When I got my 83 SD in may of this year [2003] I really had no idea what to do first, it needed so much work that I did the easy things first. One was flushing the tranny. I un- hooked the return line to rad on driver side and placed the line in a 5 gallon pail. I then started car and with the fliud going into the bucket I began adding new fluid as fast as the filler would take it with out overflowing. The fluid was dark, not real dark, like black, but sort of brown. After the fluid began to feel cool, about 4 gallons in the pail, I figured the flush was complete. I topped it of and went for a drive. It shifted much smoother than before the flush. To make a long story short I just finished flushing my tranny for the forth time and it gets smoother and smoother every time. The question is: Am I nuts? or can flushing a tranny with 230,xxx miles keep getting better and better. The 4 flushes were over a 7 month period. any and all comments welcomed. steve

Steve:

Save yourself a bunch of money and just drain the pan and torque converter, then refill with Mobil 1 ATF after replacing the filter and cleaning the pan.

No need to actually pump the fresh tranny fluid through it, it's wastefull.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

peter, I hear you on the waste, but our shop has a waste oil heater so it really is not wasted. I read that the mobil 1 atf doesn't work as well on a older tranny's .Please correct me if I'm wrong. I pulled the pan and cleaned it and put in a new filter during the first flush. steve

Yes, this was an unnecessary step. Draining the trans AND converter, changing the filter and filling with fresh fluid is the best approach.

Something very important to point out here is the SMELL of the fluid is probably a better indicator than the color. If the fluid is nice and red, there's no need to smell. If it is brown or black, smell it. If it smells like turpentine or varnish, then your clutches are burned. Under these conditions an aggressive flush can often wash out the clutch linings and the car won't move.

If the fluid is brown, but smells okay, just change filter and change ALL the fluid.

Good luck,

Suck about a quart of trans fluid out the top... put in a can of Trans-X and either put it in all the gears for about 20 minutes.. or drive 30 minutes ( or more ) .. THEN do as the above posts have suggested... this will dissolve any varnish which has been deposited and then you flush it ( hot but DON'T get burned )...

Mobil 1 is superb tranny fluid. Often makes an older tranny run better (with the proviso that any fluid change on a nelgected automatic can take if from bad performance to none - the only thing making it work is the crud, dissovle the crud and it quits).

A complete fluid change is all that is needed, and fresh automatic transmission fluid is VERY expensive fuel!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter, You are advising AGAINST dissolving any varnish which has been deposited in the auto trans valve body before draining the fluid ?

I'm confused!!!! steve

Using Trans-X seemed to save my Suburban transmission.
At about 70k it seemed to slip and not down shift properly in OD when starting up hills at highway speeds. After using Trans X and changing fluid a few times in 1500 miles, problem went away. It now has 104k with no problems (yet). Product seem to clean & flush, but previous transmission fluid never smelled or was other than red.

I don't know if I was reading Peter wrong... but all my experience and many statements by others and pure logic would indicate that getting the varnish out of those small holes in the valve body of an automatic transmission would be a good thing.. then drain to get it out of the system.. just like we drain oil out to do the same thing..
It is also cheap ( typically under $10 ) and I have never heard anyone claim they thought any damage occured using it ...
Varnish is not supposed to be in those tiny cavities with those little balls that control the hydraulic clamping at the right speed and power of the clutch bands in an automatic trans...
I do not have any indication that this is a matter of new fluid being able to dissolve Deposited Varnish... thus I think something like Trans-X to get it off... and into the stream ...making it possible to completely remove it from the transmission via draining... is needed....
Steve, does that help ?

Leatherman:

Usual problem is that the varnish is all that is holding the friction coating on the frictions, so the tranny stops working when you dissolve it. Steel on steel isn't the best clutch in the world -- that's why trains have sanders.

Varnish is also sometimes all that is closing the check ball orifices -- dissolve it and too much fluid goes past and bad things happen. Can also produce too much clearance in the valve spools so that the control system won't work.

Automatics can be tempermental beasts.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Too slow an activation of the hydraulic movements which engage the clutch bands is the same as a person not letting out a manual clutch in a normal fashion... and it causes greatly increased wear of the friction surface...
I can not agree that the continuation of clogging those small holes in the valve body is a positive affect of varnish build up... and what is likely to happen is the small steel balls in that unit get stuck and don't close or open like they should...
You almost talk like the original engineers bored the hole too large... and we should or need to have varnish from old trans fluid to make it work properly...
I vote NOT

I think I understand more now, great explaination. I still wonder why my 230,000 mile tranny would shift smoother and smoother with each flush. I really know nothing of the magic that goes on in an automatic tanny but I do know that mine is working better than ever[since may 2003]. I am now driving my 83 SD without tranny fears and that allows me to enjoy this fine automoble even more. steve

Steve:

Well, you aren't going to HURT it by flushing the tranny, for heaven's sake, just waste perfectly good tranny juice.

Watch out for the smoother and smoother, though -- MB trannies traditionally shift firmly under power, so if you are getting very smooth shifting at wide throttle, you may be aquiring slip instead.

Most people don't change the tranny fluid anywhere near often enough -- and old fluid will cause varnish on frictions and control passages. Eliminating this stuff will make for better operation.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Yes, the flushing will indeed clean passages in the valve body and that's, of course, a good thing. But, that's not the whole or most important issue here.

A really gunked up transmission, as psfred properly pointed out, has its clutch surfaces basically held together with the crud. Chemical or pressure flushing can, and often does, remove the clutch lining material and renders the vehicle immobile.

Again, SMELL the fluid, before doing any kind of chemical or pressure flushing. If it is brown, not black and does not smell like varnish or turpentine, then change it and be happy.

Going to whatever length to keep an engine crankcase clean has no downside if done with good, common sense. This same mindset will NOT always work with an automatic transmission.

My $0.02,