Even though we happen to have a centrifuge, I don't intend to reuse the oil, mostly because of the other contaminants, age, etc. I was even checking those black friday deals looking for a sale on 5gal pales of oil...... Nope!

As I mentioned, when I drained the pressure side trans filter housing, I got bright green coolant first. In the range of 2 qts, then black oil. Only way for coolant to get in the housing is pickup in trans, to the trans pump, then to the housing. So common sense says there should be bright green coolant in the bottom of trans. My concern is if it has caused corrosion or rust. Maybe not at the bottom, but with that much water in there, surely there is some nice condensation happening. I know in the right final, there is some visible rust on the gear that is visible.

You can loosen the plug and crack it a little to see how much water is in the bottom of the transmission sump with out dumping all of the oil. If there’s water green water in the final drive that would mean that the pinion seal is bad and leaking and transferring oil from the transmission to final drive probably back and forth .
There are no easy answers in this situation or because of the same oil in the torque converter , transmission , bevel gear case and steering clutch compartments . I have seen 6s 7s8s and 9 s with contimiated systems that had to rebuilt from the engine flywheel all the way threw the final drives if contimated oil was. Circulating through out .

Hi Team,
just lost an hours worth of reply to this.
It is not unknown for coolants to cause the brake linings to break down and so clog the Trans pump suction screens. Not sure of your S/No so check the scans below for location of your screens--membership here will gain you access to literature on the D7E like Service Manual, Parts Books, Operation Instructions and so on.
If the later circuit Trans/steer pump was replaced it may have failed again due to the pump drive splines interfering at the wear step that occurs in the pump drive gear internal splines--we were instructed by Cat to grind about 3/32" from the end of the new pump drive shaft--the interference load to the pump drive gear against the internal side face of the pump cover causes adhesive wear takes place causing metal to gouge out and drop the pump efficiency.

First step is to check for clogged Trans pump suction screens and rectify, then remove and dismantle and inspect the Trans pump for failure as described. This pump is mounted on the front right upper face of the engine flywheel housing.

The "O"Ring I mentioned in the suction system would now appear to be not the issue by your latest info--sometimes we have to diagnose from afar using the scant data supplied so it can become like drawing elephants teeth to get the true state of play by installments.

I maybe missed where you gave a Serial Number for this unit so both schematics for early and late machines are below just to add to the confusion.
The later machines have a suction screen with an alloy housing with a square end plate that has a removable magnetic screen and mesh screen inside it--if clogged the screens can be difficult to remove.
Early machines have their trans pump suction screens down at the lower front face of the trans case, they are under the 4 bolt flange of the suction line to the trans pump which was on the rear of the main torque converter housing, and another under the matching line flange on the other side goes to the steer pump which Cat later modified the system to use only an enlarged version of the Steer pump to supply both the Trans and Steer circuits.--you need to drain the some of the trans oil to access the early witches hat type screens by driving the machine front upwards on a steep slope will drain most trans oil back towards the rear of the machines main steer clutch casing.
Later single pump circuit machines have the suction screens accessable with out draining any trans oil.
Regards,
Eddie B.

 

Thanks so much guys!! ERB, I would encourage you to read more of the thread as I did post a picture of the screens. The dirtier one is the main suction screen. This machine is a military 75E low horse. can get the serial. Not the earliest because this one is direct start with glows. The main mag screen was directly below the trans pump. Magnets were loaded but not really much on the actual screens. I have not cleaned the screens yet but as mentioned, a bunch of black, hard, chunky stuff that indeed could be coolant contaminated brakes, clutches, etc. All really fun stuff to repair!!! lol

What I currently have is the military books for the 75E. that is parts and service. Like a total of 5 different manuals, 2 pairs are near duplicates but I have found differences, and pictures are near worthless.

ERB, thanks for posting the circuit diagram, but none I have found yet even show the charge pump and filter on the TC! i found it on another page and I want to get that filter out, but its on the bottom of the TC and I am not sure if I have to drain all oil to do that? I just want to inspect the filter.

I will be working on this machine tomorrow. Weather will be awesome. Plan to crack open the trans pump, drain some off the trans drain to see how much coolant is in it, and get a sample from the right final.

Alright, I have some updates.

1. After obtaining a sample from the right final, I do not believe it has coolant in it. What appeared green on top I believe to be fresh 80-90. The black sludge I believe to be grease. I have no idea what the dealer did here. The customer requested the oil in finals to be changed. Nothing was mentioned about "grease", but that is exactly what it looks like. A swirly of grease and fresh oil. I drained water from the bottom of the final the other day and recovered about 4-5oz of clear water in the bottom, which I suspect was condensate.

2. I am not certain of all points to drain trans fluid, but appeared the lowered area under the bevel gear section was likely it. I drained off 10gal of fresh, green coolant right there. I left the oil for now as it can help protect stuff. With that much coolant, it is fair to say it made its way into everything from the pump.

