TR2/3/3A Oil pressure readings

[karls59tr]

My gauge needle swings up to 60 psi on start up and never falls below that and stays at 70 psi when driving. Is this normal?

 

[DavidApp]

My one runs in about the same range but drops to 20 at idle at traffic lights. Probable more like 50 after it completely warms up and is running at about 2500 to 3000rpm. I did reset my pressure relief valve to 70.

David

 

[karls59tr]

My one runs in about the same range but drops to 20 at idle at traffic lights. Probable more like 50 after it completely warms up and is running at about 2500 to 3000rpm. I did reset my pressure relief valve to 70.

David

That sounds normal. What I wonder about is why mine does not drop down to 20 at idle at traffic lights but never drops below 50 or 60? Is there something wrong with my gauge? I have never done anything to my pressure relief valve/ Is it hard to reset? Can they wear out? Karl

 

[Hamish Racing]

Karl
My. “Normal” on both old and new engines is 50 at idle 70 running at 2000rpm + and reaching 80+ when flat out bending the rev counter needle .
It can go as low as 25 straight after a short sharp competition run but comes back to 50 in seconds.

 

[karls59tr]

Karl
My. “Normal” on both old and new engines is 50 at idle 70 running at 2000rpm + and reaching 80+ when flat out bending the rev counter needle .
It can go as low as 25 straight after a short sharp competition run but comes back to 50 in seconds.

So would a prolonged idle of say 15, 20,30,40 psi indicate the motor is worn out to some degree? I have never done anything to the pressure relief valve. Does it ever require removal for cleaning or to check for wear? Is it best to leave it alone? Just as an aside.... if I add a container of STP between oil changes I get a noticeable increase in oil pressure.

 

[Hamish Racing]

Any oil pressure is good. The lower idle pressure may suggest some wear but it’s the flow rate that is good.
The workshop manual I think walks you through the relief valve but this kicks in the filter bypass pressure for when the filter becomes too clogged and would otherwise stop circulation.
It’s just a spring and ball bearing type valve. Not sure it adjusts oil pressure though. Try another gauge to check ?

 

[DavidApp]

I took the PRV apart and ended up lapping the ball seat in a bit with a dowel chamfered to 90 degrees and some 440 wet and dry. I had to add a spacer to the spring to get it to reliable start to blow off at 70. I used an air line with regulator to do the setting. I know that oil is more viscus than air so with oil it may relieve at a different pressure.
The photo is my setup to adjust the valve. There should be some kind of lead washer under the lock nut I think.
David

 

[CJD]

Hey Karl,

What is your idle speed? If it is above 1000rpm, then the gage may be reading correctly, meaning you have a tight engine. If you are idling at 750 or so, then I would lean towards thinking your gage may be sticking.

Does it fall back to zero when you stop, or does it sit for a while before dropping?

 

[karls59tr]

Hey Karl,

What is your idle speed? If it is above 1000rpm, then the gage may be reading correctly, meaning you have a tight engine. If you are idling at 750 or so, then I would lean towards thinking your gage may be sticking.

Does it fall back to zero when you stop, or does it sit for a while before dropping?

Good point. Yes idle speed is above 1000. I can't get my engine to idle lower than 1200 psi or it stalls out. Even at that idle I have to blip the accelerator at a stop light or It will come close to stalling out.(Maybe the throttle shafts are worn ) When I stop the gauge never drops below 50 psi? I think the high reading shows the engine has good oil pressure so that's good. Others seem to have the oil pressure drop lower at idle.... is that just because they have set a lower idle and not because they have excessive engine wear?

 

[CJD]

It sounds like your gage could use a cleaning and calibration. You can be sure the oil pressure goes to zero when you shut down. That means your gage is not correct, so you can't trust the readings. Until you have an accurate gage, don't try to alter your oil pressure with the adjustment.

 

[DavidApp]

My idle is about 750. The engine is only 3000 miles off a rebuild so it should be tight. I did replace the oil pump because the oil pressure was lower at idle. The only thing that I have not done is the bearings in the oil pump drive. I gather you can lose some pressure there if it is worn.
After I replaced the oil pump my oil pressure at start up was 90 then as it warmed up it would drop a bit. Still 20 at idle. That is the reason I reset the PRV.

David