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Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
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Discussion Starter · #1 ·
I finally got my Scangauge, and got it to read trans temp... It's really not getting as hot as I thought it was... (though I was towing on mostly flat-ish ground, this time)... Towing a 3400# car ('97 Taurus) on a 2000# trailer...

(I have 3.42 gears)

Empty - I was running 190F

Pulling 2000# trailer, empty - 200F

Pulling 5600# trailer - 200 to 208F

This was on an 87F and sunny day, and it only went up 5F from going up the 1/2-5/8 mile 20% grade hill by my house, when I started at a stop from the bottom.

Of course, I was driving halfway-easy when the trailer was loaded, and on the big hill, I just stuck it in 1st, at about 4000rpm (light throttle), so the converter wasn't working very hard... On the hills on the interstate (where I was towing in 3), at 68mph, it never dropped lockup.

Having said this, driving both, it seems like the V8 has a little tighter converter than the I6, so it won't make as much heat when it's working. I actually remember seeing the SS guys putting in I6 converters, for the higher stall speed, I think?

I guess I'll really find out what it does when I tow in the mountains, this fall, and what it does in the winter (whether it gets up to temp or not)...

I guess a small cooler wouldn't hurt, but if it only gets up to 210F when towing, I'm not sure I'm all that worried about it...

Mike
 

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2003 chevy trailblazer_ls
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I'd be interested in learning where the measurement is made before making my decision. Those temps sound really low for towing a load of that size. When I ran a guage in the oil pan on a different vehicle, I could see temps above that running without a trailer.

As far as the transmission cooler is concerned, other than guys living north of the USA mainland, where temps are really cold, I can't see a downside to an auxillary transmission cooler.

I typically prefer to find a factory cooler from the salvage yard of a plate type (versus fin and tube). They are compact, well made (would cost hundreds of $$$ in the aftermarket), and will do the job.

I'm on the hunt for just such a cooler for my own Trailblazer right now, as I have to haul a big U-haul trailer from Kentucky to Wisconsin in August, and I'd like to run in OD for most of that trip. OD is what really makes the heat as you are over-spinning the internals of the transmission.
 

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Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
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Discussion Starter · #3 ·
It's where the computer gets its measurements, and it reacts somewhat slowly, so I'm going to guess it's either in the sump, or in the valve body... Keep in mind that the trans cooler on these isn't just a tube that runs through the end tank, like a lot of vehicles are... It's actually a small plate cooler, in the end tank, so it actually does do some work... Look at the picture on Compnine.com, in the radiator section...

It also must be noted that this was only a 45 minute tow, and about half of that was highway. Taking off from lights, I was just keeping up with traffic, and it was shifting around 2750rpm... Also keep in mind that I've got a stock tune with all the TM still in it, so it chops the throttle during shifts, so I'm not working the clutches as hard during shifts...

A downside I'm concerned about would be too large a cooler won't get it to 160F in the winter (the big-arsed aux cooler on my Caprice was like this... it would be at 140-150 on the highway, as we'd talked about before)... The main reason, though, is the 100k drivetrain warranty, that (especially now) they're looking for ANY excuse to void... The official answer from GM about an aux cooler is: "the stock cooler is good for the rated towing capacity of the vehicle"... If I lunch a tranny, I can see them not covering it, based on "aftermarket parts" on the cooler circuit...

The factory aux coolers on the recent 1/2-ton trucks are halfway nice, and pretty stout... May also play on your side with the "aftermarket parts" thing, based on the fact that they're put on the trucks, which have the same trans...

If I was running 240 or something, I'd definately put one on, but with this duty cycle, and this terrain (and the tighter converter on the V8 models), I'm not sure I need one... especially running Dex-6 from the factory...

Mike
 

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2007 chevy trailblazer_ls
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Discussion Starter · #5 ·
Sounds like you've already answered your own question... :D
Yep, I suppose so... I'm still only 90% against it, though...

Now, on my S-10 Blazer, it does get up to 220-230 when towing my 5x8 utility trailer, with just a couple dirt bikes on it, so it IS getting one, in very short order...

Mike
 

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2003 gmc envoy_slt
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270 Posts
I remember someone putting a chart up in a different thread showing trans temps, safe cold, safe hot and danger zones. I have searched for it but have not found it. Any one know what I am talking about ?

