49 8N low oil pressure when engine is hot. Cam bearings??

[canald1]

Ok. I started talking about this in another thread. I was asked, by another member, to start a new thread for this discussion. So here goes.
I completely rebuilt my engine. Running straight 30w oil, I get 60psi oil pressure. As the engine gets warmer, the pressure drops to below 5 psi at idle. I raise the rpm a bit and the oil pressure doesn't come up much. I've read all the other threads about using different weight oils. I think that I should have great oil pressure with 30W oil. I live in Colorado and use my tractor in winter. Anyway, I thought maybe I screwed up somewhere. I dropped the pan and plastigaged the crank and rod bears, with in spec. Pulled the oil pickup tube, pressurized it under water, no leaks. Checked the oil pump, which was rebuilt, all in spec. Oil relief spring and plunger new.
The only thing I didn't measure was the cam journals and block bore. I have a front distributor engine and can't find a new cam. I think this is the original cam. The journals are not black or scored and the lobes have nice peaks not rounded. The other thing I did change, I originally had a non proofmeter governor and I installed a governor that would run a proofmeter. The only reason I mention the governor is because it uses oil pressure to operate.
After all that, my question is "could the cam journals affect oil pressure when hot"?
I think the answer is yes, if like car engines. What can I do about it??
I have not found specs for the cam journals. I do have service manuals for the 8n.
I have not found a thread about the cam on any forums.

 

[used red MN]

Does any of the possibilities that are covered in this linked thread starting at reply 20 about the restriction for the oil filter apply to your oil pressure issue? Previous YT thread on N series oil press.

 

[wore out]

Ok. I started talking about this in another thread. I was asked, by another member, to start a new thread for this discussion. So here goes.
I completely rebuilt my engine. Running straight 30w oil, I get 60psi oil pressure. As the engine gets warmer, the pressure drops to below 5 psi at idle. I raise the rpm a bit and the oil pressure doesn't come up much. I've read all the other threads about using different weight oils. I think that I should have great oil pressure with 30W oil. I live in Colorado and use my tractor in winter. Anyway, I thought maybe I screwed up somewhere. I dropped the pan and plastigaged the crank and rod bears, with in spec. Pulled the oil pickup tube, pressurized it under water, no leaks. Checked the oil pump, which was rebuilt, all in spec. Oil relief spring and plunger new.
The only thing I didn't measure was the cam journals and block bore. I have a front distributor engine and can't find a new cam. I think this is the original cam. The journals are not black or scored and the lobes have nice peaks not rounded. The other thing I did change, I originally had a non proofmeter governor and I installed a governor that would run a proofmeter. The only reason I mention the governor is because it uses oil pressure to operate.
After all that, my question is "could the cam journals affect oil pressure when hot"?
I think the answer is yes, if like car engines. What can I do about it??
I have not found specs for the cam journals. I do have service manuals for the 8n.
I have not found a thread about the cam on any forums.

I'll comment on one area of what you wrote, "The only reason I mention the governor is because it uses oil pressure to operate.".

The governor does NOT "use oil pressure to operate".

Is the original oil filter canister still in place? This is a "partial flow" oil filtration system, the correct oil filter housing has a small orifice hole in the inner "rod" that allows a restricted flow of oil to pass through the filter, after which it is dumped into the governor housing for LUBE, and returns to the crankcase though the front of the governor housing.

IF something is not correct with the oil filter canister or it has been removed and/or plumbed around it's POSSIBLE for too much oil flow to be lost from the lube system and "wasted" back to the crankcase through the governor.

Probably NOT what you've got going on, but something to CHECK.

 

[Hobo,NC]

If all is as good as you state the next thing to do is confirm the oil pump can create good suction and that should have been your first priority. One check that you have oil pressure as soon as the engine cranks over with the starter ignition disabled and two it pulls a vacuum on the pick up tube as soon as the engine cranks over. If good in both test the oil pump is no your issue.
The next question where am I losing pressure, you would have to remove the oil pan pressurize the oil circuit and look for a big leak, a large leak is the suspect.

