Re: Strange oil pressure problem
[Re: Hutch]
#1276925
07/31/12 01:53 AM
07/31/12 01:53 AM
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Joined: Aug 2003
Posts: 43,228 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,228
Bend,OR USA
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Pull the bypass valve plug, spring and piston out and clean them up, do the hosuing bore also It, the valve and piston, needs to slide in and out with no tapping or forcing, I've seen that in the past . One sure way of telling is to remove the pump and bypass plug and turn the pump so the bypass valve and piston are pointing down, if the piston slides out and the valve stays in the pump housing clean it out It only takes a tiny bit of grit between the pump housing and valve to make it hang up in the bypass position, especailly when new
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Strange oil pressure problem
[Re: Hutch]
#1276927
07/31/12 02:57 AM
07/31/12 02:57 AM
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Joined: Jan 2003
Posts: 5,445 So Cal
Sinitro
master
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master
Joined: Jan 2003
Posts: 5,445
So Cal
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Pull the oil pump drive shaft.. Some drive gears were not pinned and can work loose, making unreliable operation.. Just my $0.02...
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Re: Strange oil pressure problem
[Re: Sinitro]
#1276928
07/31/12 12:37 PM
07/31/12 12:37 PM
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Joined: Jan 2003
Posts: 5,875 communist bloc of new jersey
jamesc
master
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master
Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
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Quote:
Pull the oil pump drive shaft.. Some drive gears were not pinned and can work loose, making unreliable operation..
Just my $0.02...
it could be the pump drive but not for the reason you mentioned. if the gear were to turn on the shaft the engine would lose time, check the condition of the hex on the shaft
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Re: Strange oil pressure problem
[Re: Hutch]
#1276930
07/31/12 01:33 PM
07/31/12 01:33 PM
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Joined: Aug 2004
Posts: 2,128 sweden
sshemi
top fuel
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top fuel
Joined: Aug 2004
Posts: 2,128
sweden
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Re: Strange oil pressure problem
[Re: sshemi]
#1276931
07/31/12 01:38 PM
07/31/12 01:38 PM
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Joined: Nov 2003
Posts: 1,840 NW Indiana
fbs63
top fuel
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top fuel
Joined: Nov 2003
Posts: 1,840
NW Indiana
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Sounds like an air leak in the suction side. I would look for a crack or bad seal at the pipe thread end. Also what lifters are in it? I have seen the dumbell shaped lightweight solids cause oil pressure problems.
Last edited by fbs63; 07/31/12 01:41 PM.
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Re: Strange oil pressure problem
[Re: Hutch]
#1276935
07/31/12 03:00 PM
07/31/12 03:00 PM
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Joined: Nov 2003
Posts: 2,715 closer to Canadian beer!
torkrules
I'm neurotic
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I'm neurotic
Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
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Quote:
Working on a customers car and it has oil pressure fits. When it reads no oil pressure it has none(at the guage port with the line off). Eliminate the guage , oil pump (melling HV cast iron style) , bypass , guage lines , oil filter as they have all been tried to death. Oil pickup is in good shape and away from the bottom of the pan. Oil level is correct. Has 1/2" pickup in a standard center sump pan (7qt).
Its a 440 and when you start the motor it will be fine and the oil pressure will be fine until you turn the car off. The next startup it will have no oil pressure even if you rev it. Simply shut the car off and restart (some times 2 or 3 times) and its fine. It goes from 80 psi to zero then corrects itself right back to 80 again on a restart. Sometimes its fine for many restarts. There is no pattern to this.
Im puzzled and its wearing me out. No metal in the oil , pan has been off and its clean.
Any ideas before I tear it all apart?
Hutch
Pump is losing prime for some reason. I used to see this on my 496 wedge when I changed the oil. As soon as I took the filter off, the pump wouldn't prime. I had to spin the drive in reverse and squirt oil into the hole in the pump next to the threaded nipple.
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Re: Strange oil pressure problem
[Re: Hutch]
#1276936
07/31/12 03:09 PM
07/31/12 03:09 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I seen this on my Jeep 4.0... it was excessively worn bearings... when the oil heats up the pressure would drop to almost 0... I changed the bearings and pump and its fine now
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Re: Strange oil pressure problem
[Re: Hutch]
#1276941
07/31/12 08:56 PM
07/31/12 08:56 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Have you pulled the valve covers. maybe has a bent pushrod allowing the lifter to be kicked up high enough to uncover the oil galley but unlike a flat tappet which usually kicks them right out it would be held somewhat in place by the link bar and drop down into place eventually?? Just a thought??
Last edited by Dodgem; 07/31/12 08:56 PM.
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