Oil pump replacement

[Paul Kelley]

My oil pressure is on the low side at normal operating temperature, 10-12 at idle, 30-40 cruising, 40 + harder acceleration, higher revs. It's been suggested I replace the oil pump. My questions are, please: is this a good idea? Do I just need the pump, spindle and O ring? Anything else at same time, e.g. pressure release valve? Thanks for thoughts as ever.

[dasadrew]

The pressure relief valve is part of the pump asembly if you buy an "Oil Pump".

Drew

[flying farmer]

If you do fit a new pump make sure you save the pressure relief valve spring from the old one. The new County pumps used to have a spring that gave too high an oil pressure and I don't know if this situation has changed yet
Neil

[barkerwilliams]

It is worth a look at this Triumph TR6 oil pump blueprinting, Pump has same working principles but mounted internally on TR6, if you strip yours this gives good pointers to areas to look at. Do not throw any parts of the old pump away, old pumps are a rich source of quality parts.

http://tr6.danielsonfamily.org/OilPump.htm

Alan

[Matt Cook]

Try placing a washer under the split pin that hold the relief valve in, I don’t think it will work given your description but it’s worth a try to check if the relief valve spring is a bit weak.

If the installed pump is an original Hobourn Eaton one I would rebuild that if the body is good. LDParts do a rebuild kit.

[mole42]

If you do a rebuild, it’s worth surfacing the pump cap to remove the circular scoring. That helps improve the pressure by removing a leakage path.

[Paul Kelley]

Many thanks guys, useful feedback as ever. The new one I was thinking of is indeed the Count one from Peter at LD Parts so I'll bear in mind your point Neil about switching the relief valve spring. Will also have a look at the rebuild kit Matt. In all other respects my car is working really well and getting regular use. Since rebuilding the Strombergs using the kit from Burlen (c £120) they are performing perfectly, such a difference and I have dropped any idea of switching to a Holley or Stagweber, at least for the time being. Paul

[jbuckl]

Remember that the pump only creates flow & is well capable. The pressure is only created by the tiny bearing clearances. Once the clearances have worn, the pressure is going to remain low.
If an over capacity pump is fitted, damage can result at the cam chain tensioners.
as others say avoid the county pump.... I tried one... it leaked badly & was far too high pressure.

[trunt]

Yes try shimming the spring first, not a difficult task.
My county pump ran at 75psi so I installed the original spring which I felt was too low pressure. A shim got it to about 50/55 psi pretty much all the time, which I hope tells me it’s on the relief all the time and the engine is nice and tight, — as well it should be after spending all that money on it!

Terry

[Paul Kelley]

Just checked back in and seen these extra two posts, so extra food for thought, with thanks JBuckl and Terry/trunt.

[DZP]

My new County oil pump is leaking from the securing bolts.
I have torqued the bolts as far as I dare, but oil is still appearing from around the bolts.
Oil pressure is OK.
Does anyone know how to fix this please?
Thanks.

[marshman]

My new County oil pump is leaking from the securing bolts.
I have torqued the bolts as far as I dare, but oil is still appearing from around the bolts.
Oil pressure is OK.
Does anyone know how to fix this please?
Thanks.

Either the 'o' ring is damaged/twisted/not seated correctly OR the face of the pump has been "bruised" or "bumped". You need to remove the pump and check the mating faces (engine block and pump) are perfectly flat and free from any raised bumps/bruises/burrs). Check the 'O' ring is seated correctly and not twisted - or even missing?

The bolts should not need to be that tight to stop oil coming out. You have checked you have got the correct pressure relief spring as well, earlier "county" pumps had the wrong spring fitted and this allowed far too high oil pressure.

Roger

[flying farmer]

Sounds like a problem with the O rings. There is one between the pump and the block and one between the pump body and the top of the pump.Either one could be leaking through to the bolt holes
Either that or a flaw in the casting allowing oil to escape. The only thing to do is remove it and check.

Best to contact the supplier as it should be replaced if it is faulty and not just a bit of crap caught under the block to pump O ring.

I did once buy a new County pump and could see a slivver of O ring poking out of the pressure relief valve cap. Didn't even think of fitting it before I had replaced the O ring

Neil

[DZP]

Thanks Roger, Neil,
Den

[Mark Serj]

Make sure you check all the tolerances match the spec in the manual. Sometimes a little fine dressing is needed