d6r brake coming on after machine warms up

[Tinkerer]

Tamoo posted this question to me in a conversation. I put many thousands of hours on dozers but never repaired them. So, I thought I would start a thread for him.
"d6r brake coming on after machine warms up. Cat resealed brake and steering and did not fix it. Changed modulating manifold from working machine cat said pump pressure is correct but drops after warming. Any suggestions ?"

 

[Dave Neubert]

Are you sure that the brake switch is good

 

[Nige]

It's a D6R. There are no less than 83 different versions - a Serial Number would be a very good start in this case.

 

[tamoo]

Are you sure that the brake switch is good

cat replaced it

 

[tamoo]

It's a D6R. There are no less than 83 different versions - a Serial Number would be a very good start in this case.

cat d6r 5Ln00794

 

[Mark250]

Hi tamoo welcome to the forum. Some questions please
when did the problem first show up? slowly, quickly after service or repair?
You said the machine gets hot is this normal operation temp or the transmission is over heating?
Are you sure it is the brakes coming on ,what makes you think that? does the machine stop? maybe the transmission is slipping.
does the problem occur in any gear forward or reverse?
Did any one actually check the brake pressures at the brake valve or brake units or the transmission pressures?
can you source and use pressure gauges if need be?
when CAT resealed the brake units did they pressure check and let stand to check for pressure bleed off?
Did any one check that priority valve is working correctly?
Have you checked with the priority valve solenoid disconnected?
Do you need testing and adjustment information?
Has the filter and screens been checked for contamination?
Sorry for all the questions just trying to build a picture of your problem
Mark

 

[Dave Neubert]

Mark now that you mentioned it I had a 6R that had a bad harness and would go into 2 gears at a time It would throw you out of the seat

 

[tamoo]

Hi tamoo welcome to the forum. Some questions please
when did the problem first show up? slowly, quickly after service or repair?
You said the machine gets hot is this normal operation temp or the transmission is over heating?
Are you sure it is the brakes coming on ,what makes you think that? does the machine stop? maybe the transmission is slipping.
does the problem occur in any gear forward or reverse?
Did any one actually check the brake pressures at the brake valve or brake units or the transmission pressures?
can you source and use pressure gauges if need be?
when CAT resealed the brake units did they pressure check and let stand to check for pressure bleed off?
Did any one check that priority valve is working correctly?
Have you checked with the priority valve solenoid disconnected?
Do you need testing and adjustment information?
Has the filter and screens been checked for contamination?
Sorry for all the questions just trying to build a picture of your problem
Mark

 

[tamoo]

just bought machine reports said inspection good.trucked to me unloaded ran about ten minutes just checking
seem to be ok.checked all fluids fuel it. started to push dirt as soon as temp was at normal that's wend brakes came
on called cat came out replaced brake peddle switches did not fix. replaced solenoids under seat. took to cat shop
they did pressure checks ,said brakes were worn out seeping bye they took it apart everything looked good .resealed
tested did the same thing. they checked priority valve said it was ok.s till dropping pressure making brakes come on
expence got to to high. brought it home took solenoild valves off a working machine did not fix, filter and screen clean ,stops in all gears. drives at low idle.

 

[Mobiltech]

I’d wonder if it has a leak in a steel pipe inside trans case?

 

[Mark250]

I am thinking similar to Mobiltech, if you can, remove the brake valve and fabricate a plate to cover the ports on top of transmission case, in that plate drill and tap two holes to screw a connector into .In the connector screw in a tee, one part of tee fit a 500 psi gauge the other part of tee a stop cock now pressurize the with a hand operated pump no more than 350 psi. close stop cock and watch for pressure drop. Do this for both brake port openings and see want happens
Mark

 

[tamoo]

found problem gear in pump broke on second stage of pump