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390 rebuild - on stand - no oil pressure (Read 4267 times)
brucelindholm
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Pierre, SD
390 rebuild - on stand - no oil pressure
03/31/12 at 21:01:51
 
Hi guys -  
 
I am rebuilding my 1970 390 - new pistons, cam, new bulltear cover, new dist gears, etc etc.  I put oil and filter on to day to prelube    it before installation.  I pit in my trusty prelube tool (old distributor) and spun it (clockwise) with a drill.  the drill didn't "pull down" and the oil didnt come out the pushrods.  Thinking I got a wrong filter, I put a different one on - no change.  I took the filter off and turned my pre lube tool and shot oil across the shop... I took off the pressure relief spring and the "valve" end came right out.  I took out the oil pressure sending unit on the front of the engine - while turning the oil pump it does not build enough pressure to push against your finger - although without a finger over the hole oil will flow out.  I used a new oil pickup and thread sealant where it screws into the block (just a little).  I have a stock oil pan.  I welded a small spacer on the pump screen housing to maintain some distance from the oil pan - so the pan doesnt suck up the oil pan.
 
I also disassembled the oil pump gear housing looks fine - but just for grin I removed the "wear plate" I got from bull tear.  No change.  I got the gears with the little "cuts" on them - if fell out of course and now I cant remember which way the cuts go - not that big a deal but if anyone knows I would appreciate it.
 
The bigger problem is the oil pressure issue.  My cam bearings were real tight - not sure if that matters.  HELP!  
 
Thanks
 
Bruce
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SC397
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Re: 390 rebuild - on stand - no oil pressure
Reply #1 - 03/31/12 at 21:27:23
 
Did you pack the oil pump cavity full of petroleum jelly before trying to prime the pump?
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old_and_rusty
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Re: 390 rebuild - on stand - no oil pressure
Reply #2 - 03/31/12 at 21:32:30
 
Check the timing cover gasket to make sure ALL the holes are punched out. Some after market vendors aren't checking their products enough. You might try packing the oil pump cavity with Vaseline.
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brucelindholm
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Re: 390 rebuild - on stand - no oil pressure
Reply #3 - 03/31/12 at 21:57:51
 
I packed it with assembly lube - I've done three or four that way and they came up to pressure right away - sounds like I get to take the T/C cover off.  Fun fun.  The only silver lining is that I have discovered it now...
 
Bruce
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old_and_rusty
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Re: 390 rebuild - on stand - no oil pressure
Reply #4 - 03/31/12 at 22:08:09
 
Yea, 'dem AMC engines are kinda' finiky, needin' oil and all that. LOL
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WestOzJavelinMan
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Re: 390 rebuild - on stand - no oil pressure
Reply #5 - 03/31/12 at 22:30:20
 
I had the timing cover gasket clocking the oil passage on mine, the passage was punched in the gasket but the little piece had ont been removed:
 

 
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amxlonnie
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Re: 390 rebuild - on stand - no oil pressure
Reply #6 - 04/01/12 at 04:49:30
 
Make sure the pressure releif valve is installed correctly. the "pin" end goes in first and the spring goes in the hole. make sure it goes all the way in !
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brucelindholm
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Re: update 390 rebuild - on stand - oil pressure
Reply #7 - 04/01/12 at 20:04:09
 
ok update - I took the timing chain cover off - the gasket had all the appropriate holes.  I made sure the pressure relief spring was in the cup.  I poured oil in the inlet side of the pump cavity turned it by had and watched the oil come out the outlet side of the pump.
 
I put the tc cover back on, pulled the rear oil galley plug, spun the pump and oil flowed out - not with pressure though.
 
I took off the intake and spun the oil pump... hmmmm - oil flowing from the t/c side through the drain holes into the valley of the block.  
 
I unhooked the valley oil line, spun the pump and both the front and back fittings (the now unconnected ones in the block) flowed oil.
 
Still no oil to the rockers
 
I took off a rocker and pushrod so I could see if oil is coming through the lifter.  I spun the pump and a small amount of oil filled in the pushrod seat of the lifter.  
 
So - I still dont know.  I think the oil "backflowing" through the tc cover is a hint, but I cant figure out what it is trying to tell me.. Please help if you can - thanks
 
Bruce
 
 
 
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RayAMX
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Re: 390 rebuild - on stand - no oil pressure
Reply #8 - 04/01/12 at 22:42:41
 
Check and make sure the front lifter gallery plugs are in( behind the cam gear). I forgot mine once and it did the same thing, I was in to much of a rush and fogot those. All the oil is going in the timming cover and then comming back through the the front valley holes.
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brucelindholm
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Re: 390 rebuild - on stand - no oil pressure
Reply #9 - 04/01/12 at 23:47:13
 
yeah - I checked and the front galeey plugs are in..  I was hoping I had forgotten them. Smiley
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WestOzJavelinMan
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Re: 390 rebuild - on stand - no oil pressure
Reply #10 - 04/01/12 at 23:52:10
 
Check the galley plugs are not in too far, I believe they can actually block the oil passage.  
 
Maybe sucking air somewhere on the suction side.
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ssAMX3002
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Re: 390 rebuild - on stand - no oil pressure
Reply #11 - 04/02/12 at 00:22:32
 
Are you running a roller cam? If you are then what roller lifters are you using?
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Rebel Machine
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Re: 390 rebuild - on stand - no oil pressure
Reply #12 - 04/02/12 at 00:55:12
 
Sounds like a clearance issue of some kind since there's no pressure and all the galley plugs are installed... too much clearance somewhere. Didn't forget a bearing anywhere did you.....?
 
Look to see if the oil pickup is sitting against the bottom of the pan.
 
If you're using roller lifters it could be an issue with that like ssAMX3002 said.
 
-Steve-
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Re: 390 rebuild - on stand - no oil pressure
Reply #13 - 04/02/12 at 01:34:13
 

 You need to run the pump for quiet a bit of time before oil will begin to show at the rockers.
 
 SKeown
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brucelindholm
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Re: 390 rebuild - on stand - no oil pressure
Reply #14 - 04/02/12 at 01:59:09
 
Flat tappet cam, comp pro magnum lifters.  I did not pull the front galley plugs but will do tomorrow - since the front valley line goes into where the front galley plugs are - I dont think that's it, but it is an easy check.  I was thinking pressure loss too, but don't know why the oil would flow back from the tc cover through the block drains at the top of the valley.  
 
I know some times it takes a while, but not this longs, plus the pressure never built up against the drill motor.
 
Im sure I pit the main bearing in  Smiley
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