D6H transmission overheating

[Pralhad Birdi]

Hi all,
Trying to sort out an overheating transmission on a D6H Serial No. *2KD00564* for a buddy.
The history of the machine as I’m aware of it is as follows:
He bought the machine, put it on his lowbed, and when they tried to offload it, catastrophic clutch failure in the transmission. Someone changed the clutches, the cables and the transmission pump.
Now, it’ll go about 150 metres, and just stop. Transmission getting very hot.
I measured oil cooler inlet pressure at the filter cover, and I think it’s supposed to be 98psi, and I’m getting a reading of 580psi.
Am I correct in thinking this would indicate a blocked oil cooler? And if so, what else do I need to check/clean/flush?

Thanks

 

[Nige]

Normal recommendations after a major transmission clutch failure are to replace the transmission pump and the cooler, then sponge gun all the hard lines in the powertrain oil circuit and finally run the machine for a while after recommissioning with cleanout filters installed to collect the rest of the cr@p that the aforementioned procedures didn’t get…….

Have you pulled the magnetic screen for the transmission pump suction to see what’s in it.?

 

[Pralhad Birdi]

Normal recommendations after a major transmission clutch failure are to replace the transmission pump and the cooler, then sponge gun all the hard lines in the powertrain oil circuit and finally run the machine for a while after recommissioning with cleanout filters installed to collect the rest of the cr@p that the aforementioned procedures didn’t get…….

Have you pulled the magnetic screen for the transmission pump suction to see what’s in it.?

I’m intending to pull out the oil cooler and the magnetic screen on Monday, and I’ll update you on what I find in there.
Would you mind elaborating on the sponge gun procedure please? Not too familiar with that. Thanks!

 

[Nige]

Would you mind elaborating on the sponge gun procedure please? Not too familiar with that.

See attached. Look specifically at 233-7191 & 233-7192.

 

[Pralhad Birdi]

See attached. Look specifically at 233-7191 & 233-7192.

Much obliged, thanks

 

[Nige]

That’s by no means the only way to clean out the inside of hoses, it’s just the one I’m most familiar with.

 

[Dave Neubert]

measuring pressure from the oil filter will give you main pressure not cooler inlet pressure. If you have a heat gun check temp at inlet and outlet and see what you get. there is a little plastic valve in the valve body that gets damaged and can cause a rise in trans pressure.

 

[Pralhad Birdi]

measuring pressure from the oil filter will give you main pressure not cooler inlet pressure. If you have a heat gun check temp at inlet and outlet and see what you get. there is a little plastic valve in the valve body that gets damaged and can cause a rise in trans pressure.

Ah okay, I thought the T&A said tap E was oil cooler inlet pressure.
Whereabouts can I find this valve and check it?
Also, if what I measured is main pressure, is it within range?
Thanks

 

[Nige]

I measured..... pressure at the filter cover ...... and I’m getting a reading of 580psi.

Come to think of it even 580psi (which as Dave says is pump pressure) at the filter head is way too high. The spec is 420 +/- 15psi. It sounds as though something wasn't cleaned when the transmission was overhauled and that you have a valve sticking somewhere. Either something inside the transmission control valve (was it ever removed and cleaned when the tranny was out.?) or the priority valve maybe.?

 

[Dave Neubert]

3t7727,7G9476 Don't recall witch one but if they look damaged replace

 

[Nige]

3T7727 replaced by 9W9830. See SEBD1972 attached.
Also needs a 5H8853 Seal to install it.

TBH our SOP when overhauling a transmission control valve was always to replace those plastic orifices whatever they looked like.

 

[Pralhad Birdi]

Thanks for the info guys, I’ll check the valve and revert.

 

[Pralhad Birdi]

Just to confirm, as I haven’t done this before, is getting the valve out a transmission-out job, or can I take it out with the transmission still in the machine?

 

[Nige]

Transmission has to come out.
If the valve was not disassembled and cleaned when the transmission was out before. I suggest that you do it now. If it was, then make sure that it was put back together correctly.

 

[Pralhad Birdi]

Okay. Is there a procedure I can follow to get it out and disassemble?
Thanks

 

[Nige]

I thought you had a service manual.?

 

[Pralhad Birdi]

I thought you had a service manual.?

I wish I did, but no just random screenshots off the internet.

 

[Dave Neubert]

I have been able to remove valve body by taking the plate off the back and removing the tubes I think the orifices are in the middle section it is heavy and tight but can be done

 

[Pralhad Birdi]

I have been able to remove valve body by taking the plate off the back and removing the tubes I think the orifices are in the middle section it is heavy and tight but can be done

So I’ve taken the plate off. Do the tubes come off upwards? Open up the big nut that’s on the outside and then upwards?

 

[Mobiltech]

Yes you have to remove the 2 big nuts. There will be a spring holding the tube in.
If you don’t have a winch you can pull the valve out the back through the hole.
Sounds like a valve assembled wrong or sticking.
Also you don’t mention the torque being rebuilt so you will probably be looking at that too. If you truly have 580 at the torque there will likely be damage to the inside metal seal rings.