New-to-me '85 K10 with tranny issues

[cptmoney]

Hey all -

So I've been sniffing around, peeking in back yards and driving alleys looking for a solid K10....and I've found one.

Problem is, the tranny is doing all sorts of weird voodoo! The truck is a 305V8 with a 700R4, with roughly 125K miles. Body is SUPER straight and it doesn't look to have been terribly abused - but it doesn't necessarily look pampered either. Transfer case refused to engage as well; just grinding sounds when I attempted it.

The truck has been sitting for several years, and was super low on fluid. I drove it around the block and it was slipping like mad. Low fluid was my initial thought, so we topped her off and took her around the block once again. Same slipping.

Is it premature to jump straight to "yank the tranny" mode? Are there obvious things that I might be overlooking, just because I'm a rookie to all the this tranny business?

The trans fluid didn't smell burnt, but to be honest there wasn't much in the tranny when we checked the fluid level.

I've got an extra 700R4 (the later rainbow case/K case) that is SUPPOSEDLY good - but I never saw it in motion. This is another question for another thread, but do I go through the work of installing it just assuming that it's good? Or do I swing it by the local tranny shop and have them take a peek before I go through all the work only to find that it's NOT good?


Where would you guys start? What should I check first?

Thanks for your help with this one - I imagine I'm going to be hanging around here a lot.....so I may as well get comfortable with this place!

 

[1987 GMC Jimmy]

Hey all -

So I've been sniffing around, peeking in back yards and driving alleys looking for a solid K10....and I've found one.

Problem is, the tranny is doing all sorts of weird voodoo! The truck is a 305V8 with a 700R4, with roughly 125K miles. Body is SUPER straight and it doesn't look to have been terribly abused - but it doesn't necessarily look pampered either. Transfer case refused to engage as well; just grinding sounds when I attempted it.

The truck has been sitting for several years, and was super low on fluid. I drove it around the block and it was slipping like mad. Low fluid was my initial thought, so we topped her off and took her around the block once again. Same slipping.

Is it premature to jump straight to "yank the tranny" mode? Are there obvious things that I might be overlooking, just because I'm a rookie to all the this tranny business?

The trans fluid didn't smell burnt, but to be honest there wasn't much in the tranny when we checked the fluid level.

I've got an extra 700R4 (the later rainbow case/K case) that is SUPPOSEDLY good - but I never saw it in motion. This is another question for another thread, but do I go through the work of installing it just assuming that it's good? Or do I swing it by the local tranny shop and have them take a peek before I go through all the work only to find that it's NOT good?


Where would you guys start? What should I check first?

Thanks for your help with this one - I imagine I'm going to be hanging around here a lot.....so I may as well get comfortable with this place!

No, I wouldn't jump to pulling the transmission just yet. I wouldn't drive it anymore until you checked the throttle valve cable, though. That's the silver cable attached to the carburetor that's not the throttle cable or the cruise control throttle cable. If it looks like a limp noodle or if it's frayed, you may be in luck. If the former applies, you'll need to tighten it up. I'll attach a link below. If the latter applies, you'll need a new cable. Look for fraying at the end of the silver part where it goes into the sheath. As far as the transfer case goes, I'd check the fluid, which should just be transmission fluid. It's filled up just like a differential is. See if that fixes it after you address the TV cable. If not, you can try shifting it on the fly to 4H and see if that gets you anywhere.
http://www.cpttransmission.com/tech_tvcable.htm

 

[cptmoney]

OK - sounds like something worth trying.

I don't know why.....but I've got this gut feeling that the tranny is going to prove to be smoked. It has been sitting for a long time, unused, and sitting with little to no fluids. That can't be good.

Add to that the non-functioning transfer case, and things are adding up for a truck that just needs a little extra lovin'. I can't complain, as I'm into the truck right, so there's room for just such a rebuild. Im just lazy - and didn't want to have to deal with it! Haha.

I'll post a pic of the tranny I have right now. It specs out to be a later model K-case, perhaps a 1989 model. That's what I'm figuring it is. I think I'll get in touch with the transmission guy and have him wave his wand over it. Let's get this train in motion!

 

[1987 GMC Jimmy]

OK - sounds like something worth trying.

I don't know why.....but I've got this gut feeling that the tranny is going to prove to be smoked. It has been sitting for a long time, unused, and sitting with little to no fluids. That can't be good.

Add to that the non-functioning transfer case, and things are adding up for a truck that just needs a little extra lovin'. I can't complain, as I'm into the truck right, so there's room for just such a rebuild. Im just lazy - and didn't want to have to deal with it! Haha.

I'll post a pic of the tranny I have right now. It specs out to be a later model K-case, perhaps a 1989 model. That's what I'm figuring it is. I think I'll get in touch with the transmission guy and have him wave his wand over it. Let's get this train in motion!

If it was run extensively without fluid or with an improper TV cable adjustment, it's not looking good for it. The '89 is definitely a better transmission, but there aren't any guarantees on either. You could always pull the fluid that was in there and look in it for metal while also checking the magnet in the pan and cutting open the filter to see if there's metal. If you are gonna get a rebuild, I'd do the later model one and have them put a shift kit in it. 700R4's weren't good for our trucks until around 1987-88, especially K-trucks.