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Strange oil pressure problem #1276924 07/31/12 01:46 AM 07/31/12 01:46 AM
Joined: Jan 2003 Posts: 296 Ontario Canada H Hutch OP enthusiast
Hutch OP enthusiast H Joined: Jan 2003 Posts: 296 Ontario Canada	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

Re: Strange oil pressure problem [Re: Hutch] #1276925 07/31/12 01:53 AM 07/31/12 01:53 AM
Joined: Aug 2003 Posts: 43,161 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,161 Bend,OR USA	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)

Re: Strange oil pressure problem [Re: Cab_Burge] #1276926 07/31/12 02:08 AM 07/31/12 02:08 AM
Joined: Jan 2003 Posts: 296 Ontario Canada H Hutch OP enthusiast
Hutch OP enthusiast H Joined: Jan 2003 Posts: 296 Ontario Canada	Done all that. Even installed another pump. Same deal. The press reg valve has no scratches on it or has it ever nor has it ever been stuck in the bore. Hutch

Re: Strange oil pressure problem [Re: Hutch] #1276927 07/31/12 02:57 AM 07/31/12 02:57 AM
Joined: Jan 2003 Posts: 5,439 So Cal Sinitro master
Sinitro master Joined: Jan 2003 Posts: 5,439 So Cal	Pull the oil pump drive shaft.. Some drive gears were not pinned and can work loose, making unreliable operation.. Just my $0.02...

Re: Strange oil pressure problem [Re: Sinitro] #1276928 07/31/12 12:37 PM 07/31/12 12:37 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	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

Re: Strange oil pressure problem [Re: jamesc] #1276929 07/31/12 12:41 PM 07/31/12 12:41 PM
Joined: Jan 2003 Posts: 296 Ontario Canada H Hutch OP enthusiast
Hutch OP enthusiast H Joined: Jan 2003 Posts: 296 Ontario Canada	Just changed the drive only because the old brass gear drive was wearing excessively. Did it with both drives for what its worth. Hutch

Re: Strange oil pressure problem [Re: Hutch] #1276930 07/31/12 01:33 PM 07/31/12 01:33 PM
Joined: Aug 2004 Posts: 2,128 sweden S sshemi top fuel
sshemi top fuel S Joined: Aug 2004 Posts: 2,128 sweden	Spinning bearing?

Re: Strange oil pressure problem [Re: sshemi] #1276931 07/31/12 01:38 PM 07/31/12 01:38 PM
Joined: Nov 2003 Posts: 1,839 NW Indiana F fbs63 top fuel
fbs63 top fuel F Joined: Nov 2003 Posts: 1,839 NW Indiana	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.

Re: Strange oil pressure problem [Re: Hutch] #1276932 07/31/12 01:43 PM 07/31/12 01:43 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	internet troubleshooting is never easy and it seems like you've been through this pretty thoroughly. that said it really sounds like the pump is losing prime. i would think even with the relief stuck open some it would still push some oil out the pressure port. oiling systems aren't very complicated so unless it's some bizarre problem it has to be something you've already looked at. i would concentrate on the suction side of the pump and that's a pretty straightforward setup. being it sounds like such a weird problem maybe using a drill and priming drive might be worth a shot to see if you can duplicate the problem without running/cycling the engine.

Re: Strange oil pressure problem [Re: jamesc] #1276933 07/31/12 01:45 PM 07/31/12 01:45 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	you would think if it was some sort of bearing problem it would show in other ways. i'm assuming this is a roller being he mentioned the bronze drive gear.

Re: Strange oil pressure problem [Re: Hutch] #1276934 07/31/12 01:52 PM 07/31/12 01:52 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	How much pressure does it start out with when cold

Re: Strange oil pressure problem [Re: Hutch] #1276935 07/31/12 03:00 PM 07/31/12 03:00 PM
Joined: Nov 2003 Posts: 2,715 closer to Canadian beer! torkrules I'm neurotic
torkrules I'm neurotic Joined: Nov 2003 Posts: 2,715 closer to Canadian beer!	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.

