140H tranny issue

[Jasoncarlon]

Hi,
I’m a diesel mechanic in Australia and I am having trouble with a 140H grader transmission. Serial prefix CCA.
Clutch pressure #8 and #5 in neutral are fairly low and fluctuating, between 0-200psi constantly, once you shift into a gear that uses #5 (3rd gear forward for example) the pressure comes straight into spec, but as soon as it shifts to neutral, it drops down and constantly fluctuates again. Clutch number #8 always fluctuates whether it’s in neutral or a high range gear. Issue was that in high range gears, it’s jerky, as if it’s in gear then out of gear, in gear, out of gear. (Relating to the pressure fluctuating). Has recently had all new solenoids fitted, I have re-tested them and they’re all in spec. All other clutch pressures are in spec and not fluctuating. Any ideas?
Cheers, Jason.

 

[Nige]

Do you have any idea of the hours on the transmission from new or since last overhaul..?

Seeing as all the solenoid valves have been changed have you measured initial pressures..? If so what were they like..?

 

[Jasoncarlon]

Yes sorry I forgot some important info. The transmission has only recently been done up. Probably 250hrs ago. Only had beari bf a and clutch packs replaced, control valve was not touched besides new solenoids. It has done 14000hrs from new. I have check all initial pressures. All are within spec except

 

[Jasoncarlon]

#8, which fluctuates between about 0-200psi. And #5 does the same when used in conjunction with #8 (neutral, 8F and 6R). Though #5 has the correct pressure when used in other gears, 3F, 4F and 3R. Also other clutch packs such as #6 fluctuate when used in conjunction with #8, such as 5F and 4R gears.

 

[Nige]

Was it run on a test bench after rebuilding.?
Has it been performing the same way ever since it was rebuilt..?
If yes, it looks like whoever did the rebuild is in for a teardown.

 

[Jasoncarlon]

I’m not entirely sure. What do you make of the “fluctuating pressure”?

 

[Jasoncarlon]

I thought it would just have low pressure if there was a blown seal/oring or something. I have never seen fluctuation like that.

 

[Jasoncarlon]

I removed triangle plates and the seal carriers from the back of the transmission and applied air pressure to each one, can noticeably hear them engage also.