this is my brothers car with a m42 in it. this just started yesterday... but the knock sensor has been out awhile with the CEL on. i know its easier with a video but we would start the car and right from the start it was a deafening shriek of a noise coming from the engine. i couldnt tell if it was belts/pulleys or internals if not the oil pump. now if my brother tries to start it it just shuts off while still making the noise during startup. any ideas? the car was maybe half a qt low of oil at the time and so it wasnt oil starvation but could the pump have gone out?
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edited with a lil more info, any help is much appreciated.
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A loud shriek could have been a lot of things...I'm assuming that since it has knock sensors that it is an e36. Shrieks are usually belts, at least in my experience. There is a chance that the water pump is seized (relatively common when the bearings go out) so when the engine is started, the belt has to slide across the stopped pulley, thus producing a shriek... pull the belts and make sure that everything spins freely.Comment
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mega bump, sorry been busy as hell on my e30 (rough idle, transmission, driveshaft) and my moms e34 (overheating). So since my brothers been unemployed I just haven't even paid any attention to it except for spare parts haha.
so enough excuses...it wasn't the belts. I spun the motor by the crank and all the belts/pulleys/water pump rotated fine. But, when rotating it, for about 1/4 - 1/2 of the rotation, it sounded like something grinding. I really think the bottom end seized or maybe even the timing chain. this thing sounded like a diesel right before this happened and seemed like it had loss of power.
we did a compression test and all was well from what i remember, and also a spark test which it failed. But that means it wouldn't have started correct? because when it did this before the motor failed...it would start but make that loud ass shriek. even put in new wires and plugs and nothing. hope ive given one of you m42 guru's enough info hah.
edit: something i wanted to mention, the engine fan was missing a blade possibly causing it to be off balance. not sure how that might effect things.Comment
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Is it an E30 M42 or an E36? E30 M42s do not have knock sensors. Pull the VC and see how the timing chain, sprockets, and guides look.
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will do.
it's an e36, thought they were the same engine? i'm uneducated on most cars except the e30 m20 cars. don't be surprised if it's a week or so before I come back saying i worked on it...but i will be checking daily for any other advice so please don't ignore!!! thanks for the help, Ian!Comment
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If you haven't done this already, take off the belts and spin everything (alternator, water pump, power steering pump, A/C Compressor) by hand to check for noise or excessive play.
This may help:
Another thought is....does it sound like the starter is staying engaged, or not engaging properly?Comment
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yea it sounds like the starter's working fine (from memory); it'll do everything it needs to but actually ignite and run. it doesnt fire up anymore but it will engage the starter. when it first started making this noise it would actually start up and run for awhile until it was shut it off (after a minute) but would make that loud ass shriek. i mean it was deafening....sounded like it came from the bottom end.Last edited by jw 325ic; 07-30-2011, 11:13 PM.Comment
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