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Low/Falling priority valve pressure D8N 5TJ S/N prefix

3rdgendslmech

Well-Known Member
Joined
Jul 13, 2012
Messages
55
Location
Severn Md.
Machine went through 2 different transmissions in 12 hours. The one that was in it, and then 12 hours later a rebuilt one was bad. Both had the same issue. Fwd clutch discs got hot and melted.
I rebuilt the priority/brake valve and i did find a blown o-ring on the check valve but that was it.All pressures check out okay except for priority valve pressure. I can add shims to the priority valve spool but all that seems to do is increase the pump pressure but not priority pressure. Priority valve pressure is 110-130 at low idle, but if you bump the idle up itll go to 360-380 but drops slowly (spec is 420 give or take 20) but Starting to get a feeling something is cracked and bypassing somewhere.
Has anybody experienced this before?
 
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