I juat put in a rebuilt tranny and I am still getting some slipage. I was told that it might be my transfer case. the car drives good until it warms up then the slipping start. some time it might ga 20 miles before the slipping starts,what can this be?
gmc jimmy transfer case?
- Thread starter Eileen B
- Start date
Molson02536
New member
There shouldn't be any slippage from a rebuilt transmission, only reason for slippage is worn out clutch that has not been replaced. Put a line pressure gauge ($55 Auto Parts store, or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R.
Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.490" boost valve stock i think is 0.470" (easy fix in pan).
Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R. Also try a transmission flush with BG brand products (Firestone stocks it) might fix a clogged EPC filter screen before you have your transmission oil and filter replaced.
Good practice also is to replace the Boost valve every time you service the transmission. A weak boost valve is one of the major causes of transmission failure and that might be the issue here since your transmission only starts to slip when it warms up. The part is around $45.00 and take 5 min to replace then the transmission pan is dropped.
Please keep us posted and bring the transmission back to where you got it and have them test the line pressure and replace the boost valve to 0.490" for a higher transmission line pressure to aide in the shift firmness of your transmission.
