super high oil pressure

[RonVan]

Oil pressure spikes during operation - has blown oil cooler hose twice - 6.2 1990 - all stock - Is the oil pump pressure regulator the likely cause? Would appreciate some feedback before I pull the pan. Is there a safe way to check the pump/regulator without causing possible engine damage?

Thanks

[More Power]

I'm not all that well versed in the bypass valves used in the oil galleys, but they are located in (pressed-into) the passages that feed the oil filter. One of them is there to bypass oil pressure if the full-flow filter becomes plugged and the other is there to bypass oil pressure if the oil cooler lines were to become plugged.

They are supposed to be removed during a rebuild due to possible damage when a block is dipped or heat cleaned. Your problem sounds like it may be related to one of these valves. I dunno...

Jim

[JohnC]

I think that if the bypass for the oil cooler stuck shut it could cause this behavior. The oil must pass through either the cooler or the bypass, so if the cooler is cold and the bypass stuck, the oil cooler line is the easiest way out. The oil has to go somewhere...

I used to make money working on a particular foreign car. The oil pressure relief valve was in the pump. I saw one jam shut due to a cut o-ring. The pressure blew the can clean off the filter base...

[RonVan]

Thanks guys for the info>>>>>>> I will look into this. Sounds like a plausible answer. :)

[Robyn]

As has been mentioned the bypass for the filter is in the block on the 6.2

The pressure regulator is in the pump itself.

Be sure you have a clean free flowing cooler assembly

The cooler lines and cooler should be able to withstand any normal operating pressure that is produced.

These engines can see 60-70 PSI under some very cold conditions but the normal pressure is 40 running at RPM Hot and Idle at 20 PSI Hot (approx)

I am suspect that you have an oil pump regulator that is sticking.
I would say, replace the oil pump as an assembly with a fresh GM one.

The after market units don't come with a screen and reusing an old screen can be sketchy as once the screen is removed they generally dont press back into a new pump tight enough to be reliable.

Also be sure to get the pump for the 6.2.
I have seen parts guys mix up the later pump for the 6.5 with the squirt block. These pumps are a much higher volume and you dont need that to complicate the issue.

Just be sure your cooler flows freely and that the filter bypass is free to move.
(located under the filter in the block. This is a little spring loaded disc type valve)

Best

Robyn

[oilburnertoo]

There is a filter bypass valve and a cooler bypass valve, oil bypasses the cooler when oil is cold or it is supposed to. Sounds like your cooler bypass valve is stuck ,seen this happen before. I will see if I can find the part numbers for the valves and post them here.

[RonVan]

Thanks Robyn & Oilburnertoo! I am getting ready to lift the engine and pull the pan. The part #'s for the bypass valves would be great :)
Any ideas on possible damage that could have been done to the engine or things I might look for????? The engine still fires and did pull the vehicle into the shop. I just do not trust it to run without blowing another gallon of oil on the ground!

Thanks again>>>>>>>>>>>>

[80Sierra]

You guys have me a bit concerned here...

I just started my 6.2L to bleed out the injector lines before I install my 6.5L turbo exhaust manifold and no longer have access to them. I put plugs into the cooler line ports since I don't have lines for the cooler made up yet.

Did I cause any damage by running the engine for approx 15 - 20 seconds with those ports plugged?

If I did, what do I have to do to fix it?

[john8662]

You guys have me a bit concerned here...

I just started my 6.2L to bleed out the injector lines before I install my 6.5L turbo exhaust manifold and no longer have access to them. I put plugs into the cooler line ports since I don't have lines for the cooler made up yet.

Did I cause any damage by running the engine for approx 15 - 20 seconds with those ports plugged?

If I did, what do I have to do to fix it?

15 - 20 seconds?

No problem, just don't run/drive the engine like this. What happens (just plugging them) is oil is simply bypassed via the valves in the filter boss in the block. It has been mentioned before that oil pressure volume suffers substantially due to this.

The better is a bypass hose, or loop between the ports, instead of plugging them.

John

[80Sierra]

Thats fortunate! I had no idea there was an internal bypass for blockages there... The engine is sitting on a rolling chassis, and does not have any coolant in it, so I ran it long enough to make sure each cylinder was firing, then shut it down.

[diaric]

is the 2nd oil by-pass valve under the expansion plug in the filter base? Dealer couldn't answer, said there was only one valve till i quizzed him, no pics and says number is discontinued
i saved the visable one, but if there is a 2nd, it would be destroyed from hot tanking. which one is which?
he gave me numbers 25011206-oil filter by pass
25011308-cooler bypass
rock auto lists a 25014006 for a cooler bypass

and if its under the expansion plug, what is the part number for that?

thanks richard

[More Power]

According to the GM 6.2L lubrication system diagram I have, the engine oil-cooler bypass valve is located a ways above/behind the pressed-in plug on the oil filter base, on the inboard side of center. The oil filter bypass valve, located on the outboard side of center, should visible when the oil filter is off the engine.

Jim

[diaric]

thanks, got it out. what a PITA. after all that, it looks to be ok and unaffected by hot tanking, but needs replacement now.

hope this is the right one, its smaller than the filter relief valve.
http://198.208.187.182/internet/PartImage.jsp?mfgname=ACDELCO&prodlinecd=42&acpartnbr=25014006

[diaric]

ok, i need some help here.
the dealer brought in part number 25014006, which is too small, listed as oil cooler line bypass valve.
the 82-84's take 25011208 which is discontinued by gm.
rock auto lists a 25013759 for the oil filter bypass valve, but nothing for the oil cooler bypass in those years.
in taking a close look at the two valves, they appear the same size, except for the top, where they press in. the filter bypass looks like its the same as the cooler bypass, with an extra ring mounted around it too fit in a larger opening.

i don't want to rip apart my good filter bypass to find this out or not as they arn't available anywhere locally. anyone have any ideas or expierence in this?
thanks

[diaric]

solved it on my own. found the new part number that works in 82-84 blocks