Low Oil Pressure at Idle - Need Help!!!

[jawort0]

I recently installed an electrical oil pressure gauge in the same location as the factory dummy switch. My oil pressure is showing 0-5 psi at hot idle (200 deg F Coolant temp) and 20 psi at 55MPH and 30 psi at 75 MPH. The factory dummy light for low oil pressure never came on or flickered at idle but did work and light up when the engine was off. I believe the factory setting of this switch is 4 psi. (Please correct me if I am wrong.) The engine has 167k miles and is an 87 Turbo Regal.

My question is what are my options to try to increase oil pressure? I have listed the options I see below with the questions I have. Please help me answer the questions and add options to the list.

1.) Replace main bearings - can this be done with the engine in the car?
2.) Replace rod bearings - can this be done with the engine in the car?
3.) Ensure the oil pump suction tube screen is clean - can this be done with the engine in the car?
4.) Install oil pump booster plate - can this be done without removing the front cover? can this be done with the engine still in the car?
5.) Install high pressure oil pump - I have heard concerns wear on the cam bushing. Any concern with a stock high mileage engine? Can this be done without removing the front cover? Can this be done with the engine still in the car?

Thanks, Joe

 

[turbolou]

Reply

Assuming the gauge is accurate. Drain the oil into a container & see if there is a bronze or metallic appearance in the oil. Take a pry bar & check crank thrust end play. there should be very little. If there is you can assume the crank is shot.Pull the oil pan & if there is a problem you will see shavings or evidence of damage in the bottom of the pan. Generally the center mains get the most damage. Pull the main caps & check them. If the bearings are gone so is the crank. Then you will need a complete rebuild. Its basically a process of elimination & good luck

 

[GNRick]

I used to have 55 psi on the expressway going 65-70 mph. Lately it is 35 psi at 65-70 mph. I sent the oil filter to a well known GN engine builder and he said there was no metal in the oil. I bought a new gauge and no difference. I have 70 psi at start up and 15 psi at hot idle. So I am thinking maybe the sending unit is bad? I use 10W-30 Valvoline VR-1. Didn't mean to hijack the thread, just wondering if maybe you need a new sending unit before you tear into your motor.

 

[TurboBuRick]

Defiantly drain oil and inspect for debris.

I would try running a little heavier weight oil and a high quality filter.

As long as it's not on 0 and pressure responds quick to rpm, you should be fine.

 

[TurboTnZ06]

Hook up a mechanical oil press gauge. I had both elec and mechanical at the same time. Elec was like you say, reading very low pressures, mechanical showed perfect oil pressure. Some say you can make a ground strap to increase the effectiveness of the elec sender for the ground.

 

[jawort0]

I changed the oil. No metal observed. It is not something that began after I installed the electric oil pressure gauge. The issue was observed immediately after the gauge was installed. The car runs fine with no lifter tapping and no botton end knock, but if there is nearly 0 oil pressure (gauge will either hover at 5 then drop to 0) I want to do something now rather than wait until there is a mechanical failure.

 

[Nick Micale]

.... I want to do something now rather than wait until there is a mechanical failure.

To be up front about your oil pressure, for a 25 year old performance car with 167K miles, it needs a rebuild, nothing to patch here, it is just worn out.

The oil pressure problem is normal in your case, and it is telling you "fix me, or I give up"!

To do less than a complete rebuild is the opposite of smart, it will cost more you in the long run.

 

[jawort0]

Stating a 167k engine needs a rebuild is the obvious answer. I dont want to do a full rebuild right now, so I want to know how to increase the oil pressure appropriately. If I replace rod and main bearings, that would increase oil pressure and protect the crank. Of course, no one has answered the questions I originally asked which was can these be replaced with the engine in the car.

 

[TurboTnZ06]

I had 185,000 miles on my T's original engine and it had good oil pressure. Verify oil pressure with a mechanical gauge.

 

[jawort0]

TurboTnZ06,
Can you confirm what good oil pressure is for these cars and what you were seeing on your 185,000 mile Turbo Regal?

Thanks, Joe

 

[1KWIKSIX]

increasing oil pressure

x2 on changing to a heavier weight oil.

I changed over from Mobil 1 synthetic 10W-30 to Brad Penn 10W-40 Partial Synthetic and picked up my hot idle oil pressure.

I'd give it a go & see for yourself.

good luck


dave

 

[wickedtt]

I recently installed an electrical oil pressure gauge in the same location as the factory dummy switch. My oil pressure is showing 0-5 psi at hot idle (200 deg F Coolant temp) and 20 psi at 55MPH and 30 psi at 75 MPH. The factory dummy light for low oil pressure never came on or flickered at idle but did work and light up when the engine was off. I believe the factory setting of this switch is 4 psi. (Please correct me if I am wrong.) The engine has 167k miles and is an 87 Turbo Regal.

