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rear main replacement issue...

josh89xj

NAXJA Forum User
Location
Minnesota
A few weeks ago i did my rear main seal,i took out rear cap cleand up a bit replaced seal and put her back together, now, i have a bad knock and low pressure. When i first started it it ran perfect and drove it about 500 miles before lost pressure and got noises. So I bought a used 4.0 for real cheap it has 80000 miles on it and i want to put a new rear main in while i have it on the stand but im afraid ill F--k it up again or have the same issue..What could have gone wrong?
 
If you had to take the oil pump out to get the pan off, my first guess is that a bad gasket or something caused it to starve for oil. It should be a lot easier to get everything right and check it if it's on a stand.
 
josh89xj said:
A few weeks ago i did my rear main seal,i took out rear cap cleand up a bit replaced seal and put her back together, now, i have a bad knock and low pressure. When i first started it it ran perfect and drove it about 500 miles before lost pressure and got noises. So I bought a used 4.0 for real cheap it has 80000 miles on it and i want to put a new rear main in while i have it on the stand but im afraid ill F--k it up again or have the same issue..What could have gone wrong?
With only 80k on it why F--K with it?
If it ain't broke don't fix it.
 
langer1 said:
With only 80k on it why F--K with it?
If it ain't broke don't fix it.
Second that, I just got through changing one, that wasn't leaking ( Guess I'll change it as long as I have the pan off anyway) and now it leaks.
 
Is it possible half of the rear main bearing is laying in the bottom of the can you used to clean the bearing cap? Reason this springs to mind, is after reassembling my motor, I noticed a serious, oh chit, a rod bearing laying in the driveway. I'm glad it was one of the old ones I'd dropped, but my heart stood still for a few seconds.
There is a gasket in the lid for the oil pump, it has to be complete or the pump sucks air.
Possible you put too much silicon where the two main seals meet and the cap didn't seat all the way.
Also possible your connecting rod bearings, just picked that time to fail. Mine got noisy quick and seemed to go from OK, to real loud in a period of a couple of weeks.
One reason IMO, that some rear mains seals fail, is excessive wear in the rear main bearing, which seems to go right along with reduced oil pressure at the gauge.
 
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