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Oil pressure low to 0 at idle when engine is hot


B.Liesberg

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If the engine is not noisy, it is probably not quite down to zero psi. Typically, pulling the oil pan, removing the oil pump, removing the bottom plate of the oil pump and resurfacing the bottom plate will resolve the low oil pressure. The oil pump gears typically wear the bottom plate resulting in too much clearance which causes low oil pressure. 

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I agree with all of the above.  I like the look of the old gauges, so consider buying a modern oil pressure gauge to connect temporarily at the block to check that your dash gauge is still accurate.  If the gauge is good, then I would pull the pan as the others have suggested (cleaning the screen and checking the oil pump bottom surface).  Also consider pulling the oil pump pressure valve spring to ensure that it is not broken or weak.  If you found nothing above to have any problems, with the pan off, you could also use plastigauge and check the bearing clearances.       Hugh

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The motor honey is the problem. It is

  1. Snake oil. Try to find any technical information about it!
  2. A viscosifier. It will thicken the oil.

Thick oil is harder to pump. Just use plain 10W-30 oil. It has plenty of additives in it. If your engine is a bit rattly or smokey, try something like a 5W-40.

 

If you want thick oil, use higher viscosity oil and don't guess with additives with pretty labels and high-hype advertising.

Edited by Spinneyhill (see edit history)
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If the gears are not too worn you can reface the body and cover fairly easily.  On a flat work surface place a piece of glass.  Coat the glass with grinding compound and move the cover and/or body in a figure eight motion on the compound.  You can use emery paper on the glass instead of grinding compound.  Just keel using finer and finer. The cover is easy to tell when it is flat.  With the body you need to keep measuring.  Easy done and cheap as well.

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WOW, yhat is a lot of wear.

Manual says end clearnce of gears should be .0005" to .004". You are a mile past that.

There are both steel and pot metal pot metal covers. You should see if you can a metal one. The pot metal one was a bad idea.

You can use plastigage to check that cover for clearance if you get new parts.

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5 hours ago, DonMicheletti said:

You can use plastigage to check that cover for clearance if you get new parts.

 

Mine is definitely steel, but the problem is the pump housing is worn on the driven gear side about as much as the plate is, so I think I need to replace the entire thing. I'm not even sure how it got that bad.

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The best source for any used replacement part for any 1936-1941 Buick is Dave Tacheny. You can best reach him at 763-427-3460 between 4 and 7 pm Central. If you don't reach him initially, keep trying. He should have what you need and has reasonable prices as well. 

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8 hours ago, 1924 6-55 Sport Tourer said:

If you replace the pump, you will be substituting it with another 90 year old one that is most likely worn just as bad.

For my car i just had new gears made. It wasnt cheap but it solved the problem.

 

David

 

The gear kits for the 320 I've been seeing are onIy $60 or so, but I doubt putting new gears in a worn housing will fix anything.

 

20 minutes ago, MCHinson said:

The best source for any used replacement part for any 1936-1941 Buick is Dave Tacheny. You can best reach him at 763-427-3460 between 4 and 7 pm Central. If you don't reach him initially, keep trying. He should have what you need and has reasonable prices as well. 

 

Thanks! I'll try to contact him.

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I am with Hinson. The kind of wear you see is pretty rare, but, obviously, not unheard of.

Both my '38's are 80 years old and the Roadmaster has over 100,000 miles on it and its pump showed almost no wear. It was an original car when I bought it.

Tacheny is your best bet.

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