Allis Chalmers B oil priming after filter change

[49clipper]

After having the oil cooler housing off, I cannot get oil to the filter or rocker arms unless I remove the filter and pump oil into line to the pump. Every time. It works till the next time I start it and get no oil pressure. Just rebuilt the oil pump and the rest of the engine gets oil. I put oil in the filter before replacing. Why?

 

[Butch(OH)]

First off nothing is getting oiled if the pump isn't working. It pumps oil through the camshaft which then oils the mains and rods via splash holes. I can't answer why this started when you had the housing off, but when you rebuilt the pump did you install new vane's and springs? Did you have the cover ground flat to remove wear? Lastly did you use the pump gasket supplied in a gasket set? If so you need to take it back apart and get rid of the gasket because it is waaay to thick and will cause priming and pressure issues. The OEM gasket was very thin, old timers called it onion skin the paper is so this it is almost see thru. I don't use a gasket. Bolt the cover up without one and see if the pump turns freely. If so take it back apart. Clean and dry the surfaces and apply a REAL THIN line of silicone to the cover and put it back together. This will solve your priming issue unless the housing is totally shot.

 

[49clipper]

did all of that during the pump rebuild. specs call for a max of .002" difference between the top of the rotating pump and the cover and I got it to .001" Took two of the .005" thick gaskets and some sanding of the cover. Per the specs. New vanes, springs, and rotating pump. the internal cam and crank are getting oil I am sure. It just gets air locked at the filter and the line to it. I filled the filter, and if I purge the line back to the tee from the pump, I get pressure at the gauge. If I do not remove filter and pump oil into that line, no pressure at the gauge. So, for some reason it gets air locked at the that little 1/4" line. That is the problem.

 

[Janicholson]

did all of that during the pump rebuild. specs call for a max of .002" difference between the top of the rotating pump and the cover and I got it to .001" Took two of the .005" thick gaskets and some sanding of the cover. Per the specs. New vanes, springs, and rotating pump. the internal cam and crank are getting oil I am sure. It just gets air locked at the filter and the line to it. I filled the filter, and if I purge the line back to the tee from the pump, I get pressure at the gauge. If I do not remove filter and pump oil into that line, no pressure at the gauge. So, for some reason it gets air locked at the that little 1/4" line. That is the problem.

Oil pumps maintain prime if there is no way for air to get in them in the pump output. So look for leaks that allow that. Pressurizing the system with the pan off might be educational. Jim

 

[Jim.ME]

After having the oil cooler housing off, I cannot get oil to the filter or rocker arms unless I remove the filter and pump oil into line to the pump. Every time. It works till the next time I start it and get no oil pressure. Just rebuilt the oil pump and the rest of the engine gets oil. I put oil in the filter before replacing. Why?

That is a bypass filter. Is the "stand pipe" the filter slides down over in place in the housing. That pipe has a small hole in it to limit oil going through the filter. If that pipe is missing or out of place it may not have oil pressure. What brand and part number filter is on it? There were some WIX/NAPA filters years ago that passed too much oil, too quickly, through the media and caused low or no oil pressure.

 

[used red MN]

I agree with Butch, when you show no pressure your pump is pumping nothing. I see the oil pickup tube screws in probably with pipe threads to make the connection. I wonder if there might be a problem with threads causing them to leak air so the pump looses prime. Was this a running tractor with reliable oil pump prime and pressure before or did you buy it not running so you don’t know the history of how it performed before.

 

[Butch(OH)]

did all of that during the pump rebuild. specs call for a max of .002" difference between the top of the rotating pump and the cover and I got it to .001" Took two of the .005" thick gaskets and some sanding of the cover. Per the specs. New vanes, springs, and rotating pump. the internal cam and crank are getting oil I am sure. It just gets air locked at the filter and the line to it. I filled the filter, and if I purge the line back to the tee from the pump, I get pressure at the gauge. If I do not remove filter and pump oil into that line, no pressure at the gauge. So, for some reason it gets air locked at the that little 1/4" line. That is the problem.

