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MG Midget and Sprite Technical - Oil Pressure drop 1275

Hi - Can anyone explain (I'm sure you can!) why the oil pressure on my 1275 starts at about 40lb /sq in then when on a short run drops to less than 10.
When i stopped to check if there was oil in it (there was) and re-started it went back to 40 again for a couple of minutes then dropped off. I wasn't stopped long enough to let anything cool. Is it a viscosity issue?
Thanks
Martin Booth

A 1275 should start from cold @ about 70/80lb and even when normal hot should show about 40 @ tick over,70 when rev'd.

How many miles has it covered.

Could check relief valve has no dirt under it, otherwise I would not run it until its been checked out/ bottom end examined.

Assuming this is a new occurance ? - could check with a second gauge to confirm readings correct .
richard boobier

As Richard says, if the readings are correct the oil pressure is much lower than it should be. It should be investigated.
Mike Howlett

I've had A series do that, and turned out the pump was loose on the block (factory installation on a year old low mile engine). Easier check is drop the sump and see if the pickup pipe is tight - does the same thing. Either is a "must do now".

FRM
FR Millmore

Thanks for this
Richard - speedo says 22000 but i don't think this is correct! Has had the head re-done and the pistons bored out by prev owner and not really run much since in fact was laid up for several years following this partial re-build.
I'll check the gauge as this seems to be a good place to start. then sump off oil pump etc
thanks for your help
M
Martin Booth

As I said before I would check the relief valve does not had something stuck under it before dropping the sump - its easy to do as its on the side of the engine - check its clear of debris and seating O.K.

R.
richard boobier

Yes - the oil viscosity drops with temperature.

What is the history of the car? Was it OK before (at some point in recent past) and now (after some action?) is suddenly lower? What oil are you using

BTW - normal I'd say is around 60 psi hot (>15 miles) at say 3K+ (>50 is acceptable); and at idle (hot) 20 psi is fine (depends on idle speed of course).

Certainly 40/10 is low... but hard to diagnose without further info...

A
Anthony Cutler

Does the op flactuates back and forth as it drops

Prop and the Blackhole Midget

This thread was discussed between 28/05/2012 and 03/06/2012

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