H Experts..........

Goose

Well-known Member
What all can affect the oil pressure on an H?

I have a 1951 H that the oil pressure goes to almost nothing after it warms up. It's been in the family since 1956, and the engine has not been gone into in all of that time. And it's unlikely it had been before then.

This afternoon, I dropped the pan and plastigauged one of the rod bearings. It was right where it should be, between .002 and .003. The crank miked 2.246-2.247. My book shows 2.2475. Granted, I haven't checked all of the bearings, just the one, but the minimal wear I found so far shouldn't throw the oil pressure off that much.

Is there anything sneaky, like a check valve in the oil filter or something else that could throw the oil pressure off?

Thanks in advance for any info.
 
There is a pressure regulator that can get stuck with a piece of carbon in the regulator spool. It could be cam bearings, it could be a bad gauge. Jim
 
Make sure it's got standard bearing then, that's what happen to my B, when i had it overhauled, i mowed my yard for two years with ten under bearings
 
I replaced the oil pump once, and it didn't make any difference, but I'll check it again.

I did have a problem with a Buick V6 I'd rebuilt once. I was spinning the oil pump, checking for oil pressure while it was still on the engine stand before I dropped it back into the car. I had no oil pressure. I'd gone through the oil pump, and there was a paper thin gasket under the plate, only a couple thousands thick. Sure enough, when the gaskets were stamped, two had stuck together, and I'd put both in without realizing it. I put the pump back together with one gasket, and had plenty of oil pressure. So that is kinda critical.
 
We had a 340u that always had low oil pressure-never went past midway cold and 0 warmed up. I took the regulator spring out of the oil pump and added a thin washer behind it,and then reinstalled the spring.It raised the pressure to more normal readings.Mark.
 
Make sure bolt in oil filter has just a small hole as that is a metering hole. Normally low oil pressure on a warmed up H is oil pump. The shaft wears and causes lot of clearance past the gear.
 
I've seen a couple of M sized pumps that had considerable wear on the gear end of the shaft. Made new shafts out of drill rod.
A combination of that and excess end play could do it. Looks like they've pretty well covered it.
 
When did the low oil pressure condition start? Was it all at once or has it been gradually getting worse?
 

I had the same problem on my H. I took the top off the pump, used a surface grinder to flatten it, put it back on, and the pressure came right up. I was the engineer on a oil pump job for GM. Headspace was the most critical item for pressure, if it is too high, it won't generate enough pressure.
 

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