Oil Pressure Troubleshooting

[theblindchicken]

Hey all,

my oil pressure is running lower than normal and I have a few ideas as to what it might be, but I'd appreciate some insight.

Some background information:

1974 K10 350 w/ 4 bbl Quadrajet rebuilt in the 80's with a few little improvements. She's leaking a little oil into cylinder 5, and fouls plugs every now and again (mainly due to oil or not enough warm-up time as well as having tried R45TS plugs).

My truck's been leaking oil from the pan ever since I've been cruising about with her. Even with the leaky, cork, multi-piece gasket, the oil pressure always sat at a nice 40-45psi cold idle and would drop down to 30-35psi when warm and in gear. I've always used a Fram PH5 oil filter and I've never had a problem.

She drained oil overnight since I ran outta time and it got too cold to work.

I just changed the oil pan gasket to one of the fel-pro #1885 blue one piece gaskets. While removing the old cork gasket from the block, the filter got in the way. So it had to go (plus, I figured it'd be a smart idea to limit the old oil mixing with the new stuff). New Fram PH5 filter got installed, new gasket was installed, filled up with Valvoline 10w-30. No leaks, everything's good.​

Yesterday's issue:

Took her for a quick little spin since I was adjusting the speedometer at the same time.

Oil pressure has dropped down to 15 psi at idle while in gear. Pressure increased to 30psi while going 40mph and no increase while at 70mph.
Figured she pulled some oil into the block, gauge line, etc. Checked the oil and she was about 1/4qt low. That was to be expected.
​

Today:

Changed to brand new AC Delco R44T plugs (since they needed to be changed), took her for another spin. Pressure was still the same scenario (hoped it would be a bit higher due to fully functional plugs).​

To sum up the issue:

-Prior: Oil pressure cold idle at 40-45psi. Warm idle in gear at 30-35 psi. Leaky oil pan.

-Now: Oil pressure cold idle at 30-32psi. Warm idle in gear at 15psi. No leaky oil pan.​

Causes(?):

1. The fuel pump has decided to not work properly after all this work.
2. The overnight oil dripping has allowed air to get in the top of the line behind the oil pressure gauge which is giving a faulty reading.
3. The oil pressure gauge is now out of calibration after attempting to remove the instrument cluster (couldn't get the oil pressure gauge out).
4. The new Fram PH5 oil filter has more resistance than the previous frame filter and is creating the lack of flow of oil into the pressure gauge.
​

Any input or advice is greatly appreciated.

 

[austinado16]

This will sound like I'm being a dick, but I'm going to go ahead anyway.

Wiskey Tango Foxtrot do people still use Fram filters? They are absolute crap, have been for 40yrs, and oil pressure problems like what you are experiencing, are common with them.

Do yourself a big favor and spend more than $3 on an oil filter. The NAPA Gold filters are excellent, and made by Wix. 2 sizes available, or a 3rd commercial size (what I run), if you want to increase your total oil capacity. K&N filters are excellent, as are the Mobile 1 filters.

I've seen Fram filters fail internally and blow through an engine, and I've seen them fail in ways that killed the oil pressure.......and I've read and heard about umpteen more of the same.

And just to be clear, oil leaks from an engine do not affect engine oil pressure, unless they are an actual leak from an oil pressure galley. So oil pan gasket leaks, front or rear crankshaft main seal leaks, valve cover gasket leaks, etc. do not have any affect. Nor does oil level. If the oil pump can grab oil, you have pressure. Period. And there's always air in an oil pressure gauge line. Doesn't matter.

 

[RetroC10Sport]

Have had nothing but problems with Frams.

The engine that was in my Sierra that has a knocking rod has a Fram on it. Enough said.

 

[89Suburban]

YAh bud swap that filter out with a better one. I always run WIX on mine.

 

[theblindchicken]

And just to be clear, oil leaks from an engine do not affect engine oil pressure, unless they are an actual leak from an oil pressure galley. So oil pan gasket leaks, front or rear crankshaft main seal leaks, valve cover gasket leaks, etc. do not have any affect. Nor does oil level. If the oil pump can grab oil, you have pressure. Period. And there's always air in an oil pressure gauge line. Doesn't matter.

I already figured that the leak had nothing to do with the pressure levels since I had perfectly regulated pressure with the leaky oil pan. I also figured that the oil pump is working correctly since it has the higher pressure at a cold idle and drops down once it all warms up.

I wasn't sure about the oil gauge line since the compression rate of air is completely different than that of oil which could cause the gauge reading to be inaccurate for the relative future.

Have had nothing but problems with Frams.

The engine that was in my Sierra that has a knocking rod has a Fram on it. Enough said.

YAh bud swap that filter out with a better one. I always run WIX on mine.

Main reason I've always run with Fram's is that I haven't had an issue with them before.


Thanks for the replies.

