Is this oil pump ok?

[richardl46]

My 1972 +2 came with the oil pump on the right fitted. I think the relief valve has been sealed with resin to prevent it moving. Is this a high pressure pump and could it be one reason (apart from the sump being over-tightened) why the engine leaked so badly?

On the left is a spare pump that came with the car and appears to be new. One question would be why the sprung plunger is projecting instead of being retained by a staked retainer. I assume the plunger is pushed in and retained when fitting the pump.

I don't want a high pressure pump and would like to think the new pump on the left is ok to use.

Thanks, Richard

[nmauduit]

even at a higher high pressure the relief valve should be operating, otherwise you'll end up with too high pressure at high revs... which could explain oil seeping wherever the weak(s) points may happen to be. Your gauge would tell you if oil pressure rises too much.

[promotor]

The valve in the picture (the one that looks like it has a very basic mesh on it) is an oil filter by-pass valve and it allows un-filtered oil to still get to the engine if the oil filter becomes a restriction or is completely blocked.

Usually performance oil pumps aren't supplied with this by-pass valve installed - it is blanked with a plug - as the cars usually aren't doing high mileage and therefore don't need to have this safety valve as filters are likely to be changed after only a few thousand miles and are unlikely to become blocked.

The pump with the protruding aluminium tube is suggesting that a high pressure spring is fitted as some uprating kits come with that as part of the kit - it's just an easier way of retaining the spring without having to "stake" the retainer in place (and possibly get hit in the eye while trying to hold everything in place under spring tension!!).
In the gallery underneath this aluminium tube is where the pressure relief valve (ie not the by-pass valve) sits. That valve should just drop out in the pump on the left when turned upside down.
The spring underneath the aluminium tube may or may not be a high pressure one - you would have to measure its rate if you wanted to be sure if it is or isn't before fitting it.

[2cams70]

Both these pumps appear to have been modified. The left one has an aluminium spacer installed to increase the relief valve spring tension and hence the oil pressure. The right one has the oil filter bypass valve blocked up with something (looks like epoxy in the picture). The right one could possibly have a high rate relief valve spring fitted too to increase oil pressure. The spring would need to be removed and inspected to determine exactly as it's not possible to tell from the picture. Increasing the pressure can be achieved by either installing a spacer together with the existing spring or installing a replacement spring of higher rate.
Suggest you buy a new complete pump as both of these appear to have been bodged somewhat and they aren't that expensive. NOS Ford pumps are the best if you can get hold of one. If you must you could probably use the LHS one without the spacer together with the spring retainer from the RHS one. You would still need to confirm it had a standard spring however.

Don't be surprised though if the oil leaks remain after replacement as oil pressure only acts directly at the bearings. It doesn't act on the seals or gaskets directly.

[richardl46]

Thanks for the replies. Records with the car show a new oil pump being bought from Paul Matty in 2008 and I assumed that was the new one on the left. I'm not keen to use anything that may have been messed about with on a rebuilt engine so will get a new standard pump ordered.

Regards, Richard

[denicholls2]

"High" pressure on a Twincam is not that high. Cold oil pressure on a healthy engine at idle is about 40-45 psi. My Renault Europa under the same conditions is 80+, so I would not worry much about "high pressure".

When I was a kid rebuilding a BMW 1600-2, we put the crank sprocket on backwards because it looks funny the right way. This somehow caused the relief plunger to stick. Its high pressure symptom was blowing the filter gasket almost immediately. Until you're at that point I would not have much concern about high pressure.

Higher pressure will cause a bit more squirting where the oil can get out of its passages, but I agree it is unlikely to be the cause of leaks unless they're at the oil pressure sensor or similar.

[2cams70]

I forgot to add to this - if you buy a new pump, especially a NOS one make sure the PRV is free before installing it. Make sure you can lift it off it's seat with a screwdriver. It's common for the PRV to rust in place during long term storage under less than ideal conditions.

[oldelanman]

I forgot to add to this - if you buy a new pump, especially a NOS one make sure the PRV is free before installing it. Make sure you can lift it off it's seat with a screwdriver. It's common for the PRV to rust in place during long term storage under less than ideal conditions.

