Another cooler or a fan?

[B_to_C]

I tested out the 40's off-road today

I have a 700r4 with a B+M 26,000GVW cooler on it. While off-road my temps kept rising (going up switch backs at very low speed) and topped out at 210 -when I decided to turn around.

After the new tires temps ahve been running higher then they used to (duh) but now I'm getting worried about burning the tranny up while off-raoding some hot summer day.

Should I add another cooler or a fan on my current cooler?

 

[BoondocK5]

yes an additional cooler is always a good idea with a 700r, just my .02

 

[garlicbreath]

It depends on where you have it mounted, if your running only that cooler or through the radiator also, if your running to rad then cooler or cooler then rad, if you have a fan shroud, stock mechanical fan or something different like a flex fan or electric fans, what gear you were in, what gears you have in your axles, etc. Many variables.

If your running a stock working clutch fan, with shroud or a good electric setup, running lines through radiator then to cooler, in low gear, and you have the gears to match the tires, and not running a high stall converter, then I would say upgrade to a bigger stacked plate cooler with a small electric fan.

Where is the temp sensor at for the tranny?

 

[B_to_C]

I'm running a stock 350-700r4 combo from a 1990 K5 with only the top of the fan shroud with stock mechanical fan. Gears are 4.56, tires are 40" MT/R's

I am running the cooler lines through the radiator first, then the cooler, then back to the tranny. The cooler is mounted in front of the radiator on the passenger side.

The temp sender in plugged into the vac. test port on the driver side of the tranny. I know this does not get the most accurate temperature, but with any guage what you're really looking for is "in range" and "out of range"

In town my transmission temp used to run 100-125, now runs 125-150
On the highway it used to run 125-140, now runs 150-170
On the trail it used to get the HOTTEST at 180-190, now I topped out at 210 and I think it would have kept going.

-I just recently bought this cooler, and it appeared to be the largest summit sells, so that's why I was thinking another one, not just a bigger one.

 

[4xcrazy]

I'd say just add a seperate electric fan to it, especially since you are only running half of your fan shroud,,,you're not getting full air flow through the radiator at low speeds with that.

 

[dyeager535]

One of the setups from the R/V setups would probably be ideal, that little fan they had to cool just the tranny fluid looked pretty effective.

 

[firefighter184]

I say move the cooler out back, maybe with a small fan. Or maybe James could blow on it while he hitches a ride with you.

 

[MarcS]

Regearing is the expensive and may not help that much. Another cooler is cheap and wont hurt, but gives another place for problems/leaks. And the ones with fans are pretty pricy.

The location of the temp sender doesnt matter, I agree with you, its all reletive.

I think 4xcrazy is right. Bad airflow. Your water temp is probally higher too. Why did you remove part of the shroud ??? Just curious.

You could do a fan just on the cooler, or go with a Winstar setup (Pretty cheap to do). Thats what I would go with, most bang for the buck.

 

[mrk5]

I don't think those temps are out of line for the highway. It does need to get warm enough for any condensation to evaporate out anyways. Plus a cold tranny doesn't shift properly.

If your problems are on the trail at low speeds, I would start with a small fan. You can wire it up to a manual switch. Simple install and just flip the switch when you flip-out over the tranny temp.

That's what I plan to do. 2 coolers was too cool, especially in the winter. However the tranny does get warm on the trail. So I'm doing a fan. That and swapping in a low stall converter.

You can get a larger B&M cooler, but it doesn't have barbed fittings. They are 1/2"NPT fittings. BMM-70274 29,200 BTU 11"x11"x1.5". You can get an adapter 1/2"NPT - 3/8" barbed.

 

[mrk5]

Why did you remove part of the shroud ??? Just curious.

Because the bottom of the shroud was always hitting the fan. It was too embarassing and annoying for all of his trail mates.

 

[roadnotca]

Overtemp is what kills 700s. Just my opinion, really trick sensor solution, use the B&M drain plug kit (into the pan). The B&M temp sensor is also 1/8 NPT so it screws into the drian bung, net result is the ATF temp. where its really working. There's lots of opinions on at what temp. the 700 starts to cook, but its way before ATF starts to complain.

 

[jarheadk5]

Tranny temp is why I drive most trails in low range, even on dirt road-type sections if they're steep.
...

So I'm at the point where I drive in 3rd/lo or 4th/lo (and it feels like the converter locks, so no slippage, i.e. less heat) where I used to drive in 2nd/hi.

BINGO!

I learned this one fast - on my very first 'wheeling trip, I noticed the temp gauge (water temp - I didn't have a trans temp gauge or aux trans cooler yet) shooting for the moon quite often. This had never happened to my K5 before, and after the second time I had to stop & pop the hood to cool down, I realized it was because I was pushing the truck hard in 4-Hi. Shifted to 4-Lo, and the temp stayed in the normal area the rest of the day.

I'd say try 'wheeling in 4-Lo a couple times before spending any money or time on the issue.

 

[mrk5]

Nick, were you running in 4HI? If so then I agree with jarheadK5. Actually when we hit the trail and I haven't had a chance to warm up the truck, I'll run in 4HI longer than I normally would just to get the tranny good and warmed up.

Maybe you should rebuild the TH400 in my garage.

 

[mrk5]

I hear ya there. The other day some guy asked my why I needed all those extra guages iif it came with all the regular stuff from the factory. I was thinking, "So I could stress over every detail of the operation of my truck."

I have the oil pressure gauge disconnected right now, and all I do is stare at it and wonder if my oil pressure is okay.

 

[moneypit]

Ummm......DOUBLER.. it will ease the stress and increase the dent sizes......

 

[B_to_C]

Thanks everyone, yes I was running in 4-low, looks like I'll try a fan first and see if I can't get these temps under control

 

[1985_K5_Silverado]

The other day some guy asked my why I needed all those extra guages if it came with all the regular stuff from the factory. I was thinking, "So I could stress over every detail of the operation of my truck."

I agree wholeheartedly! These keep me constantly concerned (or at least when I'm not doing something else). Before you send up a red flag over the trans fluid temp, the sending unit measures the fluid temp as it leaves the trans and heads out toward the cooler (that's not post-cooler or in-the-pan temp - I wanted to monitor the absolute hottest part of the fluid path that could be reasonably have a sending unit screwed in).

 

[MarcS]

Because the bottom of the shroud was always hitting the fan. It was too embarassing and annoying for all of his trail mates.

Its all related to engine speed and airflow. Like jms and jarhead are running in 4Lo. =higher RPMs =faster fan speed & more airflow.

I still think for the price of a cooler with a fan on it, or the hassle of finding a fan to put on the existing cooler, would still be close to the cost of doing the Winstar fan setup. But thats just my .02

 

[hawkeye649]

If you run your t-fluid through your engine rad, what can you expect but 210? I don't have a gauge on my truck, though.. My Hayden isn't a stacked plate, so not the "best" but it is about 12"x9" or so - and independent of the radiator, mounted infront of it about 2" away from it.
After about 15K miles on my 700r4/np241/3.73 and mostly 31's (it changed to 35's for about 3k) my transmission fluid came out pink, felt a little different then when it went in so next time it will get changed sooner, but not burt or anything at all - like when I got the truck off of a fresh tranny rebuild (bout 10 k on it) and it was slightly brown and smelled burnt.

 

[roadnotca]

There's a very good write-up on engineering the cooling system and the care and feeding of trannys, in the TH350 handbook by Ron Sessions. Same in the book for TH400. It's universal engineering, so its the same principals for any of the GM autos.