clvincent

guessing this applies to all models but definitely the diesels

towing a travel trailer with mine and sometimes a lighter, smaller cargo trailer

i have an edge cts monitor with a transmission temp sensor in the pan and also an egt sensor

so i know where my temps are

whole truck running hotter than i wanted pulling mountain grades with the travel trailer, actually get some increase with the small cargo trailer too but not as much

anything back there bumps it up on temps at least 10 degrees


anyway halfway through a trip through the mountains here in az i pulled the engine cover and all the pans off the bottom of the truck

10-20 degree drop in trans temp- did not do much for engine coolant but definitely a good drop on the transmission

i would recommend anyone pulling trailers to remove those, at least for summer hauling
being in az i dont have issues with needing to warm up the engine or trans anytime where the pans might help

gl450x164

Bigger trans cooler problem solved

clvincent

which one did you add? could you send a link to the one you put on and maybe some pictures of how it fit

gl450x164

Sorry didn't mean to confuse....i havent added one yet to mine but do plan on towing alot more and will be upgrading the trans cooler from an f350 or something oalong those lines

DennisG01

Need more data!

What kind of temps are you seeing for coolant, EGT and tranny? What do you see without towing? And where do you have the EGT probe mounted?

clvincent

prior to pulling the belly pans coolant and trans temp stayed about the same- now trans runs anywhere from 10-20 cooler than coolant

no trailer -- running around town/75-80 mph on the hwy and 80-90 degree outside temp
coolant 190-205
trans 187-195
egt been lazy and havent really watched - it is set with an alarm to go off around 1200 so i start keeping an eye on it- it is mounted after turbo
i use it to cool down after towing/hwy etc


pulling pretty light 6x12 cargo trailer same outside temps- running 70-75mph on the hwy
coolant 205 to maybe 217
trans temp about the same
these numbers are from before pulling belly pans

5500 travel trailer - springs over axles so big sail back there to catch wind
in the flats before belly pans off 50-63 mph outside temp 90-103
coolant 205-220
trans same

climbing mountains say tucson to flagstaff/payson area --coolant and trans are hitting 230-235 top end and i start getting worried- will pull over and let things cool and then head on

belly pans off seems to have dropped that to 215-225 on trans
coolant still hotter than i would like but maybe 5 degrees cooler

these numbers are all uphill grades, drops pretty fast if the grade slacks off for a bit etc

i dont love these numbers, but no cel or warning of any kind on the truck
pulls the mountains well, plenty of power
and in reality not much hotter heading up these big grades from in the flats with no trailer

guessing a 20-30 degree jump heading up a mountain with 5500 lbs behind it is reasonable...

if there was a good aftermarket trans cooler setup that fit i would probably do that- at this point trans is running cooler so might like extra fan on coolant or something..

not 100% set on using this truck for the travel trailer yet
so waiting on any mods etc

007_e350

Did you do the trans fluid drain & fill ? MB's revised interval is 39k miles I read somewhere..

Also just to clarify, by ' belly pan ' you mean the splash shield ?

DennisG01

I think you're right that the numbers really aren't that bad. Even the 235* coolant, while getting hot, is still about 30* from boiling. Granted, I'm not saying it's OK to run close to boiling - I sure as heck am not! This is only a guess, but I would imagine it might take quite a bit more load on the engine to raise the temps much higher.

While I'm still pretty new to this vehicle, if there are existing rubber lines anywhere for the current transmission lines, then you may be able to just splice into those and use any type of tranny cooler that you can get from, for example, Summit Racing. I have one setting on my workbench to add to my '98 Suburban (diesel). But I've been hesitant to put it in because of colder temps (which you won't have in AZ). During the winter, it might not allow the trans to get warm ENOUGH.

