Mercedes ML350 Bluetec

[rluhr]

@pattonsr: Good comments. Here's my take:

1) Air suspension on a Merc ML or GL does not affect weight distribution at all. You might have heard advice about "pulling a fuse" etc to disable the air suspension. On a car like an ML or GL with full air suspension, that makes no sense because you can't drive it that way. If you disable the air suspension the car will throw an error light and may settle to the ground.

Hitch up with the engine OFF and with no unusual load in the car. You'll see the rear sag under the tongue weight, just like any conventionally sprung car. You can measure the corners, like hitch manufacturers recommend, to get an approximate setting for the weight distribution bars.

The car will level up when you turn it on, no matter what, so the only way to be sure that you are distributing the tongue weight properly is to weigh the car before and after hitching. Compare the axle weights to fine-tune the hitch adjustments. But yes, you can easily distribute the tongue weight just like on any other tow vehicle -- I have the CAT scale receipts to prove it.

2) A compact spare would be welcome when you are driving solo, but it's still no better than run-flat tires if you are towing. Whether compact spare or run-flat, the tire will not have the capacity to carry the added weight from a trailer for very long. You still need a plan to deal with a flat tire when towing. I suggest at a minimum you carry a tire plugging kit and know how to use it.

A few random notes for Merc owners:

Our GL320 has 55,000 miles on it as of today, about 80% of which has been towing our 30-foot Safari bunkhouse. My goal is 250k miles, which I'll hit in about 9 years at current rates.

The handling is superb. I like the way it sticks to the ground on bumpy roads, when conventional trucks are bouncing in the air. But I like it even more when I'm driving solo on a winding country road...

Because of the relatively short wheelbases of the ML and GL, owners should consider a Hensley for long trailers.

Beware MB techs when it comes to towing questions. Most of them don't have a clue. Almost three years ago I went to the dealership to have my Prodigy brake controller hooked up. MB publishes a technical bulletin (T-B-31.19/07d) describing exactly how to do it with a simple pin kit ($15). The tech decided he wanted to do it his way, which involved removing the front seats, the center console, and wiring directly to the battery. He felt it was "safer." The estimate was $1200. I laughed and then went to another service center to get it installed the MB-approved way for $100. They are great cars and can be great tow vehicles, but don't expect much support from the dealership.

If you have LED taillights on the Airstream, the trailer's brakes and lights will not work. You'll need an adapter cable available from VW dealers, part # ZVW 808 004. It's about $40. Alternatively you can have an incandescent bulb wired in to the circuit to eliminate the problem. That's what we did.

@murreywalker: Looking at the 2009 maintenance recommendations, the only differences in routine service for the diesel versus gas models are:

--every 20k miles the diesel needs a fuel filter replacement (about $100 installed)
--the gas model needs spark plugs at 80k miles
--diesel models require Adblue top offs every 10k miles (and complete evacuation/refill every 20k miles) See my prior post on that subject.

Otherwise everything is the same. So I think the service tech you talked to has some 'splaining to do. What changed with the GL/ML350 models that would alter the service program that much?

[pattonsr]

rluhr,

Sounds like AIRMATIC for the mb is ok for towing. An ON&OFFROAD package will be available next year in the US for the ML. The setting for AIRMATIC and the power train will accommodate six transmission modes. There is a Trailer mode which optimizes acceleration, maneuvering and braking with a trailer. I assume all of the good stuff for the 2012 ML will be available with the 2013 GL redesign.

I do not like Run Flat tires. Expensive and harder to find. I agree the spare is only for limp home mode without a trailer.

With the heavy use of LED lights on the 2012 ML, I would wager that the tail light out problem has gone away with LED trailers. But as you say, the adapter cable will solve the problem if it still exists.

In my prior post, I said the GL350 is rated for 7700 pounds towing. The correct number is 7500 pounds.

