4100 MOTOR

Tiny
ROBERT K
  • MEMBER
  • 2012 CADILLAC DEVILLE
I have a 87 deville with a 4100 motor with a knocking sound in motor.I changed the oil pump and put a gauge in pressure is good when engine first starts then drops to almost nothing couild this be bearings or a rod. Thanks robert.
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Friday, November 16th, 2007 AT 8:28 AM

3 Replies

Tiny
PEAR69
  • MEMBER
Hello Robert, did you change the oil pump because of the oil pressure problem? Was the engine knocking before you changed the oil pump?

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Friday, November 16th, 2007 AT 8:04 PM
Tiny
ROBERT K
  • MEMBER
YES IT DID KNOCK BUT PUMP WAS BAD IM THINKING OF REPLACING ALL THE ROD BEARINGS DONT HAVE ALOT OF MONEY TO WORK WITH. BUT I DO ALL MY OWN WORK. BUT NEVER HAD A KNOCKING MOTOR BEFORE. IS IT POSSIBLE ITS A BAD CONNECTING ROD AT THE PISTON PIN. OTHER THAN THE KNOCK IT RUNS FINE NO SMOKE NO OIL BURNING NOTHING. THANKS ROB.
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Friday, November 16th, 2007 AT 11:29 PM
Tiny
PEAR69
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Rob, I must be honest, there is no easy way to tell you this but, being that the oil pump was bad there is probably more damage than just rod bearings. The clearances inside a motor depend on oil pressure. If this pressure is interrupted even for a very short time, and I'm talking seconds here, there will be engine failure eventualy. If you are going through all the work of rod bearing replacement you must pull the motor, strip it down, send it to a machine shop to do the job right, why not just buy a short block. You'll have a new bottom end--new parts--no knock--and a warranty. The cost is cheaper. The fact that there is no oil burning or smoking doesn't mean that a bearing is not bad; this means that the rings are still sealing. But they won't for long because of the wobbling around of the crank or rods. Please send me a vote or some feedback if I have helped, also try to make a donation to this site. Good luck
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Saturday, November 17th, 2007 AT 2:48 AM

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