mguerrero

Looking to service my tranny -- some people say no to flush and only a pan drop and some say do a FULL flush! Whats the thought process here?

Also, if I go with just a pan drop is there a special way I should do this? do I just drop it and replace a pre-determined amount of oil or do I need to measure and replace exacly what came out? is oil temperature an issue before replacing or is that just for checking? where do you replace it diptisck hole or tranny side fill hole?

Thx in advance for your help!

Rudeney

Given that your 722.6 transmission was sold as "sealed for life", anything you do is better than what MBZ suggests. Personally, I'd do a pan-drop fluid and filter change every 40K miles. If you really feel like you need more than that, you can do a flush. Here are WIS docs for both:

http://benzbits.com/722_6/FluidFilterChange.pdf

http://benzbits.com/722_6/TransmissionFlush.pdf

tw2

I plan to do the same thing, just change whatever volume of fluid comes out, clean the magnet, new pan seal and check the plug for the wire loom while at it. A full flush risks dislodging crap in a high mileage car.

mguerrero

my car has 50k miles

mguerrero

thanks for the info! have you done one yet? I don't see that these docs specify the amount of fluid to replace -- do you know how much comes out during a radiator swap and trans service? - hoping to do them together

Glyn M Ruck

A full flush of an unserviced transmission will always be the best possible thing you can do.

mguerrero

Glyn I agree, but I've heard horror stories of people having problems after a flush even when done at low mileage - so I'm debating if I should just do a pan drop oil service -- do you happen to know how much oil is in the pan when drop it and how much oil needs to be replaced when swapping radiator out?

looking to do radiator and tranny service at the same time ...

one last thing, I'm gonna also replace the tranny "plug adapter" while I'm there ... any specific way to do this??

Thanks in advance for all your help!

Glyn M Ruck

Your car only has 50K miles on it's 722.6 so a half change is probably OK unless the fluid is heavilly oxidised. Or you can do 2 back to back half changes.

If it has been left longer than that then a flush is mandatory. A lot of nonsense is spoken about flushing. If a transmission fails after working cleanly on it after a flush it would have failed anyway. You need to get all the oxidised fluid out & refresh the friction modifiers for smooth performance & long life.

Here is the electrohydraulic bush change.

http://www.installuniversity.com/mb/...ans_oring.html

Good luck!

mguerrero

wow! Thanks!

is it worth it to buy a tranny dipstick? I heard you have to ck it at a specific oil temperature ...

Glyn M Ruck

Yes ~ you need a dipstick & an IR thermometer to take the pan temperature.

mguerrero

ok I will buy one - whats the temp the pan should be at?

tw2

Obviously the "feeling" you get reading things on the forum doesn't necessarily correlate with actual real world statistics at all but it does seem there are quite a few failures approximately 3-6 months after full flushes on high mileage never before flushed transmissions.

I completely trust what you say, it just makes me wonder if there is a real correlation at all.

Glyn M Ruck

There is no correlation. It is another urban myth that has somehow grown legs.

We have brought transmissions back from the brink that were so fouled up that they lost drive & a flush got them back into service.

Glyn M Ruck

See procedure in the Wiki.

https://mbworld.org/wiki/images/2/21..._Oil_Level.pdf

mis3

Change the filter as well, an inexpensive item.

tw2

Thank you Glyn, full flush it is. The dealer can do it, it looks very messy.

mguerrero

I'm gonna do the filter and drop pan only and then will do full flush in another 15-20k miles