Barry

[idroba]

Originally Posted by rluhr

@pattonsr: Good comments. Here's my take:

1) Air suspension on a Merc ML or GL does not affect weight distribution at all. You might have heard advice about "pulling a fuse" etc to disable the air suspension. On a car like an ML or GL with full air suspension, that makes no sense because you can't drive it that way. If you disable the air suspension the car will throw an error light and may settle to the ground.

Hitch up with the engine OFF and with no unusual load in the car. You'll see the rear sag under the tongue weight, just like any conventionally sprung car. You can measure the corners, like hitch manufacturers recommend, to get an approximate setting for the weight distribution bars.

The car will level up when you turn it on, no matter what, so the only way to be sure that you are distributing the tongue weight properly is to weigh the car before and after hitching. Compare the axle weights to fine-tune the hitch adjustments. But yes, you can easily distribute the tongue weight just like on any other tow vehicle -- I have the CAT scale receipts to prove it.

(snip)

rluhr: Do you know if your comments apply to the 2011/2012 Jeep Grand Cherokee with the air suspension? I took delivery of a 2012 JGC just prior to departing for 5 months in AZ for the winter. I only had time for one trip with my 20' Argosy, and still did not have the hitch ball height set right, but I really did not have any load being carried by the spring bars on that trip. When I put the trailer on the ball, then used the tongue jack to raise the rear enough to put the spring bars in, then drop the tongue jack (my usual practice once I have decided how many links to "hang" from previous experience) the auto leveling took over and took all the weight off the spring bars.

Again, I have not had experience with this new system enough to understand it, but any words of wisdom would be appreciated, if the MB and the JGC have the same air suspension.

Are there any threads that have been posted on the JGC with air suspension, and how to hook up with spring bars? I have not seen any yet, but may have missed something. Anyone??

[mutcth]

I towed with a 2011 GC V8 with the air suspension. Did just the same thing you did, had the same thing happen. I'll admit to not fussing with it much since I had borrowed the Jeep from the office - but it rode and handled well.

I wish there was some more specific info in the manual about how to do this procedure, but no such luck. Rich's comments make sense for making sure the set-up is right - use weights at a scale to fine tune the number of links used.

Tom

[JamuJoe]

Great engine. I've the same 3.0 Bluetec CRD in my 08 Grand Cherokee (7200 lb tow capacity) and love it towing our '11 FC23FB (6500 lbs loaded). Tracks like a train with the Equal-i-zer hitch. Pulls like a champ over the highest mountain passes, and engine braking by downshifting the QuadraDrive II is very effective - really saves the brakes. Average 17 mpg towing 8500 miles this year. Now that I'm past warranty, I order my Mobil 1 ESP online and use my favorite lube shop for fluid changes - just make sure that they follow the Mercedes procedures re: wait times during oil change.

[rluhr]

OK, looks like there's some confusion over the air suspension issue, so I'll try to clarify.

First off, I don't know if this applies to the Jeep. I'm speaking only of my experience with the Merc GL with AIRMATIC suspension.

Your goal is to have correct weight distribution when the vehicle is level, because that's where it is going to end up once the air suspension kicks in.

So, you must start with a level trailer and level Merc, on level ground. The ball must be at the correct height for the trailer. The car must be OFF so the air suspension won't adjust while you are hitching up.

If all that is good, then you can attach the trailer using the procedure outlined by the hitch manufacturer. Typically this involves measuring the four corners of the vehicle, then hitching up, then re-measuring the drop at all four corners to estimate how much tension you need on the torsion bars. The point is to keep the car level, even as it settles from the weight of the trailer.

If you follow the procedure you should end up pretty close to where you need to be -- in other words, with approximately equal drop at all four corners of the car. Then you can start the engine and watch the air suspension raise the car back up and make any minor leveling adjustments.

Since the car was level before you started the engine, and remains level as the air suspension kicks in, you should lose little or no tension on the torsion bars. If that's the case, you can tow over to the local truck stop and get weighed on the CAT scale. (You did remember to weigh the car before hitching up, for comparison, right?)

