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Desperate for transmission help!!
- Thread starter corvette6
- Start date
this is response I sent to another list trying to get help!!
I saw your post about the 700r4 puking fluid all over the place.
Sounds
like you've had experience with my proble. My tranny was rebuilt about
30k
ago. I recently had the pan dropped by the shop that rebuilt it for
me.
Dark fluid but no noticeable debris. I have a large three core
radiator
with an auxilary cooling fan and a large tranny cooler. The truck has a
300hp small block, 3.08 gears and 33 inch tires and always stay below
200
degrees and usually closer to 180.
The problem i'm having is when towind in drive with the converter
locked up.
After driving for a while at 50 or 60 with my trailer behind it (5000
lb) it
spray fluid all over the exaust. By the time I pull over to the side
of the
road, no more fluid spraying just smoke. Then I can get right back in
and
drive another 30 to 60 miles.
I'm not sure where to go next. Can I make this tranny work for towing?
Do
I need a bigger radiator, bigger tranny cooler or fan on tranny cooler?
I'm pretty frustrated and seriously considering a 350 or 400. The only
time
I drive any distance is when i'm towing and I can't tow in overdrive...
Thanks in advance for any help or insight
Elliot
I saw your post about the 700r4 puking fluid all over the place.
Sounds
like you've had experience with my proble. My tranny was rebuilt about
30k
ago. I recently had the pan dropped by the shop that rebuilt it for
me.
Dark fluid but no noticeable debris. I have a large three core
radiator
with an auxilary cooling fan and a large tranny cooler. The truck has a
300hp small block, 3.08 gears and 33 inch tires and always stay below
200
degrees and usually closer to 180.
The problem i'm having is when towind in drive with the converter
locked up.
After driving for a while at 50 or 60 with my trailer behind it (5000
lb) it
spray fluid all over the exaust. By the time I pull over to the side
of the
road, no more fluid spraying just smoke. Then I can get right back in
and
drive another 30 to 60 miles.
I'm not sure where to go next. Can I make this tranny work for towing?
Do
I need a bigger radiator, bigger tranny cooler or fan on tranny cooler?
I'm pretty frustrated and seriously considering a 350 or 400. The only
time
I drive any distance is when i'm towing and I can't tow in overdrive...
Thanks in advance for any help or insight
Elliot
So the fluid is coming out of the dipstick tube? Are you sure that the temperature is not climbing? Where is the temperature gauge sender located?
It's possible that the vent line is plugged. Ususally, it's just a silly little straw-type thing sticking out of the top of the tranny with a little bit of cotton or something stuffed in it. If this gets plugged up, air will not be able to vent and the pressure has to be released somewhere else. Since there is air inside, it is normal for the pressure to increase as the transmission heats up. That is why the vent is there.
You're not towing with a Corvette, are you?
It's possible that the vent line is plugged. Ususally, it's just a silly little straw-type thing sticking out of the top of the tranny with a little bit of cotton or something stuffed in it. If this gets plugged up, air will not be able to vent and the pressure has to be released somewhere else. Since there is air inside, it is normal for the pressure to increase as the transmission heats up. That is why the vent is there.
You're not towing with a Corvette, are you?
I drag race corvettes but I tow with my trusty 86 K5 blazer. 320hp small block with an anoying 700r4. I beleive the fluid it blowing out the overflow tube an not the dipstick. Every time it happens, I pull over and no fluid is on the top end of the engine, it is all down on the pipes burning. Is this uncommon?
With 3.08 gears and 33" tires your only turning a little over 2,000 RPM at 65 in third gear, and less than 1500rpm in OD. your puting alot of stress on your drive train when you tow at such low rpm, since your engine isn't in the best part of the torque band. you should probally have at least 3.73 or btter 4.10 in your pumpkins. this should put your engine in a better RPM range for towing and take the stress off your tranny. engine temp isn't the best indicator you also need to install a tranny temp gauge to properly moniter the temp.
CaptCrunch
1/2 ton status
I agree w/ rugger here... 3.08's suck and should of never been put w/ an od trans. You are overheating the heck out of your tranny. What size is your trans cooler... chances are even if you think it is big enough it isn't.
1987 Chevy K5 Blazer- 350 TBI
1987 Chevy K5 Blazer- 350 TBI
Rayven90
Registered Member
-I would have to agree with the other posts, sounds like your overheating it. Be careful though, That happened to me and I got more then smoke. I got a fire! After mine did it once, my clutch plates were shot and I got a vibration from it. I tow with mine but I never use OD when towing. I was told the 700r4 od gear is weak and should not be towed with. I just stay in drive now and haven't had a problem. I am usually towing a 7000 lb camper trailer.......
RAy
RAy
Coincidentally, your engine rpm in 3rd is pretty close to what it would be in OD with 4.11's, so towing in 3rd is not only a good idea for the tranny, it is probably better all around. It sounds like you a cooler that is integrated with the radiator. With a setup like this, your transmission is basically always going to be as warm or warmer than the engine temperature. If the transmission fluid at the output of your cooler is the same as the engine coolant temperature (let's say 200 F), this is the coolest that the fluid gets: everywhere else it is hotter than 200. How much warmer, you don't know without a gauge.This is part of why it is so advantageous to put a seperate cooler after the radiator cooler. Then you can return fluid to the transmission that is cooler than your engine coolant.
But to begin with, you should never tow in OD with 33's and 3.08's. That's just asking for trouble. And you probably shouldn't even use overdrive with the right differential gears (when towing).
<font color=green>Stupid tourist at Mammoth Cave, Kentucky: "How many miles of unexplored passages are there?"</font color=green>
But to begin with, you should never tow in OD with 33's and 3.08's. That's just asking for trouble. And you probably shouldn't even use overdrive with the right differential gears (when towing).
<font color=green>Stupid tourist at Mammoth Cave, Kentucky: "How many miles of unexplored passages are there?"</font color=green>
The owners manual says not to tow with the 700R4 in overdrive. Leave it in "D" and see if things don't work better.
<font color=black>HarryH3 - '75 K5</font color=black>
<A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
<font color=black>HarryH3 - '75 K5</font color=black>
<A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
