I know that pump was just replaced when the new TC was installed. I will dig around the diagrams as it baffles me how engine oil would be on the drive side of that pump. I thought that whole thing was full of trans oil. I know the blade hydro pump sits right there too.

Hi, bobby1.
Later and bigger machines often have hinges on the belly pans so that you only lower one side and they pretty much line themselves up when you lift them back into place. Shouldn't be hard to make hinges for yours if you are so inclined.

Just my 0.02.

when unbolting anything underneath and your in there with it have some chunky bits of timber to catch it so that you dont get squished yellow iron is heavy and thats part of why it lasts so long especially when its looked after. the other name for a come-along is a lever block.

Low transmission pressure can come from 2 places if pump is new and good . The line from bottom of transmission to pump sucking air due to hard rubber sucksion hose .Another place is tubes inside transmission to bottom of transmission spool valve ,small yellow Orings blown on tubes

rjh-md wrote:

Low transmission pressure can come from 2 places if pump is new and good . The line from bottom of transmission to pump sucking air due to hard rubber sucksion hose .Another place is tubes inside transmission to bottom of transmission spool valve ,small yellow Orings blown on tube

Is there any way to inspect or check for these concerns?  I don't really want to swap oil only to find out I have further issues in that area.  I think it is possible the coolant caused snot to form on the inlet screen but aside from that, I could not detect enough blockage to totally shut down pump.  


As for belly pans, I planned to build a sling and pull up with the excavator so I can better control it.  

If the tube seals are blown inside the transmission pump may be pumping oil but all the pump oil is being dumped inside the transmission and there will not be enough pressure to unseat the safety spool valve spring so the shift lever cannot be put in gear . I used tocheck this by starting the engine and at idle remove the top transmission cover and with flashlight look at front tubes inside transmission to front bottom of spool valves . Don’ttry to move shift lever or you will get a oil bath !
You can try to tighten up the clamps on the pump sucksion line to see if they are tight . Over time the hot transmission oil hardens the rubber hose alowing the pump to suck air because of the amount of lift to the pump .If you have this suckion line off . I would replace the hose and all gaskets and seals even on the top and bottom of the megnet filter . You can drain the transmisson oil in a clean cut off piece of drum and re use the oil if your careful . I always removed and installed stump pans on a concrete floor using a floor jack and a wooden block between the jack and stump pan to raise and lower it
It is normal to see engine oil on shaft end of pump because pump is driven by acessary drive gears in engine bell housing

Not sure if you read the whole thread but there is a lot more drama than just pump pressure. While I'd like to hope for something like this as a reason for pressure loss, there are many questions. At the moment I am trying to figure out why the trans oil is black or at least very dark. I have never seen trans oil like that. maybe the introduction of coolant would do that, but I usually just see the snotty milkshake. I literally have an invoice for 30gal of TDTO30w only 60 days before pump pressure loss. So oil would be black in 60 days? That does not sit right with.

But are you talking the big trans cover? like the whole deal under the op seat?

I also don't recall any "hose" between pump and trans. That all appeared hard lined that I could see.

Hi Team,
went to check a D7E 48A in the field that the client had changed the trans/steering pump with an after market pump and the machine performed much the same as with the worn out D7E pump.

Turned out the after market Trans pump was a smaller output pump as fitted to a D7E 47A Direct drive that only needs oil for the steering system and not a higher flow as for both Trans. and Steering.
The difference externally is that the D7E pump has a thicker centre section for wider gears to then pump more oil than the thinner centre section DD machines pump.

The difference is obvious when the two units are side by side--sorry I do not have measurement differences to help further-- but is likely in the order of 5/16" to 3/8" difference--I stand to be corrected as I am recalling from some 30 years ago.

Along with the "O"Rings and gaskets mentioned on the suction tubes/screens (depending on your S/No) for the Trans. pump suction lines in the bottom front of the main trans case (even later units have swagged in tubes) there is a mounting "O"Ring that aligns to the cast suction passages in the transmission transfer case that connect to said tubes.
The P/No is hard to find and is I seem to recall it maybe shown with the chassis/frame section of the parts book--be aware that it may not be shown but listed as Not Shown in the Group No box at the bottom of the page--too long ago to be sure with no Parts Book to double check.

The scan below shows where the "O"Ring connects but it is mounted on a short tube section in the rear case--usually lack of drive issus occur on side or for and aft tilting of the machine.
Maybe fit a bleed tap to the bleed plug on the Trans/steer pump body and carefully see if you have aerated oil coming continuously from the tap--we used to run a line from our test tap into a catch bucket for this test.
Later machines have an orifice fitting in this location and constantly bleed aerated oil back to the Trans case oil filler neck if I recall correctly.


Cheers,
Eddie B.

Thanks so much! From what I see, it looks like a trans pull to fix the issue? Or is that port connected on the side of trans and the casted port inside is solid?

Honestly I don't know yet what issues will arise but I cannot even test until the oil is dropped and the trans oil cooler is replaced or gets a solid repair.

What I do know is machine operated normally after initial repair at dealer, and ran 60 days, so a fair bet the oil pump is the correct size and volume. Customer contacted dealer on a "fail to steer" issue and they determined full line pressure of 300psi was present but when steer clutch was activated, it dropped to 30psi. Apparently after this was detected, it went to the dealer where they were unable to repeat the failure so they just reamed the machine until it did! I think there are a lot of things that could have contributed to the loss of pressure but having a trans full of coolant would be high on the list IMO.

maybe worth noting, the service invoices indicate the initial problem with machine in the field is "would not turn left and not shift correctly".  I totally understand the shifting issue if pressure is abnormal but with the right final having coolant in it, and invoice says left clutch.  Could be a typo for all I know.  

But possible the pump was working its brand new heart out to pull crap oil from the trans, especially through that nasty screen filter.

I have yet to clean the filters but I have bagged them up and intend to retain all debris I find.

Question/thought - I am sharply debating whether I pull the ROPS and tank on the initial test. Oil is not cheap, even the cheap stuff (thanks Biden). If bearings are out again on the bevel shaft, obviously that would need fixed but there is no damage being done when not moving. I had the thought to fix trans cooler, swap all filters, new oil, and just test. ?? I guess my wrench head hates gambles like this and I don't like doing more damage, but a lot of work just to learn the obvious.

I really want to drop some trans oil right now just because I want to see how much coolant is in there. It is bright green! I've never seen mixed coolant in oil that actually separated clean, but machine has been sitting for probably 2yrs.

oil and water can separate if heated appropriately and left sit but generally this doesn't happen and it stays mixed. unless that has come from somewhere else and hasnt had a chance to mix. i would be draining that oil. if you have a oil centrifuge you can clean the oil removing the water and other contaminants and reuse it. on most ships that is what they do they centrifuge the oil and fuel to clean it.
the fuel is done at a rate to match fuel use from the day tank.