I need a recommendation on whether or not I should have the transmission serviced on my 1992 400E. It has over 189K miles on it. I called a local service center that specializes in German imports and they warned that I not get it done. Their justification is that the discs in the transmission have worn off the grit on the discs by this time. He said the grit is still in the fluid and that is why the transmission is still working, but if you change the fluid, you remove the grit from the transmission and it will start to malfunction. Since I have no experience with working on transmissions, let alone Merc transmissions, I'm asking for some advice from the guys in this forum who might have some experience in this area. Thanks...
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Recommendation on Transmission service.
- Thread starter jgt157
- Start date
My $0.02: That is pure, weapons-grade baloneyum. I'm surprised that a German specialist would tell you that. :?:
If it were my car, I'd change the fluid & filter if you don't know when it was last serviced. Inspect the pan for signs of anything abnormal, if it looks clean/normal, most likely the trans will continue working properly. I'd also check the serial number on the trans to see if it's original, by 190k there's a chance a previous owner may have already replaced it. Is it shifting OK now, and is the fluid cherry red?
If it were my car, I'd change the fluid & filter if you don't know when it was last serviced. Inspect the pan for signs of anything abnormal, if it looks clean/normal, most likely the trans will continue working properly. I'd also check the serial number on the trans to see if it's original, by 190k there's a chance a previous owner may have already replaced it. Is it shifting OK now, and is the fluid cherry red?
My $0.02: That is pure, weapons-grade baloneyum. I'm surprised that a German specialist would tell you that. :?:
If it were my car, I'd change the fluid & filter if you don't know when it was last serviced. Inspect the pan for signs of anything abnormal, if it looks clean/normal, most likely the trans will continue working properly. I'd also check the serial number on the trans to see if it's original, by 190k there's a chance a previous owner may have already replaced it. Is it shifting OK now, and is the fluid cherry red?
I think it's the original transmission. It still has the red cap where the dipstick would go. I was under it today and I didn't see any leaking from the transmission.
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My little experience with transmissions and valve bodies is that you never want grit in the fluid.
What that mechanic said sounds like "hog wash"
What that mechanic said sounds like "hog wash"
That's not hogwash or baloneyum at all. What your repair shop recommended was very good advice in some ways, though they may not have explained it very well.
By not maintaining the transmission properly for the past 100k+ miles, the damage that has been done is now irreversible and performing a service at this point is very risky because you have more chance of doing harm than good. This is because the fluid is no doubt full of worn clutch debris (grit as you describe), and that grit has changed the flow rates of the fluid and has deposited itself in many 'cracks and crevices' inside the valve body, apply piston seals, etc...
So performing a transmission service now will flush all that 'grit' out and clean out all those seals and flush out the valve body that most likely has worn significantly, and will POSSIBLY create problems. If the transmission is in better shape than you'd expect for going 189k+ with no service, then perhaps the transmission will keep on shifting great and last even longer thanks to the fresh maintenance. But in my experience the risk FAR outweighs the reward. Very similar to switching to synthetic engine oil after 189k miles of using dino oil, you'd expect a lot of oil leaks to start. It doesn't happen every time, but most often.
I can't tell you how many times in my 23+ years of repairing Mercedes that after servicing a transmission it will start slipping and have all kinds of new problems. Then of course the first thing the customer does is blame the mechanic/shop because "it was fine before you serviced it!!" So from a shop's point of view, any shop with good experience will recommend against taking your money for something that has more chance of doing harm than good. It's not good value for the customer or for the shop to have a pissed off customer.
Now if it had only been 60-80k miles since it's last service, then the advice would most likely be different. But since the typical lifespan of most of these transmissions isn't much past 200-250k miles when serviced properly, going 189k without proper maintenance has already done damage to the transmission and you're lucky it made it this far. So in my opinion I would just leave it alone until it breaks, and be thankful for every mile until it does.
