High oil pressure?

[ricardo]

My oil pressure reads 80psi steady no matter what, cold, hot, under load or not. Tested with 2 mechanical gauges.

I rebuilt it with all new bearings (mains, big ends and camshaft) and was thinking it was a matter of just being new, it needs to bed in, but I'm not seeing it dropping. It has now 275 miles. What do you think? Should I do anything? Shorten my spring (using spring & ball) or fit another copper washer behind the relief valve nut to drop the pressure a little?

[ivor badger]

Does it vary with rpm?

Stuck relief valve bullet?

[guru_1071]

My oil pressure reads 80psi steady no matter what, cold, hot, under load or not. Tested with 2 mechanical gauges.

I rebuilt it with all new bearings (mains, big ends and camshaft) and was thinking it was a matter of just being new, it needs to bed in, but I'm not seeing it dropping. It has now 275 miles. What do you think? Should I do anything? Shorten my spring (using spring & ball) or fit another copper washer behind the relief valve nut to drop the pressure a little?

ricardo

the easy test is that when its warm and ticking over it should show @75psi, if you rev it quick the oil gauge should drop down to @50, then recover as the release valve opens and then shuts, if it does this you can nibble a bit off the spring to drop the cold high pressure down.

if it shows 80 psi hot at tickover something is wrong.

[abri]

My oil pressure reads 80psi steady no matter what, cold, hot, under load or not. Tested with 2 mechanical gauges.

I rebuilt it with all new bearings (mains, big ends and camshaft) and was thinking it was a matter of just being new, it needs to bed in, but I'm not seeing it dropping. It has now 275 miles. What do you think? Should I do anything? Shorten my spring (using spring & ball) or fit another copper washer behind the relief valve nut to drop the pressure a little?

ricardo

the easy test is that when its warm and ticking over it should show @75psi, if you rev it quick the oil gauge should drop down to @50, then recover as the release valve opens and then shuts, if it does this you can nibble a bit off the spring to drop the cold high pressure down.

if it shows 80 psi hot at tickover something is wrong.

Sorry, I have no advice to give...just another problem to add.

My one car also runs a 80psi when cold and drops to about 65 when idling warm.

My other car runs at 75 when cold and drops to about 35 when idling warm.

Neither drop when I rev them...both go up instead

Wtf?

[ricardo]

Does it vary with rpm?

Steady with RPM. Maybe varies a bit between 80-85.

Stuck relief valve bullet?

I'm using the spring & ball.

ricardo

the easy test is that when its warm and ticking over it should show @75psi, if you rev it quick the oil gauge should drop down to @50, then recover as the release valve opens and then shuts, if it does this you can nibble a bit off the spring to drop the cold high pressure down.

if it shows 80 psi hot at tickover something is wrong.

Thanks Rich, will have another look at it to make sure what happens and when. But I don't think it ever drops below 75. What can be 'something wrong'? Don't tell me the words I don't want to hear

By the way, I'm using Millers 20W50

[guru_1071]

Neither drop when I rev them...both go up instead

Wtf?

if you hold the revs they will go up as the pump is spinning faster, but if you just 'goose' the throttle the gauge should drop as the oil pressure 'gulps' in the couple of seconds that the pump takes to recover - this shows that the pressure relief valve is opening, then been defeated by the spring pressure and shutting again.

if it doesn't do it then you have to assume that the oil shuttle is sticking, or something like that

[guru_1071]

[
Thanks Rich, will have another look at it to make sure what happens and when. But I don't think it ever drops below 75. What can be 'something wrong'? Don't tell me the words I don't want to hear

By the way, I'm using Millers 20W50

I would just nip a coil or two off the end of the spring until the pressure is 75 psi cold.

it should behave then

[abri]

Neither drop when I rev them...both go up instead

Wtf?

if you hold the revs they will go up as the pump is spinning faster, but if you just 'goose' the throttle the gauge should drop as the oil pressure 'gulps' in the couple of seconds that the pump takes to recover - this shows that the pressure relief valve is opening, then been defeated by the spring pressure and shutting again.

if it doesn't do it then you have to assume that the oil shuttle is sticking, or something like that

Ok thanks.

35psi at warm idle...is that healthy?

[guru_1071]

35psi at warm idle...is that healthy?

my minisprint shows less then 10 psi when its hot at idle.

maybe not the best example, but its run fine for years

it did recover when I filled it up with ep90 gearbox oil though, so theres a top tip!

[Spider]

Certainly the high OP could be the Relief Valve being held shut with the spring. For a test, I'd try another old spring, cut to about 70 - 80% of it's length, the OP should drop a long way, but as I say, only do this for a brief test with the engine and oil at running temp.

If it doesn't drop and the valve itself is not stuck in the fully closed position, then it's likely during the Block preperation during the re-build, the brass plug(s) on the relief valve back vent have been knocked in and so the relief valve is locking up, not allowing much relief (if any). One of these plugs is visible & accessible from the front of the block, it's just below the relief valve. The other is in the sump rail.

[ricardo]

Spider, I know which brass plugs you're talking about, the one which faces the gearbox and the other right above it in the front of the block. I was about to remove them, but then I didn't. They're original and unless they're blocking the oil way since the 60s, I'm pretty sure they are fine.

I took the car for a drive again and noticed the following:

- Cold start -> straight to 78-80 (if you split the space between the 75 and 100 readings on the gauge, it's not actually 80 but it's above 75).
- Cold -> If I put my foot on the throttle and quickly release it -> it drops almost to 75, it's just a tiny movement on the needle.
- Normal tempertature, running -> 78-80 (doesn't change with revs/load)
- Normal tempertature -> If I put my foot on the throttle and quickly release it -> Rises to 85
- Normal tempertature -> If I put my foot on the throttle and leave it for a bit -> Rises to 85
- When I put 1st or 2nd gear and start releasing the clutch pedal to make the car move, it drops quickly to 50 and then makes a constant rise to 78-80 as the pedal returns to stationary position

50 was the lowest reading I got without making the engine stall. I think I'll try to find another spring to cut and see what happens.

[Lord Croker]

My 1330 S ran 85 psi oil pressure when driving at anything above 1500rpm, at tick over, it dropped to 45psi, I was well pleased. Five rallying years later, the pressure readings were exactly the same, but the engine died due to worn bores, the crank was perfect. My mate's out of the showroom Mk 2 1275 'S' always ran 90psi when driving & 50psi on tick over, he was well pleased. Not trying to be funny, but what is wrong with 80psi oil pressure?