One of the neatest things I put on the rack is a set of 6" tall L-brackets. It makes it very convenient to haul wood or longer things as it will contain them left-to-right and keep them from shifting.

clvincent

Sorry don't know the technical term for those plastic/rubber shields that cover the bottom of the engine and transmission

My vehicles fluids are always changed way ahead of time, if I continue pulling big trailers with this truck will probably be changing the transmission every 25,000 or so

Dennis would like to see pictures of your L brackets

I agree the numbers are not terrible but I would love to see it cooler across the board

My experience adding aftermarket stuff on the Mercedes has not been as easy as my other vehicles
probably because there's not as much room

Will do a few more trips with it and then decide and if I'm going to continue hauling with this set up or swap trucks

If I'm going to be using the Mercedes good chance I will add some extra cooling stuff

goalie_k

Check out the larger trans pan for the 722.9. Speedriven makes one. The extra capacity helps a lot.

clvincent

Excellent info goalie, thank you, will research that for sure

I will probably do that anyway, even if not towing

clvincent

quick search found the speedriven which is really expensive and then this one with more fluid capacity

http://weistec.com/722-9-transmission-pan.html

just wrote them to see if there is a port for plugging in my trans temp sensor

goalie_k

thats even better

clvincent

got this back from them----

Thank you for your email and interest in Weistec products. Our transmission pan is designed to work with any 7G transmission. As long as your car has the 7 speed MB transmission, it will ft. In regards to screwing in a trans temp sensor, there are provisions for A/N fittings used in a transmission oil/cooler setup that could potentially be used for that purpose. Whether or not it will be a direct fit, I cannot tell you.

If you have any further questions or concerns, please let us know. Thank you and have a good day.

----

so seems like no issue on the trans sensor, should be able to make it work...

Callisto1

Thank you for the link! Just placed an order with Weistec. In 2 weeks, I am taking the family on a 3000 mile journey towing a 5000 lb 1968 Airstream. Until now, all my Airstream and boat towing has been in relatively flat Florida. Worries about NC mountains have been keeping me awake at night. With the Weistec tranny pan, I will sleep a little better.

goalie_k

Did they have them in stock?

Callisto1

They said they are in stock, but I haven't received notice of shipment or a tracking number yet.

goalie_k

Towed my 18ft travel trailer from Phx to the Grand Canyon. Did some data logging. Engine temps can on pretty high climbing the hills... almost all the way to the top of the gauge! Off the top of my head that is 120C.

Egts were about 1100 max
Trans temp 230f
Boost 23psi but never got fully into it (the ecu is tuned)

Has anyone else dataloged EGTs while towing.

mefferso

goalie_k What are you datalogging with?

goalie_k

Torque app.

KrustyKustom

I have been towing my 30 foot Airstream for about 5 years now with my 2011 GL350. I concur on the temps, especially towing across colorado on huge climbs. I take it real easy, back off throttle and let the torque do the work. In addition more frequent fluid changes i think have helped.

Really like the deep pan for the tranny. Wonder how you check fluid level without the OEM tube?

clvincent

I dont think mine has a dipstick for trans but not sure

What WD hitches are you guys using for towing? I have a blue ox and like some things about it but have adjusted several times and dont think i have it dialed in perfect

Considering a propride hitch

Callisto1

Krusty is probably the man to ask, but I've never felt like I needed a WD hitch, towing a 1968 26' Airstream. It weighs 4500 empty, with just over 500 on the tongue. It tows straight, no sway or pull even in gusty wind, and the GL rides and steers fine. Leaving in 2 days for a 3 week 3000 mile trip up the east coast and back thru NC mountains.

But I did just install the Weistec tranny pan. A beautiful piece of engineering that I expect it will reduce transmission temp significantly. Makes the OEM pan look like a piece of junk. As a bonus, it has a drain plug (no need to drop the pan), and 2 ports for an additional cooler, or temp sensor.

Callisto1

The fill procedure is the same as the OEM. There is a fill port with an overflow tube. Fill until overflowing, run car until proper temp, let excess drain out until it slows to drops.
Does your GL have some kind of dipstick for checking transmission?

clvincent

I think the biggest issue with mine is my trailer has the axles over the springs, so I have awesome clearance everywhere but catch A lot of wind

I would not mind spending the money on a propride if it would really tighten this up but I don't know if it will....

You certainly never hear anything bad about them, everyone says they are worth the money