Cat 980B burnt transmission fluid

[oarwhat]

We bought a 980B and checked everything out but missed that the tranny fluid is dark and smells burnt bad. The tranny works excellent so my question is do I change the fluid or leave it? I've heard of guys changing fluid and then having problems.

 

[kshansen]

I would be taking a sample, I know a one off sample might not tell much but still worth the small cost to me.

Next I would pull suction strainer and filter to inspect real close.

If either are full of crap might be thinking about biting the bullet and do a before failure rebuild. Guess that would be a before "major failure rebuild" as it (something) has already failed! And if doing a rebuild DO NOT for get to replace oil cooler!

If everything looks good with the exception of the nasty oil smell I would change it and the filters and after it has run a day or two change filter again. I would also be checking all temperature senders/sensors and gauges and confirm they are operation correctly. Clean and maybe flush radiator just to be safe.

Seeing you are from Buffalo I'm going to guess this old machine is going to be pushing snow in a couple weeks so better get to work! Not to be nasty but.......................

 

[oarwhat]

Kshansen That's pretty much what I plan on doing. Yea it can snow here early. Worse one was Oct 13th. 30 " on all the trees with the leaves still on what a mess. Almost everyone lost power.

 

[oarwhat]

So I finally got a chance to run this loader pushing snow. Everything worked well. The transmission oil gauge came up as it should and never got up to half way. When I parked I saw steam coming of the tranny where water dripped on it. Checked with a IR gun and it was 275 degrees . I then checked the oil cooler lines and they were 90 degrees. So I don't think there's enough oil going through the cooler. Any ideas? I don't have my book here to check out how the oil flows. Now I know why the oil is so burnt.

 

[kshansen]

Are you saying the inlet and outlet lines for the transmission cooler are both 90º? I believe the transmission cooler on the 980B is off to the right side of the radiator and the Hydraulic cooler is a larger cooler about the same width as the radiator core.

Don't recall you giving a S/N but I looked on SIS and there are three ranges of S/N's 89P1 to 2167, 2168-4783, 4784-up.

I looked at the middle one and got this information on the oil flow if that helps any:

 

[John C.]

Where on the transmission did you check that you got that high of temperature? The only thing that could cause that high of temp is a bad torque converter and you would likely see a ground power problem and the paint on it change color to almost brown.

I seem to remember the B's had a shell and tube cooler using engine coolant to transfer heat from the transmission oil. I could be wrong on that? Anyway what I've seen with those types of coolers was the rubber O rings from the bottom of the cylinder liners in the engine would erode and the rubber was exactly the same size as the inside of the tubes. When the engine got older there would be enough of those ring pieces in the cooler to cause the overheat. At any rate it is a cinch the cooler will need to come out for a check.

 

[oarwhat]

Ok guys thanks for the quick replies. First off the serial number is 89P56XX Second the whole transmission was 250 to 290 degrees. Third these tranny's are air cooled. Fourth yes both cooler lines were the same temp. The gauge was reading and acting normal. The only reason I knew it was that hot was the melting snow dripped on there and was steaming. I went to touch it and wow it was hot.

On a good note this machine had steam coming from the blowby tube and I found the water pump seals shot. (Thanks to Kshansen) The steam continues to become less so that problem seems solved.

Kshansen I'm going to look at your attachment now. Thanks again Randy

 

[oarwhat]

Kshansen from your PDF looks like I have a problem in my hydraulic valve body and or a plugged cooler.

 

[kshansen]

Kshansen from your PDF looks like I have a problem in my hydraulic valve body and or a plugged cooler.

Could be, below I believe is a picture of the side of you transmission where the two lines to and from the oil cooler attach. The one with the circle around it should be the one the temperature gauge is located in. Can you check the temperature there and then the other one?



I'm also attaching the Testing and Adjusting pages on this transmission:

 

[oarwhat]

When it was hot both of those lines were just warm to the touch. The temp gun said 100. I'm pretty sure they we're the same temp. I'm going to take the machine back to my shop. To cold to mess with it out side. I'll check those lines more closely then. Thanks Randy

 

[kshansen]

When it was hot both of those lines were just warm to the touch. The temp gun said 100. I'm pretty sure they we're the same temp. I'm going to take the machine back to my shop. To cold to mess with it out side. I'll check those lines more closely then. Thanks Randy

If you can get it to someplace clean and easier to work I think I would look in to running some of the pressure tests to see if any are way out of spec.