Re: Strange oil pressure problem [Re: Hutch] #1276936 07/31/12 03:09 PM 07/31/12 03:09 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	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

Re: Strange oil pressure problem [Re: MR_P_BODY] #1276937 07/31/12 06:01 PM 07/31/12 06:01 PM
Joined: Mar 2005 Posts: 2,644 North Carolina sasquatch master
sasquatch master Joined: Mar 2005 Posts: 2,644 North Carolina	You mentioned roller cam what lifters are you using and are the lifter bores bushed? Todd www.mopartsracing.com

Re: Strange oil pressure problem [Re: sasquatch] #1276938 07/31/12 08:48 PM 07/31/12 08:48 PM
Joined: Jan 2003 Posts: 296 Ontario Canada H Hutch OP enthusiast
Hutch OP enthusiast H Joined: Jan 2003 Posts: 296 Ontario Canada	No problem in the suction side. Keep this in mind. It doesn't lose oil pressure and it doesn't loose its prime. It either has it or it doesn't. It will go from having perfect oil pressure then you shut the car off and start it right back up and it has zero. shut it off and start it right back up and it goes back to 60-80 depending on temperature. I drove it 50 miles , shut it off for gas , started it up and it had zero. shut it off , started it again , back up right where it left off and I drove it all around until the next time I shut it off. Its just stupid. Hutch

Re: Strange oil pressure problem [Re: Hutch] #1276939 07/31/12 08:53 PM 07/31/12 08:53 PM
Joined: Nov 2003 Posts: 1,839 NW Indiana F fbs63 top fuel
fbs63 top fuel F Joined: Nov 2003 Posts: 1,839 NW Indiana	Did you try a different gauge?

Re: Strange oil pressure problem [Re: Hutch] #1276940 07/31/12 08:53 PM 07/31/12 08:53 PM
Joined: Dec 2006 Posts: 3,667 Arizona C Chris'sBarracuda master
Chris'sBarracuda master C Joined: Dec 2006 Posts: 3,667 Arizona	Bad Gauge? Chris..

Re: Strange oil pressure problem [Re: Hutch] #1276941 07/31/12 08:56 PM 07/31/12 08:56 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	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.

Re: Strange oil pressure problem [Re: Hutch] #1276942 07/31/12 09:05 PM 07/31/12 09:05 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: No problem in the suction side. Keep this in mind. It doesn't lose oil pressure and it doesn't loose its prime. It either has it or it doesn't. It will go from having perfect oil pressure then you shut the car off and start it right back up and it has zero. shut it off and start it right back up and it goes back to 60-80 depending on temperature. I drove it 50 miles , shut it off for gas , started it up and it had zero. shut it off , started it again , back up right where it left off and I drove it all around until the next time I shut it off. Its just stupid. Hutch That is a weird one.. hope you find it soon EDIT Just thinking... is the intermediate shaft long enough so it isnt jumping up on start up and spinning on top of the pump spline then when you shut it off it drops in Last edited by MR_P_BODY; 07/31/12 09:31 PM.

Re: Strange oil pressure problem [Re: MR_P_BODY] #1276943 07/31/12 09:33 PM 07/31/12 09:33 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	i'm trying to recap according to the OP Gauge, he says when it loses pressure it won't even pump oil out the pressure port. Bearings, if something is a problem bearing wise any engine that would go from 80# to 0 is going to show it some other way. Pump drive, said it's been replaced Pump, it's been replaced and they've been disassembled and inspected Filter, been replaced Lifters, if it was uncovering the galley it shouldn't come and go. if it had a bent or displaced pushrod the engine should show a problem by being noisy or running rough though i've never seen it happen i guess it could be possible the inner rotor is spinning on the drive stem but OP says the pumps have been inspected and if this was happening you'd think it might show metal in the oil although anything from that should go through the filter now just to make sure i'm understand you correctly it not only loses pressure intermittently on a restart but also when it's been running it will lose pressure while running? starting to sound like you need to call Father Merrin

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