My question is what are my options to try to increase oil pressure? I have listed the options I see below with the questions I have. Please help me answer the questions and add options to the list.

1.) Replace main bearings - can this be done with the engine in the car?
2.) Replace rod bearings - can this be done with the engine in the car?
3.) Ensure the oil pump suction tube screen is clean - can this be done with the engine in the car?
4.) Install oil pump booster plate - can this be done without removing the front cover? can this be done with the engine still in the car?
5.) Install high pressure oil pump - I have heard concerns wear on the cam bushing. Any concern with a stock high mileage engine? Can this be done without removing the front cover? Can this be done with the engine still in the car?

Thanks, Joe

Well with the oil pressure you stated above I would think the motor would be making some kind of noise. If not then the electric gauge as their known to be is off. If you want to increase the pressure slightly just get the car to run 160 degress instead of 200 +. Get a biggie filter adapter with larger filter throw some 20/50 oil in there and drive it. The other option is rebult the short block .. Leaving the motor in the car and replacing mains and rod bearings in the car is a waste of time.

 

[salvageV6]

15-50 Mobil 1 and 200K with triple that pressure.

" I had 185,000 miles on my T's original engine and it had good oil pressure. Verify oil pressure with a mechanical gauge. "

Bingo.

It's not that hard to verify the pressure with a mechanical gauge.

Factory idiot light is set to 4 psi. if it was still working.

 

[STP]

Stating a 167k engine needs a rebuild is the obvious answer. I dont want to do a full rebuild right now, so I want to know how to increase the oil pressure appropriately. If I replace rod and main bearings, that would increase oil pressure and protect the crank. Of course, no one has answered the questions I originally asked which was can these be replaced with the engine in the car.

Mains and rods can be replaced with the engine in the car...However, if you intend to put new bearings in, I would pull it and do work on the stand.

Are you running an oil cooler?

Put thicker oil in it immediately...Then put a mechanical gauge on it and verify...I think you probably have an inaccurate gauge, as an engine with 0-5lbs of hot idle oil pressure is going to make some noise.

 

[TurboTnZ06]

What's your address, I'll mail you my mech gauge and some line and you can hook it up since I'm not using it. It should just screw in where the elec sender goes so should be easy to add to test.

I put an electrical and a mechanical in at the same time. The electrical read something like 20psi lower than the mechanical. Hot idle was I think 7-10 psi (the elec low sweep is hard to read that precisely anyways) indicated electrical and the mechanical was I believe 25-30 psi hot idle. Cold start the electrical was probably showing 50+ and the mech was showing 70+. Oh, and I tested 2 new autometer senders, both read low, one was lower than the other, but both were low compared to the mechanical. I just duct taped the mech to the windshield to drive and verify til I was satisfied oil is good to go. Now the elec is all I have in the car and I know the offset, 10 means 30, 50 means 70...etc.

 

[Rich Gio]

X2 on the Mechanical gage! Also, make sure you have the electric gage grounded well. Does it have it's own ground or share with other gages/accessories? Also, my press at hot idle with VR1 10W30 is low... 10-12ish. These cars always read low. (Well mine has anyways) I run 20W50 VR1 in the summer and get 20ish at hot idle. My guess is that your gage is inaccurate. But Nick has a point. That's a lot of miles! Might be time for a rebuild.

 

[TRICKSIXPA]

Couple of things to check. Is the sending unit thread making metal to metal contact with the brass block coming off your motor? Did this sending unit come with the gauge you are using. If it is not matched to you gauge you will have a very low pressure read out. I did the same mistake myself. I'm know using an Autometer Phantom electric gauge with no problems.

 

[jawort0]

Update!

Update!

Ran a wire from the electrical sending unit to the ground. Still low oil pressure.

Installed a mechanical oil pressure gauge and still low oil pressure (5 psi).

Went to Advance Auto Parts and ordered Melling P20I Booster Plate (aka Thrust Plate) and a Melling K20I stock oil pump rebuild kit.

Got the parts today and installed. The cover and gears definitely needed to be replaced with scoring present.

Could only get the coolant temp up to 190 deg F (as compared to 200 deg F previously) on the test ride and the oil pressure is now 15~18psi at hot idle at 190 deg F.

At highway cruising at 70 MPH the oil pressure is 45 psi.

At WOT the oil pressure goes to 50 psi.

(The above numbers are with the mechanical gauge. I have not yet reinstalled the electrical gauge.)

What is everyone's opinions of these numbers?

 

[salvageV6]

Everything looks good but the engine coolant temp.

The oil pressure looks rather good.

 

[jawort0]

SalvageV6,
What are your thoughts on my engine coolant temps? I have a F body radiator installed and goes to 190 deg F on 80 deg day and 200 deg F on a 90 deg day. (This is with an electric coolant temp gauge.)

Thanks, Joe