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Oil pump tightness

Good evening all,
Some advice on my oil pump please.
I’ve stripped it & cleaned it & polished the gear spindle bores where the gears were a little on the tight side. Everything’s running nice and freely with the two small bolts fitted (that hold the pump together). However, once fitted to the crankcase with the two larger bolts it seems to tighten up. With a very light nip on them I can still turn the drive shaft with my fingers but the final nip prevents me from doing so.
Is this normal?
As always, any help appreciated,
Gino.

email (option): gino_ketekes@yahoooo.co.uk

Re: Oil pump tightness

If what you mean by "the final nip prevents me from doing so" is that the gears bind, then no, this is not normal. In my opinion there should be a very slight drag during the entire shaft rotation, after priming the pump with a little oil. This indicates a good seal between rotating parts, essential to efficient oil flow.

Check with the technical section of this website, "oil pumps - how to check" for complete pump reconditioning instructions.

I reconditioned two m20 oil pumps using this method with satisfactory results.

Good luck.

Dave W.

email (option): Dwdiak4@gmail.com

Re: Oil pump tightness

Thank you Dave,

Having read the technical reference page for oil pumps everything is clear (I must remeber to that first next time I have an issue)!
The last two bolts that hold the pump in position (in the engine) are clamping the gears ever so slightly, it turns but not freely. I will lap the gears this evening and test the pump clamped with some nuts and bolts to simulate this - as it says in the article.

In hindsight, the problem has been casued by the lapping of the pump endplates, they had swirl marks on them from the gears, effectively I've lapped out any clearance that naturally occured. They did need doing though, the end plates weren't very flat!

pump

upload



Thanks again,
Gino

email (option): gino_kerekes@yahooooo.co.uk

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