Chevy & GMC Vans

Knowing how hot these trannies will run while towing, I would go for the size a bunch of us used in the cooler install thread. That kit also comes with all the proper fittings and mounting brackets you can use. The size is 1.5" x 11" x 11" and the brand/part number is Tru-Cool #4590. It is a little more money up front but this cooler works perfectly for these vans, especially when towing.

overdrive75 wrote:Thermostat link fixed, sorry.

That's a cool part. Didn't even know such a thing existed!

LiftedAWDAstro wrote:Knowing how hot these trannies will run while towing, I would go for the size a bunch of us used in the cooler install thread. That kit also comes with all the proper fittings and mounting brackets you can use. The size is 1.5" x 11" x 11" and the brand/part number is Tru-Cool #4590. It is a little more money up front but this cooler works perfectly for these vans, especially when towing.

Not disputing, what others have done here. But can please explain hot when towing. These transmissions are designed to run at a certain temperature and I dont' want to over cool it. The reason I say that is there is a temperature at which, if you are below it your transmission will not adapt shifts. Installing the trans T-stat would help prevent this. That being said 200 - 210 while towing is acceptable and 225 climbing grades is fine as well, based on what I know about GM transmissions.

From what I've been told and experienced, "trannys" can never run too cool ......i have never had any problems with shift points in 0* weather and have only seen the needle move off the base line a few times in the winter when plowing heavy wet snow.

now for about a year I have been wondering if my 165* thermo should be replaced with a 185* , because I have been told these engines like to run hot......but that's another subject.

dunedog wrote:From what I've been told and experienced, "trannys" can never run too cool .

I'm not an expert, but from what I've read over the years, you can run them too cool. I don't know exactly what the negative effect is... and whether it can damage or just change the performance. For years I've read where people living in colder climates would bypass their transmssion coolers in the winter when they weren't towing their RVs and the temps were really cold. (Hence my interest in the transmission line thermostat... which would eliminate the need to worry about it.)

The heavy hitter is fuel economy. The colder the fluid, the higher the losses in the trans. The higher the losses, the mover power to move down the road. More power means more fuel. There is a reason you can find operating temperature numbers.

overdrive75 wrote:The heavy hitter is fuel economy. The colder the fluid, the higher the losses in the trans. The higher the losses, the mover power to move down the road. More power means more fuel. There is a reason you can find operating temperature numbers.

Exactly...

Great Post

overdrive75 wrote: But can please explain hot when towing. These transmissions are designed to run at a certain temperature and I dont' want to over cool it. The reason I say that is there is a temperature at which, if you are below it your transmission will not adapt shifts. Installing the trans T-stat would help prevent this. That being said 200 - 210 while towing is acceptable and 225 climbing grades is fine as well, based on what I know about GM transmissions.

When I say hot, I mean easily in the 250+ range climbing hills. I do understand that trannies need to be at a minimum temp for proper operation in the winter. I also do know that you will lose a little fuel economy with a cold tranny. You also do use more fuel warming the engine for more than just a minute or two that a cool tranny not shifting into OD causes you to lose. Luckily GM made these things pump fluid in park so as the engine starts to warm up, the fluid in the tranny is too. The Tru-cool cooler I posted has a built in thermostat just for the cold morning starts.

It make no difference to me what cooler you run as long as you run one! I hate to see someone lose a tranny because they were too cheap to spend $75 to $100 on an aux cooler. I always fit the largest (within reason) cooler I can fit into the space when installing them.

PS...these trannies don't adapt shift to driving styles like some do. My wife's 2005 Trailblazer did and I am sure many of the cars do as well. Astro's and Safari's did not.

LiftedAWDAstro wrote:PS...these trannies don't adapt shift to driving styles like some do. My wife's 2005 Trailblazer did and I am sure many of the cars do as well. Astro's and Safari's did not.

We will have to agree to disagree on this one, but suggest if you have a 4L60E especially in the GEN III's next time you plug in with a TECH2 you can actually see the shift pressure adaptive cells having non-zero values in them. There are very few transmissions that adapt to driving style like many like to talk about. What many do is adapt line and shift pressures to account for variation and worn components to get it back to normalized shift times.

