# bad oil pressure when warm



## mbspeed (Sep 25, 2012)

Hi all 
I got a 67 GTO with a rebuilt 73 455 in it hyd-roller lifters my oil pressure will start up around 90psi after warm it drops to 5 psi and the roller lifter will start ticking all of them I talked to machine shop that did my motor he thinks it lifter bore clearance problem I have tried all types of oil 20-50 all the way down to 30w ...motor has less then 1000 miles any other thing could be changed oil pump lifters rockers ...is my motor junk????? is there no repair for bad lifter bores bearings look good clearance 003 :banghead::banghead: any info or idea will be helpful


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## Goat Roper (Oct 28, 2014)

I had the same problem, 60 pounds cold less than 5 once warmed up.
Bottom end was tired and I pulled the engine and sent it off to CVMS in Va.
I doubt the engine is junk but maybe you need to take it to another builder who will find the problem.
I don't know where you are located but there is a guy local to me that has a 73 Grandville conv. that runs pretty good with a 455 in it if you do need another engine.


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## PontiacJim (Dec 29, 2012)

If I understand you correctly, the same machine shop that rebuilt your engine is now saying that the lifter bore clearance could be the problem? WTF? Didn't they check that during the rebuild?

When did this start?

IF there is a problem with excessive wear in the lifter bores, they can be sleeved and brought back to spec - so don't throw out the baby with the bath water quite yet.

Pontiac lifters have a specific position to the oil supply groove that goes around the lifter. If someone is not aware of this, or does not check to ensure that the replacement lifters are exact to the Pontiac lifter, that oil groove can either raise above or drop below the lifter bore and allow the oil to flow out, rather than be contained by the bore (sorta like a seal), and bleed off a lot of oil pressure. So, it is critical when rebuilding a PONTIAC engine that the correct lifters - hydraulic, solid, roller - be used. There are CHEVY lifters that have the same dimensions and will fit, but the oil groove is in the wrong place. http://www.jbp-pontiac.com/techDoc/PontLifters.pdf

Some builders like to install restrictors in the lifter galley or use restricted pushrods to keep oil in the bottom end. http://www.jbp-pontiac.com/techDoc/OilRestrictors.pd

Here is a Pontiac oiling system diagram showing the oil flow. http://www.jbp-pontiac.com/techDoc/oiling.jpg

There are a number of things that can cause bad oil pressure. 

First is the gauge/sending unit - it may not be reading correctly or flat out be bad. But since you can hear your lifters clattering, it doesn't sound like a faulty gauge or sending unit.

Excessive bearing clearances will drop oil pressure once the oil is hot -.003 is too much for street use. Is this a race only car? 90 lbs of oil pressure? What oil pump are you using? Too much pressure is not a good thing and can do damage. Oil pressure, the real story | Synforce Lubricants

Your oil pump pick-up tube could have fallen off. Not common, but I have heard of this happening and it can affect oil pressure.

Bad oil pump, to include the check valve is either stuck shut or like my experience............when I first fired up my rebuilt engine I got a chunk of a tiny bit of rubber that floated in the oil system which went through the by-pass chamber of the oil pump and lodged under the by-pass ball not allowing it to close and the oil pressure could not be maintained. I had high oil pressure when cold, and it would drop 20 lbs hot and continued to drop over a period of time until I lost all oil pressure. BUT, my big indicator (which I did not know what to make of it at the time) was that my oil pressure would climb slowly and steady when I first started the cold car - rather than shoot right up to high oil pressure as it should have.

The oil plug on the back side of the engine near the distributor which is hidden behind a freeze plug could have been left out or a front oil plug could have come loose if not correctly installed and staked - threaded plugs are usually used to replace these during a rebuild just to ensure this doeasn't happen.

Not knowing what you had done to the engine during rebuild or what the rebuilder did, there can be things like checking the crank for straightness, align boring the main caps, wrong bearing size, excessive thrust bearing clearance, etc.. You may want to give us some more info on the engine and what you had done to it.

Have you pulled the valve covers while the engine is running to see what kind of oil pressure you are getting through your pushrods? It will get messy real quick, so you don't need to run it long, just observe the oil flow at initial start up. Pull the covers (or one side at a time to minimize the mess) and start the engine. Keep some rags handy. 

If the issue is the lifters/bores, you may want to pull the intake and valley cover, pull the distributor coil wire and back out the spark plugs so the cylinders won't build any compression, and then spin the engine and observe to see if the oil pours out of the lifter bores. You can also see if the lifter oil grooves are becoming exposed either above or below the lifter bores.