I am with Mike on this one. I was all set to get a trans cooler, but after doing some runs out to the lake with the boat in tow after my new trans temp guage was installed, I am wondering if it is worth the cost and hassle since I am not getting really over 200 towing in the hills...
 

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Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
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Discussion Starter · #7 ·
I remember someone putting a chart up in a different thread showing trans temps, safe cold, safe hot and danger zones. I have searched for it but have not found it. Any one know what I am talking about ?

I am with Mike on this one. I was all set to get a trans cooler, but after doing some runs out to the lake with the boat in tow after my new trans temp guage was installed, I am wondering if it is worth the cost and hassle since I am not getting really over 200 towing in the hills...
For optimum life, you want trans temp to be above 160F and below 200F (Dex 6 has a little more room on the top end, due to being semi-synthetic)... 240-250F is considered an "overheat"

Mike
 

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2004 gmc
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Mountains make a huge difference, as does high ambient. I have an aux in front of everything else, and just towed my 3500# trailer all over the northwest. Worst it got was in 1st gear, 4000-4500 RPM, 93 degree ambient, on a couple of TEN MILE climbs: 235 degrees. Before I got the cooler, I'd see 240 on similar hills in 90-100 ambient, with the Roadiemobile ALONE (no trailer) in second gear.
 

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2007 chevy trailblazer_ls
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Discussion Starter · #9 ·
Mountains make a huge difference, as does high ambient. I have an aux in front of everything else, and just towed my 3500# trailer all over the northwest. Worst it got was in 1st gear, 4000-4500 RPM, 93 degree ambient, on a couple of TEN MILE climbs: 235 degrees. Before I got the cooler, I'd see 240 on similar hills in 90-100 ambient, with the Roadiemobile ALONE (no trailer) in second gear.
Definately! Not only is it a lot hotter where you are, but the humidity is almost nothing, so the air has a very low specific heat... Here, the air helps a LOT, because you can swim in it, so it carries a ton of heat away... It wasn't too humid on Monday night, but still probably 60-65%, if I had to guess (which is average to low, here, I think)... IIRC, you guys are lucky to get above 15%?

Same Caprice that would stay below 150F in the winter with the gigantic tube/fin cooler, when towing in second gear at WOT up mountains in northeast PA (5-6 miles at a time), the trans on that would get up to 215 or so, towing a 2000# trailer, with 3 people in the car, and the car loaded...

Mike
 

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2005 chevy trailblazer_ls
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Mountains make a huge difference, as does high ambient. I have an aux in front of everything else, and just towed my 3500# trailer all over the northwest. Worst it got was in 1st gear, 4000-4500 RPM, 93 degree ambient, on a couple of TEN MILE climbs: 235 degrees. Before I got the cooler, I'd see 240 on similar hills in 90-100 ambient, with the Roadiemobile ALONE (no trailer) in second gear.
:iagree: Exactly why I'm putting in a cooler.
 

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2002 gmc envoy_slt
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What gearing do you all have? (I see Bartonmd has 3.42)
I have the 4.10s in ours, so I'm thinking the motor will be in it's power band a lot sooner then say a 3.42 or 3.7 gears. (I will however still stay in 3rd gear while towing.) I'm asking because no one seems to take the rearend gearing into consideration. Most folks I believe have 3.42 or 3.7 gears in their TrailVoys.

I posted on the towing thread and after some good inputs, (Including your inputs Bartonmd.)
I'm deciding to just change the filter and trans fluid--going with DexVI.
Pulling 3.5K# --1,800 miles from Florida to Idaho.

My concern is that a cooler wouldn't allow for proper trans temps during the Idaho winters when not pulling anything. Plus not sure when I will ever pull anything else.

-Drew
 

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Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
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Discussion Starter · #12 ·
Roadie has 3.73, big, tires, a lift, a 300# bumper, and carries 1000# of gear in the envoy...

Plus, as mentioned, the I6 has a looser converter match than the V8 models do, so it will make more heat when unlocked and working...

IMO, get something that can see trans temp (scangauge, $160), change to dex 6, and tow in 3... If it starts to get above 240 in the mountains, just stop and idle the enging to get the trmp down...

Mike
 
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