Hydro system clean outs? A waste? Filtration? Options?

[Nige]

From your attachment 5372 above - is the gear #13 in the illustration listed as a quantity of two.? If so that's the pair of gears for the second section of the pump.

What's inside the converter appears to be a magnetic screen assembly from the parts illustration. In technical terminology that assembly is designed to remove "dogs, small children, & tree branches" - a filter it ain't..........
Is there another filter housing in the lines between the circulating pump for the converter and the cooler.? Upload the parts listing for the lines if you have it.
Where exactly was the magnetic screen located that you found plugged up with particles.?

Regarding "what gets filtered where", all the oil that is sucked by pump #14 is sent through the filter #2 before it goes anywhere, be that transmission, steering clutches, or converter. Everything else in the way of oil that is moving anywhere within the system after filter #2 at best goes through some sort of a screen, magnetic or otherwise.

Do you have any parts manual pages that show the power train oil lines (transmission, converter, cooler, whatever).?

 

[fastline]

Yes, there are two #13's in the parts list. That sort of confuses me because you can see it has a keyway cutout, yet the parts list only calls for one woody. Never the less, It does seem to have two stages. Sure wish they would uses these stages to isolated components!!!! Unless that filter unit did miraculous things to protect its downstream friends, everyone suffered at this ballgame.

OK, so, there is some indication there is another converter filter somewhere. Have not see that one yet. However, I have not found a breakdown of that filter unit.

In pic 5374, the filter housing about #27 is the magnetic prefilter for the main hydro pump, and is the one that is very obviously plugged. The pump is right above it and very obvious how that is plumbed.

When you look at the double filter unit in 5375, you can see the filters are the same but it is assembled differently, making me think it might be a series filter unit for the trans.

What I am starting to think (CAT guys don't shoot me) is the CAT dealer did not get this properly repaired from the start as the machine predates most of the mechanics on staff. It was logged in with concerns of TC overheat. The TC was pulled and verified to be eroded so the TC and pump were replaced.

As well, the bevel ring gear bearing was noted to be out, so it was changed. That is not normal. I am a bearing guy and I would want to see that bearing. Very likely to see FOD damage on that bearing which came from somewhere.

Looking at that mag screen, either something died fast and furious, or it was never even touched and inspected when the TC was swapped.

 

[Nige]

I understand the difficulty of trying to interpret the Parts Manual. That’s probably because it’s not a genuine Cat Manual, the illustrations give the game away. That’s the reason for all the questions.

I believe that the magnetic screen shown in the housing of the TC is actually likely to be the only mag screen between the circulating pump and the cooler. I was asking you to confirm whether or not there is another one by physically following the lines from the pump to the cooler.

So the magnetic screen that you found plugged with debris is the suction screen for the main transmission pump (#12 on the Schematic), not the one in the converter housing.? Don’t get confused with the fact that it’s shown as a separate component on the schematic, it’s most likely to be built into the side of the transmission case.

 

[fastline]

It will be a day or two before I can confirm that. At some point, I will just have to move the machine to my own place, then I will have a little more freedom to comb over it.

So being this is an Army spec machine, can we assume the Army put this manual together? It does not seem aftermarket and there is a LOT of info on rigging the machine, making me think so.

With my other CATs, the books are very details. Very happy to see a full explanation of how the fluid moves and why.

 

[Nige]

Unless there is something somewhere that says the manual was produced by the Army I wouldn’t think so. Did the manual come with the machine or did you buy it separately.?

I think what you likely have is an aftermarket manual.

 

[Delmer]

TM5......... in the upper right sure looks like a military publication to me. Google seems to agree.

 

[fastline]

Lets go with an Army manual. Why they would want to write their own is beyond me..... All I can see is they adde two rigging points and green paint.

 

[Nige]

OK, the smoke is clearing. There IS a separate mag screen on the transmission pump suction line - circled in blue. The oil flowing through the suction line follows the red arrows and goes through the mag screen before arriving at the pump, then follows the green arrows to the filter and afterwards the blue arrow to the entry to the transmission control valve where, as discussed, it splits into three (transmission, steering clutches, & torque converter).

