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Low oil pressure update.

2494 Views 28 Replies 8 Participants Last post by  Steve Wood
Ok guys here are some specifics. At start up my oil pressure is 40 psi @ idle (cold)and I can peg my VDO oil pressure gauge if I rev. After the engine warms up my pressure drops to 8-9 psi with engine idling 800rpm (hot). When the engine is warmed up my oil pressure while driving is 14 psi at 1200rpm, 16 psi at 1500rpm, 21-22 psi at 2000rpm. If the car kicks down to 3rd or I just build speed the oil press rises with rpm staying just above 10psi per 1000rpm. THE CAR HAS A BOOSTER PLATE ON THE OIL PUMP. When the new front cover was put on new oilpump gears were installed also. I also put a new oil pickup with screen and new gasket at this time. Why does my pressure differ so greatly hot and cold? I know oil thins as it heats but should I see this much of a difference? I use non synthetic 10w30. Steve you mentioned teflon from timing gears but I have a double roller set installed. The front cover is the one that takes the front seal from the outside (front) of the cover.
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Has it been this low since you installed the new cover and gears?

I think so Steve. I didn't really notice how much the pressure dropped off hot until about two-three weeks ago but it may have always done that. This is a freshly broken in motor and hasn't been in the car long (about 2 1/2 months).

[This message has been edited by Nasty Wendy (edited April 25, 2002).]
did you check the end clearance on the oil pump gears to be sure it was at the low end of the spec?

Do you know what the bearing clearance is?

Mechanical gauge or electrical? I wonder if it is accurate?

No to both of your questions Steve. I thought that new oilpump parts in the new cover would be in spec. I don't know what the tolerances are supposed to be. The gauge is a VDO electric gauge.
No, the clearance to between the plate and the pump gears needs to be .002-.003". You normally change this by using thicker/thinger gaskets.

Can you find a mechanical gauge to double check the electrical one? I may have a spare one if you cannot borrow one locally.

You loctite the oil pick up bolts?

You did not use a tensioner on the chain, did you?

No locktite was used. I did torque them to factory specs tho. I don't think there was a tensioner on the timing chain not sure.
Well, the pressure is way low for a new setup....in my opinion...I would say the first thing to do is verify the gauge reading.

Did you check the front cover to see if any of the passages were partially blocked by casting flashing?

I have a good 12-13 lbs at idle, motor just re-built. Just like Wendy, I'm showing 27# at 2400 rpm. My guage is electrical, and reads to 90 lbs.

To get at true reading, a mechanical guage is needed. Or if you are using a guage like mine, go and get one that reads to 60 lbs, or so.

I've got the cheapo 2" guages from Postons, and the only thing I expect out of them is repeatability. (if the pressure drops, then maybe it's time to worry) My engine builder double checked the reading, and oil pressure was where it should be..
No Steve, I didn't know to do any of these things. I guess I'll check my pressure and take it from there. Why shouldn't I have a tensioner on the DR timing chain? What could that cause? Thanks for all your help thus far. I think I'm going to sleep now - my head hurts.
usually, the double roller chews up the tensioner and spits the pieces into the engine....don't worry, it will fell better when it quits hurting.

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Just put a higher pressure spring in it "yellow one"
I have a booster plate.

18psi. at idle 160 degree water 180 degree oil. 10/30 real oil.

140K miles.

About 40 psi. at 2400 rpm. Same temps.

I would verify with a good mechanical gauge.
I don't use the booster plates,but I will ask a question anyway.Is there supposed to be a gasket between the thrust plate and the booster plate?

Give em' hell!
Originally posted by fast86:
Just put a higher pressure spring in it "yellow one"

It sounds like he has enough spring in it as he has high pressure at the beginning. A spring will do nothing for the idle oil pressure.

40 PSI at startup(cold) doesn't sound that great either...both my GN and T have 60+ PSI
at startup even when it's 110 here in AZ...what clearances were used for the mains and rods for the rebuild...maybe a little loose?
Originally posted by MSDGN:
40 PSI at startup(cold) doesn't sound that great either...both my GN and T have 60+ PSI
at startup even when it's 110 here in AZ...what clearances were used for the mains and rods for the rebuild...maybe a little loose?
I bought the engine rebuilt already - don't know what clearances were used. I'll post what a mechanical gauge reads maybe if I'm lucky my electric is reading low.
Picked up a new Melling High Volume Oilpump kit today. When I read the instructions and saw all the parts (mainly the sleeves) I screamed. I don't have some of this installed and that may be the problem. The directions say I have to drill two 1/8th holes that I didn't do and like I said I didn't put them sleeves in around the gears. I hope to have the new pumpkit installed tonight I'll post the results.
Not sure exactly what you bought...but whatever it is, follow the instructions...

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