High oil pressure

[jcblue]

What would cause high oil pressure and is it a bad thing? My stock gauge is pegged out.. Have an aftermarket gauge ordered to see what it's reading.. I do think the pressure is making it leak a little oil..

[pwdcougar]

It isn't over filled is it? A blown head gasket could also be the problem.

Paul

[cleszkie]

Is it an issue that just started, increased gradually, or has it always been high? Have you done any work to the engine recently? Are you running a standard oil pump or a high pressure unit? Have you changed grades/viscosities of oil recently? Is the gauge always pegged, or does it actually move. If it is always pegged (hot, cold, idle, high RPM) then I would suspect a faulty gauge or sending unit.

I have a newly built small block in my Blazer that will peg out the stock gauge when cold or running high RPM. My mechanical oil pressure gauge will be reading above 40psi when the stock gauge is pegged.

[jcblue]

It's not over full.. Motor is recently rebuilt . Stock with a small cam. Probably still has the break in oil in it.. I haven't changed it yet

[cleszkie]

Break in oil is typically thinner than the recomended daily use oil in my experience. Don't think that is the source of the pressure. If the engine is a new build, ask the builder if they installed a high pressure oil pump.

[Dave]

Fwiw, I've rebuilt a few SB engines that I installed the high pressure oil pump spring , like the corvettes used back in the day. This would cause the stock mechanical 60 lb gauge to stay at 60 thru the warm up cycle into the normal operating temperature. It wasn't until about 5k miles later that it started to come down a bit. In addition, all of your crank, rod and cam bearing tolerances are the tightest they'll ever be given this a new engine.

[toolboxchev]

Originally Posted by Dave

Fwiw, I've rebuilt a few SB engines that I installed the high pressure oil pump spring , like the corvettes used back in the day. This would cause the stock mechanical 60 lb gauge to stay at 60 thru the warm up cycle into the normal operating temperature. It wasn't until about 5k miles later that it started to come down a bit. In addition, all of your crank, rod and cam bearing tolerances are the tightest they'll ever be given this a new engine.

Thats a HOT trick, now where to find the part.

[Jrainman]

on fresh engine 60 lbs is normal on cold start up as engine warms up you should see the pressure come down , at full warm up you would like to see 35 lbs min this is all at idle rpm .

As you increase engine speed you increase oil psi . I would address your concerns with your engine builder ,like previous poster said about the oil not retuning back to sump ,this can happen ,but you would have other signs of failure . also as poster said about oil pump it self could be new high volume oil pump installed or also spring change .

there are other things such as is your engine properly breathing rite , your best bet is to go back to the engine rebuilder. if you did not get in in writing on what was done only he knows and will be able to quickly evaluate your concerns,

[jcblue]

Does it really matter that it's high? Is it something I should worry about?

[Robznob11]

Originally Posted by jcblue

Does it really matter that it's high? Is it something I should worry about?

If you did not wash the engine real good before assembly and if you had any machine work done you may hav a restricted oil gally. Not good I smoked a sbc crank and mains in 600 mi because of this. In short high oil pressure is not good like some think. You want high volume. Most race engines restrict oil to mostly the bottom of the engine tho. I would pull the pain and check a main before I drove any more. In my case the front was just a little marked and got worse going back last one was trashed. Had to turn the crank

[leftybass209]

Interesting suggestions. It seems though, you should first ensure your 45+ year old mechanical oil pressure gauge is in proper working condition, before you go chasing an issue that may not exist.

Connect a gauge that can read above the 60lb limit of the original, so your scale is more accurate.

It's similar to chasing electrical faults when the whole time your battery was never properly charged.

[jcblue]

I hooked up an aftermarket gauge.. Truck idles at 60 psi and goes up as Rpm go up.. Is that pretty normal?

[hamjet]

Originally Posted by jcblue

I hooked up an aftermarket gauge.. Truck idles at 60 psi and goes up as Rpm go up.. Is that pretty normal?

Is that hot engine or cold. you say it goes up, how high?