@pattonsr: I wish the off-road package was available when I bought my car, but it was special order only at that time and I couldn't wait. There have been a rare few times when I would have liked to have had Low Range (when off-roading), although I have to say the AWD system is fantastic.

I believe the "trailer mode" existed in the 2009 GL models as well, although MB wasn't very vocal about that. It's buried in the Owners Manual. Mercs don't have a "tow/haul" or "overdrive" setting, because the computer figures out that you've got a heavy load and adjusts automatically. Mine has an "offroad" button that is suggested for towing heavy loads but in practice the only difference I find is that it costs me some fuel economy.

By the way, at highway speeds the Mercs with AIRMATIC normally lower the car about an inch for better fuel economy, but the car is smart enough to recognize when it is towing a trailer, and so it locks out the suspension lower/raise modes that normally are available.

Note that it is difficult to achieve the 7500 lb tow rating on the factory hitch. The hitch is placarded at 600 lbs tongue weight, which means 8% at the full tow rating of 7500. Many Airstreams carry 10-12% tongue weight, which is why some Merc owners end up modifying the hitch. For example, I was shocked when my 1977 Argosy 24 weighed in at 800 lbs on the tongue. A friend's 1965 Safari 23 is 650 lbs (measured with tongue scale). It's good practice to actually weigh the tongue -- don't go by published estimates.

@jamujoe: I found the best price for Mobil 1 ESP from the dealer of all places. Seriously, I never would have expected that!

[Tallgrass]

I am considering a 2012 ML350 Bluetec as possible tow vehicle for a 25FB International. Does anyone have experience with this combination? Are the hitch receivers on the 2012 ML350 an improved design over previous models or would you advise after-market reinforcement?

Thank you for any advice you may be able to provide

[murreywalker]

Tallgrass, my guess is the hitch receiver on the 2012 is the same as its predecessors. It says on the label, 600 lbs is the maximum.

Your trailer, I think has a hitch weight of over 800 lbs.

If you find someone in KC who's knowledgable enough to understand the dynamics, I would appreciate the contact.

If you haven't read rulhr's blog, you should. And, of course, all of the post on this thread.

[JFScheck]

Few quick comments....

The TDI Diesel Engine for VW/Audi (soon Porsche too in the States) and the ML350 are the exact same design & software, suspect all will get a boost in torque & HP in the next year or two - but I found 406lbs with a 2009 Classic 25FB Airstream was fine through all the mountains across North America. Suspect same design diesel for Jeep too (remember who Jeep used to be owned by for a brief period?).

LED lights on your trailer are fine with Cayenne's, Touareg & ML350's made after 2007 model year - all use the same tow module that controls the trailer lights and no more error or "!" with LED's.

If you have air suspension - you can use with Weight Distro Hitch if setup as described above - but be aware of the bags weight limitations! After air suspension on the Cayenne and steel on the T-Rex - I was happier with steel...

Connecting the brake controller can be challenging - but I have docs out there that tell you how to do it (at least how to use a Prodigy).

Weight Distro Hitches and Touaregs/Cayeene/Q7 may/have been reported to crack or deform and have been reported separating from frame (nothing drastic yet - all caught in visual inspections) if you have a heavy tounge weight and use the weight distro hitch to balance it out - I call it the bottle top remover effect (hitch is placing stress on bolts, frame, hitch, etc. as when you pop the top off a bottle). Same for ML350 - I don't know.

Q7 has 100lbs less hitch weight and 1,000lbs less tow capacity than Touareg & Cayenne (longer frame, more GVWR, etc).

ML350 diesel is as great a tow platform as TDI Touareg, just read above once more - and keep an eye on that tounge weight and for best results, go visit Andy or someone technically similar...

