eric_in_sd

Welp, my transmission decided it had enough of this life. Started rather abruptly getting rough shifting, then 3rd gear slipping followed by rough engagement ... then momentarily refused to engage first gear ... wouldn't go into reverse until I switched off and then back on ... then it kind of shuddered when backing into the garage.

About four error messages on my icarsoft, including "turbine sensor failure". Wish I'd written them down because the tool doesn't save them, and now the car is in the shop.

One piece of info: The mechanic said Mercedes dropped the price of the conductor plates substantially. They're now about $400. So whereas they were having them rebuilt, they are now buying new ones. Food for thought, considering those 722.9 transmissions are everywhere. You can actually get the transmission serviced by an indy shop; it's just a question of finding one with the cojones to do it.

Updates will follow as I find out just what all has gone south on this thing.

eric_in_sd

Welp. The entire trans is lunched. From El Mechanico:

0718 failed turbine sensor
0717 signal from turbine sensor not available
0893 hydraulic fault in trans, disagreeing shift element does not operate.
0513 missing can signal from trans or invalid.
05420 fault disturbance in CAN message from control unit n15/3 egs or trans control module.
5399 gear selected from trans control unit is implausible.

Found tsb to replace the valve body and conductor plate due to the current faults, but unable to preform tsb due to major build up of clutch material and other metal materials from transmission assembly when the pan was removed.
Found all fluid metallic. At this time transmission clutches and gears have been compromised. Found unable to shift into any gears or unable to move under its own ability.
At this time recommend replacement of whole trans assembly and also major flush needed. Reprogram needed to latest software when replacing.



I knew I picked a bad week to quit sniffing glue.

alx

I was about to say that your syndromes are more of a mechanical nature than electrical.

Junk yards have plenty 7 trannies and they are all pretty much the same.. about $1k .... it actually is not going to be much more expensive compared to replacing the valve body and conductor plate of your old tranny was in good mechanical shape

eric_in_sd

If I could find a low mileage used tranny ... dunno.

He said he found a used tranny, six month warranty, with torque converter, for $2900. He said my GL needs the torque converter cos of the metal contamination.

I don't know for sure but I suspect he won't want to do parts w/o some warranty.

If it were just me, I might be more inclined to chance it, but my daughters drive the car too.

That, and it's an oil burner (1 qt/kmile) and has had a couple of 0420 cat errors.

I'm shelling out the bux to check the compression (wish I'd done that while the thing was still in my possession!) and will try to figure out what to do from there.

Hey, you have any idea what might have caused the mech failure? You think maybe the speed sensor problems caused hard shifting that led to complete failure? I had occasional rough shifts for a fair while.

I'm wondering if the tranny service (pan, fluid, filter) might have caused this. Like wrong fluid or not enough or something. The thing had already thrown 0717 errors when I had that service done, though. Went into 3rd gear limp mode once.

alx

Turbine speed sensors don't cause mechanical failures. They cause tranny stuck in gear and limp mode which goes away with a restart.

Bad tranny service (wrong fluid, wrong level) absolutely can cause a problem and there is no system that monitors tranny fluid level so if it was low it absolutely could destroy your transmission.

It is your call, but you are having problems with the two major components of your vehicle. That is not common and I am wondering what caused it. I will leave it at that.

eric_in_sd

Well, one thing's for damn sure, and that's that they have different causes. We'll see what the compression comes back as. The only hope is the oil consumption is due to the PCV valve. That seems farfetched, but el mecho seemed to think it was a reasonable probability.

You sure failure of the valve body, etc., doesn't lead to mechanical damage? Lots of people talk about the failure mode causing rough shifting.

Anyway, it's likely water under the bridge. I'll ask the guy about whether the trans had adequate fluid and whether he could tell if it was the right stuff.The place that did the fluid / filter is a pretty much on the up and up outfit, so I'd be pretty surprised if they screwed it up.

eric_in_sd

Compression came back very strong - 180 min, 189 max.

So it's probably worth putting a transmission in.

This also raises an important question: Where is the oil going?

alx

assuming throttle body is dry (no oil) - loose/ worn out oil piston rings. good compression, bad oil scrubbing resulting in oil on cylinder walls above the piston surface which then burns.

if oil is presented in throttle body (a lot in your case) pcv / egr system needs to be troubleshot.

or.... oil leaks (usually from oil plugs in the back of engine) and burns on the exhaust manifold. when you come to a stop after motor has reached operating temp - take a whiff on driver side in the windshield wiper area- is there a strong burnt oil smell? yes? it leaks and burns on the exhaust.

eric_in_sd

Hm. Seems a little unusual to have worn oil control rings but not compression rings.

Def will check out the PCV. El Mecho suggested that when I brought it in.

