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87 coupe deville
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4 Posts
Discussion Starter #1
i have a 87 deville with the main bearing thump what is the part number thati need to correct the problem,and do i have to repalce both halves of main bearing number 1. does anybody have a copy of the gm bulletin that they could post on the board thanks. oh i am getting a egr code too would this make the same noise i torque brake the engine and you can hear the thump.
 

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1991 Deville / 1989 BMW 635csi
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896 Posts
Just drive the car, my 87 deville also has it, but it didn't change my oil pressure, and the part is discontinued. I've tried 4 different part numbers and 3 different dealers, apparently they have been changed and what not. So i gave up, yes it is annoying and embarrasing, but oh well. My car has balls and runs perfect. What is your mileage, my dad's old 87 deville now has 205,000 miles on it with orignal engine and it hasn't had head gaskets or intake fized and it still runs real strong. New owner drives it everyday happy. So don't worry about this thump,
 

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87 coupe deville
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4 Posts
Discussion Starter #3
is there anyway that you can quiet this noise i tried rotella 15-40 that didnt do much at all oh and my car has 128,000 miles on it.
 

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93 Sedan Deville 4.9L
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Your egr code could be causing a ping sound which is best heard on acceleration. I dont have a main bearing thump that I know of on my 4.9 so not sure what it sounds like, but i do have some noise related to egr and timing/fuel octane being off.
 

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Cadillac
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Man,I miss the days of the HT 4100 the 4.5,and the 4.9 Liter.There was always work at the dealer on these engines! Anyways,there was a bull. on replacing the # 1 and #5 main bearings.As long as the crank does not look like a record(all groved) generally just replacing #1 and #5 will take care of the thump.Usally the noise is only there hot and in gear at an idle.Get an oil pan gasket(they are composite and have been updated several times over the years)get a oil pump o-ring,and #1 and #5 main bearings.Release the serpentine belt-this will take pressure off of the crank-and yes,you must replace the upper and lower bearing half's.As far as I know the bearings are not discontinuned-but I can check tomorrow for part #'s.Just roll the old main bearing out of top half,put oil on bearing and roll the new in.Also,always dip the main bolts in oil before reinstalling and torqueing the bearing cap.
 

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Man,I miss the days of the HT 4100 the 4.5,and the 4.9 Liter.There was always work at the dealer on these engines! Anyways,there was a bull. on replacing the # 1 and #5 main bearings.As long as the crank does not look like a record(all groved) generally just replacing #1 and #5 will take care of the thump.Usally the noise is only there hot and in gear at an idle.Get an oil pan gasket(they are composite and have been updated several times over the years)get a oil pump o-ring,and #1 and #5 main bearings.Release the serpentine belt-this will take pressure off of the crank-and yes,you must replace the upper and lower bearing half's.As far as I know the bearings are not discontinuned-but I can check tomorrow for part #'s.Just roll the old main bearing out of top half,put oil on bearing and roll the new in.Also,always dip the main bolts in oil before reinstalling and torqueing the bearing cap.
Man,I miss the days of the HT 4100 the 4.5,and the 4.9 Liter.There was always work at the dealer on these engines! Anyways,there was a bull. on replacing the # 1 and #5 main bearings.As long as the crank does not look like a record(all groved) generally just replacing #1 and #5 will take care of the thump.Usally the noise is only there hot and in gear at an idle.Get an oil pan gasket(they are composite and have been updated several times over the years)get a oil pump o-ring,and #1 and #5 main bearings.Release the serpentine belt-this will take pressure off of the crank-and yes,you must replace the upper and lower bearing half's.As far as I know the bearings are not discontinuned-but I can check tomorrow for part #'s.Just roll the old main bearing out of top half,put oil on bearing and roll the new in.Also,always dip the main bolts in oil before reinstalling and torqueing the bearing cap.
Do u know the bearing I need for number 5 I can find the one for #1 but not #5
 
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