By not maintaining the transmission properly for the past 100k+ miles, the damage that has been done is now irreversible and performing a service at this point is very risky because you have more chance of doing harm than good. This is because the fluid is no doubt full of worn clutch debris (grit as you describe), and that grit has changed the flow rates of the fluid and has deposited itself in many 'cracks and crevices' inside the valve body, apply piston seals, etc...
So performing a transmission service now will flush all that 'grit' out and clean out all those seals and flush out the valve body that most likely has worn significantly, and will POSSIBLY create problems. If the transmission is in better shape than you'd expect for going 189k+ with no service, then perhaps the transmission will keep on shifting great and last even longer thanks to the fresh maintenance. But in my experience the risk FAR outweighs the reward. Very similar to switching to synthetic engine oil after 189k miles of using dino oil, you'd expect a lot of oil leaks to start. It doesn't happen every time, but most often.
I can't tell you how many times in my 23+ years of repairing Mercedes that after servicing a transmission it will start slipping and have all kinds of new problems. Then of course the first thing the customer does is blame the mechanic/shop because "it was fine before you serviced it!!" So from a shop's point of view, any shop with good experience will recommend against taking your money for something that has more chance of doing harm than good. It's not good value for the customer or for the shop to have a pissed off customer.
Now if it had only been 60-80k miles since it's last service, then the advice would most likely be different. But since the typical lifespan of most of these transmissions isn't much past 200-250k miles when serviced properly, going 189k without proper maintenance has already done damage to the transmission and you're lucky it made it this far. So in my opinion I would just leave it alone until it breaks, and be thankful for every mile until it does.
What Steve said. It mirrors my experience exactly. Thanks, Steve! You saved me from having to write it. The only reason to change the fluid in a transmission that has gone a great mileage without servicing is to hasten its lurking total failure while you are still close to home. And, yes! I have recommended it for precisely that reason where appropriate...
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I guess I've never encountered a never service transmission and had problems afterward. Every transmission I have serviced, it has only improved shifting and operation. A clean filter flows oil better and besides 722.370's the failure is the reverse clutch pac traditionally. He should count how many seconds when shifting into reverse before it engages to see where it's at. Maybe it's clicking and needs attention now.
I agree it would be a bad choice to use sythetic fluid. Doubt it is truely dry and leak free without seeing some service. Ussually ppl mean leak free= no oil on my driveway. Seen MB owners complain about oily tailights(yes), before they were convinced the oil leak needed attention.
I can see where a service advisor may want to run from a car- heck I've been to MB tech sessions where I swear those diesel were found in a field and had never had an engine bay wash in their lives.
Michael
I agree it would be a bad choice to use sythetic fluid. Doubt it is truely dry and leak free without seeing some service. Ussually ppl mean leak free= no oil on my driveway. Seen MB owners complain about oily tailights(yes), before they were convinced the oil leak needed attention.
I can see where a service advisor may want to run from a car- heck I've been to MB tech sessions where I swear those diesel were found in a field and had never had an engine bay wash in their lives.
Michael
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OK, let's back up a little. Do we know even a rough guess of when this transmission was last serviced? And what is the condition of the fluid - red, brown, burned smell, etc? There is no "red cap" on the 722.3 dipsticks, but some of the dipsticks have a red top. Flip up the locking mechanism and pull out the dipstick for starters. The fact that the transmission isn't leaking is a primary indicator the trans has been touched at SOME point in its life, as I seriously doubt any 722.3 has gotten remotely close to 200k without sprouting at least a minor leak.
Steve/Klink, while I understand the shop POV about high risk for the shop (i.e., possible trans failure blamed on shop), I don't quite understand just leaving the old fluid in there and waiting for the trans to fail. How many more miles will the trans be expected to live with gritty brown fluid, compared to the lifespan after servicing? Wouldn't the better course of action be to drop the pan (saving the brown fluid), inspect for debris in the pan, and putting it back together if anything scary is found? If the fluid is clean & red and the pan is clean, why in the world wouldn't you want to service it?