"Air lock" on that line is not causing your problem, it is a symptom of another problem and to figure it out you need to know exactly how the oil system works. The pump draws oil from the sump and from the vane's it has two choices, out through the drive stem and to the camshaft or up the pipe to the Tee before the filter. Inside the pump stem there is a ball and spring. What it does is create a restriction on the stem so that a portion of the pump flow is forced to pipe leading to the filter. The oil gauge on those tractors does not read pressure to the bearings, all it reads is the restriction caused by the bypass oil filter element. Because the Tee in the oil line is before the oil filter the restriction in the filter element causes a portion of the oil to be forced up the line to the rockers (and governor on the later tractors) A quick look at the external lines will confirm this flow. This being on the pressure side of the pump means it is impossible for it to become air locked. If the pump is pumping oil to the camshaft and bearings it must also be forced up the pipe to the filter and force the air out,, unless the spring and ball in the pump stem isn't working correctly OR there is debris in the line blocking it, neither of which is going to be fixed by filling the filter or oil lines I still say your pump is loosing prime. Those tractors will crack the pipe leading from the sump to the pump and it causes the issue you are having.

 

[KL in Wi]

I agree that if there is no pressure to the upper end of the engine, there is no pressure to the lower end. I overhauled my RC, same engine. everything checked out good on the pump. It had pressure before I took it apart and the first time I started it after the overhaul. After that, it would never build pressure unless I took the line going from the T to the filter off and shot oil into it then, the pressure was fine. Split it and took the pump out. Everything looked good. Put it back together, same thing, no pressure. Took it apart again and started to take the pipe out of the pump and it snapped off with very little pressure where the threads start. Had to have had a crack there which let air in so the pump lost prime. I put a new pipe in it and it has been working perfect since.

 

[Fixingfarmer]

Pressure was good before cooler was removed?

 

[KL in Wi]

I didn't remove the filter housing. I just separated the line at the T, shot oil in it and reconnected it. After I put the new pipe in it has been working perfect. That pipe had a crack that was letting air in so, the pump would lose it's prime

 

[Fixingfarmer]

Glad you found it!

 

[49clipper]

Mine started working two days ago. Why? Who knows, but after changing back to 30W oil (with a 1/2 pt of STP just because) and priming four times, it finally gets pressure now at the gauge. I think it was Butch that made the comment the oil pump has two choices. There are no choices, if it goes to the cam, it goes to the external line to the filter and rocker arms. I found no leaks at the external line or anywhere on that piping. A real mystery. However, all the sudden it works. The only common factor that started this was that I changed to 10W-30 oil and that is when the gauge quit working. The pump never needed to be primed before that. After removing the pump and installed the new kit, it started. My manual says .002" max tolerance at the cover to pump, so I rigged up a jig and got it down to .001" which I figured was good enough. Then the problems. But hopefully I think its fixed. Being a mechanic, I just don't like unsolved problems.

 

[Fixingfarmer]

Yeah once it’s warm that shouldn’t matter when it’s cold I can see pressure would be better but it should be more difficult to prime...

 

[Butch(OH)]

Mine started working two days ago. Why? Who knows, but after changing back to 30W oil (with a 1/2 pt of STP just because) and priming four times, it finally gets pressure now at the gauge. I think it was Butch that made the comment the oil pump has two choices. There are no choices, if it goes to the cam, it goes to the external line to the filter and rocker arms. I found no leaks at the external line or anywhere on that piping. A real mystery. However, all the sudden it works. The only common factor that started this was that I changed to 10W-30 oil and that is when the gauge quit working. The pump never needed to be primed before that. After removing the pump and installed the new kit, it started. My manual says .002" max tolerance at the cover to pump, so I rigged up a jig and got it down to .001" which I figured was good enough. Then the problems. But hopefully I think its fixed. Being a mechanic, I just don't like unsolved problems.

Glad it's working but I am correct about two choices, you might not like my wording but technically it is correct. When the oil leaves the pumping chamber it can go to the cam through the hollow drive stem or to the outlet for the the external pipe, it's a tee and the oil will follow the path of least resistance. If not for the ball and spring in the drive stem almost zero oil would go to the filter because there is much less resistance to simply go out the pump stem into the hollow camshaft. The entire system relies on resistance to flow to keep the proper amount going to each area. The same engineering was used in the external oil piping and filter. There is a tee, oil can go to the filter, or it can go to the rockers and governor. The only thing that forces oil to the rocker shaft is the resistance of the oil filter and the small diameter line going to the governor which acts as an orifice. You can read anywhere that Allis is discussed about a run of NAPA wix filters 15 years ago that they changed the filter media and they had much less resistance than the proper cotton ones, result was oil didn't go where it was supposed to go, it was easier to flow through the bad filter instead of to the camshaft and ruined engine bearings was the result. Hope it stays primed for you now.

