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  #1  
Old 11-19-2017, 12:08 PM
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80 PSI oil pressure???

Long story, short.....New distributor gears turns into bolt backed out of cam gear and new timing gears/chain and timing cover. Might as well replace the pump since I am there. Ran fine for a few miles. Now it makes about 80 psi of pressure and seems to have pushed out the rear main seal (or at least it has started pouring oil after this started). The gauge is right. 86 360 with 43K original miles. It has not been driven much in the last couple of years due to the dizzy gears issue.

Any ideas, before I put a rear main in to only have it pushed out again.
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Old 11-19-2017, 02:22 PM
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Pressure relief valve stuck? Wrong spring installed? Been a while since I've done an AMC oil pump, but I know the Buick kits come with multiple springs.

That's my best thought.
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  #3  
Old 11-19-2017, 04:09 PM
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I hope the mechanic remembers which spring he used.
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Old 11-19-2017, 04:48 PM
Ristow Ristow is offline
 
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the rear main seal does not see engine oil pressure and cannot be pushed out.

on the late dash a disconnected gauge will peg. check the wire to sender.
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  #5  
Old 11-19-2017, 05:28 PM
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Woodchomper Woodchomper is offline
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I'd would kind of like to hear the long story. Especially, if it goes something like, "The mechanic said... so he did...". I can honestly say I have never seen an AMC V8 where the cam gear bolt backed out. I'm not saying it couldn't happen but this is the first time I've heard of it.

Most of the people that have worked on these engines for years are very skeptical of new replacement timing covers because so many people have had such bad outcomes with them in the past. The next thing to worry about is the alignment of the oiling slot on the cam timing gear. After that it is the choice of gears used for the cam/distributor drive.

The good news is that most of the AMC oiling and timing cover problems are well documented and easy to find on the internet. The bad news is that unless a mechanic is intimately familiar with the problems of AMC engines, he/she stands the possibility of overlooking a potential problem. This is not an indication of a bad mechanic, it is a reality of crappy offshore parts being made for our engines.
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  #6  
Old 11-19-2017, 06:28 PM
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Ristow...the gauge is correct and working. Checked it.

longer version.....had some one put carb/intake/hei on. He didn't swap the new and old dizzy gears. sheared the cam gear. Left quite a few things loose. Took it to a different mechanic. He replaced the sheared first set with a matched Bulltear set. He got it all back together and running. After about 5 minutes of idle it made a loud pop and quit running. I watched him loctite and torque the cam gear bolt....Housing busted and the bolt in the bottom of the cover with the rest of the timing chain. He replaced all of that and I ordered a new pump/cover kit from BJ's. He got it all back together and running. Runs great. Started having high oil pressure so I checked it with mechanical gauge. Now it's leaking a lot of oil from the rear main. Had a rear main "pushed out" by heavy weight oil years ago....or so I was told by a Chevy dealer.
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Old 11-19-2017, 06:51 PM
440sixpack 440sixpack is offline
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You can't push out a rear main with oil.

Maybe it's just coincidence your rear main started leaking , but are you sure it's the rear main and not leaking down from above ?

80 psi is a lot for an AMC. I can't say it's not 80 but I've never seen it. you say your gauge is correct, have you checked it with a mechanical gauge to confirm it ?

Something just doesn't add up. if it is 80 I wouldn't care for it myself, the wimpy pump drive on an AMC is only going to be worse with extra pressure. and it's not need anyway, 10 psi per 1000 rpm is more than enough.
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Old 11-19-2017, 07:56 PM
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Quote:
Originally Posted by 440sixpack
You can't push out a rear main with oil.

Maybe it's just coincidence your rear main started leaking , but are you sure it's the rear main and not leaking down from above ?

80 psi is a lot for an AMC. I can't say it's not 80 but I've never seen it. you say your gauge is correct, have you checked it with a mechanical gauge to confirm it ?

Something just doesn't add up. if it is 80 I wouldn't care for it myself, the wimpy pump drive on an AMC is only going to be worse with extra pressure. and it's not need anyway, 10 psi per 1000 rpm is more than enough.