It does not sound good and may require you to pull the engine, but I'd do a few checks first and hope it is something real simple you can remedy.:thumbsup:


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## mbspeed (Sep 25, 2012)

PontiacJim said:


> If I understand you correctly, the same machine shop that rebuilt your engine is now saying that the lifter bore clearance could be the problem? WTF? Didn't they check that during the rebuild?
> 
> When did this start?
> 
> ...


this problem started when I first ran motor after rebuild one of my rockers # 3 cylinder did not get enough oil turned comp cam roller tip rocker blue from lack of oil ...so I replaced all lifters also changed to full roller rockers have 2 oil pressure gauges running same time both same reading ..machine shop told me not a good idea to sleeve lifter bore :banghead::banghead: I am in a bad state for machinist shops I guess I going take motor out of car look at all bearings over next few weeks its a lot bad luck with Pontiac over last few years may need go with a 454 /427 chevy got over 10,000 in motor parts and service dam Pontiac :reddevil::reddevil:


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## mbspeed (Sep 25, 2012)

pontiacjim....the oil pump is meling 80 psi pump the.... motor has 003 bearing clearance was spec from butler Pontiac he sold the stroker kit...the machine shop tells me he does not check lifter bore unless asked


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## PontiacJim (Dec 29, 2012)

mbspeed said:


> pontiacjim....the oil pump is meling 80 psi pump the.... motor has 003 bearing clearance was spec from butler Pontiac he sold the stroker kit...the machine shop tells me he does not check lifter bore unless asked


Did you try a new filter just to see if any difference to make sure it is not plugged up in some way? You can cut it open and look at the filter to see if you have any bearing material in it.

OK. I can't argue against Butler as they are far more qualified than me by a long shot. The .003" clearance works with the 80PSI oil pump, so that should be OK. Here is a cool YouTube video by Mellings which shows what happens to oil flow at different bearing clearances. https://www.youtube.com/watch?v=7IpJlYssvkM

I am wondering why you had bad oil pressure to the one rocker which blued. Did you pre-load the lifters, meaning tighten them to the manufacturers spec to push the lifter plunger down inside the lifter body? This is important as well as correct pushrod length.

OK, ruling a few things out:

Did you prime the oil pump and engine prior to starting it up? You should have gotten the oil pump shaft spinning the oil pump enough to see oil come out of the pushrods. If the engine was started "dry", it is possible to damage bearings. YouTube video: https://www.youtube.com/watch?v=tOYLlr8uQ8k

If the bearings were not installed with the chamfer to the crank weight side where the radius is on the crank, this will damage the bearings.

Is it possible that the oil pump has loosened up where it mounts to the block - maybe forgot to tighten/torque? Was the gasket put in between the oil pump and block?

I have never had a problem with the oil filter adapter and don't know what the symptoms would be if the small spring inside it were to go bad (weaken) or be left out. 

It seems odd that you have 90psi cold and it drops when hot - which means your oil is thinner when hot and flows much easier. When I pulled my 400 CI apart, the bearings were definitely worn. I had been adding the thick STP trying to make my oil thicker when it got hot to keep oil pressure. It worked for some time, but as the bearings wore more and more, the clearances became excessive and eventually even the STP did not help to keep any kind of oil pressure. 

BUT... my problem was the oil pump as the bypass check ball relief valve)was being held open. So the oil pressure did slowly build up when cold because it was thicker and better at higher RPM's because the pump was putting out maximum oil pressure, but it dropped when hot and really dropped at lower RPM's and idle. The bypass valve is very important to maintaining oil pressure. The relief valve is designed to limit oil pressure as engine speed increases. The valve opens when pressure reaches a preset value (typically 40 to 60 psi). This *vents oil back into the crankcase and limits maximum oil pressure *in the engine. The reason for doing so is to prevent oil pressure from reaching dangerous levels. But if it sticks open because of a small piece of debris under the check ball, it can cause low oil pressure.

Again, I hate to think it, but you may have to pull the engine and check the bottom end to see if you can determine what is happening. If you catch it early as you have, any damage - if any, will be caught right away and it may be a simple fix to get you back up and running again.

Some shops do and some shops don't check lifter bores, but it should have been done in my opinion because you were going from a factory lifter type to a roller style - but again, my opinion. You can purchase a very inexpensive set of what are called telescoping gauges which you use with a digital micrometer to measure the lifter bores yourself. They have them on Ebay for about $15.00. I got a set locally which were about $18.00 and they did the trick. No need for the $100 plus set. I got an inexpensive digital micrometer at Home Depot that works great. They come in handy for other engine checks as well.

Have you contacted Butler to get a possible opinion from them? I think I would email them and see what they may offer as what to look for or check before you go into the engine.

BTW, here is an article on sleeving the lifter bore -its a Mopar 440. Read the first paragraph and maybe you will know why your machinist doesn't think it is a good idea. Hopefully, it is not something you will need anyway. #3---Sleeeving Lifter Bores 06/16/11 

AND........I don't want to hear any more about a Chevy engine. :nonod: Now go to your room because you get a "time-out" for that kind of thinking. :yesnod:


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## geeteeohguy (Feb 2, 2008)

Man! Jim has never sent anybody to their room before. This is getting serious! Jim stated pretty much everything. On my first Pontiac engine (the one that's still running in my '65) that I did way back in 1981, the machine shop left out ALL 3 oil galley plugs. I had your same issues. A huge PITA, but I installed the plugs and the engine lived happily ever after, blowing up transmissions, rear ends, and universal joints with wild abandon. I have really bad feeling about ANY machinist who doesn't do a thorough job 'unless asked' to. YIKES.


