M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: KenC on December 31, 2009, 06:18:49 PM
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So my #4 cylinder is dead... 50psi or so upon compression test. The car was idling for ~2.5 hours, started to run a little rough, I thought it might have been carbon build up on the plugs so I revved the engine up. It idled fine again for 5-10 min and then got pretty rough again. I pulled the plugs and #4 was full of gas (3-4 table spoons... like swimming in fuel).
I'm deciding whether or not to rebuild the bottom end, or just purchase another used block.
I've completely torn apart an M42 before aside from the bottom end. I'm familiar with the parts and such, but not super familiar with the process by which to rebuild it. Cylinders 1,2, and 3 are great, so I'd probably just replace the rings on #4, and rehone it if it looks scarred.
Any advice? What does it all entail? New crank bearings?
M44 crank time?
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Rebuild requires bottom & top end gasket kits, piston rings, crank main bearings, conrod big end bearings, a new oil pump rotor set, oil pressure relief valve and cyl head bolts.
I would replace rings on all 4 cylinders. May just be cheaper to buy a reconditioned block or a used motor complete.
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I'd be looking for a decent used block and just compare to a rebuild. Search for "e30 LS1 swap" and I'm sure you'll find a few lonely M42s.
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So my #4 cylinder is dead... 50psi or so upon compression test. The car was idling for ~2.5 hours, started to run a little rough, I thought it might have been carbon build up on the plugs so I revved the engine up. It idled fine again for 5-10 min and then got pretty rough again. I pulled the plugs and #4 was full of gas (3-4 table spoons... like swimming in fuel).
I'm deciding whether or not to rebuild the bottom end, or just purchase another used block.
I've completely torn apart an M42 before aside from the bottom end. I'm familiar with the parts and such, but not super familiar with the process by which to rebuild it. Cylinders 1,2, and 3 are great, so I'd probably just replace the rings on #4, and rehone it if it looks scarred.
Any advice? What does it all entail? New crank bearings?
M44 crank time?
Sounds like a failed injector on that cylinder.
I'd suck the fuel out and put a couple tablespoons of oil in it.
You may have just washed the cylinder wall down and lost compression.
Redo the compression test and do a leak-down. You may have no problem.
(If you've already done this part just ignore me! :cool: )
Dave
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Sounds like a failed injector on that cylinder.
I'd suck the fuel out and put a couple tablespoons of oil in it.
You may have just washed the cylinder wall down and lost compression.
Redo the compression test and do a leak-down. You may have no problem.
(If you've already done this part just ignore me! :cool: )
Dave
I'm ashamed I didn't think of this first. Def try it, you have nothing to loose. Good time for those 19# disc injectors, eh?
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Sounds like a failed injector on that cylinder.
I'd suck the fuel out and put a couple tablespoons of oil in it.
You may have just washed the cylinder wall down and lost compression.
Redo the compression test and do a leak-down. You may have no problem.
(If you've already done this part just ignore me! :cool: )
Dave
Way ahead of you :). I think I fried the ring when I drove it ~2mi with the failed plug at high rpms :-/.
Injectors are brand new and have maybe 1k miles on them.
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They never start running better without fixing something.... :)
Hopefully it just washed the ring and did not hurt the cylinder walls.
Dave