Oil pressure

DPittman · Aug 10, 2019

I'm sure this has come up lots of times before but I'm gonna rehash it again. Went on a 30 mile FFA fundraiser ride today on our ZA. Started off with 40 psi on the oil pressure. Slowly but surely psi dropped off the hotter the engine got until it was down to 18 psi at road speed, 10 psi at idle. Fresh oil and filter using 10-40 and a spin on Wix filter. Same setup I have on our other Z that doesn't have a problem. What else should I be looking for besides a tired pump which is obviously my first suspect? Engine never got hot and ran quite well the whole day. Thanks. DP

neverfear · Aug 10, 2019

I don't think that's too bad for using a multi weight oil.

Dennis P · Aug 10, 2019

Have you tried adjusting oil pressure at pump when hot? Also, there are paper ?shims? between oil pump and block. Manual tells how to shim correctly.

molinegb · Aug 10, 2019

Bottom end on good shape? Did have problem before filter changeup?

DPittman · Aug 10, 2019

Bottom end is in good shape as far as I can hear, in other words I don't hear any rods banging or any other alarming sounds. As for the shims as far as I know it's still got the factory shims in it. The problem was worse before the filter change up so that did help the problem, I just can't remember when the problem first started. I did consider turning the pressure up after it warmed up but then would pressure be too high when it's cold? Don't know if 50 psi would be too much when it's cold or not. Got things to think about though. Thanks again.

molinegb · Aug 10, 2019

Don't get excited as long as it maintains 10 at hot idle. Old TC stuff lucky to hold 5. Check thrust.

SWMolines · Aug 11, 2019

If this was the first oil change using high detergent oil, the sludge inside the engine could be loosening and clogging the oil pick up screen.

DPittman · Aug 12, 2019

Been using high detergent oil since 09 when I rebuilt the engine. When I got down to the screen then it was not a pretty sight. I really don't know how it had oil pressure at all. I think I'm gonna try turning up the pressure next time I get it warmed up really good. Keep in mind this is not a work tractor, it gets run often enough to keep oil on the cylinders and the battery charged. Just kind of unsettling to look down and see a pressure gauge not where it was when you started out at that morning. Thanks again.

Alan K · Aug 12, 2019

Generally on the RE engines you lose about 5-7 psi after warm up.

SWMolines · Aug 12, 2019

I know what you mean. I used HD oil a rebuilt engine thinking it was clean enough to handle any sludge that remained. Several hours later it started loosing oil pressure due to sludge clogging the pickup screen.

Charlie Biler x · Aug 15, 2019

Dpittman,
Generally the symptom you describe is too much end play in the oil pump. You need two to four thousandths end clearance. Anything under two will bust the drive gear and any more than four thousandths will cause the pressure to dive on warmup.
Most people use the too thick gaskets that come in the gasket sets. I have a hard time imagining how you get two to four clearance with a stack of ten thousandths gaskets, that the gasket makers supply.
It sounds funny but the real problem is it is so darn hard to get the really thin gasket material. When I order thin gasket material; the factory demands a minimum of a hundred pounds of one thickness material. That is a several lifetimes supply for making those thin gaskets.
Best of luck.

hanz98 · Aug 21, 2019

Try a different gauge on it. Had same problem with a TC and everyone said check gauge. I stubbornly responded that there was 2 gauges on and both read oil pressure and equally dropped after few seconds. But then it lost all pressure at both gauges one day. Frustrated I unhooked both and put on an older good one and it then ran 18 lbs and 14 after warm-up. No problems since. Loosened dirt can plug up little oil gauge inlet hole restricting flow. Not to mention a cracked head helped do a crank case steam job with old ones hooked up. Wrecked them fast.

DIM · Aug 23, 2019

Early R and Z's only carried 10 to 15 psi when they had a mag. The distubuter turn twice as fast The gearing has to be changed and the oil pump runs on the same shaft. Therefor the oil presure is higher

Oil pressure

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