Won't engage reverse when warm

[89mulletbird]

I have a built 200R4 and it recently does not like to engage reverse when it's warmed up. Fluid level is fine, TV cable is adjusted. I was thinking of installing a 300PSI sensor and wiring it to powerlogger, would this be useful to diagnose the problem? I'm guessing it might be the pump? All forward gears work great, shifts are crisp.

 

[Steve V]

Could be a cross leak in the valvebody gaskets, could be bad low/rev seals, could be bad direct drum seals/rings on center support. Pump does not know forward and reverse. It always turns the same direction making pressure. I would guess the pump is the least likely of the issues.

 

[bison]

Pressure test first


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[89mulletbird]

Where is the pressure test port on the 200R4? I'll wire in a pressure sensor to powerlogger.

 

[Steve V]

Left side above shift linkage slightly forward.

 

[89mulletbird]

Thanks, found it

 

[89mulletbird]

Line pressures COLD
Park 100psi
Drive 150psi
Reverse 220psi (engages well)

Line pressures WARM (190 deg)
Park 50psi
Drive 100psi (seems to shift OK)
Reverse 80psi (won't engage)