I have been thru this more times than most and made the wrong calls and it hurt. In the end this simple plan found the issue with out spending hundreds if no thousands and never got past GO!.

You are fooling yourself if you think a heaver weight oil is going to resolve the issue. The most improvement on a HOT engine you will see is around 1 pound increase in oil pressure BTDT got the tee shirt. Its not the answer and never will be.
\
I have seen the oil pump relief spring be an issue but it caused to much oil pressure I had to replace it with a CNH OEM spring to resolve that issue. Yes cam bearings are always suspect and the last bearer to make good oil pressure. i would think that would be easy to eliminant the office in the oil filter with out making a guess. Plug that line off and test : )

 

[canald]

Does any of the possibilities that are covered in this linked thread starting at reply 20 about the restriction for the oil filter apply to your oil pressure issue? Previous YT thread on N series oil press.

I just had an oh crap moment. That restrictor fitting, where does it go? Ive been working on this tractor for a better part of three years. I have been replacing brass fittings because most were rounded off. I could have missed the small hole not knowing what it was for.

 

[canald]

I'll comment on one area of what you wrote, "The only reason I mention the governor is because it uses oil pressure to operate.".

The governor does NOT "use oil pressure to operate".

Is the original oil filter canister still in place? This is a "partial flow" oil filtration system, the correct oil filter housing has a small orifice hole in the inner "rod" that allows a restricted flow of oil to pass through the filter, after which it is dumped into the governor housing for LUBE, and returns to the crankcase though the front of the governor housing.

IF something is not correct with the oil filter canister or it has been removed and/or plumbed around it's POSSIBLE for too much oil flow to be lost from the lube system and "wasted" back to the crankcase through the governor.

Probably NOT what you've got going on, but something to CHECK.

My mistake on the governor. I thought it used oil pressure to function. Yes I still use the original oil filter and canister. Please see the reply to "used Red MN above. I've been replacing rounded brass fittings and may have missed a restrictor fitting.

 

[used red MN]

I just had an oh crap moment. That restrictor fitting, where does it go? Ive been working on this tractor for a better part of three years. I have been replacing brass fittings because most were rounded off. I could have missed the small hole not knowing what it was for.

Should have been clear, I think that will only apply if the oil filter canister is not original.

 

[canald]

If all is as good as you state the next thing to do is confirm the oil pump can create good suction and that should have been your first priority. One check that you have oil pressure as soon as the engine cranks over with the starter ignition disabled and two it pulls a vacuum on the pick up tube as soon as the engine cranks over. If good in both test the oil pump is no your issue.
The next question where am I losing pressure, you would have to remove the oil pan pressurize the oil circuit and look for a big leak, a large leak is the suspect.

I have been thru this more times than most and made the wrong calls and it hurt. In the end this simple plan found the issue with out spending hundreds if no thousands and never got past GO!.

You are fooling yourself if you think a heaver weight oil is going to resolve the issue. The most improvement on a HOT engine you will see is around 1 pound increase in oil pressure BTDT got the tee shirt. Its not the answer and never will be.
\
I have seen the oil pump relief spring be an issue but it caused to much oil pressure I had to replace it with a CNH OEM spring to resolve that issue. Yes cam bearings are always suspect and the last bearer to make good oil pressure. i would think that would be easy to eliminant the office in the oil filter with out making a guess. Plug that line off and test : )

Hobo, I have been chasing this issue for a better part of 3 years. I was a mechanic on British cars so I'm not a novice. However, I am not to old to learn something new. I agree that oil weight is not the issue because this is not an old rebuild. I have seen the same on MG oil pump relief springs too high pressure. My engine doesn't have cam bearings just riding on the block castings. I used the term Cam bearings to direct all to a possible issue. I have not turned the engine over with the ignition off to see if there is oil pressure when cold. I can say that when I have ignition on, and start the engine, the oil pressure jumps up to about 80 PSI almost immediately, even after sitting for months. Then gradually decline as the engine gets warm. Your idea to pressurize the oil system is intriguing. Can you shed some light on how to go about that? using air pressure?
Thanks to all of you. I'm tired of beating my head against the wall.

