This is not the Z. I need some help diagnosing a problem with my auto in the truck (dropped in a L31 5.7L Vortec and 4L60E from a 99 Suburban). The tranny had 62,xxx miles on it when the Burb was wrecked (not terribly bad damage), but I have no history on the vehicle, its maintenance or condition of drivetrain.
The tranny seems to have been working fine until recently. (I now have about 800 miles on the drivetrain since the conversion). One thing that has been a slight concern is the driveshaft length. I could have had it shortened another 3/4" or so, but it seems OK. It can push another inch or so into the tranny from the position it currently sits in. The driveshaft is a 2 piece design, with a center bearing, so the yolk doesn't slide in and out of the tranny as the suspension moves. OK....that's the background, here are the new symptoms:
When in 4th gear, it seems to surge (like it's running out of fuel) at 60mph. If I try to go over 60mph, the tranny begins searching and then just slips and RPMs increase.
When I manually shift to 3rd gear, the tranny whines really loudly.
Running through the gears (placing the tranny in OD and letting it shift) from a stop to about 60MPH or so, everything seems OK.
The tranny fluid has been double and tripple checked and the dipstick shows good level. No contamination evident in the fluid and the fluid is new since the conversion.
I am running through an external B&M cooler mounted in front of the radiator and no leaks are present. The fluid is not running through the radiator (internal tranny cooler).
If this tranny is on its last legs, I plan to get a remanufactured one from this place , but I want to make sure it is warranted, or do I have an installation issue that will manifest with the new tranny also?
Any expert opnions?