Captain Bud

Here is a synopsis of the history.
1960 Corvette with basic 283. The engine has an oil filter adapter for the spin on filter. I had the oil changed and apparently the previous owner did not use red loctite on the threaded nipple and when the new oil filter was installed, the threaded nipple screwed itself into the adapter leaving only about 2 threads holding the filter on.
While driving the car, the filter blew off and I pumped out 5 quarts of oil immediately. I got the engine shut down quickly. I bought a new spin on adapter and installed it with a new filter. The engine does not appear to be damaged BUT I now have high oil pressure. When I start the engine it shows 60PSI and when I accelerate, the needle is pegged at 60+ PSI. After the engine warms up, the idling pressure is 30-35PSI and at cruise is 55-60PSI.
I have checked the gauge with an external gauge and it's accurate. I'm running 5W30 oil. The oil filter is not bulged out. I seem to recall prior to the filter blowing off, the oil pressure was 25-30 at idle and 45 at cruise.
Will this high oil pressure cause any problems? Would using a lower viscosity oil (0W20) lower the pressure or should I not be concerned about the high oil pressure.
Thoughts?
Thanks,
Captain Bud

Utahcarguy

I have a'61 with the original 283 (freshly rebuilt with about 900 miles on it). I've owned the car for 1.5 years and it always starts with high oil pressure. Pegs past 60. Once warm and I put a load on it (acceleration), it drops to about 35-40 PSI. That's about where it stays during highway speeds. Once I idle, it increases back up towards 60.

My understanding is that high oil pressure is a good thing. Low oil pressure can be a sign of big problems.

Someone correct me if I'm wrong here, but I think your engine is running as it should in regards to the oil pressure gauge.

Donald #31176

I'm running 5W30 oil. The oil filter is not bulged out. I seem to recall prior to the filter blowing off, the oil pressure was 25-30 at idle and 45 at cruise.


As long as there are no strange noises coming from the engine I would not be too concerned. However You are using 5W30 oil which is probably API rated SM or SN . A better choice of oil is API CJ-4. CJ-4 has a higher amount anti wear additive that a flat tappet cammed engine like yours require. SM or SN oils have a maximum limit of 800 PPM of phos whereas CJ-4 oils contain about 1100 PPM phos. Common brands of CJ-4 ared Shell oil Rotella, Chevron Delo.

Utahcarguy

I'm no oil expert....but this guy IS. He runs a very informative blog and tests oils to their breaking point. Here's a quick intro on the guy:

"Before we get into motor oil tech, let’s briefly touch on a little background info. I’m a working Professional Degreed Mechanical Engineer, as well as a U.S. Patent holder. Mechanical Design Engineering is what I do for a living. A Mechanical Engineer is clearly the most qualified Engineer to test motor oil that was formulated by Chemical Engineers, for wear protection capability between mechanical components under load...The intended audience is Automotive Enthusiasts, Gearheads, Hotrodders, Racers and Engine builders. So, it is written in normal everyday spoken language, rather than overly technical jargon. That way, it will be the easiest to follow and understand by the widest possible audience."


After spending hours educating myself and finally asking a few questions of the blogger, I determined that 5W30 Oil Extreme “Motor Oil”, API SM synthetic or 5W30 Mobil 1, API SN synthetic was what was going into my '61. He says that, "5W30 is preferable to 10W30 because of its better cold flow capability".

Mobil 1 can be found anywhere and is reasonably prices for being an outstanding motor oil.

FFBillysCor

Be sure you use oil with proper viscosity for your application. Warmer outside temperatures do not require the lower viscosity start-up blends that colder temperatures do. You want to have the oils that best protect your engine when it is operating at it's optimum operating temperature. You also do not want to add additives to your oil. If your flat tappet cam should have a certain amount of zinc to prevent premature wear, buy the oil that has what your application requires.

SI67

That seems strange to me.

Steve

veeeight

Must have got it back to front

DansYellow66

Posted 1:22 AM - probably writing in his sleep.

Utahcarguy

I don't get it. I re-read my post and that is exactly what happens. Is this not normal? Seems that the OP and I have the same issue then.

Hi oil pressure until the car is warmed up, oil pressure lowers with an increase in load, and increases again at idle.

Frankie the Fink

Not quite....high oil pressure at cold start up is pretty normal; once at operating temp; increasing RPMs should result in higher oil pressure. Nothing else even makes sense... Think about it...the pump is driven off the distributor/cam gearing...more RPMs = more pump revolutions...

veeeight

As you increase the engine speed the oil pressure should rise and drop when you are at idle.
Phil

DansYellow66

About the only abnormality that I can think of that would cause that is a very weak pressure relief spring that opens as soon as the rpm rises and boosts the flow volume - bleeding off pressure. And it barely closes at idle so the pressure jumps back up. Not even sure if that is possible.

street62

I would check the oil pressure in another location if there is one the filter could be blocked or theirs something wrong with the bypass in your spin on adapter

MikeM

That is a symptom of loose main bearings.

wombvette

High volume oil pump pumps oil up to the top. Pressure drops from starvation. Pressure increases when rpm falls back to idle.

Frankie the Fink

i have a hi-vol.pump in the 61. Doesn't act like that ever. I guess insufficient oil level could do it tho.

street62

Go to mellings web site or mellings on utube. They can answer a lot of your questions about oil pressure problems.

Powershift

Good suggestion. I would also pull the pan and check for any debris on the oil pump pick-up screen and also the clearance between the pick-up and the oil pan.

Sounds like the oil pump may be starving for oil, and thus not able to provide the proper pressure when at higher RPMs.

Larry

MikeM

[QUOTE=Captain Bud;1588783354

BUT I now have high oil pressure. Captain Bud[/QUOTE]

Just reading the OP's post, seems like his problem is a new event? What happened before his filter fell off?

The oil pump is a constant, the filter falling off is a recent event.

I'm so confused.

Frankie the Fink

When my canister gasket blew and dumped 4-1/2 qts of oil on the highway...my hi-vol pump reacted by the pressure oscillating between about 20 and 45 pounds. The dancing gauge is what caught my attention and quick action saved the motor.