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D-360 Low oil pressure, at wits end


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Grab some popcorn. I've got a 766 with the D-360 diesel, it has an M&W turbo on it. Complaining of low oil pressure. 10 psi at idle when hot, if that. 

 

A little backstory. Bought the tractor, non-running, in college as an engines project. Stripped it down to bare block for a major overhaul. New oil pump, 1", Added all 12 piston cooling jets, virgin ground crank 0.010" mains, 0.020" rods, new wrist pins and bushings, new cam bearings and re-worked camshaft from hy-cap. Green plasti-guaged rods and mains, oil clearance was 0.002", tighter end of spec. Got the tractor running, purrs like a kitten, cant remember what oil pressure was exactly, mays 20 when hot at 1000 rpm. Tried another oil pump, oil pressure regulator, bypass valve, and oil change. I use 30w. Removed the turbo and plugged the line to rule that out. 

 

Fast forward 4 years and 180 hours, doesn't get use alot, but it still has to work. Its getting worse and I finally broke down and tore it apart. Hooked up a pre-luber first to check for a missing plug anything obvious. Found evidence of low oil pressure, bearing with premature wear, camshaft, rods, and mains, but no cause. Sent the camshaft to Barry cam to get measured, polished or ground if needed. Cam came back looked perfect. Installed new cam bearing, rod bearings, and main bearings. Plasti-guaged again, oil clearance, 0.002", tight end of spec on mains and rods. Inspected the oil pressure regulator, nothing wired, soft plugs were in place on the front and rear of the block. Plugs were in place in the rocket shaft. Inspected the rocker arm/lever bushings, they were barely in spec but i went ahead and spent $1100 on new levers, yeah, after discount. Get everything together. Fire it up, its 20 psi when warm. did'nt run it long enough to get hot because i knew it wasn't fixed.

 

So, A few thoughts i've had. Is the 1" pump enough for 12 piston jets and a turbo? The needle on the gauge moves with RPM. As you increase RPM you increase oil pump displacement. Pressure and flow are independent but you have to have enough oil in a circuit to create pressure otherwise you're starving the circuit.

 

Am i getting bad new pumps, i understand there is a service bulletin where they opened of the gerotor housing to prevent siezing, could this extra clearance dump oil?

 

If a regulator was good it should in theory make some sort of minimum pressure, spec is 38-44 for the pressure regulator, could be wrong. 

 

An 1 1/4" oil pump for a DT-466 will fit with a 4 spoke dampener. My only concern is will i have enough oil? I've heard of people putting the big pump without upgrading the cover or pickup tube to the larger style.

 

I am at a complete loss with this thing. Nothing is making sense, oil clearances are all normal. Its either not getting enough oil or its dumping it somewhere. I've seen other threads of guys having this problem after an overhaul. Might just have to put the big pump on and hope for the best. Any help would be appreciated. 

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Pressure tank on the oil galley has always pointed the problem to me. Even a bad oil pump shows up as oil running back out the pickup tube. That made me think of something stupid. An air leak in pickup tube could cause the problem and would not be obvious in a pressure test. Is correct gasket used on pickup tube?

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22 minutes ago, snoshoe said:

Pressure tank on the oil galley has always pointed the problem to me. Even a bad oil pump shows up as oil running back out the pickup tube. That made me think of something stupid. An air leak in pickup tube could cause the problem and would not be obvious in a pressure test. Is correct gasket used on pickup tube?

Yes. The bolts are the correct length. The brazing looked in good shape. Didn't see any evidence of cracks.

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Where are you checking oil pressure by injection pump? Ck it at the back of the block as well that will give you came bearing pressure. Are you running 30wt oil ?

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4 minutes ago, Binder686 said:

Where are you checking oil pressure by injection pump? Ck it at the back of the block as well that will give you came bearing pressure. Are you running 30wt oil ?

Using 30w. I'm using the gauge on the dash, it is accurate.

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Put a gauge by injection pump and one in the back of block and see what the pressure drop is 

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Those engines usually peg the factory gauge at 75 psi when cold -- and run 3/4 of the way when hot at idle

the pressure regulator is set to 75 psi

I would not call that factory gauge "accurate" -- use a real gauge for testing -- tho I have only had to replace a very few of those gauges

Remove one of the other galley plugs and connect an air hose to shop air -- or rig up and air powered oil tank like @snoshoe mentioned

The 1" pump is minimal with the cooling jets -- makes no matter the size of the engine

Have you checked the oil usage of the injector pump ?

Suction tube gasket was mentioned -- the later engines had a larger opening in the housing
 

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4 hours ago, HydroTek said:

Those engines usually peg the factory gauge at 75 psi when cold -- and run 3/4 of the way when hot at idle

the pressure regulator is set to 75 psi

I would not call that factory gauge "accurate" -- use a real gauge for testing -- tho I have only had to replace a very few of those gauges

Remove one of the other galley plugs and connect an air hose to shop air -- or rig up and air powered oil tank like @snoshoe mentioned

The 1" pump is minimal with the cooling jets -- makes no matter the size of the engine

Have you checked the oil usage of the injector pump ?

