Tim240z Posted October 24, 2005 Share Posted October 24, 2005 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? Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted October 24, 2005 Share Posted October 24, 2005 According to the ATSG service manual, it sounds like one or more of the following. Valves stuck in the valve body, damaged servo assembly, worn band assembly, worn or damaged oil pump assembly or one of several problems related to the case. A reputable transmission shop should be able to diagnose this closer. I'd look at the site you've hyperlinked but our network security is over the top with restrictions so I can't get there from work. Quote Link to comment Share on other sites More sharing options...
skipzoomie Posted October 24, 2005 Share Posted October 24, 2005 It is VERY important that the throttle valve be adjusted CORRECTLY. This valve controls the shift schedule and if it's not right on then all sorts of things act wierd. Quote Link to comment Share on other sites More sharing options...
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