 

[oarwhat]

Kshansen the first PDF shows oil from the converter going through the hydraulic valve then to the cooler. The second PDF shows oil going directly from the converter to the cooler. I'm wondering if it's because it's a newer serial number or??

 

[oarwhat]

We were typing at the same time yes I'm going to check the pressures. I've never done this before I take it the trans can be run with that top cover off?

 

[kshansen]

We were typing at the same time yes I'm going to check the pressures. I've never done this before I take it the trans can be run with that top cover off?

Yes and many Cat transmissions have small access covers on the main cover so you don't have to remove the big cover. Might need maybe a 4 inch piece of 1/8 pipe to reach the pressure tap port in the valve body.

I'm thinking the difference in the two drawings is just one was drawn a bit simpler than the other. As converter and everything is in the same case they just left out the details of how the oil is routed .

The one bad thing is if this is like other machines of that vintage the top of the transmission where the pressure taps are is under the seat and batteries in the cab. I know the 966C's and 988 87A's were that way. Can be a fun job especially if you have to remove the valve body! Been there done that a few times. Just need to be very careful to not drop any thing!

If you look in the picture with the red circle a couple post back you can see the small access cover where you can check three of the pressures B, D, and E in the pressure testing chart I sent you.

 

[oarwhat]

This is a later model 980B where they moved the batteries out of the cab. That will help but it's still a tough spot to work . I've come up with four ideas of what the problem could be. I'll list them from the easiest to pull the tranny (I hope not but with my luck)

1. There are 2 tubes that connect the cooler lines to the valve body. inside the trans. I'm hoping I find the orings blown out and by passing oil.

2. The oil cooler is plugged up.

3. Something is wrong in the valve body.

4. The sealing ring on the out put of torque converter is bad . That would allow oil to dump back into the trans without going to the cooler. Man I hope it's not this one!!

I'm hoping when I open it up and run it I can see where the oil is bypassing.
Thanks again for your help Randy

 

[kshansen]

Well have my fingers crossed it is one of the first three!

 

[oarwhat]

Well got it back to the shop and checked the pressures before the Blizzard snow hit today. First of all it's not leaking at the sleeves. (Dammit)
1. Torque converter outlet press 4 PSi Idle 4PSI full speed . Should be 4 PSI idle 60 PSI full speed

2. Torque converter inlet press 0 to 10 PSI Idle 25 +- full speed. Should be 125 PSI full speed

3 Lube press 0 PSI idle 0 PSI full speed. Should be .5 to 5 PSI idle 60 PSI full speed

Pump,speed clutch and direction clutch Seemed ok my gauge is off but they were all proportionally correct.

So if the converter output pressure is low I would think my cooler is not plugged. That would read high correct?

So what do you guys think it could be with these pressures?? All help is greatly appreciated Randy

 

[John C.]

Outlet pressure is on the convertor side of the outlet valve and has nothing to do with restriction through the cooler. What was the max pressure on the gauge you used to check those pressures? I don't recall ever seeing inlet pressure being more than 40 or 50 PSI. Lube pressures are usually pretty low to begin with. So if you used a 500 or 600 PSI gauge it would barely read it, if at all. Have you taken an oil sample on the transmission? A bad torque converter will show up with high amounts of aluminum in the oil. Lacking that I would probably pull the cooler and check the water side.

 

[oarwhat]

John thanks for the reply.
1. this transmission is air cooled by a radiator style cooler.
2 We used a very large test gauge with a 160 PSI max. I will double check it with air pressure at very low PSI. I d
3 We did an oil sample but I don't have it with me now. I don't recall high Aluminium. The oil was very dirty and burnt.
4. I got the test pressures from the Cat manual.
4. My manual shows oil going directly from the converter to the oil cooler with the test port in between. That why I thought it would read high if the cooler was plugged.Maybe it's just drawn that way for simplicity?
Thanks again Randy

 

[Mike Van]

Just my 2 cents, i'd get that machine hot & change the oil & filters. My IH tractor some years back I let go too long, oil stunk like that, gummed up the mcv, had things sticking in there.