 

[49clipper]

Glad it's working but I am correct about two choices, you might not like my wording but technically it is correct. When the oil leaves the pumping chamber it can go to the cam through the hollow drive stem or to the outlet for the the external pipe, it's a tee and the oil will follow the path of least resistance. If not for the ball and spring in the drive stem almost zero oil would go to the filter because there is much less resistance to simply go out the pump stem into the hollow camshaft. The entire system relies on resistance to flow to keep the proper amount going to each area. The same engineering was used in the external oil piping and filter. There is a tee, oil can go to the filter, or it can go to the rockers and governor. The only thing that forces oil to the rocker shaft is the resistance of the oil filter and the small diameter line going to the governor which acts as an orifice. You can read anywhere that Allis is discussed about a run of NAPA wix filters 15 years ago that they changed the filter media and they had much less resistance than the proper cotton ones, result was oil didn't go where it was supposed to go, it was easier to flow through the bad filter instead of to the camshaft and ruined engine bearings was the result. Hope it stays primed for you now.

 

[49clipper]

Well, it stopped working again. So, I think there is something wrong at the pump. It should not drain back like its doing without a reason, and the pump is letting flow thru it. I removed the oil pan yesterday and removed the oil sump line to the case to check for anything I could find. Perfect line and tightness. No issues there. No leaks in any of the lines external to the engine either. So, what's left, but the pump. If the pump rotates, oil should flow both directions. The only restriction then is the ball and spring for the 15psi. Yes, I heard about the filters, but I never had one of those. These pumps are positive displacement pumps, therefore even if air got into a line downstream from the pump it would just pump oil thru it and displace the air. Just like a gear pump. I used the phrase "air lock" but that was incorrect due to the positive displacement type pump. Oil will push that air right on down the line. Anyway, the engine is coming off again. I am thinking the pin in the cam just might be a place to look although it looked fine when I put it together last time. The pump turns CW from the rear of the engine and I am sure I put the vanes in correctly, but I will check that too. (Engine turns CCW from the rear so that makes the cam the opposite.)
Thanks for your insights and comments. I appreciate all the knowledge and thoughts.

 

[Jim.ME]

Well, it stopped working again. So, I think there is something wrong at the pump. It should not drain back like its doing without a reason, and the pump is letting flow thru it. I removed the oil pan yesterday and removed the oil sump line to the case to check for anything I could find. Perfect line and tightness. No issues there. No leaks in any of the lines external to the engine either. So, what's left, but the pump. If the pump rotates, oil should flow both directions. The only restriction then is the ball and spring for the 15psi. Yes, I heard about the filters, but I never had one of those. These pumps are positive displacement pumps, therefore even if air got into a line downstream from the pump it would just pump oil thru it and displace the air. Just like a gear pump. I used the phrase "air lock" but that was incorrect due to the positive displacement type pump. Oil will push that air right on down the line. Anyway, the engine is coming off again. I am thinking the pin in the cam just might be a place to look although it looked fine when I put it together last time. The pump turns CW from the rear of the engine and I am sure I put the vanes in correctly, but I will check that too. (Engine turns CCW from the rear so that makes the cam the opposite.)
Thanks for your insights and comments. I appreciate all the knowledge and thoughts.

Is the standpipe, the filter fits down over, in the filter housing. It should only have about a 1/8" hole in it, if I remember right.

 

[49clipper]

Is the standpipe, the filter fits down over, in the filter housing. It should only have about a 1/8" hole in it, if I remember right.

yes

 

[49clipper]

Pressure was good before cooler was removed?

yep, pressure was fine.

 

[49clipper]

I agree with Butch, when you show no pressure your pump is pumping nothing. I see the oil pickup tube screws in probably with pipe threads to make the connection. I wonder if there might be a problem with threads causing them to leak air so the pump looses prime. Was this a running tractor with reliable oil pump prime and pressure before or did you buy it not running so you don’t know the history of how it performed before.

When I bought it, it had sat outside for a year. He had just recently put one of those caps on the top of the exhaust pipe, so I figured it had water in it. As soon as I got home, I pulled the plugs and water ran out. I spun it over and shot all the water out and then use compressed air in each plug hole till no more water came out. Put it tougher and it ran like a sewing machine. never once did I have to prime the oil pump. Always worked till one day when I put 10W-30 in it. Then the problems began.