722.6 Leak from Torque Converter Area - PeachParts Mercedes-Benz Forum

shertex · #1 07-15-2015, 07:35 AM

My 98 is leaking ATF from torque converter area. I have confirmed that it's not coming from the TC drain bolt. In addition to front pump seal, what are the other possibilities and how much labor would be involved in getting it fixed?

It looks like I'm losing about 7 to 8 oz. every 1000 miles. Trying to figure out whether to keep topping it off or get it fixed.

I am assuming that the location of the leak rules out certain possibilities (e.g. the plug adapter), but perhaps I'm mistaken.

Thanks.

m1tch · #2 07-15-2015, 08:05 AM

Could the oil be leaking from the plug adaptor and then wicking up the wire into the control box and dripping from there?

shertex · #3 07-15-2015, 08:11 AM

Quote:

Originally Posted by m1tch

Could the oil be leaking from the plug adaptor and then wicking up the wire into the control box and dripping from there?

I wouldn't think so since the plug adapter was replaced about 20k miles ago. Plus it's hard to imagine that that volume of fluid could wick up then drop down over that mileage.

Zulfiqar · #4 07-15-2015, 10:21 AM

you have the older style NAG1 gearbox that utilises bushings in the K2 rather than bearings as they have in the later model.

The leak happens when the bushing wears thin and the input shaft starts moving around - this overwhelms the converter seal function and it starts to leak from the torque converter snout. In most cases the turbine bangs around in the converter pump and makes a racket.

Its best to address this problem before the bushing gets so bad it starts to chew the front planetary gearset and spreads metal throughout the transmission.

For starters - check the condition of ATF and metal bits in the pan, also check for any noise - you will needs to test it in a very quiet area to hear any screeching/grinding noise from under the car while moving slowly.

shertex · #5 07-15-2015, 10:56 AM

Quote:

Originally Posted by Zulfiqar

you have the older style NAG1 gearbox that utilises bushings in the K2 rather than bearings as they have in the later model.

The leak happens when the bushing wears thin and the input shaft starts moving around - this overwhelms the converter seal function and it starts to leak from the torque converter snout. In most cases the turbine bangs around in the converter pump and makes a racket.

Its best to address this problem before the bushing gets so bad it starts to chew the front planetary gearset and spreads metal throughout the transmission.

For starters - check the condition of ATF and metal bits in the pan, also check for any noise - you will needs to test it in a very quiet area to hear any screeching/grinding noise from under the car while moving slowly.

That's helpful....sounds like I need to get it addressed sooner rather than later. In fact I do hear some mild screeching when I tap the accelerator and when I release.

shertex · #6 07-15-2015, 08:23 PM

Quote:

Originally Posted by Zulfiqar

you have the older style NAG1 gearbox that utilises bushings in the K2 rather than bearings as they have in the later model.

The leak happens when the bushing wears thin and the input shaft starts moving around - this overwhelms the converter seal function and it starts to leak from the torque converter snout. In most cases the turbine bangs around in the converter pump and makes a racket.

Its best to address this problem before the bushing gets so bad it starts to chew the front planetary gearset and spreads metal throughout the transmission.

For starters - check the condition of ATF and metal bits in the pan, also check for any noise - you will needs to test it in a very quiet area to hear any screeching/grinding noise from under the car while moving slowly.

Zulfiqar, if the tranny performs perfectly and all I hear is mild screeching when I tap the accelerator (I assume this is from the K2), have I likely caught the problem early enough before damage is done?

shertex · #7 07-16-2015, 07:17 AM

I'm gathering that the attached diagram is a good description.

If I'm reading it right, it sounds like simply replacing the bushing is not optimal. ...that there's an upgrade package. Who knows what that would cost.

RunningTooHot · #8 07-17-2015, 01:45 AM

I know that Mark at Sun Valley transmissions modifies (lathes down) the shaft to accept a roller bearing, thus avoiding the expense of replacing the entire assembly. I don't know if he uses the MBZ factory bearing or an alternative though. Maybe he can help you out - he's a really great guy.

I'll say that it's a bit disturbing to see this happening at only 94K on "Murray". I'm curious - do you know the prior service history on that trans, i.e., has the fluid been changed during reasonable service intervals, or did the prior owner drink the koolaid and believe in the "lifetime fill" BS?

shertex · #9 07-17-2015, 06:52 AM

Quote:

Originally Posted by RunningTooHot

I'll say that it's a bit disturbing to see this happening at only 94K on "Murray". I'm curious - do you know the prior service history on that trans, i.e., has the fluid been changed during reasonable service intervals, or did the prior owner drink the koolaid and believe in the "lifetime fill" BS?