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## mbspeed (Sep 25, 2012)

PontiacJim said:


> Did you try a new filter just to see if any difference to make sure it is not plugged up in some way? You can cut it open and look at the filter to see if you have any bearing material in it.
> 
> OK. I can't argue against Butler as they are far more qualified than me by a long shot. The .003" clearance works with the 80PSI oil pump, so that should be OK. Here is a cool YouTube video by Mellings which shows what happens to oil flow at different bearing clearances. https://www.youtube.com/watch?v=7IpJlYssvkM
> 
> ...


Thanks for all the good info Jim.... butler thinks detonation may have wiper out rod bearings .. my oil adapter is new I got it from Kauffman with new spring. I have changed oil like 6 times with in the 1000 miles put on new motor .oil was getting dirty fast think rings did not seal quick enough ..I did see little metal particles on mag drain plug but machinist said its normal on new rebuilt motors .. I have GTO in garage now starting pull motor..the motor cost to much $$$ take chance of blowing out a rod or worst oh and two mods made to oiling system small hole drilled in front gall plug spray oil on chain and on back gal plug spray on dizz gear I was told this is done all the time and its not the problem ..I did change dizzy 3 times maybe I over advanced with my HEI dizzy did not have a advance lock out on that one my MSD is locked out at 33-BTDC ....And now I am going to my room to study my bible .... HOW TO BUILD MAX-PERFORMANCE PONTIAC atriot:atriot: thanks again for all the help and good info


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## mbspeed (Sep 25, 2012)

I did prime oil pump before first start up and all rockers got oil but #3 or 5 got lot coming out around lifter bore same one that made rocker turned blue think I took a picture of this and posted on this site when it first happened last year this has not happened with new rockers but I am running a full roller set not roller tip


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## BearGFR (Aug 25, 2008)

Another thought. Are you positive that you used the correct lifters? I've recently read about one supplier (I forget which one) who's been providing 'chevy' lifters for Pontiacs. Problem is the location of the oil band on the lifter is too high and can actually rise out of the lifter bore at full lift. Several destroyed engines have resulted from the edge of the oil band catching on the edge of its bore. I can see where that could also have a detrimental effect on pressure.

Bear


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## mbspeed (Sep 25, 2012)

BearGFR said:


> Another thought. Are you positive that you used the correct lifters? I've recently read about one supplier (I forget which one) who's been providing 'chevy' lifters for Pontiacs. Problem is the location of the oil band on the lifter is too high and can actually rise out of the lifter bore at full lift. Several destroyed engines have resulted from the edge of the oil band catching on the edge of its bore. I can see where that could also have a detrimental effect on pressure.
> 
> Bear


Hi mr. B.... I have comp cams roller cam 276 with retro fit roller lifters I also called comp cams because of rocker problem and comp sent me 1 new lifter for problem bore still same this was over a year ago.... I even installed new set of lunati roller lifters no improvements :banghead: I have changed oil filters lot over last year ..used ACdelco pf24 wix mobile 1 royal purple but never fram I am doomed :nopity:


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## BearGFR (Aug 25, 2008)

Ut oh.... if I'm remembering correctly it may have been the Lunati lifters that had the oil band location problem. It's worth pulling the intake and lifter cover to make sure.
Pontiac Street Performance - Wrong lifters? I'm going to lose it!
http://www.gtoforum.com/f50/wrong-lifters-im-about-lose-my-mind-80090/
https://www.facebook.com/permalink.php?story_fbid=1089655437730198&id=100000572568296
https://www.google.com/url?sa=t&rct...oxJ2BlSLrjgHyoKew&sig2=dxkJ_1t9kcoEbTCJwO7Aaw

Seems I remembered part of the story incorrectly... it's not that the band is too high, it's too low and allows oil leakage when the lifter is on the cam base circle.

Bear


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## mbspeed (Sep 25, 2012)

BearGFR said:


> Ut oh.... if I'm remembering correctly it may have been the Lunati lifters that had the oil band location problem. It's worth pulling the intake and lifter cover to make sure.
> Pontiac Street Performance - Wrong lifters? I'm going to lose it!
> http://www.gtoforum.com/f50/wrong-lifters-im-about-lose-my-mind-80090/
> https://www.facebook.com/permalink.php?story_fbid=1089655437730198&id=100000572568296
> ...


Well I have the retro roller lifter looks like my crank and rod bearing can see copper not looking good also lifter has lot of wear makes on roller lifters I also did a leak down
Test what is the worst % you can have in a cylinder before its garbage :banghead::banghead::banghead:


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## geeteeohguy (Feb 2, 2008)

You want less than 25% leakdown in general. Less is better. Perfect engines have about 5%. Tired ones 30% or more.


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## mbspeed (Sep 25, 2012)

geeteeohguy said:


> You want less than 25% leakdown in general. Less is better. Perfect engines have about 5%. Tired ones 30% or more.


I guess I am good best cylinder 4% worst cylinder 15% motor was cold...... I just took engine apart FM got into oil supply main bearings don't look good as well as most rod bearings


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