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700R4 prob question

malignd1

malignd1

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Lakewood, CO.
3 weeks ago hit the highway headed north to the FT. Got to loveland and noticed a big puff of white smoke in the rearview and smelled burning ATF. Pulled over to check the tranny and noticed fluid around underside on transmission. Had co-pilot start motor whilst I was inspecting and noticed pressure bubbles emanating from between 2 front trannypan bolts so I figured pressure was forcing fluid to spray exhaust pipe causing smoke and smell. Checked fluid, bought more and continued on. Noticed when really gettin into throttle (pushing it above 65mph) that the plume of white smoke and smell of burning ATF appeared. Finished trip and returned home. Picked up a trannypan gasket/filter kit. While removing pan I noticed all but 3bolts were only finger tight, and 1/2 (8) bolts appeared to to not fit correctly. Got gasket and filter replaced along with 8new bolts, refilled and checked for leaks. Everything looks good, take it for a test drive then park and check for leaks, everything looks good.
This past weekend, decided to take her out again...Get on the highway and open'er up and get burning ATF smell and white smoke when laying into throttle. Pull over to check it out and find wet around transmission but not coming from pan gasket this time. Any info will be greatly appreciated.:dunno:
 
It sounds like the breather tube at the top of the trans is plugged and when the trans gets hot that fluid has to expand somewhere. First it was out the gasket, now who knows. Maybe the pressure unplugged the vent tube.

The real question, why is it getting so hot?
 
Doesn't appear to be happening from overheating. Only happens with the pressure increase under higher workload. Doesn't do it under normal driving in the city or even on the highway. Only when gettin heavy on the throttle and going for quick acceleration(puttin it to the floor) or trying to push it above 65. Anytime the tranny is put under higher pressure and forced to work. but then again im not an expert by any means. :confused:
 
What year 700r4? Might have too much fluid in it. Are you checking fluid level with the engine running? Reach up and see if you feel fluid at the vent tube. Pull the inspection cover and check for fluid and I'd put a pressure gauge on it and watch it while driving.
 
If the fluid is super clean it can be hard to find leaks without using a dye and uv light.That said take a look at the shift shaft seal.
 
I'd look at the cooler lines,one might be crimped or restricted--that reduces flow to the cooler,raises the temparature of the fluid,and the resistance to flow could cause pressuure to back up inside the tranny...
 
As far as I'm aware the tranny is stock and the truck is a 90', so im assuming its a 1990. Fluid is being checked in park with motor running just like dipstick says to do. Fluid is registering on stick just above fill line. I will check the breather tube and the cooler lines and see if anything looks or feels out of whack. Just continue troubleshooting anything I can. Thanks guys!!
 
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So i checked the number on trans and found out that it's 1985. does this make a difference? Looks like filler tube seal is about 1/8'' from flush with top of trans. Not sure about breather tube yet. Planning on gittin inthere today
 
1985 won't have the auxiliary valve body but that wouldn't make it leak. Keep searching for the source of the leak.
 
I know on a TH350 if you are loosing a clutch pack, it can bleed ATF out the breather on the top under a load. Also could be a bad pump seal
 
malignd1 said:
What is an auxiliary valve body?
Click to expand...

It's an extra accumulator they added to soften the shift from park to drive.

This thing.

ck5avb1.jpg
 
Wow. not sure if im sure this is a 700r4. Starting to think it may be th350. Gonna take it out and run it to count the gears of shift.
 
Also check and make sure your t.v. cable is adjusted properly . the t.v. cable regulates line pressure . If you have too little or to much pressure in a certain gear it can smoke a clutch pac quickly. But the good news is T.C.I. makes a valve body that maintains 200 psi at all times to keep ya from burning up that poor ol slush box. Also I dunno if anyone has heard of a company called mad dog transmissions but they built me an awesome 700. That is damn near bullet proof . Very good quality and stands behind his work. And very good prices. Sorry for getting off topic but if you have a question give him a call and he will have ya fixed up in no time at all. Phone #770-781-0949 . website is www.maddogtransmissions.com good luck :waytogo:
 
Have you checked for a leak where the TV cable goes into the trans? There is only one bolt that holds it down (at least on my 700) and it seems like an easy sorce for a leak. Also I know a guy that burned his K5 to the ground because he had tranny fluid come up out of the dip stick tube and leak onto the headers and catch fire. Is it possible that the leak is coming from there?
 
TV cable appears to be connected properly. Not finding the breather tube plugged. Sprayed tranny down with brake cleaner to get nice n shiny and took her out for a drive. Counted shift times as 3. Ran her on the highway and opened her up a little. Got back and looked underneath but could find no where leaking. Didn't get the burnt ATF smell or smoke but didn't run her hard. Tried to lay into the throttle a little to raise the pressure and get a spray but didn't seem to happen this time. Still not sure what's up. Gonna try a hard run today to see if anything happens. Also I noticed after my last camping trip when I parked her in the driveway that there is a small spot of oil on the ground directly behind the front passenger side wheel. Directly underneath the grease fitting. Would this indicate a leaky axle seal? allowing differential fluid to run down the axle and leak out by the ball joint:confused: Also there is no fluid inside engine compartment so no evidence that anything leaking from fillertube. And as I stated before that the fillertube grommet appears to be about 1/8" from sitting flush from tranny, but not seeing any sign of leakage coming from there. Having a difficult time diagnosing this. Also cooler lines do not appear to be pinched or damaged
 
Why not look into getting a pressure gauge on it? Probably a local tranny shop can even go for a test drive with you. They use a long hose and tape the gauge to the windshield or something. Maybe the pump is stuck and instead of regulating pressure it is just based on speed. Regardless, it will be good to know what the pressure is doing.
 
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