 

[canald]

Should have been clear, I think that will only apply if the oil filter canister is not original.

But, I believe I've seen a restrictor like that. Was it at the bottom of the canister?

 

[used red MN]

But, I believe I've seen a restrictor like that. Was it at the bottom of the canister?

In the YT thread I linked JMOR shows the original restriction orifice in the canister center tube in the photos of his reply 32. The tractor was running before you overhauled it and did not have this problem?

 

[Hobo,NC]

Hobo, I have been chasing this issue for a better part of 3 years. I was a mechanic on British cars so I'm not a novice. However, I am not to old to learn something new. I agree that oil weight is not the issue because this is not an old rebuild. I have seen the same on MG oil pump relief springs too high pressure. My engine doesn't have cam bearings just riding on the block castings. I used the term Cam bearings to direct all to a possible issue. I have not turned the engine over with the ignition off to see if there is oil pressure when cold. I can say that when I have ignition on, and start the engine, the oil pressure jumps up to about 80 PSI almost immediately, even after sitting for months. Then gradually decline as the engine gets warm. Your idea to pressurize the oil system is intriguing. Can you shed some light on how to go about that? using air pressure?
Thanks to all of you. I'm tired of beating my head against the wall.

First you must confirm the health of the oil pump. If a pump is good on suction side you can bet its good on the output side.
Oil pressure is made off of restrictions most all have the same clearance specifications are all the mains have the same clearance spec, all the rods and cam journals etc. You are looking for a more than normal leak from any of those areas.

I have rigged up several different types of pressure vessels to induce oil pressure into the stream, mostly I tap at the oil pressure sender. I add oil and charge the vessel with air pressure I regulate flow with a gate valve. Its much like priming the system with an external oil supply. You will not find much about this in a book its something you learn when tapped out with no knowledge of where the root cause is at.

It has solid lifters the only indicator you have would be the oil pressure gauge. Before I move on I confirm the accuracy of the gauge with a tool for that. If it"s taking time to make oil pressure that's a no brainier your first test should be on the pickup side of the pump and go from there.

Most of what i have ran into would be lifters rattle till warmed up are timing chain rattle on start up. Those highly decorated engines Buick 3.8, Toyotas 22R are some of the worst for this type of issues. When you say the mains and rod bearings are in spec I hope you checked them ALL. These two engines are where I came up with the idea of checking oil pressure off the starter motor only. It only takes one haft of a bearing insert set to cause issues, noting above a healthy oil pump will affect the oil pumps ability to suck and discharge oil. Once I determine the pump sucks at the first indication of crankshaft rotation I'm looking past the pump for the problem.

 

[Tall T]

Hobo, I have been chasing this issue for a better part of 3 years. I was a mechanic on British cars so I'm not a novice. However, I am not to old to learn something new. I agree that oil weight is not the issue because this is not an old rebuild. I have seen the same on MG oil pump relief springs too high pressure. My engine doesn't have cam bearings just riding on the block castings. I used the term Cam bearings to direct all to a possible issue. I have not turned the engine over with the ignition off to see if there is oil pressure when cold. I can say that when I have ignition on, and start the engine, the oil pressure jumps up to about 80 PSI almost immediately, even after sitting for months. Then gradually decline as the engine gets warm. Your idea to pressurize the oil system is intriguing. Can you shed some light on how to go about that? using air pressure?
Thanks to all of you. I'm tired of beating my head against the wall.

Well since you're still open . . .
first of all the W of an Oil's viscosity does not mean "weight", it indicates that the oil has a viscosity of 15 at zero degrees Fahrenheit
15W40 for example is an oil where 15W is the cold flow measurement and 40 at a standardized engine operating temp.

My point in telling you this is that 15W40 will give you a viscosity of 40 when your engine is hot
making it ten points higher on the viscosity scale than 30.