 

[Nige]

The transmission filter housing does not appear to have any form of bypass in it, unless the elements can lift up against those springs #12 & #21..?
I don't know about anyone else but I've seen plugged filter elements collapse in older machines before.

 

[Nige]

Regarding your pdf 5373, that appears to be the powertrain (aka transmission) cooler and again there is a separate screen/filter housing in that system (circled).
To me that layout looks like the lines to and from the converter recirculation pump. Where do the tubes #2 & #22 connect to.? I'd lay odds that #22 is the outlet from the recirc pump and that #2 will feed back into the recirc pump inlet somehow, possibly via a hose.

 

[fastline]

Yes sir! The mag filter you circled IS the one I inspected and has debris in it. I also opened one pot on the double filter unit on the trans. I did not fully remove the filter because I didn't want to cause more contamination until I knew more. However that filter did not appear to have any serious matter stuck to the outside and was not collapsed.

Yes, I think the "bypass" function is pushing past the springs. Bypass is mentioned in the service book.

I also agree that it looks like there is another filter housing for the converter? I will have to look for it. Seems like there is a mag filter in the converter as shown in the TC pic I posted, plus the other filter shown above?

I guess it does wage 'some' hope the system has some protection.

What is annoying is CAT apparently noted the low pressure issue to the clutches, THEN decided to test it for hours!!!!! WHY!!??

Because the bevel ring gear bearing was noted as being bad and replaced, I am sort of wondering if the trans pump mag filter was never even checked and was already plugged from that failure???

The condition it presented initially when in service is "TC was getting hot and would not pull". The TC and pump were replaced but I think they roasted the first one because it was deprived of oil and was slipped bad. Someone wasn't looking at gauges. They have a TC gauge for a reason. There is also a trans pump pressure gauge.

It sounds like the machine returned to service VERY shortly after the TC was installed so I can only hope they did not kill that one too.

 

[Nige]

I'd suggest to pull & clean both the blue-circled mag screen assemblies (TC & transmission). It's hard to tell exactly where they are located but the transmission screen appears to be on the RH side of the machine so I guess I'd go looking on the LH side for the converter recirculation system screen. Take photos of what you remove, and clearly indicate what came from which one.
Then replace the two elements in the powertrain filter housing. What Part Number of Cat element does it call for..? There may be a finer micron-rating of filter element available for "system clean-out" purposes that could help clean things up.

After that strike it up and get some gauges on the transmission, steering clutch, and torque converter pressure taps to see how the numbers stack up versus specification.

 

[Nige]

With the age of this machine (mid-60's) I'm going to suggest another source of information at this point. The Antique Caterpillar Machinery Owners Club www.acmoc.org/
I think that it would be worthwhile to register on the ACMOC Forum and ask what is the equivalent S/N prefix of the "civilian" version of your D7E, because I'm sure that there will be one. That might open up a whole load of possibilities to get hold of technical and parts information for your tractor.

 

[fastline]

Good call on the cleanout filters. I guess a lot will hinge on what is found when the oil is dropped and filters come out. Obviously if there are enough chunks to fill a coffee can, I'd say a "clean out" is not in my future.....lol

I was planning to get some bargain barn oil for the cleanout and let it walk around a bit (if it will) and see if it functions normally. Obviously checking pressures as well. I was hoping to pull the head off the main transmission pump but looks like that will be pretty involved as the hard lines attach on the bottom so removing the whole pump seems the only way. I'd like to know if that pump chewed up any wild animals.

 

[Nige]

I'd like to know if that pump chewed up any wild animals.

By your description of the state of the magnetic screen located in front of the pump I think it would have been struggling to suck anything TBH......!!

I guess a lot will hinge on what is found when the oil is dropped and filters come out. Obviously if there are enough chunks to fill a coffee can, I'd say a "clean out" is not in my future

Either way it would be good to ascertain if a cleanout element is available for when you do get things back together. One thing is certain, a failure like the one you are dealing with will be nigh-on impossible to completely clean out everything. That's where the fine filter elements come in.