That's the frustrating part....I don't know that it could have been taken care of any better. Prior to my ownership, tranny was resealed by the dealer at 40k miles (why and what the details were, I'm not sure). When I bought the car at 73k miles, I changed fluid (drained pan and TC) and replaced filter.

97 SL320 · #10 07-17-2015, 07:17 AM

Fluid change intervals have no affect on the longevity of the bushing, the oil never gets that "bad". What would have an effect is lots of time / frequent hard acceleration in the lower gears 1 - 3 as this is when the highest rotational speed occurs. In 4 th everything is spinning at the same speed, in 5 th there is some rotation.

I have a core trans from a 98 S320 ( 150 K miles ? ) that wore out the bushing and the cage from a thrust bearing in that area. The thrust bearing rollers fell in to the planetary damaging the rear gear train. The converter seal never leaked near as I can tell.

In any event at minimum, pull the trans and pump / bell housing, replace the pump bushing / seal and K2 bushing. The cost of making the roller bearing update could be on the high side. Also, if you do change the gear train be sure to get the correct gear ratio , there are 2 for MB and 3 or more for Chrysler.

The later trans got a roller bearing, Sonnax makes an adapter bushing when mixing early and late parts.

shertex · #11 07-17-2015, 07:26 AM

Quote:

Originally Posted by 97 SL320

Fluid change intervals have no affect on the longevity of the bushing, the oil never gets that "bad". What would have an effect is lots of time / frequent hard acceleration in the lower gears 1 - 3 as this is when the highest rotational speed occurs. In 4 th everything is spinning at the same speed, in 5 th there is some rotation.

And of course the fact that it's chipped tuned means there's even more power going to tranny.

97 SL320 · #12 07-17-2015, 07:31 AM

True but I don't see that causing an issue in the short term, this is a long term issue. ( 10 of thousands of miles , hard in the throttle at every start.) And, even with a chip, if the throttle isn't pushed hard, power levels are same as stock.

Zulfiqar · #13 07-17-2015, 10:36 AM

Quote:

Originally Posted by shertex

I'm gathering that the attached diagram is a good description.

If I'm reading it right, it sounds like simply replacing the bushing is not optimal. ...that there's an upgrade package. Who knows what that would cost.

the upgrade in actual terms is new guts of the transmission because the toothcount of the planetaries are different and dont mesh with old/new parts.

new parts from MB are 1000 USD. - might as well find a post 2000 model year transmission, shifter and TCU for your car. I think the diesel has the v8 ratios, will need to read the manual for this.

sonnax make the bushing, which you can tap into the drum, provided your planetary set is not chipped.

but - if sunvalley transmissions are now providing a bearing machine/upgrade job then that would be the absolute best. While at it, renew the torque converter with a CVC rebuilt one.

All the above information was provided by @MAVA to me - he is a gem of a person and rebuilds these gearboxes.

Zulfiqar · #14 07-17-2015, 10:48 AM

Quote:

Originally Posted by shertex

That's the frustrating part....I don't know that it could have been taken care of any better. Prior to my ownership, tranny was resealed by the dealer at 40k miles (why and what the details were, I'm not sure). When I bought the car at 73k miles, I changed fluid (drained pan and TC) and replaced filter.

the word reseal should be more explained, the usual culprit of a leakage in the early life of these transmissions were the wiring harness pilot bushing leaking.

It can also be termed resealed. Not trying to diss any dealer but sometimes the words can be misleading.

e.g. while cleaning out my camry I found a work order from a dealer, it claimed that they resealed the engine, parts list has one tube of FIPG, one oil filter, one crush washer and 5 qts of oil.

I dont know if they just resealed the sump or the timing case or anything else. But they did reseal something there.

Dan Stokes · #15 07-17-2015, 11:22 AM

In the years I worked for car dealers (like, 8 years or so) I NEVER heard the term "reseal" used because it has no meaning. What we used (and this was at several dealers and among different makes of cars) was "repair (engine, transmission, whatever) leak at the (oil filter, speedo drive, whatever)". This actually means something and tells the mechanic what to do.

The term "reseal" is like "restored". Many sellers say a vehicle is "restored" when all that's happened is that the vehicle had a paint job. Both these terms mean what the speaker WANTS them to mean. A real "reseal" on, say, a transmission should mean that every nut, bolt, and screw of that transmission was removed and each component was cleaned, machined if necessary, and assembled as the manufacturer intended to assure leak-free operation. Anything short of that is a repair - which may be all that's needed.

Anyhow, I use a local trans shop run by a father and son team who are EXCELLENT. When you get the trans back not only has the failed stuff been renewed but he'll upgrade anything that has an upgrade so the trans can work as well as possible and last as long as possible. They're not cheap but, as usual, you get what you pay for.

My personal belief is that if you've pulled the trans out of the car it is so much labor that you might as well get it fully rebuilt. That way you have the best shot at putting it back in for good.

Dan