700R4 issue

[scottsdale86]

I had a perfect shifting and feeling trans in my 86 K10 until about a day or so ago. Today after a short 3 mile trip to drop my son off at day care I noticed that the trans was puking fluid out from the top of the transfer case. I checked the fluid level and it was low so I added a little and went around the block. All was fine and I parked it and went inside. this morning I went to grab some breakfast and it felt like it didn't want to shift out of first. I pulled over and checked the level and it was low again. Where I park my truck is on a slight grade so the front of the truck sits higher then the rear. I think the seal between the TC and the trans is letting trans fluid back into the TC. I am going to fix that but do you think I killed the trans? I didn't smell any burnt fluid or see anything abnormal on the dip stick but I won't know i suppose until i drop the pan and take a look around. Also the detent cable is adjust correctly and functioning as it should as far as I can tell but I am just worried I murdered this transmission. Any advice would greatly be appreciated.

 

[76k5blazerr]

If the trans operates properly when the fluid is filled to the correct level you should be fine. Its odd that the trans would let fluid into the t case though. Are you sure its not leaking it. Thats a lot of fluid to lose overnight. You have to be at least 1-2 quarts low before the trans will start acting up. I would check to make sure its not leaking it onto the ground first (which is easy if you park on concrete or asphalt). Then make sure its not leaking while driving.

 

[scottsdale86]

Only time it was leaking onto the ground was when it was spitting out out of the top of the transfer case. Sometimes the truck sits for a week or two before I drive it again in the same spot.

 

[76k5blazerr]

Most likely theres a problem in the rear of the transmission thats causing fluid to be let into the t case. Im not exactly a transmission guru though. See if you can send Greg Ducato a PM, he's the transmission guy on here, an expert.

 

[livid4dirt]

It's most likely the seal at the front of TC.

 

[wetoolowdingbangow]

Theres an o ring seal between the TC and tranny...better check the bolts though, they loosen up like mine did. Put a lock washer or lock tite them because theyll loosen up again.

 

[scottsdale86]

I am going to drain both and drop the TC and replace the seal there. I know there is one on the TC side but not on the trans side facing the TC. I believe there is just a drain hole for it to go back to the trans. The one in the TC is supposed to prevent the two from sharing fluids. I think they keep overfilling each other as I park either in my driveway(hood facing downward) or in the street (hood facing upward).

 

[Greg Ducato]

As long as you didn't push it too hard while low on fluid the trans should be OK. While the TC is out check over the rear of the trans case well, these have a tendency to crack at the rear of the case.

 

[scottsdale86]

No I literally drove it a few miles home and shut it off. Didn't smell burnt or look abnormal. What about if the level was too high?

 

[76k5blazerr]

No I literally drove it a few miles home and shut it off. Didn't smell burnt or look abnormal. What about if the level was too high?

If the level is too high the fluid will usually get puked out the vent on top of the tranny, high fluid is not as dangerous to the tranny as low fluid, but still not great for it.

 

[Greg Ducato]

Excess fluid will try and find a way out, by vent, dipstick tube or weak seals. There is very little pressure in the trans cavity where this excess fluid would reside so it really isn't hurting anything, same difference as a deep sump pan, but the 700R4 in particular will puke out the vent if the fluid is warm and too far over the full line.

 

[scottsdale86]

Ok. Fingers crossed when I pull this think apart next weekend for Christmas break.

 

[JOES89K5]

My trans is in process of being rebuilt. I noticed Trans fluid leaking from transfer case end. I did change seal during the summer but it still appears to be leaking. I figured same that trans seal between trans and case is bad. The guy rebuilding the trans indicated yoke bearing in transfer case is probable bad so he will repair along with all seals at install.