 

[John C.]

I'm getting to this kind of late but might have a few things to add. The basic lay out of the system is that the transmission pump pulls a suction on the bottom of the transmission housing. That oil is the same as the steering clutch oil. The suction strainer is very common to Cat dozers. All the debris that you usually find in that strainer is steering clutch and transmission clutch related. It's pretty normal for that strainer to get plugged up on an old machine that has seen little maintenance. It is not normal to see a lot of shiny stuff in it but there will be lots of steel on the magnets. Clean the strainer with some kind of solvent and you will have to blow the steel stuff off the magnets and out of the strainer mesh to clean them. Shiny chunks indicate something broken, but it could be steering clutch related, bevel gear related or transmission related. It also might be from an old failure and have nothing to do with current condition.
The scavenge pump on the converter is on the converter housing underneath the drive line. The suction strainer is also there. It has been years since I've been into one of those machines, but I don't recall an access plate in the belly pan for access to either one. I believe you have to pull the pan just to see them. As I recall the scavenge pump provided lube pressure to the transmission bearings and only ran about 10 PSI. I don't recall any filters before the cooler like it shows in the diagram above. What I recall is a filter housing right next to the transmission pump. Oil out of the pump would go through the filter and then to the transmission control valve on the transmission. It went first to a safety valve spool and then to the to the direction and range valves. When you shifted into gear the pressure would drop off the torque converter and go to fill the range and direction packs in the transmission. Once those filled, the pressure would build in the torque converter.

The common problem in the system was as has been observed. The strainer would plug and starve the pump which would pull air either around the strainer top cap or along the pump input shaft. The other place where air commonly enters the suction side of the pump is on those hoses at the base of the transmission. There should be a plug on top of the pump where a gauge can be plugged into. I've seen a few machines where a petcock was plumbed into that plug to vent the air that got into the pump. That is also a cause of transmission oil getting into the engine.

I wouldn't recommend just gutting the system and fixing everything that could be wrong because on a machine that old, everything will be wrong in someone's eyes. If it were mine, I'd clean everything up first. Put some new filters in and run the machine noting any problems. I'd put a gauge on the pump and watch the pressures as the machine is worked. Does it go into all the gears? Does the transmission slip when running a stall test? Does the converter temperature rise up real fast and drop real slow when running the stall test? What does the transmission pump pressure do when you are running those tests? What happens when you pull a steering clutch lever?

Keep in mind that this machine is a dinosaur. It will run and make money with dirty oil and lots of stuff wrong with any and all the components. You just note the quirks and run the machine with those in mind. In my philosophy, I only want to fix what I have to fix in order to keep the machine working. When it is time to make a decision to rebuild is when you estimate the cost of the parts and labor to determine if that process is cost effective over the projected live of the rebuild.

 

[Nige]

John, could the Military-spec machine be different to a “civilian” one of the same era when it comes to where those magnetic screens are located.?

I’ve been doing a bit of digging offline and apparently the only equivalent to a MIL-spec 75E D7E is another 75E, which I found somewhat strange seeing as the D7E was produced in many guises in the late 60’s....

 

[John C.]

I don't know. I've never worked on a Mil Spec Caterpillar. I did see three D7F model units that were in a warehouse in Alaska that had some difference in the attachments; blade, winch and ROPS, but I never got into the build up of those machines. In the very early D8 with the oil convertors, the suction hose for the transmission pump attached directly to the rear main case and pulled oil from the right side steering clutch compartment. There was a strainer at that connection point that extended into the steering clutch compartment.

I have worked on a Mil Spec Fiat Allis that was on an Air Force Base and the parts books were the same as the civilian versions.

 

[Nige]

Regarding my previous post about equivalency - here's the evidence. Thanks to Cmark because my Serial Number reference book is about 5000 miles away from me right now.

 

[Bluox]

For all of you wanabe Caterpillar sexual intellects manuals for D7E 48A6883-up is as close as it gets .
Good luck fastline raising the dead.
Bob