100psi oil pressure!

[Monkfish]

My freshly rebuilt race pinto is showing 80psi oil pressure at around 2k rpm and over 100psi (off the gauge) at near 5k rpm. This was on first startup of the engine - water temp was 75c, oil (20/50 mineral oil) was still relatively cold as it had only been running for maybe 10 mins.

This engine will be run to 8k rpm so the oil pressure seems way too high! The pump is a new high-capacity one from Burton, the previous one I used was a high-capacity cast-iron Melling pump and oil pressure was 70psi at 7k rpm 40psi it idle

Should I change the pump - or could it be ok??

cheers

[Graham]

get the oil hot then see what the pressure is

[Erikmex]

That is quite high, relief valve stuck or perhaps tight crank bearing clearances ?

[Monkfish]

Thanks Graham - Unfortunately the first chance I'll have to get the oil properly hot is when I get to the track for my next race I can't run the car under load at home, plus the bottom end is all brand new and I'm trying to be mindful of the 'correct' break-in procedure. I could try to get it hot by running it up and down the revs for a while?

[Monkfish]

Erik - The bottom end is all new, but the short motor turned freely with one finger when I got it back.

[Erikmex]

Could still have tight bearing clearances, depends on what they’ve been set to through machining

[Forest_rallying]

You really can't get a proper picture of what's happing with the pressure until you get your oil stinking hot. You'd be suprised how many people post on here saying their oil pressure's sky high on a new build, then we hear no more from them. It could be a possibility that the oil pump manufacturer has got a little careless and put too stiffer spring for the relief valve.

[Monkfish]

I completely agree that it might turn out to be just fine with the oil up to temperature and the cooler connected up etc. My worry is that I won't find out until I've towed the car and all the tools and spares ~300 miles to the track.
I think I'll pull the pump off and make sure the relief valve isn't stuck. I have a standard cast-iron pinto pump in perfect condition that I could swap in if it's up to the job?

btw - the bearing clearances are 0.0025 and 0.0020

[Graham]

you cant tell if the relief valve is stuck as you cant see it!

ive had engines showing 70psi oil pressure spinning the oil pump with just a battery drill, in use they were fine, it not that unusual to see really high oil pressure on cold engine

[onecamohv]

you should still see the relief valve opening though on a decent oil pressure guage (assuming your guage goes up to the pressure your relief valve is set at.

in my XE at the moment the relief valve is set at 80psi, and when i start it cold the guage shoots up to around 85/90psi (and would keep going) but then almost immedately the relief valve opens and it settles at 75/80 until it gets warm dropping all the time
i can take a video if it helps

[Monkfish]

Graham - I can access the relief valve at the base of the housing in my old pump and move it freely with the tip of a screwdriver (see the picture below) I was planning on checking the relief valve on my new pump in the same way?

On closer inspection the old pump doesn't look that bad..

[Monkfish]

onecam - my oil pressure also shoots straight to 80psi on startup too, it stays steady there though until I increase the revs. I wish I'd shot a video of the oil gauge to show folks here.

[Monkfish]

I’ve booked a dyno session for this Saturday so we’ll find out if it’s ok or not when the oil is up to temperature.

[onecamohv]

seems strange, when i increase revs you can clearly see the valve opening via the pressure guage

[Monkfish]

On the dyno at the weekend the oil pressure settled down to 80psi when hot, thanks for all the advice - saved me from tearing it down and messing with a perfectly good pump!

A summary for anyone in future:

- New Burton High Capacity, High Pressure oil Pump - 2.0 Pinto
- Freshly rebuilt motor

- Cold cranking oil pressure - 80psi, cold running pressure 80-100+ psi

- *hot* running oil pressure (dyno pull) 80-90 psi

Thanks again guys.

[Monkfish]

On the dyno at the weekend the oil pressure settled down to 80psi when hot, thanks for all the advice - saved me from tearing it down and messing with a perfectly good pump!

A summary for anyone in future:

- New Burton High Capacity, High Pressure oil Pump - 2.0 Pinto
- Freshly rebuilt motor

- Cold cranking oil pressure - 80psi, cold running pressure 80-100+ psi

- *hot* running oil pressure (dyno pull) 80-90 psi

Thanks again guys.