[Rawn77]

I just received my '12 ML350 BT. I'll be taking it to Andy to reinforce my hitch just as he did my '09.
I tow a '10 FC 30' with a Hensley. It's absolutely awesome!
Can't wait to try the '12 with the increase in torque.
You can't go wrong with a diesel ML

Ron

[pattonsr]

Ron,

Did you stay with the steel suspension or upgrade to Airmatic for your 2012? Be sure to take pictures of what the hitch reinforcement looks like.

Barry

[Rawn77]

Barry,
I went with the steel suspension just as I did with the '09.
I will only be getting the hitch reinforced in the spring; probably end of March, beginning of April.
But I will post pics of the process.
Ron

[Rawn77]

John
As per your statement that the LED RV lights pose no problem for those TV's made after '07 is incorrect.
My old '09 ML required that Andy make an adapter so that the onboard computer saw the resistance of bulbs; otherwise the TV thinks that the trailer lights are not working.
I'll let you know if the problem persists with the '12 ML when I hook her up in the Spring.
BTW, my comments are just for the ML; not sure about the VW and others.
Ron

[mikapen]

Ron or anybody,
I have seen photos of Andy's ML hitch reinforcement, but I haven't seen one that shows good detail of how the connection is made at the forward end. I am interested in seeing what bolts are reused and what holes are drilled in the rear suspension mount.
I have talked to Andy and would like to make the trip, but it's three days in each direction and I still have a day job.
Can anybody provide such detail, especially on a 2010 ML? PM would be fine, if that's more appropriate.
Mike

[JFScheck]

Originally Posted by Rawn77

John
As per your statement that the LED RV lights pose no problem for those TV's made after '07 is incorrect.

Sorry, for the VW/Porsche/Audi it's the case - assumed Mercedes updated their modules at that time as well - sorry....

[murreywalker]

JFScheck, I've been told that the GL will have updated modules in 2013.

But, don't take that to the bank. ;-)

[Disterheft]

Hi Ron:

I am in the process of purchasing a ML350 2012 to pull my 200o classic Airstream. Are you still going to post pictures of Andy rebuilding the hitch assembly. I am in Vancouver and it is proably a threee day drive to go to London in order for me to have Andy rebuild the hitch. I would like to see the pictures before I commit.

Would like to here your comments after pulling you trailer with the new ML350 2012.

Brian

[BaroloRed]

I drove to CanAm (2,200 miles) to get a hitch on my 2007 ML350 then picked up my first Airstream in Connecticut and drove home. I'm very pleased with the hitch and the service at CanAm. The 1965 Caravel was a gem to tow.

[Rawn77]

Hi Brian
I finally drove over to CanAm last Sunday and had the hitch reinforced on Monday. The whole process took about 3 hours. Unlike my '09 ML320 BT, you can't tell visually from almost any angle that the hitch has been reinforced.

Sorry, I didn't take pics of the installation. I just got under the ML a couple of hours ago to take these photos. I hope they're self explanatory.

I pulled home my '30 Flying Cloud (I stored my RV there for the winter) from London to Montreal; about 8 hours. I averaged 69 mph and got close to 15 mpg. In comparison to my '09 ML, the '12 cruises more effortlessly. There are no huge hills on the 401 between London & Montreal, but there are many long grades. I've pulled the route countless times. The ML downshifted only 2 times!! The 455 lbs of torque is ridiculous. Even my '12 RAM 1500 with 3.92's will downshift to 3rd gear and scream to 4500 rpm.

I know that the Hensley plays a large part, but I would have to say, that the '12 ML is the most comfortable and relaxed towing experience I've had.

I know it'll be a long trip, but going to CanAm is worth it.
I have never found anyone as genuine and knowledgeable in any industry as Andy Thomson. He's worth it!

Hope this helps,
Ron

[mutcth]

Looks nice Ron - congrats on the new ML (and Ram).

Curious - the ML has a temporary spare that your 2009 lacked, right?

Tom