit the kickdown,ive been told that if the cambelt had jumped it would be hard to start or would not start at all.i will check it out anyway.I just want to be sure what the problem is before i go ripping out the radiator or head to get to it.

[Jimocles 0]

or possibly a bent valve

managed to do that on my dads Jag many years ago

and it cost me lots and lots

[westie88 0]

might have to bite the bullet & take the head off,it will be worth doing the valves anyway.ill check the cambelt as i go.

thanks for your advice.

[Guest Andrew]

Rocker arms start to break at 8000 rpm +

[CaM 0]

check the compression, That'll determine whether or not you have a bent valve or something gay like that, don't go rushing into pulling the head off just yet...... It's not smoking, using water, or knocking?? breathing any heavier through the crankcase breather than normal???

wont be rocker arms in my opnion, I dont see how it could have hit anywhere near 8k just on the auto kickdown

also could be something as tedious such as leads or a crook plug or something stupid like that, cracked dizzy cap, broken the tip off the distributor rotor maybe?(i dont know bmw engine distributors that well)

worth a try

[westie88 0]

cehecked compresion,4 cylinders @ 150 ,2 @ 130-140.not sure if its a huge difference.

[CaM 0]

ample compression, obviously not a bent valve

[318is 0]

Put a couple of squirts of oil into the cylinders before taking a reading. If the compressions comes up alot from a 'dry' test, you have ring damage. Possable even piston damage.

[westie88 0]

thanks, ill add a reply when i suss it out in the weekend incase someone else comes acrooss the same problem.

[westie88 0]

took off my rocker cover and found one of my rockers had shatterd in half.

the valve has popped back up so i dont think it jammed.

[petone 0]

Happened to my mate but all the exhaust rockers broke. Check your valve adjustment people!

[CaM 0]

f**k man, check nothings floating round in there