Hey everybody, In the 2 years since I’ve had my 68 442, I’ve never had a working oil pressure gauge. I just installed electric gauges by Auto meter. My oil pressure reads 0 on idle and about 20 when reving up. On Auto Meters web FAQ they say you might not get accurate readings until you drive a bit. (Below is a screen cap of that). Does anyone think that sounds reasonable?
A friend of mine hooked up a mechanical pressure gauge in the sending port and got the same readings? Is this what happens when an oil pump goes bad? And coukd my pressure be that low when I’ve been driving it?


—Billy

 

Could be oil pump, but more often caused by worn bearings or excessive clearances.

 

What you posted pertains to Oil TEMPERATURE. You are asking about Oil PRESSURE. Oil PRESSURE that low should be a concern if it has been tested with a reliable mechanical gauge and reads what your gauge says.

 

Thanks for noticing that the FAQ I read was about Oil temp. So disregarding that, all the other readings are as I said.
I will have someone do another oil pressure test to confirm. If it still reads low, is there a way of telling if it’s the oil pump or the bearings and clearances? I guess changing the oil pump is the first hopeful solution? Thanks for the advice and welcoming any other opinions. —Billy

 

If you pull the pan to change the pump, put in bearings at the same time.

 

Ok. I thought the bearings were a much more involved job. Sorry but I’m a newbie to all this.

also as a check we pulled the gauge off, started the car and did get a spirt of oil shoot out. Does that mean there is pressure? —Billy

 

Well, it means that pressure isn't exactly zero. Other than that, it doesn't really prove anything.

 

Try a mechanical gauge.

 

x2

 

From Post #1:

 

If you only got a spirt of oil, you might have another problem besides the pump. There should have been a stream shoot nearly to the hood if the pressure was correct.

 

Not "nearly to the hood" it should have hit the hood soundly and splattered all over the place.
At least that's what I recall from the ONE AND ONLY time I forgot to install the sending unit and cranked the engine.

 

Oops. Missed that.

 

Before doing anything else, cut the filter open. Look for debris in the filter pleats. If there is a bunch of metallic crap in the filter, you know there fine has some pretty bad wear

Use tin snips or vise grips to rip the filter open, using a hacksaw will create metal chips and make it difficult to tell what’s bearing debris and what’s cutting debris.

If you really have zero pressure at idle, I’d expect some bottom end noise.

What weight oil are you using? Some 10w40 or even 20w50 might help, though it’s just “fixing” the symptom but not solving the problem.

 

I’m using 10w30 and I’ve had 3 people who know the car say there is no unusual noise.
One person who helped me with the car 2 years ago when I just bought it, just reminded me that he had noted back then that the mechanical oil pressure gauge that came with the car was reading 0 on idle. He assumed the gauge was bad. If the gauge was good, then I’ve been driving the car for two years with low oil pressure.
Isnt that hard to believe?

 

Confirm your readings with a mechanical gauge. If readings are low it is probably worn main bearings. Replace the bearings and the oil pump. The "can of worms" starts if the bearings are worn and the crankshaft is scored. You won't know until you look.

Good luck!!!

 

I just bought an oil pressure tester for a more reliable reading. Here is what I got : cold start at 15psi, it warmed in a minute to idling at about 5 psi, at 2000 rpms it went to 20 psi. So I’m bringing it in for service Monday. I won’t be doing the work myself. Thanks for all the advice. Any other thoughts on this are appreciated.
I want to get back on the road in time for the OCA Northeast Zone show. —Billy

 

If you're taking it in, my money is on a diagnosis that says "you need a rebuilt engine". I doubt a shop is just going to change oil pump or even just bearings without selling you a rebuilt motor. I hope I'm wrong for your sake.

 

You could put it 15-40 or 20-50 and run it IF there aren't any noises.

I'd want a cylinder leakdown test before jumping into a rebuild. As stated the shop may push for a rebuild so they can guarantee the work.

Good luck!!!

 

Billy,

In my 40 or so years of experience I cannot say I have ever seen an oil pump "fail" More than likely the engine is just worn out and needs to be rebuilt. This is not something that is going to happen quickly. Personally I would not waste my money on an oil pump or trying to put bearings in it while it is still in the car.

This is going to sound pretty terrible but ..... how much have you driven it in the last 2 years that you have had it ? How far of a drive is it to the show ? If you had not decided to put the gauge in would you have continued driving it ?

My S-10 has almost 300k miles on it and when it is hot the oil pressure is almost nothing at idle and about 20 driving down the road. It has been that way for the last 90-100k miles and I have no plans to do anything about it. I agree with Sugar Bear..... put some 15w40 in it and see what happens.

 

I'm in agreement with BillK. I've heard this scenario many times. Guys obsess over oil pressure. Does the engine run decent. What is your goal for the car. Ice cream stand, car show, short drives? It might last your lifetime. Now if your goal is Bonneville or drag racing, then get the wallet ready. Jmo.

