2007 Suburban Z71 towing question

[Jpedigo]

Hey guys
I'm new to towing a camper. We have a 24' tt dry weight 4500#. I just found out we have the gt4 (3.73) gear ratio on our tv.
We have put a transmission cooler on the vehicle to cool it down but it still runs over 250 on the interstate. On our last trip I got a little more comfortable with towing the camper and I got up to 70 mph. After about 15 miles the transmission warning came on.
I was wondering if anyone might know of anything else I might try. We have looked at 3/4 ton trucks but we cannot find one that fits our needs and budget. Lol
I thought about replacing the rear gears with the 4.10 but didn't know if that would create a whole new set of problems.
Any suggestions would be greatly appreciated.

[coolmom42]

Stick to 65 or lower. IMHO 60 is a good towing speed.

Lock OUT your overdrive so the tranny is not constantly shifting up/down.

Use ONLY OEM tranny fluid.

Make sure your fans work and the air flow is not obstructed in any way.

[Jpedigo]

Thank you. Someone mentioned that to me the other day. I need to check that.

[jsteih]

One of the other things for you to check is your fans. 07 will have electric fans, so make sure they are working.

[Jpedigo]

Oh...we have had the truck for two years. I don't know about before us but I had it serviced when he put the cooler on. We have towed it 3 times this summer. The fluid looks good but I will have it changed along with the filter before we get on the road in December.

[Jpedigo]

It's an aftermarket cooler but there was no oem. I'm going by the computer on the vehicle. When I'm not towing it is usually in the 150-170 range. I had the cooler put on by a transmission shop owned by a friend. He has rebuilt a different transmission for us and we were pleased. My wife and I do not understand why it's doing this either. We bought this particular camper because of its weight.

[ktosv]

How long have you had the truck? What is the service/maintenance history of the tranny? How are you measuring the tranny temp? Your tranny cooler, is that in addition to an OEM one? What temps do you run unloaded? Are you using tow/haul and what gear?

In my opinion, you shouldn't have an issue towing that weight trailer (unless you loaded it with 3000# of stuff) and your temps shouldn't be that high on flat land. I am going to jump to a conclusion that you have something wrong with your tranny (wrong tranny fluid, torque converter not functioning properly).

[N-Trouble]

I would start by slowing down <65mph and try a lower gear. You using tow/haul button?

[Campfire_Time]

A couple of comments and concerns.

It's a Z71. 4WD? If so changing gears will be very expensive because it's not just the rear axle that would get changed. Besides, that won't solve your issue. You need to get to the root of your problem.

Does your truck have a custom grill insert or shell? They look cool but can and do impede air flow. I have one on mine and didn't realize how it was affecting trans temps while towing until I towed in 90 degree heat around Indy last Sept. I was running close to 220. Once I realized what was going on I took the insert off and temps ran at 180. Air flow is critical.

Your trailer is most likely equipped with ST tires. They have a max speed rating of 65 mph. Running them at 70 is asking for a blowout. Something to keep in mind.

Dry weight it a fictional number. Dry weight it without options. As delivered it's at least 500# heavier than the listed dry weight. Now put your "stuff" in it. No one tows their trailer ready to camp at it's dry weight. It's very likely your trailer is 6000# ready to camp. But realistically even if you are towing at capacity, which is something like 7000# - 7500# for that truck, you still should not see trans temps that high.

Have you kept up with the maintenance? Fluid on a 4L60E should be changed every 50k miles with Dex VI.

[donn0128]

I have to assume you have a 1500 Suburban? Have you weighed everything yet? Before you go spending ambunchmof $$$ on stuff you need to load up like your going camping and get to the scales. My guess with family on board your overloading the Suburban. If thats the case, no amount of money is going to stop the self destruction. BTW once you have towed that hot it is highly likely the trans coolant is toast. Get it serviced before it costs you a transmission rebuild.
Also, towing faster than the trailer tire manufacturers rated speed is asking for another disaster.

[Jpedigo]

Thanks! I will look into that.

[jsteih]

My 02 silverado would run about 210* in stop and go, and 195* at 65mph on the interstate. I had the stock cooler, and I installed a Trucool 40k on mine and now it runs 155* all the time, the most I've saw was 175*.

Check out this, I have no affiliation with him, but I installled mine with his kit. Should fit your 2007. It will help with the install. It was really easy.

http://www.performancetrucks.net/forums/member-made-tools-parts-classifieds-197/tru-cool-max-trans-cooler-4739-47391-install-kit-brackets-fittings-hardware-508374/

[BarneyS]

The best place is in the signature. That is where everybody looks first and it will show up on every page that you post on. Often, people post questions or answers to a question and it helps a lot to be able to look at their signature to see where they are coming from with their answer.
Edit: Perfect example is the post just below this one. Thank you jsteih for your perfect timing! :B
Barney

[Jpedigo]

Thanks! I put it in the subject line. But I guess in the post would be better.
It's a 2007 Suburban Z71.

[BarneyS]

Good morning and Welcome to the forums! Glad you are here and I hope you get all your questions answered. We have a whole bunch of very informed and helpful folks here.

If you have not done so, you might check out our Forum FAQ. There is a ton of information that may help you as you get into the RV lifestyle. Also we have a couple of sticky threads at the top of this forum that would probably help you out. Give them a look.:)

It would help a lot if you were to fill out the signature portion of your profile. The members can not give you accurate or helpful information without knowing something about your tow vehicle. At the very least please put that information into a post soon on your thread. You won't get much help until you do.

Once again, welcome and please come back and post often.:)
Barney

[Jpedigo]

Btw this is on flat terrain. Thanks