Because the 30 is not a multigrade with the additive that regulates the temperature variable
30 has a slower (thicker) flow when cold than 15W40
and is thinner when hot than 15W40

The W has nothing to do with the 40, it refers to the 15. (15W)
Simply put there is an additive in a multigrade that thickens with heat, to offset the oils natural tendency to thin out when hot.
That's why multigrades are better . . . get a desirable fast startup flow but retain the desired viscosity when hot.

Something to think about re. your high pressure when cold and low when hot, while using 30.

Most of the guys here use 15W40

 

[Hobo,NC]

Well since you're still open . . .
first of all the W of an Oil's viscosity does not mean "weight", it indicates that the oil has a viscosity of 15 at zero degrees Fahrenheit
15W40 for example is an oil where 15W is the cold flow measurement and 40 at a standardized engine operating temp.

My point in telling you this is that 15W40 will give you a viscosity of 40 when your engine is hot
making it ten points higher on the viscosity scale than 30.

Because the 30 is not a multigrade with the additive that regulates the temperature variable
30 has a slower (thicker) flow when cold than 15W40
and is thinner when hot than 15W40

The W has nothing to do with the 40, it refers to the 15. (15W)
Simply put there is an additive in a multigrade that thickens with heat, to offset the oils natural tendency to thin out when hot.
That's why multigrades are better . . . get a desirable fast startup flow but retain the desired viscosity when hot.

Something to think about re. your high pressure when cold and low when hot, while using 30.

Most of the guys here use 15W40

So he picks up a pound whats the point its not a fix. You can hope and pray its not a magic fix.

 

[canald1]

In the YT thread I linked JMOR shows the original restriction orifice in the canister center tube in the photos of his reply 32. The tractor was running before you overhauled it and did not have this problem?

Correct. Here's the back story. I did a complete rebuild on this engine in 2003. It ran great had 40 psi oil pressure. At about 600 hours, after rebuild, there was a knock in the engine. There was good oil pressure, should have been my first clue, but I brought it back to the workshop and shut it down. I thought it was a rod knock. So I split the tractor, took out the engine and put it on a stand. Removed the oil pan, didn't see anything obvious. Ok, started removing the rod caps, the bearings didn't look like they had any wear. Checked the mains, also good. Couldn't find the reason for the knock.
Big mistake was when I decided to tear it completely down, clean everything, and measure to insure all within spec. Anyway I did find that the lifters had lots of carbon on them. That was probably my knock, sticky lifters. Anyway here I am. Keep throwing ideas my way because I'm out. Thanks

 

[canald1]

In the YT thread I linked JMOR shows the original restriction orifice in the canister center tube in the photos of his reply 32. The tractor was running before you overhauled it and did not have this problem?

Correct. Here's the back story. I did a complete rebuild on this engine in 2003. It ran great had 40 psi oil pressure. At about 600 hours, after rebuild, there was a knock in the engine. There was good oil pressure, should have been my first clue, but I brought it back to the workshop and shut it down. I thought it was a rod knock. So I split the tractor, took out the engine and put it on a stand. Removed the oil pan, didn't see anything obvious. Ok, started removing the rod caps, the bearings didn't look like they had any wear. Checked the mains, also good. Couldn't find the reason for the knock.
Big mistake was when I decided to tear it completely down, clean everything, and measure to insure all within spec. Anyway I did find that the lifters had lots of carbon on them. That was probably my knock, sticky lifters. Anyway here I am. Keep throwing ideas my way because I'm out. Thanks

Well since you're still open . . .
first of all the W of an Oil's viscosity does not mean "weight", it indicates that the oil has a viscosity of 15 at zero degrees Fahrenheit
15W40 for example is an oil where 15W is the cold flow measurement and 40 at a standardized engine operating temp.

My point in telling you this is that 15W40 will give you a viscosity of 40 when your engine is hot
making it ten points higher on the viscosity scale than 30.