That's what I thought. the Chevy dealer swore that's what caused it. I checked with a mechanical guage. It only stays at 80 until the oil gets low.... LOL
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  #9  
Old 11-19-2017, 08:19 PM
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Woodchomper Woodchomper is offline
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Glad to see you used good parts in your rebuild. You are off to a great start by using a mechanical gauge to verify your oil pressure. I think I would change the oil filter (no orange ones) and remove the lower part of the oil pump to verify the plunger moves freely and that there are no shavings in the plunger port. The spring that comes in the Melling oil pump kit has always been good for me.

Aftermarket AMC valve covers, especially the cheap chrome ones, are really good at leaking at the rear of the engine. Also there are oil two galley plugs at the back of the block that could potentially leak. If you are really getting 80 PSI to the engine maybe the leak is from the fact you are pumping more oil to the valve train then can drain back to the pan and the excess oil is escaping out of a valve cover.

What weight oil are you running?

Good luck and keep us posted on your progress.
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Old 11-19-2017, 09:06 PM
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Four years ago I chased a (huge) oil leak at the rear of the engine. Sort of simulated a rear main seal leak, but oil was clearly coming from higher up on the engine. I finally figured out it was leaking from both valve covers. Replaced the gaskets with good cork, Permatex, and carefully torqued them down. Last spring, started noticing the oil drips on the driveway -- some of the valve cover bolts were so loose they could actually be turned by hand.

Re-torqued them, and no more drips.

It's just another maintenance item on these later engines.
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Old 11-19-2017, 09:22 PM
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I will check the back of the engine again...may have missed that. I guess I will pull the pump and check it.

I am not sure what oil we put in it. I used some zinc additive to make sure all the new parts wore in well.
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  #12  
Old 11-20-2017, 07:35 AM
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TexasJ10 TexasJ10 is offline
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I agree that a filter change is in order and oil leaking from the valve covers is more common than rear seal. You had so much damage from the distributor gear issues that there could easily be a lot of debri floating around in your engine. Any oil passage blockages could cause higher oil pressures. A lot of people assume the higher the oil,pressure the better, but you were right to investigate what is causing it.
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  #13  
Old 11-20-2017, 10:45 AM
440sixpack 440sixpack is offline
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On Mopars you can find 1/8" plugs on the block to test oil pressure, on AMC's I can't remember ?

If there is a place on the block to test the pressure this would tell you if you're really getting that much pressure or if you have a problem before it hits the block. a restriction or something.

You could try a lighter oil if what you have in it is heavier than normal.
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  #14  
Old 11-20-2017, 01:52 PM
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*****UPDATE*****

Oil changed. Pressure back to normal...may have been some really thick break in oil the mechanic used?????

Still dripping oil out the back somewhere. Didn't see any oil on the back of the heads/valve covers. None on the top of the bell housing. Narrowing it down to the rear main.....
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  #15  
Old 11-20-2017, 04:05 PM
440sixpack 440sixpack is offline
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The back of the intake is a common leak.
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  #16  
Old 11-20-2017, 08:15 PM
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Quote:
Originally Posted by 440sixpack
The back of the intake is a common leak.

I will get a mirror back there tomorrow so I can see better.
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  #17  
Old 12-12-2017, 11:49 PM
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DarkMonohue DarkMonohue is offline
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I know this isn't fresh news anymore, but since someone had his hands around the carburetor, make sure the PCV hose is not kinked shut. That caused a huge rear main seal leak on my 360 by increasing crankcase pressure. Replacing the kinked hose with a smooth loop (since the original molded hose is NLA) dropped the crankcase pressure and eliminated the leak at the rear main.
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Old 12-13-2017, 03:59 PM
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The line isn't kinked...but I may replace the PCV anyway.
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Old 12-13-2017, 04:10 PM
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The line may even be collapsed internally. Just something to look into.

If your oil filler cap keeps popping up rather than staying down in the tube, you likely have too much crankcase pressure.
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