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Series MM side valve oil pumps

Posted: Wed Dec 27, 2023 9:23 pm
by rsawatson
Is an oil pump from a USHM3 engine suitable for fitting in a USHM2 engine? The oil pump I have is from the USHM3 engine (which used to be in my car) and apart from the shape of the hood I cannot discern any difference between them (based on the diagrams in the workshop manual). The oil pump I have got has a gauze inside.

Attached are photos of my oil pump and the one shown as correct for a USHM2 in the manual (red arrow illustrates the only difference I can see).

Advice would be much appreciated!

Many thanks,

Ryan

Re: Series MM side valve oil pumps

Posted: Thu Dec 28, 2023 8:11 pm
by Mick Lynch
It’s okay if the USHM2 block has been modified to have an external filter, otherwise fitting an USHM3 pump to an USHM2 engine will leave the engine with no oil filtration!

What you have looks like an USHM2 pump (or military generator/ marine engine). The USHM3 has quite a different body and pickup. See photo.
D78FB948-9366-4011-8BAD-12F71E1FF9CF.jpeg
D78FB948-9366-4011-8BAD-12F71E1FF9CF.jpeg (306.58 KiB) Viewed 2505 times

Re: Series MM side valve oil pumps

Posted: Thu Dec 28, 2023 8:23 pm
by rsawatson
Oh yes - I see what you mean - having referred back to the diagram I can see the difference now!

Interestingly, the engine this pump came from was a USHM3 with external oil filter - so it would have had the filter and the gauze inside the pump for filtration. It’s strange that it doesn’t seem to have that ‘lip’ in the body which you can see in the workshop manual diagram.

Many thanks.