Because the 30 is not a multigrade with the additive that regulates the temperature variable
30 has a slower (thicker) flow when cold than 15W40
and is thinner when hot than 15W40

The W has nothing to do with the 40, it refers to the 15. (15W)
Simply put there is an additive in a multigrade that thickens with heat, to offset the oils natural tendency to thin out when hot.
That's why multigrades are better . . . get a desirable fast startup flow but retain the desired viscosity when hot.

Something to think about re. your high pressure when cold and low when hot, while using 30.

Most of the guys here use 15W40

Thank you for the education. However, I know all about viscosity. I used the W instead of writing out weight. Even using straight 30, the oil pressure shouldn't drop like that. And yes I did try 15w40 no change. Just a waste of oil. No one has said much about the cam.

 

[used red MN]

Well since you're still open . . .
first of all the W of an Oil's viscosity does not mean "weight", it indicates that the oil has a viscosity of 15 at zero degrees Fahrenheit
15W40 for example is an oil where 15W is the cold flow measurement and 40 at a standardized engine operating temp.

My point in telling you this is that 15W40 will give you a viscosity of 40 when your engine is hot
making it ten points higher on the viscosity scale than 30.

Because the 30 is not a multigrade with the additive that regulates the temperature variable
30 has a slower (thicker) flow when cold than 15W40
and is thinner when hot than 15W40

The W has nothing to do with the 40, it refers to the 15. (15W)
Simply put there is an additive in a multigrade that thickens with heat, to offset the oils natural tendency to thin out when hot.
That's why multigrades are better . . . get a desirable fast startup flow but retain the desired viscosity when hot.

Something to think about re. your high pressure when cold and low when hot, while using 30.

Most of the guys here use 15W40

I applaud your breakdown of this oil designation, my point would be the original manual for these called for straight weight oils. When they came out of the factory I am quite sure they all had acceptable oil pressure using those oils. Bottom line is there is problem and the effort is to sniff it out.

 

[soaked]

How thick is the oil pump gasket?
This post gets into it:

Ol Pump

I completed working on my 48 8N oil pump and reinstalled the engine and started it up and ran it for a couple of hours today. Result was that by eliminating the excess end clearance that came from the new replacement gears that are 0.007-0.008" thinner than the original along with the...

forums.yesterdaystractors.com

Here are some I've measured--

 

[Btzj02]

Hobo, I have been chasing this issue for a better part of 3 years. I was a mechanic on British cars so I'm not a novice. However, I am not to old to learn something new. I agree that oil weight is not the issue because this is not an old rebuild. I have seen the same on MG oil pump relief springs too high pressure. My engine doesn't have cam bearings just riding on the block castings. I used the term Cam bearings to direct all to a possible issue. I have not turned the engine over with the ignition off to see if there is oil pressure when cold. I can say that when I have ignition on, and start the engine, the oil pressure jumps up to about 80 PSI almost immediately, even after sitting for months. Then gradually decline as the engine gets warm. Your idea to pressurize the oil system is intriguing. Can you shed some light on how to go about that? using air pressure?
Thanks to all of you. I'm tired of beating my head against the wall.

Canald, Maybe this doesn't need to be said but please don't forget to post back once you find your problem, the fix and the method you used to find it. Lots of good information in this thread and I have a similar problem that eventually I will need to address. Hobo, great info.

 

[Hobo,NC]

How thick is the oil pump gasket?
This post gets into it:

Ol Pump

I completed working on my 48 8N oil pump and reinstalled the engine and started it up and ran it for a couple of hours today. Result was that by eliminating the excess end clearance that came from the new replacement gears that are 0.007-0.008" thinner than the original along with the...

forums.yesterdaystractors.com

Here are some I've measured--View attachment 94863

Yep good info as i am not sold all he states he has checked to spec. BTDT and missed a my shot that's why I jumped ship with all this talk about oil I am not riding that boat. The problem is in his sites he needs to confirm the easy stuff that can be missed. TOH has taught us to not overlook what we get to rebuild a oil pump I know I will not skip over those parts again.

 

[soaked]

Hi Hobo, agree.
20-50 makes me feel good for summer mowing, but isnt fixing any low psi issue.