I just got done redoing the motor in my 1941 h. When I start it when the motor is cold I have about 35-40 psi oil pressure. After the tractor warms up it drops. At a lower idle I only have around 10 psi or so. This seems a little low. I use it for food plots and tractor pulling. Any advise is appreciated. I also use a 5w30 oil if that matters.
- Thread starter CJ_1080
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mattofvinings
Member
My thoughts are you'll do better on 10W30 or 10W40.
I had the same issue with a non-IHC, non-tractor engine, was running 5W30 and the oil pressure seemed low, went to 10W40 and it is now right where I expected it.
I had the same issue with a non-IHC, non-tractor engine, was running 5W30 and the oil pressure seemed low, went to 10W40 and it is now right where I expected it.
Janicholson
Well-known Member
A 5 wt oil is designed for engines made within the last 5 to 8 years. I would go with a brand name 15-40 diesel grade (believe me it is a great oil.
Or 10-40 automotive oil. I would change it, and if it is fresh oil, I would run it through a coffee filter just to get particles out of it, and use it in a car. JimN
Or 10-40 automotive oil. I would change it, and if it is fresh oil, I would run it through a coffee filter just to get particles out of it, and use it in a car. JimN
As Jim says 5W-30 is too light. 10 pounds is not too low for idle. But, I think 75 lbs at full throttle, at least when cold, is more like it for the H engine. When hot your oil pressure will drop. If the cam bearings are worn, the pressure will continue to drop to the 10-20 lb area. Sounds like you did not change the bearings.
I Miked the journals against the bearings and they were all prety tight tolerences. Could an oil pump be worn? I have no problem putting heavier oil or lucas treatment in the engine, but if there is a problem I would like to correct it! If you all think it is the oil, I will run out and change it tommorrow. Thanks for all you help in the past, present, and future!
Janicholson
Well-known Member
Do the oil first. then if not satisfied, the cover plate on the oil pumps often warp. This causes a leak and will lower pressure. Flat sand the plate with 320, then 600 silicon carbide paper on a glass plate. End clearance should be .001 to .0005"
adjusted with thin gaskets from IH. JimN
adjusted with thin gaskets from IH. JimN
Did you put in new cam bearings? If they are loose, you won't get much oil pressure, no matter what you do. Personally, I'd use any of the oil types the others have recommended, or straight 30 weight and not worry too much about it. H engines are fairly forgiving if they get any oil to the bearings. (My $0.02 worth. jal-SD)
CenTex Farmall
Well-known Member
I'd say the same as JNicholson, use a 15w-40 "diesel" oil, such as Chevron Delo 400 or Shell Rotella. (If you read the label real close they're actually intended for mixed fleet use) They're made from premium base stock and have anti-wear additives in them that these flat tappet, shaft rocker engines just love!
Same on the oil pump end clearance. One time I had an M oil pump that had a lot of shaft wear right near the gear end causing. The gear was starting to eat into the pump housing. Had a new shaft made to avert a disaster.
Same on the oil pump end clearance. One time I had an M oil pump that had a lot of shaft wear right near the gear end causing. The gear was starting to eat into the pump housing. Had a new shaft made to avert a disaster.
Anonymous-0
Well-known Member
Another thing, don't overlook the relief valve in oil pump. A lot of wrong plungers were installed over the years. The correct one will be same diameter for the full length of plunger. Wrong one has a reduced diameter for about a half inch or so on closed end. I have found this on several H and M tractors over the years and did on my own H I just went through two years ago. Should carry over 60 psi warmed up high rpms.
I run 5W30 oil in all my gas tractors and have good oil pressure even when hot. What 5W30 means is that in cold temperatures it acts like 5 weight oil and at hot temperature it acts like 30 weight oil. Changing to heavier oil is only to compensate for some other problem in the engine as some others listed.
Steven f/AZ
Well-known Member
I run Mobil Delvac 5w-40 in my rebuilt H and it carries 70 psi all day long. When it is hot, the pressure will drop down to 50 psi at idle.
Spec for H's and M's and such is 75 psi.
I would start with the relief valve, then the oil pump. Heavy oil is a band-aid, I wouldn't be afraid to run 0w-20 in my H.
Spec for H's and M's and such is 75 psi.
I would start with the relief valve, then the oil pump. Heavy oil is a band-aid, I wouldn't be afraid to run 0w-20 in my H.
The relief valve should work the same with cold oil or when hot so I wouldn't worry too much about the relief valve.
I would be more concerned with the bottom plate bolted to the oil pump. This will get worn over the years and this creates oil bypass internally, parts also expand with heat and it doesn't take much to lower the pressure of the oil.
This is most likely the problem since the oil pressure drops after it warms up. When oil pressure drops after warming up is an indication of worn parts or excess clearence between parts. When the oil warms up and gets thinner it can escape thru these smaller clearences and cause loss of oil pressure.
The oil system is like any other hydraulic circuit, if there is a leak pressure will drop.
I would be more concerned with the bottom plate bolted to the oil pump. This will get worn over the years and this creates oil bypass internally, parts also expand with heat and it doesn't take much to lower the pressure of the oil.
This is most likely the problem since the oil pressure drops after it warms up. When oil pressure drops after warming up is an indication of worn parts or excess clearence between parts. When the oil warms up and gets thinner it can escape thru these smaller clearences and cause loss of oil pressure.
The oil system is like any other hydraulic circuit, if there is a leak pressure will drop.
Anonymous-0
Well-known Member
I noticed your max oil pressure was also low that is one reason I suggest checking the relief valve plunger. This is almost exactly the psi you will see with cold oil and wrong plunger and it will drop very low at warm low idle. An H and M carry well over 60 psi normally warm or cold at moderate engine speeds. When you are looking at the relief valve you will get a chance to check pump end clearance and shaft wear also. The relief valve I am talking about was sold during the 50's over the counter, don't know if they were mispackaged or what but they found their way into many tractors. The MD through 450 D carried about 40 psi and also used a different oil pressure gauge calibrated for that pressure.. Always check easy things first and proceed from there.
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