Very good advice.
Can also happen when an engine is not run for a long period.........

[richardl46]

Following on from my original post.

I did buy a new standard oil pump from Paul Matty and after getting the car on the road in 2022 it has covered only 1000 miles, due to continuing restoration and chasing oil leaks etc. The engine was rebuilt by me after a rebore and crank grind by Exon Engineering. At 500 miles the Castrol Classic 20/50 oil was changed along with a new filter. The car is running well, with some reservations regarding setting up the dellortos, and I have just started taking the revs above 4,000 rpm in short bursts.
On starting from cold the oil pressure has always gone straight to 50 psi (maybe 55 psi if taken to 2,000 rpm) and settled at 45 psi ticking over. When at normal running temperature the pressure is 40 psi at tickover and 45 psi at 3,000 rpm or above.
Reading various other posts regarding oil pressure I have not come across any with such a short range, between hot and cold, also between tickover and higher engine speeds. I've just tried a remote oil pressure gauge with similar results so I don't think the mechanical 0-60 psi gauge is faulty. Next step would be to buy another new standard oil pump, but before doing so I would appreciate comments from the forum.

Thanks, Richard

[512BB]

I have written about an oil pump bought from PM around 2010 before. It was faulty, and under read the pressure at 3000 rpm when hot. Read 30 psi. Changed it for a NOS Ford pump after carrying out various checks and normal pressure was resumed. Well, it was there all along. Normal being 20 ish at idle and 45 at 3000 rpm. Both values when hot.

I think your pump is faulty Richard. Don't mess about, buy a new one from QED. Not a high pressure one.

I have also written before, a good condition used Holbourn Eaton or Ford oil pump will be a much better quality pump than the crap made today.

Leslie

[richardl46]

Thanks Leslie, for confirming these pumps can be faulty. As suggested, I've ordered a standard pump from QED.

I was wondering if there are any other possible reasons for the higher than normal pressure, especially at tickover?
Also, could the generally higher pressures be a factor in the persistant oil leak I have at the back of the engine, rear of sump/rear crank oil seal area? This leak only appeared once I started working the engine harder.

Regards, Richard

[Craven]

I have found that crank case pressure can be a culprit with various engine oil leaks, ensure your breather system is ok, the tube between the head and airbox is not restricted. BTW there is a High Capacity High pressure pump as well, identified by a thicker than standard backplate.

[richardl46]

Thanks Craven.
All parts of the breather system were replaced or cleaned when rebuilding the engine and there are no signs of leaks from the dipstick tube or oil filler cap.
I did sort the front end leaks by replacing the timing chain cover, also the cam cover has been leak-free after making sure it was flat.
There is some spread of the flat cork gasket each side of the semi circular cork at the rear end of the sump. I've probably overtightened the back two sump studs. I don't fancy changing these gaskets in situ so may wait until the engine comes out, as I also have a weep of gearbox oil into the bellhousing.
I just wondered if there was a connection between the high oil pressure and the rear crank seal leaking, even though it was replaced during the rebuild.
The new oil pump from QED arrives tomorrow, just 24 hrs after ordering, so hopefully I can get it fitted by the weekend and report back the result.

Regards, Richard

[512BB]

'I also have a weep of gearbox oil into the bellhousing.

Did you seal the botton right hand bellhousing bolt with PTFE or similar?

'I just wondered if there was a connection between the high oil pressure and the rear crank seal leaking'

No, unlikely to be any connection. Did the rear crankshaft sealing surface, ie where the rear seal runs, have a good finish to it? If it was not highly polished in that area, or was pitted, it will leak there. Also, if a deep groove had been worn into the sealing area it will leak. To cure that, you will need a speedy sleeve or similar.

Leslie

[tonyabacus]

I agree with 512BB regarding the older pumps, they were built using different material to the rubbish produced today and is a well known fact with some of the Lotus engine builders, just make sure they are thoroughly cleaned and checked before fitting
Tony