case 150 running hot

Here's my problem: drained hydraulic oil, cleaned screen, changed the two hoses on the lift cylinder. Now the little baby is running hot. Thought i might have a blockage somewhere so took hoses off temperature exchanger. Oil ran and looked brand new and i could also blow through the exchanger with no problem. Took the line loose at the reservoir from exchanger and oil in reservoir brown. Yes i'm running 20w50 in this. My question is does the oil actually circulate through the exchanger or is it like a passive system. i have downloaded all the parts lists and it looks as if everything is hooked up right. any ideas?

i forgot to mention it has a tiller hooked up and it also looks correct.

The oil is sucked into the pump, pushed out the other side of the pump and goes directly to the hydraulic PTO valve on the rear of the tractor. It flows through that valve and goes to the travel valve that supplies oil to the drive motor. The oil flows through the travel valve and then through the oil cooler before returning to the trans-axle reservoir to begin the trip all over again.

In other words, oil is always flowing through the cooler. There is nothing passive about the cooler. If you had a blockage in the cooler, a rubber hose at the cooler would have blown off because those hoses are all low pressure type.

Do you have a fan on the mechanical PTO clutch and is that fan in good working order? Tilling is one of the highest demanding jobs for these tractors to perform and that fan is essential to try and keep the temps down.

It's always best if the oil temp does not exceed 140 F but on a really hot day, it can push higher than that. If you are over 180 F, then you have a problem. How clean is the oil cooler? The 150's did not have the best design for a grille and they dropped the perforated metal the next year for a louvered grille to give better air flow over the cooler.

Try using a meat thermometer dropped into the fill plug in the trans-axle to see if you can get an idea just how hot the oil really is.

if thats the case then shouldn't the oil that came out of the heat exchanger be the same color as that coming out of the reservoir? Also when runnin g the switch to the tiller felt warm to the touch while the cooler did not. Yes it has the louvered grill and i checked to make sure the fins weren't blocked

Case 150's came with a mesh screen grill that has folds in it and small holes in the mesh. The 155 model had metal louvers and no mesh. If you have hydraulic lift for the implements, then I suspect that you really have a late model 155 because the hydraulic lift was not available for the 150's.

It could be that someone put the wrong decals on your tractor. I gave you the link to Ingersoll's parts books. You can see how the tractor's hydraulic system is plumbed. And you can consult the book for the 155's to see the difference in the grilles. If your tractor has dual disc brakes, the 100 percent it is a 155 model.

Yes, the oil should be all the same colour. Even if you drain the trans-axle completely, you won't get all of the old oil out of the system. There will always be a bit less than a quart still in the lines, hoses, valves, pump, cooler etc. Oil colour isn't all that important but smell is. If the oil smells burnt, then you should change it out again.

you are right it is a 155, i typed it wrong. Answer me this though. if the oil coller is in fact "in line" then why isn't it under pressure? not being critical or sarcastic just trying to understand. in my mind i am seeing something plugged because of the two different colors of oil but at the same time if something was plugged would something not be working?

Pressure is something that comes from "work" being performed. You are capable of pressure, just like a hydraulic pump is. If you weigh 100 pounds and stand next to a closed door that swings toward you but are not touching the door, you are exerting no pressure but you still have the potential to make pressure.

If a 60 pound person tries to push the door open but you don't want them to come in, you just lean your 100 pound frame up against the door and keep them out. If they call over another 60 pound person to help them, now you have to really work at putting pressure to keep them out because there is 120 pounds of force pushing against your 100 pound frame.

So you manage to defeat the two of them but they call over their 400 pound buddy. Now, you are forced to use every ounce of strength you have plus your total weight. More than likely, you will lose and the door will get opened.

Hydraulics are no different. Oil takes the path of least resistance. The pump pushes the oil through the entire system and back to the reservoir. The only resistance it sees is from the minor restrictions created by the lines that carry the oil and the valves that it passes through. But once the oil is PAST the travel valve, any pressure drops down to well below 100 PSI.

But if you ask the tractor to move forward or backward, that's when the pressure begins to rise because the combined mass of you and the tractor does not want to move. The hydraulic motor must generate torque on the gears to make the tractor move and that's what creates pressure in the system. Now it might only take 500 PSI to move you and the tractor across the lawn while mowing grass but if you try to tow a trailer loaded with 1000 pounds of sand in it, then the pressure will rise accordingly.

Ask the tractor to tow that loaded trailer up a steep hill and the pressure might soar to 1500 PSI. When you are rototilling, the system pressure would be very close to the setting of the relief valve which is around 1600 PSI on those tractors. High pressure means high heat and that's why you not only need a cooler but you also need a proper cooling fan to move air through it.

If you installed a pressure gauge between the pump and the rear PTO and another gauge between the rear PTO and the travel valve and a third guage right at the line going into the oil cooler, this is what you would see if you were in the garden tilling.

The first gauge would show perhaps 1400 PSI thanks to the hard work the tiller is performing.

The second gauge might show anywhere from 200 to 900 psi depending upon how hard you were trying to make the tractor move forward while tilling.

The third gauge would only show perhaps 100 PSI because all of the work is being performed by the tiller and the drive motor. No real work is being performed by allowing the oil to flow through the cooler.

There is only one route that the oil can take. Every drop of oil that leaves the pump ends up passing through the oil cooler. You can trace it out for yourself by following the hydraulic lines in your tractor.

Pump outlet to rear hydraulic PTO

PTO to travel/lift valve

Travel/lift valve to cooler

Cooler to trans-axle

Trans-axle to pump inlet.

this is how mine is routed: starting at large line with screen goes to the pump on back of motor, motor to tiller control (forward/reverse)
tiller control to transaxle valve (what you might be calling rear pto valve)
transaxle valve to lift control
lift valve to heat exchanger
heat exchanger back to reservoir
Does this sound right as some of it is for better words cobbled together.
Thanks for your help.

Sounds absolutely correct. We just differ on language but I totally understood what you said.