Hey all, I am stumped on this one, 1986 CAT D4H SN# 8PB00761 power shift trans. Problem I am having is the torque converter housing over filling with trans oil TDTO when sitting tested and confirmed with dye. When its running its fine. The trans/ trans charge pump/ torque converter were rebuilt around 500 hrs ago. The hydro pump was resealed at the same time. This is a recent problem, if it sits for a day or so the housing gradually fills up with oil and will leak out the top of starter where the solenoid and pin are. Here is what iv found. The converter inlet pressure is right about where it should be (135 psi cold) as well as outlet/ relief pressure (43 psi cold). Machine operates/ shifts with no issues what so ever. Seems the problem is some how its draining ether out of the converter while sitting or from the charge pump. The charge pump suction line is pretty much on the bottom of the trans housing so it has a possibility of getting head pressure and leaking that way but is there anything else I am overlooking or any further diag. before I pull that pump out of the housing enough let it sit and see if say the front seal is leaking? I bolted a piece of lexan with a gasket over the starter hole and after a day its a third of the way up the hole, so its a slow bleed. thanks all.
I'm thinking the trans might be over filled Don't know about your model but is it checked fully warmed up idling?
I'm not sure but if this is a wet housing you need a wet starter motor on it.
Wet housing. No scavenge pump.
It can be checked cold or hot had both ranges on the stick and its within both ranges actually just a touch low. it has a wet type starter in it iv pulled the starter and replaced all seals all actually looked fine. the starter was also rebuilt when the trans was done so there was about 500 hrs on that. so I guess the question is what regulates the fluid level in the housing? I cant find anything in SIS explaining the housing oil level and how its regulated
I would suggest the starter motor getting checked. The housing is supposed to have oil in it. A wet starter is a sealed armature unit built for that type of application. Its common for starter rebuilders to rebuild their units as dry motors unless a wet one is specified. Its unlikely that you have any serious problem at this point
are you sure the hyd. pump seal is not filling it up
It’s definitely a wet starter, nothing looked failed at all inside it, it now has all new seals, where it was leaking was where the solonoid meets the cast part of the case and where the pin goes through the cast snout for the rod to throw the bendix there are no seals there or none that I saw in any parts brake down It’s definitely not hydro oil Iv tested that by putting cat fluid dye in with the transmission fluid and that’s what has showed up in the housing
What you call a transmission charge pump is a 3 section gear pump. A scavenge pump, a transmission pump and a brake/steering pump. Since the transmission oil level is below the starter seems as thou it would be hydraulic oil in the flywheel housing. Transmission oil is supposed to be in the housing. Check the hydraulic oil level and see if there is any dye in the tank ,I would have put the dye in there instead of transmission. Bob
Looks like gravity feed back to the transmission if you are not over full then maybe your breather is clogged on the trans pull the filler cap off and see if it still fills if not then it has to be coming from some where else