Ridiculously High Oil Pressure

[marshman]

Help!

Ideas and suggestions please. A few months ago I posted that my oil pressure seemed to settle around 70-75psi hot. It was suggested that this was too high and either the pressure releif valve in the pump or a faulty oil pressure gauge was to blame or possibly it was fitted with a high pressure pump.

Well I stripped changed the gauge to a known good one from another car and it read pretty much the same. Next I stripped the pump and check the releif valve operation - all seemed OK. So I "invested" in a new pump

Fitted it and wow now I get 75psi at tick over and it increases linearly with engine rpm to over 100psi at 4000rpm:shock:. It still gets to 90 psi with a hot engine. I sent the pump back - its been checked by the manufacturer - no fault found - and a replacement pump supplied and fitted. Its exactly the same.

Three pumps, two gauges and all thats happened is the pressure is higher than ever. :XThere is good oil flow all around the engine right up to the topand no funny noises from the engine anywhere, (which says to me that something must be wrong)

Any ideas whats wrong??

Thanks in advance

Roger

[alan230752]

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hi

what grade oil are you using?

any signs of water in the oil?

is the level correct,not overfilled?

have you used an engine flush to clear any blockages?

are you using a synthetic oil?

sludging of oil can occur is synthetic oils are used after mineral oils have been in engine

hope that helps

alan

[singapore stag]

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You are scaring me now Roger, YOU are supposed to be the know it all in these engine, Stag related stuff.

Sukh.

[Barry Brown]

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Hi Roger
Is your gauge capillary or electrical. If electrical I would change the sender.
If capillary check for washers or 'O' ring damage they can act like valves and skew the readings.
Barry

[marshman]

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Thanks for suggestions so far.

"normal" mineral 20/50 changed 500 miles ago. Don't beleive in synthetics for older engines!

Heads were off 500 miles ago for new gaskets etc. All seems OK - no water loss, oil is clean, temp is normal. Oil ways were all clear. Good oil flow to cam bearings and buckets - so confident there are no blockages. Oil level mid way betweenmax and min on dipstick.I have standard oil filter - changed 500miles ago. Pressure gauge is capilliary fed from 'T' on block next to oil transfer housing - as i said have also swapped gauge for a known good gauge and no difference in reading. I'm convinced the reading is correct asI have several nasty oil leaks from the transfer housing and oil filter even though they have new seals.Everything says to me that the pressure relief valve is stuck shut, butI stripped the pump and checked the valve before fitting. Also last pump went back to manufacturer and they said it was working correctly!

Does anyone know of a peculiarity with the Stag engine, ok i know there are lots of them, but one which could cause this symptom. I can't believe i have 3 pumps with faulty relief valves. My next step is tofit a weaker spring to the valve to see if it makes a difference.

Does anyone know of a supplier of non "County" make oil pumps?

Roger

[Bob Heritage]

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Hi Roger

Agree with you, it certainly sounds like the relief valve on the pump. Do you still have your original pump? might be possible to cannibalise some of it.

Bob

[Ferds]

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I'd look at the relief valve. Can you drop it out and clean it? It sounds like its stuck to me!

Regards

Chris

[marshman]

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Hi Chris,

its a new pump and i did check the releif valve before fitting. i plan to remove the spring and fit a weaker one this evening and see what difference that makes.

thanks

Roger

[GDPR]

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How much for one of your pumps then? I'd like a few pounds more......

[marshman]

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kryten wrote:

How much for one of your pumps then? I'd like a few pounds more......

No need for a pump, i'll just send you one of my releif valve springs

Have just finished "playing" with the releif valve spring. I spoke with Peter at lDparts this morning - fantastic, helpful bloke. he stripped an old pump and measured the deflection of the spring - approx 3/8" for about 3.5kg force.

I removed my spring and plunger - it litterally flew out when I removed the split pin so it wasn't stuck! Now I got a bit scientific and measured the diameter of the plunger and calculated its area then worked out what the force on it would be at about 70lbs/sqin oil pressure. It equated to around 10lbs. I then checked the compression of the spring. With 10lbs force on it it only compressed 0.2" - not enough to open fully to expose the holes in the plunger and releive the pressure. It need a force equal to around 110lbs/sqin to move it sufficiently. I have found a much weaker spring that sort of fits, but it is too weak and now i have around 15lbs at tick over slowly rising to around 50lbs at 4000 rpm. if you rev all the way to 6500rpm then the pressure increase to around 60lbs and then drops back to 50lbs - showing the releif valve is working. I'm not happy with this as I know the pressure will drop as the oil heats up - this was with a cool (not cold) engine. (and I know you shouldn't rev the nuts of off a cold engine - but sometimes you have to do these things)

I'll get back in touch with the supplier/manufacturer and try to get a decent spring to save me having to change the pump again.