Suction tube gasket was mentioned -- the later engines had a larger opening in the housing
 

Before I stripped it down I hooked up an oil pressureizer to check for any big leaks. I hooked it up directly to the injection pump and sent 50 psi to the injection pump and it just oozed out, it didn't spray. I made very sure that the suction tube gasket was correct. When you say 1" pump is minimal what do you mean?

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5 hours ago, HydroTek said:

Those engines usually peg the factory gauge at 75 psi when cold -- and run 3/4 of the way when hot at idle

the pressure regulator is set to 75 psi

I would not call that factory gauge "accurate" -- use a real gauge for testing -- tho I have only had to replace a very few of those gauges

Remove one of the other galley plugs and connect an air hose to shop air -- or rig up and air powered oil tank like @snoshoe mentioned

The 1" pump is minimal with the cooling jets -- makes no matter the size of the engine

Have you checked the oil usage of the injector pump ?

Suction tube gasket was mentioned -- the later engines had a larger opening in the housing
 

Isn't that just a pipe plug on the back of the block?

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You say the pressure regulating valve looked okay, but are you certain that it is, that there's not a junk of debris of some sort that's keeping the valve hung open, and its dumping pressure?  Had a friend that worked on a DT407 & found a chunk of debris in the oil pressure regulating valve on that engine, it suffered from the same problems you're describing.  He replaced that valve, and the problem was solved.

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52 minutes ago, Nebraska1206 said:

You say the pressure regulating valve looked okay, but are you certain that it is, that there's not a junk of debris of some sort that's keeping the valve hung open, and its dumping pressure?  Had a friend that worked on a DT407 & found a chunk of debris in the oil pressure regulating valve on that engine, it suffered from the same problems you're describing.  He replaced that valve, and the problem was solved.

It was replaced after we got it back from college and noticed the pressure wasnt great. After tearing it apart this time I couldn't see anything in the valve. I worked the plunger back and forth several times and it moved free and smooth. It felt "stiff" and looked like it was seating against the retaining ring. I do have the o-ring end in the cap like the book suggests.

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Check the bypass valve and spring, and test/check/replace the regulator valve spring. 

IMG_20240306_1751201.jpg

IMG_20240306_1750214.jpg

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1 hour ago, Nebraska1206 said:

Might sound like a dumb question, but what kind of oil filters are being used on this tractor?

Case ih

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58 minutes ago, ny hay farmer said:

Another thought,   the difference between a 966 and 1066, have different dip sticks,  1066 is shorter, more oil in pan,  I just had some problems w dt436,  oil pump.  Call me if ya want,  three,one,5-868-639three,  john

This engine capacity is 3 gallons. I use 3 1/2 gallon.  I even tried 4 once just to see.

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1 hour ago, HydroTek said:

Bypass valve will not reduce the oil pressure -- only allow oil to bypass the filters

The 1" pump is fine on engines without the spray jets

But a stuck bypass valve will allow unfiltered oil into critical components.

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24 minutes ago, Nebraska1206 said:

Okay, are you being given the correct ones?  What part number?

I don't know off the top of my head. I picked them out of the parts book.

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I just had one of our IH members call me last fall on a 1486 with low psi . He did a complete overhaul , cam bearings , new cam , crank ground , head rebuilt , sleeves , pistons .I had him pull the front cover off in front of the injection pump and run the motor and the oil was just pouring out the front of the pump . He put a different pump on and it went to 80 psi and 50psi at idle hot . Make sure it has the correct suction tube gasket where it bolts to the front cover , this gets changed and guys don’t realize there are two in the package , one works and one don’t .

There is a a bushing inside the housing of the pump that the cam rides on and that bushing is more than likely bad leaking  all the oil return to sump . I would tell you to get the wider oil pump if you end up taking it off again , I always update them if they have the narrow pump .

Danny

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2 hours ago, DirtBoyz07 said:

I just had one of our IH members call me last fall on a 1486 with low psi . He did a complete overhaul , cam bearings , new cam , crank ground , head rebuilt , sleeves , pistons .I had him pull the front cover off in front of the injection pump and run the motor and the oil was just pouring out the front of the pump . He put a different pump on and it went to 80 psi and 50psi at idle hot . Make sure it has the correct suction tube gasket where it bolts to the front cover , this gets changed and guys don’t realize there are two in the package , one works and one don’t .

There is a a bushing inside the housing of the pump that the cam rides on and that bushing is more than likely bad leaking  all the oil return to sump . I would tell you to get the wider oil pump if you end up taking it off again , I always update them if they have the narrow pump .

Danny

He changed the injection pump? I asked a pump shop if they could cause low pressure, he said yeas if the bushing was wore. This pump has 180 hours on it, we put a new one on with the overhaul. I went ahead and hooked my oil pressurizer up to the pump, ran 50 psi through it, it oozed out of the front drain, but didn't spray.

 

I'm currently running the 1" pump which I was led to believe was enough and used on 10s, 14s, and 15s that use jets, idk of they used 6 or 12. The only other option is 1 1/4"

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