 

X3

I would drain the oil and put a inspection camera in to see if the nylon timing chain gear is not clogging the pick up.

 

Thanks everybody. I’m really hoping to survive this car season still on the road.

So how has an S 10 survived 100k with hardly any oil pressure? Anyone else have opinions on that?

so today I put in 15w40. It helped some. The difference I found was that it maintained better pressure when heated up. Now I’m getting 5 psi at 1K rpms, 10 psi at 2k rpms.

im still leary about this 10 quart custom oil pan that was on the car when I got it. I’ve never been sure I’m getting an accurate dipstick reading. I would just put the amount of oil back in when I get 10 quarts out. Does anyone think that pan or a high volume of oil affects things?

I’ll be taking it in to the pros for a look on Monday.
Thank you everyone for the helpful tips. —Billy

 

Think about whether or not to tear it down as part of the diagnosis, so many cars get torn apart and then sit. If it isn't making noise and you don't drive it hard and often there may be time left to wait for an off-season teardown instead of a rush now. If you do hear an odd noise stop running it.

How does a motor last like the S10 with low oil pressure? Honestly it isn't uncommon, yours may have been that way for a long time. They last because they are still getting sufficient oil volume but less pressure. "Back in the day" engines that were intended to be run hard were often built with extra bearing clearance to get more oil volume; but, their oil pressure was lower.

Good luck and keep us posted...

 

10 quart pan, I would say you have a steel timing gear set so you do not have to concern yourself with a nylon gear plugging the sump pick up.
You can leak oil pressure in a number of areas. Bearing clearance like others have stated. rod side clearance. bolt on oil pump pick up not flat, oil pump to block not sealing.

 

Oil pumps rarely fail, but it only takes a small piece of dirt in the relief valve to cause it to stick open.
I once lost oil pressure in my car & upon disassembly found a small piece of cast iron casting flash stuck in the pump relief.

I also did this once in when in my late teens after an engine swap. I had a temporary gauge connected under hood when I primed it, then forgot to reconnect the one for the car. With no hood on the car, the oil immediately hit the garage ceiling, splattering everywhere. I was looking at the gauges to watch for oil pressure & in about 2 seconds oil was everywhere by the time I could shut it off.

 

I never saw a 10 qt Oldsmobile oil pan.

 

Thanks again. So my mechanic says it’s worth a try to change the pump and pick up. What’s the general opinion on high volume or regular oil pumps?

 

High volume goes with big pans and big clearances.

 

If pulling the pan they are 90% percent of the way to checking main bearing clearance with plastigauge. After checking you will know vs guessing. Start with the bearing farthest from the oil pump.

Good luck!!!

 

Im going back to a stock size oil pan. Will it hurt if I put in a high volume oil pump?

 

 

I have went thru this scenario back when I was a kid and had older sorta worn out cars. I put a oil pressure gauge on my 65 Cutlass 330 and from then on was very worried. Oil pressure was lower than it should have been similar to yours. Same thing on a old Buick 350. But on both cars the idiot oil light never came on before adding gauges. I never did do anything with either of those cars and they ran until I sold them. (after going back to idiot light) I then found that the old idiot lights wouldn't come on till only about 2-3 psi. I have standard oil lights on my Cutlass and Ford 300 in my truck. I watch them and make sure they go off when I start them, good enough I figure. Now if I was racing that would be a different story....

 

I agree with Greg Rogers. I had a 1960 Chevy 283 work car. Oil pressure ( idiot) light would actually flicker stopped in gear. I drove it for a year till the power guild quit.

 

Thanks for all the advice. My 68 442 with the low oil pressure problem went in for service today. They changed oil pump, pickup, new stock oil pan, stock tube and dipstick. now at 6 quarts i finally can measure my oil fill. The old pan was an 8 quart that the previous owner put 10 quarts in -probably because the deep pan didn’t have the correct dipstick. My oil pressure now at idle is 25 psi. At 2000 rpms 50 psi. They had to drop the transmission, disconnect the fly wheel and one header to get the old pan out.

On to the OCA Northeast Zone show in Morgantown PA on 8/28. Maybe I’ll see some of y’all there.
—Billy

 

Excellent news!

 

that is good news but I dont think a stock pan holds 6 quarts. I run 5 quarts in a stock pan using a 1 quart filter

 

Wow, really surprised that it fixed it but certainly glad for your sake

 

If thr previous owner had 10 quarts in a 8 quart pan, I bet the low oil pressure problem was aeration. The crankshaft was spinning in the oil, whipping it up into a foamy mess. You can’t compress a liquid, the air in the oil can be.


Im pretty sure that’s why the engine has oil pressure now. Either way, glad it’s fixed!

 

Yeah, same here. 6 quarts sounds overfilled.