I have not decide on which cooler yet. I do agree 250 is hot. In the winter time the van is on basically "soccer mom" duty, so I want to make sure the trans comes up to temp, not only for F.E. but for the simple fact that it will get up to temp and properly lube all parts and be above the temperature to adapt and keep the shift times in check.

Going to be blunt here guys.Look-I owned a 1994 LT 700r/4L60E tranny van for a number of yrs.I live in Roch,NY which sometimes in the winter,well in the summer too,the temp isn't too kind.That van dolly towed two vans back here from out of state and a number of times trailers around here.I bought the van with a blow up tranny and had it rebuilt with just a standard stock rebuild.

Now what I used for a tranny cooler was the biggest tube style cooler I could find.I don't like the plate styles because I think they have a greater tendency to clod up like the ones in the rad's.Nothing special here.No thermostats or fans or well anything else.Never had discoloration of the fluid or any problems.Heck-the trans still worked perfectly the day I scraped the van many,many,miles later.I have been on this board since 2005 and I have NEVER read about anyone having a problem with their tranny that installed a aftermarket cooler that they didn't have before putting the cooler on.NEVER.So if you doing more,it is more for your own head than for the trans.That is the facts.Heck get a trans temp gauge which would be more useful.

Where these vans need extra help for towing that is pushing towards the outer limits of the van's capacity is the braking system.Trailer brakes is one way,larger calipers/pads is also helpful.Leaving extra distance is another for stopping..................

Let's be safe out there and please don't post I am only towing once and a while or just up the street.If your doing that,let us know what date your leaving and which direction you going in so we can give you a head start. #-o

Gary,

Thanks for keeping us in check. I will post a new thread after the install, I have yet to order parts as no plans to tow the boat with the van in the near future. Brakes yes that is under stood every trailer I own has brakes on it weather electric (car trailer and utility trailer) and the boat trailer with is 4 wheel disc surge. I know that most vehicles are not designed to stop more than their GVW in most cases.

I do have a trans temp gauge, it's in my DashDAQ. I just happened to have left that in the 2500HD the day I towed the boat.

When running down the road without a trailer I see the trans temps anywhere from 160 - 195 depending on terrain. The 195 was on the drive from MI to FL down I-75 with the cruise set at 80 through the mountains, so a fair amount of 4th with TCC off, guess I should have been in tow haul though those hills as that would have kept the TCC locked up.

Any how back to the original topic, I was surprised how well the van handled the boat and got it down the road. The only issue left is to fix the a$$ sag, which I think will be the ride rites' as I can't use a WDH with my style surge coupler.

Have you looked into a product named Timbren?

mdmead wrote:For years I've read where people living in colder climates would bypass their transmssion coolers in the winter

We're talking about deep subzero climate where the tranny struggles to reach operating temperature. Unless you live in the Yukon or something I don't think overcooling will be an issue.

Matt-the snow sled technology doesn't apply here. #-o

I am not a regular here so after reading all the posts i feel incredibly blessed. The good Lord has been having mercy on my ignorance. I travel on average about 45 to 50 weeks a year in my 91 ext rwd passenger Astro and am towing 99 percent of the time. She had 63,??? on the odometer when i pulled her out of a field. I removed the hornets nest, a few rats nests and a 5 foot black snake, replaced rusted out brake lines, put in a battery and 5 gallons of gas and drove her from just east of Ktown to Las Vegas. There i picked up a tow dolly and a 1964 Pontiac Bonneville, set the cruise and a/c and averaged 20 MPG all the way back to Ktown.
I didn't know about the tow in D till i found this website. Mileage is 153,??? now and it has been converted to quasi RV status fully loaded i am 290lbs under GVWR and pull a trailer w/ motorcycle 550lbs, tools, food, trike, trike trailer, canoe, all the camping , canoeing, and cycling gear, and spare parts. Been doing it like this since July 31st 2006, and have not done any upgrades or PM. I did r/r the fuel pump because the "mud dobbers " had ruined it. r&r'd wind sheild and right front fender from deer attack.
Since family emergency has brought an abrupt halt to my travel plans; i will attempt to try some of these ideals before i hit the road again.