Just got a 6.2 K5 with trans trouble

[62K5]

Hi all.. I just purchased an 82 K5 with a 6.2 and a 700R4 and I hope to get some help diagnosing the trans problem it is having. Thank you to anyone who can help. According to the original owner, the 700r4 was rebuilt less than 5k ago with an upgraded pump, red alto clutches and a corvette servo. First I should say that the fluid is super clean and doesn't smell even a bit burned, and it also has an aux cooler. The fluid looks like its right out of the bottle with no visible debris at all that I am used to seeing with burned clutch packs. 1st to second gear is fine and solid, but 2nd to third is completely dead. The diesel just revs and never pulls at all in 3rd. The prior owner stated that it never slipped going 2nd to 3rd, but that it just all of a sudden quit working. When the shifter is placed in OD, the 2nd band applies again I believe (still trying to understand this fully), and its llike it is back in 2nd again, but without the engine braking that I have when the shifter is actually in 2nd. How should I diagnose this? I would just think the clutches were burned as is so common, if it weren't for the lack of mileage on the trans and perfectly clean non-burned smelling fluid. What is the best course of action here to determine the failure? I have a pressure guage that came with a BTO 700R4 that I bought a couple of years ago. Can I use it to somehow prove a clutch failure, or lack thereof? Thanks!

 

[diesel4me]

I'm no expert..

A good tranny shop can test the line pressures by using a gauge,tapped into the test ports on the side of the tranny's case..they will install the gauge,and run the car with the wheels in the air,and note the readings at different RPM's and speeds...they can also use air pressure to check the forward clutch seals,but they will have to pull the valve body out to do it...

This testing might not be cheap--so maybe it would be best to save the money from an "autopsy" ,and use it toward the next tranny,or to rebuild this one again...

You'll like the fuel mileage of a 6.2/700R4 combo,but the diesel might tear up that tranny faster than a gas engine would,due to its higher torque..big tires and high gears are what kill most 700R4's,that and high mileage and little or no maintenence..yours must have not been rebuilt correctly,it should have gone at least 50K before having problems..

 

[62K5]

Yeah, see I'm trying to stay away from tranny shops. I have learned. If I replace it, I will just buy one of those Mad Dog ones I think. The last one I bought for my 67 camaro was from BTO, but the sun shell shattered within a week, so I wasn't too impressed , though they did fix it. What I'd really like to know is if one of the 2 ports on the passenger side is the test port for the 3-4 clutch application, and if so, which one . If I find that I am getting pressure past the accumulator and the problem is likely the 3-4 piston or seals or something in the input housing anyway, I'll forget it and buy a new trans online. However, if there is no apply pressure, I am assuming this could be a valve body or accumulator leakage issue for which I wouldn't even have to pull it. Unfortunately, none of the manuals I have specify anything about the test ports. If anyone has a factory svc manual, I'd really appreciate the info as I would guess it is in the FSM.

 

['79shortbox]

I have the exact same problem on my '82 6.2/700R4 combo. I was goin' up a hill one day and all of the sudden redline. It goes great in 1st and 2nd but nothin' after that. It is the second 700R4 i've toasted so I just cussed it and parked it in the yard. If you come up with an easy fix let me know and I may give it a try. From the way that it doesn't shift my first thought was a valve body problem, but I never investigated further.