I'll drop by the parts store and pickup a different filter later today or tomorrow and swap it out and see if that'll fix my issue.

If that doesn't fix it, where should I be looking next?

 

[austinado16]

Do yourself a huge favor, and purchase a nice filter. The junk from others is just as bad as the Fram.

Low oil pressure AFTER you have a quality oil filter installed, will be due to:
-Oil pump output
-Failed oil pressure relief valve (if fitted as part of the oil pump)
-Excessive wear in the rod bearings, camshaft bearings, or crankshaft main bearings.

 

[theblindchicken]

Do yourself a huge favor, and purchase a nice filter. The junk from others is just as bad as the Fram.

Low oil pressure AFTER you have a quality oil filter installed, will be due to:
-Oil pump output
-Failed oil pressure relief valve (if fitted as part of the oil pump)
-Excessive wear in the rod bearings, camshaft bearings, or crankshaft main bearings.

Alright, thanks for giving me more insight. I'll pickup a new filter and swap it out in the morning.

It's unlikely that it'll be due to excessive wear since the truck has approximately 80k original miles and the engine was rebuilt in the 80's after my father cracked one of the heads out in the Mojave. But is still something to think about.

How would I know if the issue is caused by an oil pressure relief valve (if one was installed) as opposed to the oil pump?

 

[Stroked]

I've heard of a lot of people having low oil pressure issues after installing a new fram filter. I don't know how they're still in business.

Sent from my Kindle Fire HDX using Tapatalk

 

[Driver4r]

Damn, ive never had trouble with fram. And my oil psi is 55ish(at 700rpm i might add ) at idle. Always has been.

 

[austinado16]

Damn, ive never had trouble with fram. And my oil psi is 55ish(at 700rpm i might add ) at idle. Always has been.

You're extremely lucky. Kinda like using Jiffy Lube or Midas for oil changes and exhaust/brake work and saying, "Gee, never had an issue."

IMO, engines are really expensive compared to paying $6 or $8 for a good filter, instead of $3. And when a Fram grenades internally, you lose oil pressure and destroy a set of bearings and journals, what do you think Fram is going to tell you? Something like

There are a ton of great oil filter analysis websites. I highly recommend visiting them and seeing what the inside of these cheap-ass filters look like, both in amounts of filter media used, and in the quality of their bypass valves, and filter cartridges. It's kinda shocking.

@theblindchicken; Don't waste time continuing to guess passed the cheap Fram filter with a known failure. Replace it.

 

[theblindchicken]

Replaced the Fram filter with a K&N HP-3002.

The oil pressure all around was approximately 2-3psi higher than with the Fram filter, but still lower than prior to any changes.

I feel that it's unlikely that the pump decided to not work properly after changing the oil and filter. I'm more feeling like it's the gauge that is messed up.

If I install an aftermarket mechanical gauge to check the accuracy of the stock gauge, where would be the best location to receive the most accurate pressure reading?

 

[NOPHO84K30]

I just changed mine today. i had a napa premium on it at running temp it would read 0 to 5 psi. I used a WIX filter this time and it shows 30 at idle and at 3000 rpm dosent fluctuate ....

 

[austinado16]

This passed summer I installed a mechanical gauge in mine. I T'd off the OE sender location next to the distributor.

Bummer that this wasn't cured by replacing the filter.

If your mechanical gauge confirms the low oil pressure, you might want to pull the pan, plastigauge the rods and mains, and if they're in spec, replace the pump.

And to your question about the pressure relief, I don't specifically know if the pumps on these engines have that feature. It's on the German/European vehicles I work on. Basically a ball and pressure rated spring, that are designed to be deflected above a certain oil pressure and in that scenario, the extra oil is dumped out of the pump, back into the pan. When these fail, the ball or whatever is acting as the valve, will get hung up and stop sealing properly, or the spring fails, and then you have an oil pump that is continuously bleeding off oil pressure. So that's why I suggest plastigauge the bearings and if they check out, R&R the oil pump.......but confirm true oil pressure first.

 

[87sierra]

I've never had a problem with from filter heck my oil psi is at 60 psi when cold and around 35-40 operating temp and if you plastiguage you lose the crush on the bearings which means they are pretty much junk since bearings are suppose to be installed only once and as far as I know there is a pressure relief valve on the oil pump which could be the problem

 

[shortboxchevy77]

I've never had a problem with from filter heck my oil psi is at 60 psi when cold and around 35-40 operating temp and if you plastiguage you lose the crush on the bearings which means they are pretty much junk since bearings are suppose to be installed only once and as far as I know there is a pressure relief valve on the oil pump which could be the problem

There is no such thing as "crush" on an engine bearing, never has been and never will be. Bearings float on the crank using oil pressure as the cushion. Fram filters are junk, blue line carquest filter is a wix filter. Verify oil pressure with another mechanical gauge at the port next to your distributor and then go from there.