Roger

P.S. it takes about2 seconds for the pressure to drop to zero with the engine running when the relief valve plunger exits the pump - with the weaker spring I couldn't getit out again so used the oil pressure instead:shock:

[Guest]

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I want also to ask this questions to you: what grade oil are you using, any signs of [highlight= rgb(255, 255, 136);]water[/highlight] in the oil, is the level correct,not overfilled, have you used an engine flush to clear any blockages, and are you using a synthetic oil?



_________________
Refrigerator Water Filter

[Pommie Stag]

imported post

marshman wrote:

kryten wrote:

How much for one of your pumps then? I'd like a few pounds more......

No need for a pump, i'll just send you one of my releif valve springs

Have just finished "playing" with the releif valve spring. I spoke with Peter at lDparts this morning - fantastic, helpful bloke. he stripped an old pump and measured the deflection of the spring - approx 3/8" for about 3.5kg force.

I removed my spring and plunger - it litterally flew out when I removed the split pin so it wasn't stuck! Now I got a bit scientific and measured the diameter of the plunger and calculated its area then worked out what the force on it would be at about 70lbs/sqin oil pressure. It equated to around 10lbs. I then checked the compression of the spring. With 10lbs force on it it only compressed 0.2" - not enough to open fully to expose the holes in the plunger and releive the pressure. It need a force equal to around 110lbs/sqin to move it sufficiently. I have found a much weaker spring that sort of fits, but it is too weak and now i have around 15lbs at tick over slowly rising to around 50lbs at 4000 rpm. if you rev all the way to 6500rpm then the pressure increase to around 60lbs and then drops back to 50lbs - showing the releif valve is working. I'm not happy with this as I know the pressure will drop as the oil heats up - this was with a cool (not cold) engine. (and I know you shouldn't rev the nuts of off a cold engine - but sometimes you have to do these things)

I'll get back in touch with the supplier/manufacturer and try to get a decent spring to save me having to change the pump again.


Roger

P.S. it takes about2 seconds for the pressure to drop to zero with the engine running when the relief valve plunger exits the pump - with the weaker spring I couldn't getit out again so used the oil pressure instead:shock:

OMG!

I have already got my coat:shock:

Ill try again after a few drinks!!

[Guest]

imported post

marshman wrote:

kryten wrote:

How much for one of your pumps then? I'd like a few pounds more......

No need for a pump, i'll just send you one of my releif valve springs

I'll get back in touch with the supplier/manufacturer and try to get a decent spring to save me having to change the pump again.


Roger

P.S. it takes about2 seconds for the pressure to drop to zero with the engine running when the relief valve plunger exits the pump - with the weaker spring I couldn't getit out again so used the oil pressure instead:shock:

Hi Roger, I'd be a bit pissed at the supplier, claiming they had checked and found nothing wrong, You could stand on two of those springs and they wouldn't move ! I admire your persistence, not to mention an ability to whip pumps on and off repeatedly ! Martin.

[flying farmer]

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A useful tip for anyone having oil pressure problems and wanting to fiddle with spring pressures, is to weld half a washer to theplugof the oil pressure relief valve spring. The hole in the washer lets the retaining split pin fit, and it gives you something to pull on so youdon't have to strip the pump each time- or blow it out with oil pressure:shock:I have done this on both my engines and certainly intend doing it to any new pumps I fit.

Neil

[NickA]

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Martin Stevenson wrote:

marshman wrote:

kryten wrote:

How much for one of your pumps then? I'd like a few pounds more......

No need for a pump, i'll just send you one of my releif valve springs

I'll get back in touch with the supplier/manufacturer and try to get a decent spring to save me having to change the pump again.


Roger

P.S. it takes about2 seconds for the pressure to drop to zero with the engine running when the relief valve plunger exits the pump - with the weaker spring I couldn't getit out again so used the oil pressure instead:shock:

Hi Roger, I'd be a bit pissed at the supplier, claiming they had checked and found nothing wrong, You could stand on two of those springs and they wouldn't move ! I admire your persistence, not to mention an ability to whip pumps on and off repeatedly ! Martin.

So who's the supplier we should avoidand what's the make of the pump? I'll lay a £10 on it not being Holborn Eaton