GazM3

High oil pressure M10B23

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Hey chaps.  

Had the engine started and running a few times but had oil weep through the rear exposed head studs.  Just to be safe we put an oil pressure gauge and the oil pressure was very high.  Around 40psi at idle and increasing under free revs.  

 

Mkst at likely oil pressure relief valve in the pump?   Is it a big job to rectify?  Other thing we done a fresh oil change with new filter.  Mechanic used 20w60. Is this oil possibly too thick for the engine causing this high oil pressure?  Questions questions.  

 

Ahh the joys of older cars. Every time I seem to make progress there is another hurdle to jump.  

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Yep, the oil's pertty thick, there.  But 15- 50 usually starts at 40 idle, 85 at 3500 cold, then drops to 30ish idle hot, 65 at anything over 2k.

 

But if you don't see over 90 cold at revs, and 65ish hot, you're fine.

 

The problem is when you see 200 psi cold at 5500, and your oil filter departs... through the hood.

 

And yes, the relief's in the pump itself, so it's a bit of hassle to get to.

 

hth

 

t

 

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And... what are the "exposed rear head studs?"

 

Do you mean the exhaust manifold studs?

 

If so, seal 'em.

 

Cheers,

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They are the ones.  That's what suspected oil pressure too high.  We saw 150psi @ about 4000rpm.  Thought gauge may have been faulty so swapped for another one and saw the same. 

 

Oil pump being removed and rebuilt as we speak.  Just another slight setback but I guess a small delay is better than grenading an engine. I'm thinking of installing permanently oil pressure and temperature gauges.  Have to get one of those triple port adaptors. 

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Lubrication system/Oil pump with drive    

150 psi at 4000 rpm, is that with the engine cold?  If you rev a cold M10 even with a properly functioning pressure relief valve you can easily go well past 100psi.  My guess is the oil pump was assembled wrong.    Look at #8-12 They need to be assembled in EXACTLY this way.  The tube #10 needs to have the long end pointed down through the washer #11.  If it is pointed UP it will not let the piston move far enough to open and the

oil pressure will be HUGE.  Don't worry about #24 that is from an earlier version of the pump,  Also your pickup will look different this is just a picture of a 318 pump because the diagram was easy to copy.

 

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Pump removed and the relief valve piston has seized into the bore which explains things.  

Also will get a new timing chain and sprocket as they haven't used the correct crank sprocket it seems.  Anyway will have parts today so it's only caused a week delay which is not too bad considering.  

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