I have an 87 ext cab s10 that was already converted to v8/th350. I bought the truck minus the v8 which was fine because I just happened to have a very healthy one to put in. So anyways it has been well over a year since I put the motor in and the truck has been perfect. The th350 that came with the truck was supose to have been just rebuilt and to this point a perfect tranny. Yesterday I hooked on to a 2500lb trailor to use to remove debris (from hurricanes) I was traveling and suddenly I am blowing tranny fluid smoke all over the place so I pulled over to prepare myself to replace a line. I wiped everything down started the truck back up in park and could find no leak.**first thought is if a line is leaking it wont matter wheather it is under a load or not. but no leaks at all. I topped the tranny off and tried agian only to find myself blowing smoke agian. I parked the trailer and took off home wondering what was going on. All the way home I blew no smoke at all. I got home and cleaned everything and dried it. I topped the tranny off and started it up and got on my creeper and laid under the truck for 20 min and no leaking at all. So I thought perhaps that under a load one of the lines was swelling so I went and bought all new lines and replaced them. I checked for leaks and there were none. I set off to go get the trailer and had no problems at all I drove 25 miles and when I got to where the trailer is I checked for any signs of leaking and everything was as dry as it could be. I hooked on to the trailer feeling everything would be ok and just after 2 miles I was leaking like crazy once agian. What is going on guys? When looking there is know way to tell where that fluid is coming from but really looks like perhaps the front seal area or the front of the pan but I figure if it was the pan there would not be any fluid on the flywheel or torque converter. Anyone been through this before? Its a 9in tail th350 and I have a ready to go 6 inch but dont have the means to extend the drive shaft.





just-speed

The fluid is expanding due to overheating while pulling the trailer.
An external transmission cooler is needed.
http://members.troublecodes.net/stuart/Fancooler.jpg[

maybe I should have said that I already have a cooler. But that is a thought. maybe the temp is getting to high somehow. I will look at the cooler itself.

[QUOTE]Originally posted by stu
[B]The fluid is expanding due to overheating while pulling the trailer.
An external transmission cooler is needed.QUOTE]


I agree. When the 88 up Chevrolet 1500's came out, they had a fold over dip stick cap on the transmission filler............to prevent the fluid from boiling out.

You need a bigger cooler or it may be plumbed incorrectly. Is it plumbed before the radiator or after ???

__________________
I went to the school of hard knocks ... where the tuition is high but the retention is exceptional !

it is before the rad. The cooler is not connected to the rad at all. the rad does not have provisions for any tranny lines. The rad is a griffin race rad.

Ok you need a larger cooler then.

I thought about it and the cooler I was running really was to small and very well could have been the problem. I looked in summit and jegs to see about a larger cooler with maybe a fan attached. I then went down to advanced auto parts and bought a 11" by 11 3\8 cooler and a 10" fan and made my own fan cooler combo for about $120 which is a whole lot cheaper than what I could have bought one for. So anyways I put it in and so far so good but I have not pulled a load yet. I just got back from a sand pit and did some hill climbing and such and it did no leaking. I have a tranny temp setup somewhere and I think I will look for it and hook it up. so I feel better now. still if anyone has any input please speak up. I still dont know what will happen if I pull a trailer


justspeed

I have a very similar problem. I just bought a 66 C10. #50 3-speed. I dropped a rebuilt TH350 in it and it ran fine. Apart from little gremlins here and there. Suddenly, I start leaking fluid and its burning all over. Looks real cool...
Or not.
I put it on stand and crawled under while it was in gear. Right past the cooler lines, there is a round, um, thing. It has a clip holding it in. The fluid is leaking from the space in the clip. What is that thing? Is there a gasket or something I can buy?
I went to the boneyard and picked up a pretty hefty tranny cooler, but the tranny fluid and pan stay plenty hot for quite a while after the truck is off.

Thanks,
Brandon

That's called an accumulator.
Clean all the crud away from the cover area.
Remove the snap ring and pull the cover out.
There is a short spring behind it but not very strong.
Replace the "O" ring on the cover.
Clean the "O" ring area well and reinstall it.

Thanks much, I appreciate it. I have really gotten close to the point of just giving up on this truck, but I don't think I can. It's my new project, and being a Chevy, everything is pretty cheap. Right now, cheap=good!

Brandon

I bet the breather is blocked. This can happen 1 of 2 ways.

1) Front pump gasket put on wrong. You can either take the trans out, remove the front pump, make sure the gasket is on right; or poke around in there with a coat hanger to try and pierce the gasket.

2) There is a stupid little L-tube that bends down. That is all the vent is. It could be pluged up somehow (mine had mud dried in it). I pulled it out, tapped the hole for a 1/8" NPT barb, and ran the hose up a bit higher.