Author Topic: Why does my e30 m42 sound like a diesel engine? (Read 8709 times)

dblmikeusa1 · « **on:** August 29, 2009, 10:10:29 PM »

When I start it and let it idle the car sounds like a diesel.

what I know:
It has oil,
No idea if the chain tensioner has ever been replaced

Any one have an idea?

I will be replacing the valve cover gasket soon as oil is leaking from that area...

teh Phil · « **Reply #1 on:** August 30, 2009, 01:20:26 AM »

Take a long screwdriver and hold use it like a stethoscope on your timing chain cover. Is it coming from there?

roundel318 · « **Reply #2 on:** August 30, 2009, 08:39:10 AM »

some guy was doing a first start on a buildup and wasnt getting oil to the top end, it sounded very much like a diesel.

KenC · « **Reply #3 on:** August 30, 2009, 08:55:22 AM »

Make sure your spark plugs are seated well.

dblmikeusa1 · « **Reply #4 on:** August 30, 2009, 02:16:02 PM »

Quote from: roundel318;77622

some guy was doing a first start on a buildup and wasnt getting oil to the top end, it sounded very much like a diesel.

Was this on this site? What ended up being the issue?

Quote from: KenCopperwheat;77626

Make sure your spark plugs are seated well.

I will check that... curious how that would cause the issue...

Quote from: teh Phil;77612

Take a long screwdriver and hold use it like a stethoscope on your timing chain cover. Is it coming from there?

Will check soon

1991 E30 M42 · « **Reply #5 on:** August 30, 2009, 09:43:59 PM »

the last two m42's i had that sounded like a diesel the problem ended up being tore up rod bearings from sustained high rpm abuse

roundel318 · « **Reply #6 on:** August 30, 2009, 09:49:46 PM »

http://www.youtube.com/watch?v=goq3BWyl9Wk&feature=channel_page

then fixed at

http://www.youtube.com/watch?v=YuEMfLMKbEE&feature=channel_page

"Finally after no oil getting to the head the m42 is sounding right! "

ob_318is · « **Reply #7 on:** August 30, 2009, 10:22:22 PM »

I think this is a cylinder head problem. When i first purchased my 318, it sounded like a diesel truck (i remember some girls in a suv laughing at my sh*t)...but yea, turned out that I had a warped head, after replacing it, all was well...

dblmikeusa1 · « **Reply #8 on:** September 13, 2009, 10:12:27 PM »

Quote from: roundel318;77646

http://www.youtube.com/watch?v=goq3BWyl9Wk&feature=channel_page

then fixed at

http://www.youtube.com/watch?v=YuEMfLMKbEE&feature=channel_page

"Finally after no oil getting to the head the m42 is sounding right! "

Was it an oil pump? something clogged or broken?

Deftones · « **Reply #9 on:** September 14, 2009, 06:57:50 AM »

that sound is because the chain tensioner is empty of oil and until the oil gets inside and make pressure the chain is free to move and cause that noise.

i have a problem like yours, car seems running like disel at idle but after running a lot and high rpms the problem disappear, i think it's probably a combination of rich carburation (i have turned the screw on the maf), used plugs and maybe throttle heating deleting which cause bad combustion...

Asserti · « **Reply #10 on:** May 07, 2010, 03:53:46 PM »

where you able to find the problem?

jon885 · « **Reply #11 on:** June 11, 2010, 01:00:51 AM »

old thread revival!!

jmsra · « **Reply #12 on:** July 04, 2010, 12:56:17 PM »

I had the diesel sound after replacing the head gasket.
It turns out it was the cam gears off by one tooth exactly.
If you've never had the chain off then i would take a guess that your timing components are pretty well worn and causing the same result as being a tooth off on both cam gears. Good Luck!

lookitsranday · « **Reply #13 on:** October 18, 2011, 01:33:17 PM »

this happened to me where everytime i rev or in high rpm it sounded like a turbo school bus was in my e30. i replaced fan clutch and water pump (all the belts while i was there) the turbo sound was now gone.