4r100 boost valve

[Josh Oldenburg]

Probably should have started here instead of asking about another tranny. My transmission slips in reverse only when you get on it or try to back up a hill with a load. Somebody pointed me towards the pressure boost valve for reverse stating that if my clutches were shot I wouldn't have first gear either. Can this be confirmed? He told me line pressure should be upwards of 250 psi in reverse I currently see the line pressure at 180 psi in forward gears but I've never looked in reverse

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[Josh Oldenburg]

Just checked my line pressure and I'm at 134 forward and reverse at idle.

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[Josh Oldenburg]

Line pressure at stall is 181 in reverse. I read it should be above 250

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[trackspeeder]

Reverse and direct (3rd) use the same drum. You can lose reverse and have all forward gears.
The line pressure is on the low side. This could be a weak pump,sticky accumulator valve, worn piston seal, or worn frictions.