Slant oil pump

[matienzo]

I'd replaced the Sprint oil pump last year as the old one was worn internally.
Having replaced it with a re-furbished one there wasn't a great change and as the oil pressure was OKish I left things..thinking that's the way this engine is.
A sudden drop to near zero oil pressure a few weeks ago had me worried and thinking the worst.
I mulled it over for a while letting it sit on the drive. Nothing to lose by changing the pump first I thought, but not expecting any great change. BUT Lo and behold...more oil pressure than ever before!
Just goes to show the difference between a 30 year old unused NOS pump now fitted and re-manufactured pumps (fitted last year and failed already)!
I'm just glad it was a quick fix and a pleasant surprise!
Anyone else come across this?

[Edin Dundee]

No, but I would be VERY interested to hear where you got your nos pump from, I also have low oil pressure and I'm hoping it's the pump....

[tony g]

I would be looking at the relief valve and spring first. Pumps work very well when the end clearance is ok. Pitting in the gears hardly changes the pressure (but is why most people change pumps). If the relief valve is off its seat no pressure (or very little) will occur.

Tony

[SprintMWU773V]

Isn;t there an issue with the pressure on some remanufactured pumps? I seem to recall that Robsport advertise them as being wrong but there's a solution that goes with it?

[mahony]

Isn;t there an issue with the pressure on some remanufactured pumps? I seem to recall that Robsport advertise them as being wrong but there's a solution that goes with it?

I think Rob sports slant pumps have the wrong pressure relief spring fitted which causes to high oil pressure and they advise you use your existing spring for the correct pressure

[matienzo]

I found the NOS pump at an auto jumble. It was a lucky find.

[gmsclassics]

Has the club ever considered having oil pressure relief springs re-manufactured?

I have yet to find a suitable source and any I have tried produce an oil pressure far higher than I am comfortable with.

If you do, I'll buy the first two off the line.

Geoff

[Edin Dundee]

"These are 1 3/4 ins long and will compress to 1 1/2 ins long when a 4 kg load is applied if a check is needed."
Does anyone have the diameter?

[Henk]

produce an oil pressure far higher than I am comfortable with

I installed a oil pressure gauge which shows about 40 psi at 3000 rpm (engine warmed up). Compared to my brothers MGB that's a low figure, his car reaches 70 psi in the same circumstances.
What's the figure with the wrong spring installed?

[80Sprint]

That would all depend on the spring rating. Each car will run differently though and can't always be compared like for like. My Sprint runs at 40 psi at idle and 60 psi on the motorway.
You don't need to go above 60 and I believe you could drop to 30 ok at idle. The engine and seals are not designed to run at a very high pressure.

[Jon Tilson]

Gauges vary a lot too...

As long as you see evidence that the oil pressure reaches a maximum at about 3000 rm and then doesnt keep going up the relief valve is working ok and it should limit pressure to 60 psi.

MGB's are no guide and run a higher pressure at around 75 psi but they dont force oil through the jackshaft to the head.

If a B shows only 30 at idle its probably clapped.... whereas a dolly is fine at 20.


Jonners

[Henk]

Thanks, a "relieve" to read that

[matienzo]

Jonners,
You're right about gauges. I compared a couple a while ago...there was 15-20psi difference between them. Not good.
As for the old pump I took off. I couldn't see anything wrong with the PRV. It appeared to be seated ok and there was no visible muck in the system.
What I did notice was a very different feel to the action of the pumps when I filled them with oil on the bench and span them by hand. Not very scientific admittedly because one pump was "bedded in" but the new pump pumped oil out of the pump body all over the bench whilst the old one simply stirred it around.
Having got oil pressure I'm afraid I couldn't be bothered to refit the old pump to see if fiddling with the PRV had made any difference!
Steve

[Jon Tilson]

Be careful though because if the pressure is too high it will put a load on the front jackshaft bearing
and make it wear...

Jonners