Steve/Klink, while I understand the shop POV about high risk for the shop (i.e., possible trans failure blamed on shop), I don't quite understand just leaving the old fluid in there and waiting for the trans to fail. How many more miles will the trans be expected to live with gritty brown fluid, compared to the lifespan after servicing? Wouldn't the better course of action be to drop the pan (saving the brown fluid), inspect for debris in the pan, and putting it back together if anything scary is found? If the fluid is clean & red and the pan is clean, why in the world wouldn't you want to service it?
OK, let's back up a little. Do we know even a rough guess of when this transmission was last serviced? And what is the condition of the fluid - red, brown, burned smell, etc? There is no "red cap" on the 722.3 dipsticks, but some of the dipsticks have a red top. Flip up the locking mechanism and pull out the dipstick for starters. The fact that the transmission isn't leaking is a primary indicator the trans has been touched at SOME point in its life, as I seriously doubt any 722.3 has gotten remotely close to 200k without sprouting at least a minor leak.
Steve/Klink, while I understand the shop POV about high risk for the shop (i.e., possible trans failure blamed on shop), I don't quite understand just leaving the old fluid in there and waiting for the trans to fail. How many more miles will the trans be expected to live with gritty brown fluid, compared to the lifespan after servicing? Wouldn't the better course of action be to drop the pan (saving the brown fluid), inspect for debris in the pan, and putting it back together if anything scary is found? If the fluid is clean & red and the pan is clean, why in the world wouldn't you want to service it?
I am actually at agreeing with the both of you! You made excellent points Dave, and some of the things you've pointed out should be taken as indications that the transmission had been "serviced" at least at some form in its life to that point. I don't think that it's a great idea to just leave an unserviced transmission unserviced and wait for it to fail. But an experienced technician and service advisor will warn the customer what could be about to happen in those situations, which ironically, already starts him suspecting you as being at best an opportunist, or at worst a thief. Experience has shown that a marginal transmission will often start to malfunction badly shortly after it gets fresh fluid in it, the high viscosity fluid possibly being the only thing that is sealing against the hardened elastomers, as the friction coefficient complements the aged materials. As Steve said, I cannot tell you how many times I have seen this scenario take place.
That being said, yes I think the transmission should still be serviced, but this should be extensively discussed with the customer beforehand, or you may be about to buy him a new transmission a couple weeks later. Believe me.
I think more of the shop that advised him against this, not less.
Where I differ with some is that I think the possibilities should be explained, and then the customer should decide. My advice on a car that is keep a keeper is to service it, and then if it fails, you Mr. Customer pay to repair it. As I also frequently say, this is Mercedes-Benz, not Yugo!
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When a trans like this comes in & we decide to service it, I take a hard look @ the fluid off the stick...if it has visible particulate we leave it be.
If its just old, we drain/drop the pan and inspect. Of clutch build up is minimal/moderate we drain the TC.
If its heavy/metallic we leave the fluid in the TC and re-fill with type F to give those old clutches a chance. I'll usually turn a little pressure into the mod valve while in there...just to keep everything Pushed together nicely...don't want any fluffy shifts on a tired box!
Jono
If its just old, we drain/drop the pan and inspect. Of clutch build up is minimal/moderate we drain the TC.
If its heavy/metallic we leave the fluid in the TC and re-fill with type F to give those old clutches a chance. I'll usually turn a little pressure into the mod valve while in there...just to keep everything Pushed together nicely...don't want any fluffy shifts on a tired box!
Jono
How does decide how much grit is too much grit?
I am not being sarcastic with my next question
'Would it help or hurt to add a little more grit into the transmission?"
I am not being sarcastic with my next question
'Would it help or hurt to add a little more grit into the transmission?"
Stevester, if I could answer that, I'd be so rich I wouldn't even talk to myself...
That's why I always fill neglected boxes with type F regardless...help whats left of those frictions do their job...!
Not sure if the lack of additives/modifiers in type F lessens the detergent factor some...cause lord knows DM III will clean stuff!!
Jono
Not sure if the lack of additives/modifiers in type F lessens the detergent factor some...cause lord knows DM III will clean stuff!!
Jono
Yep! Sometimes a tired neglected old box just needs a little tightening up...
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