3. I tore down the main trans pump for inspection. It was a new replacement with only 60 days on it. I was very happy with the internals. I could still see machining marks in much of it. No major nics in the gears. A couple tiny ones. that tells me either the inlet screen did amazing, or there is not too much metal. The gear OD compared to the pocket had about .005" clearance. The width of the gears relative to the center section width had about .002" clearance. I am a machine shop owner, but I didn't bust out anything more than a digital caliper. I forgot to see if I could get a feeler gauge between gears but I feel pretty good that the pump should be good enough to run right now.

4. I got the belly pan dropped. Used one of our big 6" lifting straps and forks over the machine. If it goes back up this easy, I will be very happy. It will be off for quite a while as I do testing. It also is banged pretty good and I was not really excited to see the engine drain plug so exposed!! Will have to do something about that.

5. I just sample tested the drain plug I found at the front of the trans cooler. Had just a small touch of brown yuck, then bright green coolant. I will get this all dropped tomorrow.



My goal for tomorrow is to get that cooler out. If all the bolts work with me, I think that can happen. But I am screwed on the belly pan. I don't have the blade off or anything so I think just leaving it right where it is and working around it is my only option. The back bolts will not be fun.

Hi Bobby1,
alas, I was on vacation for a week or so and came home to see this many page thread that I do not have time to read--sorry!! when time permits I will endeavor to read it all.
 Your pump looks like a low hour unit should and clearances seem good to go too.
    Black oil could be burned trans oil from slipping clutches in the trans and/or the steer clutches or riding the brakes hard. 

  Another source of black oil is from the engine due to a blocked engine crankcase breather forcing oil thru the rear crank seal which from memory is still a simple oil scroll (I stand to be corrected as I do not have a Parts Book etc.) and so not a positive seal, or drawing engine oil in via the Trans. pump seal--- NOTE that the seal lip faces outwards as per the Parts Book diagram or else due to internal drillings the area behind said seal is at pump suction side low pressure hence the oil is drawn past the seal lip if the lip faces inwards.

Pump at bottom of the T/C housing is the T/C scavenge pump which pumps leaked oil from the T/C and lube oil from the Torque Divider planetary gear system that is in between the engine and the T/C.

I believe the plug on the bottom of the Trans and engine oil cooler caps is fro draining the coolant entirely from the cooling system as shown in the Grey OMI book--see scan below fro my 48A1-up Operation and  Maintenance Instructions book, Form No33736-2, printed 2-63. The higher the dash number (-2) the later the publication.
I would suggest you remove the engine oil cooler or at least the end caps as well as any crud in the cooling system can lodge at the ends of the cooler core tubes and restrict coolant flow and so contribute to overheating--see an example of a clogged cooler core on the coolant side from a different machine but shows the issue I speak of. Also some cooler core end caps have a bridging partition that makes the coolant flow thru half of the cooler core tubes in different directions.

Hope this is of use.

Cheers,
EDB.

Whoops, I am not yet sure I can actually remove that cooler without dropping the oil!? Can anyone confirm? It is sitting pretty low.

Also, does anyone rebuild these coolers? I see them out there new. There is one used one for sale, but after this mess, I can hardly see used being a wise choice! I am sure the Iron is just fine and needs a new core.

Hi bobby1,
it is all a big learning curve and after working at the local Cat Dealer for 43 years I am still learning about these jiggers even after being retired now for some 17years.
Cheers,
Eddie B.

my update. Didn't get as far as I wanted today but I think I now understand how I will get the cooler out. I decided against pulling it until I have parts ready to do so I can keep the weather out. it appears if I unbolt the holder/end cap loose secured to the engine. I can move it back a bit and drop it straight down. really wish I had the blade off!

I pulled the drain bolts off of the cooler on the coolant side and it did have a little oil in it. No surprise there.

I then went for broke on the TC filter and just opened it. I had concerns how much oil would come out. It was about 4 gallons. that was 2 gallons of coolant, then 2 gal of oil. The filter screen there also has bits of black chunky stuff but not too much. Also had pieces of RTV type material. Good news is that screen had no metal in it and was far from plugged. I was able to look up in there a bit and though I do see some slight surface rust on the cast housing, I did not see a "mess" or anything rusted up. The gears that I could see looked good and it seemed like the coolant that was sitting in there likely was far enough down in the case to not be a storage issue.

Next step will be cleaning all the filters and examining the goods. I plan to cut open the main pressure filters but at first glance, they did not look too bad.

But I will say working under that machine is a treat! If I had the hoe onsite, I'd probably lift each side and set it on lumber. The only way to access the TC filter is under it.

Cute post Bobby 1 ....dealership sucks but I have no idea what I'm DOING. Don't take it to heart I'm trying to get banned from this *?!** show Of AcMoC