oil pressure

[marcusclive]

evening gents,
just got back from three weeks holiday in southern Ireland with the stag, brilliant, superb vehicle.
Apart from breaking down on the approach to the Severn bridge on the way home the car was faultless, unfortunately the distributor drive gear stripped and i had to get recovered back to the Island.
anyway to the point of the post, my oil pressure does appear to be a bit high 50 psi hot at idle and when i rev the engine it can go up to nearly 100 psi.
I took the oil pump apart as i am sure i had heard there is a washer inside that can be removed to allow the pressure relief to come in earlier and couldnt find one. The pump is new and also the crank and bearings so i would expect the pressure to be good but maybe not that high.
Marcus.

[jleyton]

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I expect you'll get several much more authoritative replies than mine but as a former Islander (but not a corkhead) I thought I'd reply.

Most, if not all, new pumps are 'County' pumps and the pressure from them is higher than the original.

Many advocate using the PRV spring from the old pump on the basis that too high a pressure could be harmful (oil seals etc) although some say it's not a problem.

My car'sgot too low oil pressure, so can I have some of yours please

Cheers

Julian

[marcusclive]

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Yea, give me a bucket and i will post some over.

[Stagdad]

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I think too higher oil pressure can push too hard on the chain tensioners and reduce the life of the chains.

Cheers Steve

[jleyton]

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marcusclive wrote:

Yea, give me a bucket and i will post some over.

Although it doesn't happen too often, when my oil pressure light flickers I say something a bit like 'bucket'

[Stevekid1]

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I fitted a county pump when I first got my car a couple of years ago and had similar pressures to yours. Got persuaded that it was detremental although car ran ok and so I changed it again this year for a reconditioned pump from soc spares. Pressures back down to 20-25psi tickover and 50-55 hot at 3000rpm. Doesn't leak oil any less than it did before but hopefully the chain tensioners are not under quite as much strain.

Steve

[flying farmer]

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I dismantled an engine a few years ago to find the dizzy drive gears and jackshaft gears very badly worn. I replaced both, and having rebuilt the engine and fitted it to another car,started it to find the oil pressure went off the clock and buggered the gauge.It turned out a coil of the pressure relief valve spring had broken off and jammed sideways preventing the prv operating. I had checked the pump for wear before reassembly, but never thought to check the spring

Neil

[marshman]

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Hi Marcus,

If it is a new pump then the problem is almost certainly the pressure relief valve spring. See this thread I started last year:

http://stagownersclub.mywowbb.com/view_topic.php?id=6131

I eventually replaced the spring with an old one sent to me by Rob at Robsport and it got things back to normal.

If you look at a new oil pump for sale by Robsport on eBay it states that the springs are incorrect and to "use your old one"

http://cgi.ebay.co.uk/Triumph-STAG-Dolomite-TR7-Saab-OIL-PUMP-NEW-/230519803248?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item35ac0d0d70#ht_644wt_706

Hope this helps

Roger

[marcusclive]

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Neil,
seeing your post this seems right. if my pressure is too high the load off the oil pump would be too much for the gears to take. I will put my old oil pump back on with the new gear and try that. The oil pressure was low with the old pump but the crank was worn. When i measured the old pump it was within spec's so should be O.K.

[marcusclive]

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Hello Roger, this seems the sensible thing, saw Niel's post before yours. I will change the pressure relief spring over and check then. I am sure the relief valve isn't working as the pressure keeps increasing with the rev's.
Marcus.

[marshman]

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In a sense you are correct, it is not working, mine was the same. The problem is the spring is miles too strong. The only plus point it is easy to change it. Just remove the split pin and it should pop out. If it does not then you could do what I did which is place a tray under the engine and crank it over a few times to build up a bit of oil pressure, this will push out the spring and the plunger.

The attached picture shows the difference in the springs and also 100 psi at 4000rpm!

Roger

[jleyton]

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marshman wrote:

If you look at a new oil pump for sale by Robsport on eBay it states that the springs are incorrect and to "use your old one"

Roger

One thing confuses me - although Robsport say use your old spring, Peter at LD - who I trust implicitly - says;

".....and a slightly longer pressure relief spring meaning it takes about 72 psi to open the relief valve as opposed to 50 psi.

This will result in slightly higher maximum oil pressure than original. In our experience OE max is 52 lbs psi. It also gives a higher pressure at idle of nearer 60psi than 30.
(This is on our engine which has 100,000 miles since bearings were done)

We are aware of anecdotal expert opinion to suggest that higher pressure is not a problem and in fact could even be beneficial for your engine."

As I plan to replace minesoon I'm now not sure what's the best thing to do :?

Cheers

Julian

[marcusclive]

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72 psi maximum and 60 at idle, i wouldn't mind that but i think this is way too high.
Marcus.

[Moraystag]

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I changed out my pump last winter and although the pressure was ok with old one god know's why. I only removed it to change seal on pressure sensor housing,when I noticed it was scored to bits inside. Bought County pump and changed out pressure relief spring. Absolutely no problem with new Countypump and old spring. Correct oil pressure as indicated in repair manual apparent on my oil pressure gauge.

Mike

[marshman]

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jleyton wrote:

One thing confuses me - although Robsport say use your old spring, Peter at LD - who I trust implicitly - says;

".....and a slightly longer pressure relief spring meaning it takes about 72 psi to open the relief valve as opposed to 50 psi.

This will result in slightly higher maximum oil pressure than original. In our experience OE max is 52 lbs psi. It also gives a higher pressure at idle of nearer 60psi than 30.
(This is on our engine which has 100,000 miles since bearings were done)

We are aware of anecdotal expert opinion to suggest that higher pressure is not a problem and in fact could even be beneficial for your engine."

As I plan to replace minesoon I'm now not sure what's the best thing to do :?

Cheers

Julian

The thing to note is that Peter at LDparts's engine had done 100,000 miles, in this case the increased pressure will help put off the inevitable rebuild. Mine and Marcus's have fairly new bearings and in my case I had oil leaking from lots of places - past new seals due to the excessive pressure. Also there is no way the valve in my pump opened. the pressure kept increasing with engine revs. i bottled out at 5000rpm when the reading was literally off the scale.

Why are you planning to change your pump? - low pressure?If you do change it then simply swap the relief valve springs and the problem is sorted.

Roger