MB+

Hello are you wonderful people. I have a 2010 GL450. x164 production 10/2009
Do I need to change the bolts which hold the pan of the transmission fluid?

I'll be changing the transmission's filter, gasket and fluid. I'm not sure when the last change of it was and have no means (as of this moment) to check the bolts since my purchase of vehicle 3 yrs ago and driven ~30,000 miles. Price will vary if I get combo kit which includes bolts by $16 so thought to ask. All items will be OEM Mercedes. Fluid to be used for my specific model: ATF 134 Red, 236.14

Video:

Plutoe

No!

alx

kombifan

ItalianJoe1

Both are true, they are aluminum, and they have a torque/turn value so they are technically stretch bolts. That's more to do with the way the clamps that hold the pan work, but just replace them. I have reused them in cases, but in general if you try to re-use them and overtighten them AT ALL, or sometimes even at the normal torque, they can snap off. They are still easy to remove at that point but it's not worth it for the cost of bolts.

KrustyKustom

Change em! As others have said they are a stretch bolt and they go into a magnesium case. If on the second use one snaps off you would be in trouble, and have a potential pan leak. Just do the job right!

MB+

Much thank you each and every single one who replied. I can not thank you folks enough!. Have a good week ahead.

/ Solved.

Chazz Michaels

Look, it is the wisest thing to do. However while dealing with some trans issues I had the valve body apart 7-8 times. It just started turning into a serious pain trying to change them everytime until I knew the car was sorted. So I did reuse them and retorque them without any issue. Is it best to replace, yes.....but I have reused without issue. Just FYI.

lkchris

Never ask “really necessary.” If Mercedes says so, believe it. Anecdotal samples are meaningless.

And btw, it’s only a bolt if you put a nut on it. Otherwise it’s a screw.

Max Blast

Not that I’d ever service my own 7G, but what’s the torque spec on the pan bolts? I imagine they must be gronked on there star tight for them to yield, which is contrary to common wisdom when doing any kind of fluid pan.

unless they’re aluminum in which case they float and yield very early.

$330 ish with a coupon gets the whole flush job done at a dealer fwiw.

chassis

What city are dealers quoting $330 for a trans fluid change? In Indiana I called three dealers and the quote is $500-$600 for a 7G.

Max Blast

Seattle and Bellingham WA. It’s seasonal though.

texas008

I heard that people replacing these aluminum bolts with steel ones...

Max Blast

and damaging the magnesium case in the process

texas008

good point..
guess you are referring to the transmission body, maybe made of aluminum alloy

eric_in_sd

Given that the transmission bolts compress a spongy, springy gasket, I'd say this application of stretch bolts is silly. I'm seriously tempted to change over to steel bolts. I'd lubricate the threads to avoid galling - which I ended up with on a few of my intake manifold M6 bolts, necessitating thread repair that I still haven't gotten around to.

Stretch bolts are normally used on cylinder heads, where they need to keep tension on the head gasket. I really am not seeing how that principle applies to a transmission oil pan.

People tend to assume that because MB did something, that thing must be Very Superior, and not knowable to us Mere Mortals.

lkchris

if you have any automotive knowledge, that is exactly what you assume.

The airplane crashes caused by “mechanics” that thought they knew better than designers get more publicity, but …

rapidoxidation

What Ikchris said. I'm smart, but I'm not trained in Mechanical Engineering. What the car specs is generally what the car's gonna get.

BlackML550

At my last trans service the mechanic advised that at the previous service, another mechanic had reused the pan bolts. The pan was dry and hadn't leaked. We replaced them anyway, if only to ensure they don't break off when tightening. Single use fastners on a trans pan is a bit of overkill.

eric_in_sd

Sure, all the more power to ya.

You can put in premium gasoline, too, if you want. Doesn't seem to make a lick of difference, except to your wallet. I've been checking the ignition adaptations, and they have yet to recognize I'm feeding it 87.

The single-use bolts is a trivial additional expense. But it raises the possibility of stretch failure on the bolts.

When it comes to these vehicles, some people seem to have a fresh glass of MB Kool-Aid handy. It's just an automobile, and you are allowed to tinker with it. Just be careful, and if you don't know what you're doing, you probably ought to stick with the mfr's recommendations.

eric_in_sd

Like I said, stretch bolts are typically reserved for things like cylinder heads, where there is thermal expansion and impulses of stretching force. Unless you are using heat treated steel, the bolts tend to not have enough elasticity. I believe this is why aluminum, which work hardens and becomes like heat treated, is often preferred.

That and weight savings, but this is a 5500# vehicle.

BlackML550

I'm removing the ashtray next week. Just waiting on the new bolts and torque settings before I start, lol

eric_in_sd

lol

Speaking of tinkering, I removed the satellite radio and cell phone modules, jumpering the MOST connector. Tapped holes in the intake manifold to do water injection cylinder carbon cleaning. Gutted the cats and installed mini cats.

And for real weight reduction, I took out the third row seats.

You're allowed to tinker. Just - if you are not confident in what you are doing, ask a lot of questions and learn. You don't want to end up on Just Rolled In.