Checking 722.6 transmission fluid level - PeachParts Mercedes-Benz Forum

jjrodger · #1 08-24-2004, 07:53 AM

I wish to check the transmission fluid level on my 1999 R129 SL500. It has a 722.624 transmission. I have ordered the special tool and parts from the dealer. I understand I should check the level at 25 deg C and again at 80 deg C. My questions are simple and probably stupid:

1. Do I check the fluid level with the engine running?
2. In what position should the transmission selector lever be when I check the level.

I have assumed that should I check the level at 25 deg C with the engine off and the transmission in P. I also assume that I should check the level at 80 deg C with the engine off and selector in P, and then check it again with the engine running and the car in P.

Thanks in advance.

Ferdman · #2 08-24-2004, 09:01 AM

To the best of my knowledge the transmission fluid level is checked with the engine running and the transmission in Park. If you change the fluid you typically add all but the last pint or so then start the engine and shift the transmission from Park through the various gears several times. Recheck the 'cold' level and add fluid, as required. Then drive the car to bring the transmission up to temperature and check the 'hot' level. Add fluid, as required to bring it to the full 'hot' level being very careful not to overfill.

jjrodger · #3 08-26-2004, 07:10 AM

I've checked it and it seems to me to be too full. The level comes right past the uppermost mark and up to the top of the measuring part of the dipstick. The dealer does not seem to think this is the end of the world and the soonest he can look at the car is 14 September.

Meanwhile, I am concerned about my transmission:

Full load upshifts from 1st to 2nd are noticeably jerky. These used to be slurred just so.

Downshifts from 3rd to 2nd are jerky, too.

Often the transmission seems hesitant or reluctant to change.

There is no slippage at any time.

Changes at less than full load and between other ranges are generally OK.

Any ideas?

Ferdman · #4 08-26-2004, 08:29 AM

Use a suction device to remove excess transmission fluid. Overfilling is not recommended.

Ali Al-Chalabi · #5 08-26-2004, 09:56 AM

I am not sure if the procedure with the 722.6 is different than a "normal" transmission. I believe the HHT or star diagnostics software used by the dealer only will display trans temp with the tranny in gear. I wonder if maybe it is supposed to be checked when in gear?

jjrodger · #6 08-26-2004, 10:21 AM

Quote:

Originally Posted by Ali Al-Chalabi

I am not sure if the procedure with the 722.6 is different than a "normal" transmission. I believe the HHT or star diagnostics software used by the dealer only will display trans temp with the tranny in gear. I wonder if maybe it is supposed to be checked when in gear?

You're correct about the HHT/star diagnosis system only giving a temp read out when the transmission is in gear; however, my understanding is that the fluid level is taken with the transmission in Park.

blackmercedes · #7 08-26-2004, 10:31 AM

Quote:

Originally Posted by jjrodger

Full load upshifts from 1st to 2nd are noticeably jerky. These used to be slurred just so.

Downshifts from 3rd to 2nd are jerky, too.

Sounds like ETC problem.

http://forums.mbworld.org/forums/showthread.php?threadid=48087

jjrodger · #8 08-26-2004, 12:03 PM

Thanks for chipping in BlackMercedes, I have been hoping you'd see this post. I read of the difficulties you had with your own 722.6 when I searched the forum before posting. My car was March 1999 build and it has a 722.624 tranny. Will it not already have the upgraded ETC? I note the TSB at MBWorld is dated 29 December 1999, so maybe not.

I'm also concerned that mine might be a hardware problem: it used to shift beautifully. I'd welcome your further input, BlackMercedes, I'm worried about getting a bill for a new transmission! Also, how much is the ETC upgrade?

blackmercedes · #9 08-26-2004, 02:53 PM

Don't your shifting problems sound EXACTLY like the problems described in the TSB? They do to me!

Do you have a good relationship with your dealer? I know a few folks that have had the ETC updated on MB Canada's tab even though the car was out of warranty. Even a cost-sharing arrangement would be preferable to picking up the whole tab. I think that the ETC replacement was about $1100 of my warranty bill. It was about $5000 for the new tranny, $1100 for the ETC, $1600 for the converter, and "sundry" bits brought it to about $8000.

Talking to local techs, MB Canada won't authorize ANY warranty repairs on any 97-99 model year 722.6 trannies. They immediately replace all the bits. While it's more expensive, they upgrade the tranny, ETC and converter.

My indie had a rival shop replace some trannies without updating the ETC, and the new box would be wrecked by the old ETC. He had some disgruntled customers come to his shop, and he replaced everything (cars WELL out of warranty...) and problem solved. However, he has had good success treating patients with shifting problems by replacing the ETC on it's own.

Once sorted out, it seems that the 722.6xx is a deadly tranny, but thank you Mercedes for experimenting on the first three years of owners.

jjrodger · #10 09-02-2004, 08:49 AM

I had the car in to the dealer today because I was really worried about it. The tech drove the car about 500yards, said this isn't the transmission, it's engine management, probably the MAA. He put it on the machine and apparently his diagnosis was confirmed. He showed me the print out but I can't remember what it said. The tech explained that when the air flow meter is defective, this can retard gearshifts and and generally confuse the car; the engine also felt down on power.

Sure enough, it runs like a dream again. Phew. Now, what can I do with that GBP5,000 I set aside for a new transmission...