No burning oil smell at any time. That I would not overlook. The car sleeps in a garage and there's no way to miss that.

eric_in_sd

Decided to go for the tranny replacement. I found a rebuilder, Sun Valley Mercedes, that sells a full rebuild, w/ torque converter, for $3500.

I did a back-check on the fluid. El Mecho said fluid level was okay, and it looks like the previous fluid was kosher.

No, I didn't do neutral drops or any crazy stuff like that.

The transmission rebuild shop says they ordinarily start failing at around 100k miles. That seems short, but maybe not if there's a lot city driving in there.

I like the truck and wasn't happy about the prospect of selling it for parts; looks like y'all will be stuck with me for a while longer.

BlownV8

I have over 200k miles on my original tranny with no current issues. The valve body/turbine speed sensor was replaced around the 100k mile mark.

eric_in_sd

Yah, I suppose it's erratic. I dunno; you talk to ten different people and get ten different answers. For what it's worth, the class action lawsuit seems to blame rough shifting and tranny destruction on the electricals. But knowledgeable people have said the electrical faults don't kill the tranny.

Have you changed the fluid regularly? Is your mileage mostly long distance, steady speed?

It's a puzzle because, like I said, the 120k filter & fluid was supposedly very clean. 9k miles later, she go crunch crunch - and rather abruptly. 8500 miles of shifting more or less fine, then boom.

BlownV8

I believe I've changed the tranny fluid twice. I have not had a fluid and filter change in a long time and it is probably due for another one.

alx

women do the same thing... regardless of how well they are maintained.

just trying to make your day a bit brighter...

eric_in_sd

hahaha

The truck runs great with the new trans. Now I'm committed to it, I guess. Just like a woman.

I swapped out the oil separator and cam plugs today. Jeepers but the old one was a mess. There was oil in the hose leading to the intake. Didn't look in the throttle body; didn't immediately see how to look inside. Hey, should I check it, and should I clean it if oily?

Of course, I'll pay attention to the oil consumption and report back to the board.

Thanks for your tips and info. Never forgot your "that truck ages well" comment. It's true.

BlownV8

I just took apart my headlights because I had some clouding inside the lenses. The wire sheathing was completely falling apart. All the wires needed to be replaced or covered in shrink wrap. I just ordered new headlights because I didn't want to go through the process of replacing all the wiring.

If you have an older GL, you might want to take a look. If you can see the main headlight or high beam wires starting to come apart, it is much worse than you can see buried inside the housing. I rarely ever used my high beams and the wire sheathing is crumbling.

eric_in_sd

Did you post to the wrong thread?

Anyway, my low beam lenses are milky. Have been ever since I got the truck. Are they supposed to be clear?!?

BlownV8

No, it was a comment based on your these trucks age well. Pretty crappy that the wires are already disintegrating. These are manufactured by Hella for MB so it's not MB's fault but rather their suppliers.

I was referring to the inside of the clear headlight covers. Mine were cloudy on the inside. Yes, I believe it is normal for the low beam H7 reflectors to look cloudy.

eric_in_sd

That's just weird. Are you sure it isn't some environmental problem where you park your truck? I haven't noticed any sort of degradation. What you describe is scary, the sort of thing that causes catastrophic system failure.

BlownV8

The wiring is not exposed to light nor is it exposed to the environment since the headlights are sealed. The access covers have always been sealed tight. Yes, total failure to the point I was worried about the car having serious issues. I've heard about some of the German wiring insulation doing this but have never seen it in person. Read something about the requirement for the plastics to be able to decompose quickly in a landfill. Just don't think they meant this quickly.

alx

the wiring crackling and splitting is not normal... i have not seen any trucks doing that.

now the clouding in front of the lenses - that is normal on an older vehicles. it is usually due to extreme and prolonged sunlight exposure combined with dirty roads.

eric_in_sd

yeah, that's crazy.

auto-decaying plastics for landfill purposes? That's nuts. You sure that isn't an urban legend?

BlownV8

Pretty common. Just do a search on the wiring degrading in German headlights.
http://rennlist.com/forums/porsche-c...nsulation.html
http://jalopnik.com/5570865/11-terri...ing-decisions/

Biodegradable German Wiring

In the 1990s, Germany's Green Party passed a law requiring a certain percentage of the parts in an automobile to be biodegradeable. You'd think that manufacturers would have tried to satisfy this requirement by making biodegradeable seat cushion foam, or door panels, or something else that would only be mildly annoying if it started to rot while you were driving it. Mercedes-Benz, however, decided to rely on biodegradeable wiring insulation to meet these requirements. There's nothing like a wiring system that simply devolves into a mass of jumbled, short-circuiting copper after a set period of time, is there? (And you thought forty-year-old British electrics were bad.)