Low Oil Pressure at Idle (Page 1/2)
robmox MAY 11, 02:46 PM
I’m looking to buy a 1988 Fiero Formula (2.8L V6), and when talking to the seller, she said it has low oil pressure at idle. Of course, worst case scenario is a spin bearing, but I’m trying to decide how much work it could take to correct the oil pressure.

When I go check out the car in person, is the best way to ensure the engine is in good condition for me to check the top end by removing a valve cover? And then to check the oil drain plug for metal bits?

My thinking is that if the bearings are in good working order, then it’s one of the following: oil pump, oil pressure sensor, gasket leak (valve, head, or oil pan), rear main seal, or clog in the oil pickup. Other than the rear main seal, all of that can be fixed in a day. And the rear main seal, I can inspect before I buy.

Any thoughts from you guys who have more experience with this specific engine?

[This message has been edited by robmox (edited 05-11-2022).]

olejoedad MAY 11, 02:53 PM
How many miles?

The gage or the sender. Take a mechanical gage with you to check it out. The oil pressure sensor is easily accessible from the top of the engine.

If it carries good pressure running down the road (10 psi for every 1000 RPM), I wouldn't worry about it.
robmox MAY 11, 02:55 PM

quote
Originally posted by olejoedad:

How many miles?

The gage or the sender. Take a mechanical gage with you to check it out. The oil pressure sensor is easily accessible from the top of the engine.

If it carries good pressure running down the road (10 psi for every 1000 RPM), I wouldn't worry about it.



Awesome. I’ll check this when I take it for a test drive. Thanks for the advice.
olejoedad MAY 11, 03:02 PM
The senders/gages aren't all that accurate after 30+ years and the 88 oil pressure warning light triggers at a lower set point than earlier models.

It's a crapshoot sometimes to rely on the gages.
Patrick MAY 11, 04:43 PM

quote
Originally posted by robmox:

When I go check out the car in person, is the best way to ensure the engine is in good condition for me to check the top end by removing a valve cover?



I suspect you've never removed a valve cover on a Fiero 2.8 engine. It's pretty tricky to do without removing both the upper and middle intake. If I was selling a Fiero, I sure wouldn't allow a prospective buyer to do all that with my car.

In regards to the apparent low oil pressure at idle, is it low with a cold engine as well? Ask the owner what weight engine oil he's running.
robmox MAY 11, 09:10 PM

quote
Originally posted by Patrick:

I suspect you've never removed a valve cover on a Fiero 2.8 engine. It's pretty tricky to do without removing both the upper and middle intake. If I was selling a Fiero, I sure wouldn't allow a prospective buyer to do all that with my car.

In regards to the apparent low oil pressure at idle, is it low with a cold engine as well? Ask the owner what weight engine oil he's running.



You’re suggesting that it might have too heavy weight of oil in it?
Patrick MAY 11, 09:18 PM

quote
Originally posted by robmox:

You’re suggesting that it might have too heavy weight of oil in it?



No... the opposite.
Dennis LaGrua MAY 11, 09:55 PM

quote
Originally posted by robmox:
When I go check out the car in person, is the best way to ensure the engine is in good condition for me to check the top end by removing a valve cover? And then to check the oil drain plug for metal bits?



You need not remove the valve cover get an inspection camera that attaches to your cell phone and look in.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

82-T/A [At Work] MAY 12, 10:39 AM

quote
Originally posted by robmox:

I’m looking to buy a 1988 Fiero Formula (2.8L V6), and when talking to the seller, she said it has low oil pressure at idle. Of course, worst case scenario is a spin bearing, but I’m trying to decide how much work it could take to correct the oil pressure.

When I go check out the car in person, is the best way to ensure the engine is in good condition for me to check the top end by removing a valve cover? And then to check the oil drain plug for metal bits?

My thinking is that if the bearings are in good working order, then it’s one of the following: oil pump, oil pressure sensor, gasket leak (valve, head, or oil pan), rear main seal, or clog in the oil pickup. Other than the rear main seal, all of that can be fixed in a day. And the rear main seal, I can inspect before I buy.

Any thoughts from you guys who have more experience with this specific engine?



These cars are getting harder and harder to find, especially in good condition. If it has the options you want, I would absolutely consider it, even if you were potentially looking at an engine rebuild.

As the bearings wear, the clearances become greater obviously, so the oil pressure does go down. A main bearing has to be worn pretty much for it to become "spun" as they say since there's a little notch that holds it in place... most often, the bearings just wear to the point where it can no longer maintain oil pressure and the top-end (lifters / cam) no longer get the oil pressure it needs to properly hydraulically pressurize the lifters.

But again, if the car is otherwise in really good shape... then it might just be worth buying.


Do you have any pictures of what you're looking at? What are they asking for the price of the car?

A general engine rebuild with a machine shop (if you pull the engine out) can run you about ~$2,500.
If you want some performance parts to give a bit higher quality, etc... better cam, lifters, rods, compression, etc... $3,500.

If you want someone to do it all for you... probably add another $1,500 to $2,500 bucks.

But you'll have something that will be far more reliable.


Even if you bought a Fiero Formula for $10k, it might still need work unless you can verify it has low miles and has been taken care of.


Just my opinion...
robmox MAY 12, 03:34 PM

quote
Originally posted by 82-T/A [At Work]:

These cars are getting harder and harder to find, especially in good condition. If it has the options you want, I would absolutely consider it, even if you were potentially looking at an engine rebuild.

As the bearings wear, the clearances become greater obviously, so the oil pressure does go down. A main bearing has to be worn pretty much for it to become "spun" as they say since there's a little notch that holds it in place... most often, the bearings just wear to the point where it can no longer maintain oil pressure and the top-end (lifters / cam) no longer get the oil pressure it needs to properly hydraulically pressurize the lifters.

But again, if the car is otherwise in really good shape... then it might just be worth buying.


Do you have any pictures of what you're looking at? What are they asking for the price of the car?

A general engine rebuild with a machine shop (if you pull the engine out) can run you about ~$2,500.
If you want some performance parts to give a bit higher quality, etc... better cam, lifters, rods, compression, etc... $3,500.

If you want someone to do it all for you... probably add another $1,500 to $2,500 bucks.

But you'll have something that will be far more reliable.


Even if you bought a Fiero Formula for $10k, it might still need work unless you can verify it has low miles and has been taken care of.


Just my opinion...



Yeah, thanks for the advice. I'm definitely strongly considering buying it. I should get pictures today, so I'll have a better idea of the rust situation. But yeah, hard to turn down a running V6 fiero with a manual. I'm mostly looking for people's thoughts on inspection when I get to see the car in person. I'm hoping I can see where the oil pressure loss is, but if it's not the oil pressure sending unit, then I have to guess it's a clogged oil pickup or a blocked oil passage. Because a loss of oil pressure like this isn't likely to be caused by just a gasket leak. At least, that's what I'm thinking until I see the car in person.