[GASoline71]

Sounds like someone installed a high volume/high pressure oil pump during the rebuild.

Gary

[Davidf]

My 283 in "seen better days" condition pegs the gauge cold and shows 1/4 on hot engine at idle, 1/2 while cruising.

[Skinny Kid]

The 383 in my Chevelle was built by a friend of mine, who is a very well known engine builder used a Melling pump that is spec'd for the 69 Z28 302. I can't remember the part number right now, but it is a factory high volume/std pressure pump and the pressures are right where he said they would be. Cold - 60psi idle, hot - 25psi idle and 60psi cruise. Excessive oil pressure isn't necessary on a street car and just puts extra wear on parts and hurts economy.

Now on the other hand, the 422 he built for my Nova, which is a dedicated race car and not on the street ever is a different story. That one makes about 70psi idle and I see about 100psi on a run. But, that is a big solid roller, 14:1 engine that turns 8,500 rpm. Works for the race engine, but totally overkill for a street engine.

[Skinny Kid]

I once heard someone use the analogy, "If your engine was a human, the doctor would diagnose hypertension."

[leddzepp]

I wouldn't worry about it.

[toolboxchev]

Based on the wide variety of responses I would definitely be looking into that one.

Its not worth losing an engine IMHO. Keep us posted and let us know what you find.

On my top end rebuild we keep everything in the bottom. Including the High Volume pump we found.

On a hot day when engine is fully up to temp I am at a hair over 1/4 on the stock gauge. At normal cruise, a hair over 1/2.

Under WOT it is almost fully pegged and drops when I let off the throttle.

I hope this helps, pretty much a stock motor with HEI and an edelbrock carb.

[jcblue]

Ok I went for a drive today and this is what the readings are.. 60 at startup cold.. Warm idle at 35-40. Crusing is anywhere in between those depending on how much I'm in the throttle. Thanks for all the responses

[Robznob11]

I dont think that's bad, I thought it was 60+ all the time

[Jrainman]

Sounds like good numbers to me for a fresh rebuild ,with mild cam , I would recommend you add zinc additive for the next few oil changes ,for extra lubrication during the break in..........

[hardwaycooke]

Originally Posted by jcblue

Ok I went for a drive today and this is what the readings are.. 60 at startup cold.. Warm idle at 35-40. Cruising is anywhere in between those depending on how much I'm in the throttle. Thanks for all the responses

Just a note. When I built my 383 I ordered an oil pump with a couple different springs. I was a normal pressure pump but I accidentally left the high pressure spring in. Was pegging the stock gauge but when I primed it it was really good pressure too. Anyway, took the pump out, replaced it with the normal pressure spring, all's good. Just fyi.

[Jrainman]

Originally Posted by hardwaycooke

Just a note. When I built my 383 I ordered an oil pump with a couple different springs. I was a normal pressure pump but I accidentally left the high pressure spring in. Was pegging the stock gauge but when I primed it it was really good pressure too. Anyway, took the pump out, replaced it with the normal pressure spring, all's good. Just fyi.

You are Correct Sir , it is very doubtful his engine builder put a high flow oil pump in ,being it was built with only a slightly larger cam ,

the spring and ball operate the pressure relief in the oil pump this is how the pressure is made to keep constant , high oil pressure with in reason is better for your bearings

bypass valves in oil filters opens at 10-12 pounds , remember your filter is on the return side of the oil flow , bypass valve operation is for the filter it self if the filter becomes restricted (dirty) at 10-12 pounds it will by pass dirty oil is better then NO OIL , also on a very cold starts some oils might be to thick and again the bypass valve will do its job.

I added the by pass valve in the oil filter operation for a reason , lets say the pressure relief spring in the oil pumps fails or hangs up , to check for this failure all you have to do is drop your oil filter if your filter look expanded or very mangled you know your oil pump pressure relief valve has had a failure.

if your engine at idles and oil PSI is below 25 psi its getting worn out.

[jcblue]

Noted on the zinc.. Thanks guys