Trans Flush 85sd - PeachParts Mercedes-Benz Forum

greazer2b · #1 07-01-2019, 03:48 AM

I would like to flush my transmission by using the cooler lines up front.
But I don’t know which is side is the out flow back to transmission l hope I said that correctly.
I changed filter and gasket 15000 miles ago.
Can someone tell me I have a 85 300sd California model.

Thanks in advance

greazer2b

JHZR2 · #2 07-01-2019, 07:36 AM

Just a thought, but if you changed everything that short of a time ago, you might consider just extracting the amount in the pan via vacuum and then refilling with fresh. Possibly not as “complete”, but also more gentle and uses a lot less fluid.

The drain and refill is my favored way to do intermediate service...

Sugar Bear · #3 07-01-2019, 09:08 AM

I don't know but if you can detect a temp difference between them after the trans is fully up to temp, the hotter one would be outbound from the transmission.

Good luck!!!

ROLLGUY · #4 07-01-2019, 11:17 AM

I made up a hose with a banjo bolt and connected it to a blower nozzle. It can be connected to either side, as it pressurizes the whole system. You can also just use a rubber tip blower tight against the banjo fitting (bolt removed). If you do this with the filter removed, and converter drained, you will get most of the old fluid out of the system.

barry12345 · #5 07-01-2019, 12:04 PM

Is flushing really a good ideal on older transmissions? If it is working well removing the fluid from the torque converter and changing the balance of fluid is about all I would want to do. Plus the filter of course.

You get most of it that way and perhaps less risk involved.

vwnate1 · #6 07-01-2019, 12:13 PM

You must drop the pan and replace the filter or you're wasting time and effort .

As mentioned, the Mercedes torque converter has a drain plug that requires a 5MM ATF allen tool to remove, this is important because it acts like a centrifuge and traps dirt & silt in it .

Lazy 'mechanics' will always come up with B.S. about new fluid ruining and old tranny......

CDTurbo001 · #7 07-01-2019, 02:55 PM

With a drain plug in the converter, a "flush" as it's normally done is mostly pointless and unnecessary trouble. If you're having trouble that one complete drain+filter hasn't solved, a flush isn't going to solve it either. If you're just maintaining it, change at 15K instead of 30-50K as is normal.

DeliveryValve · #8 07-01-2019, 03:15 PM

I guess I am in the minority. I am a big fan of flushing, I think it's the best and quickest way to get all the old fluid and particles out of the system.

My procedure..

1. Get 16 quarts (4 gallons) of desired new ATF
2. Slightly overfill transmission by 3 quarts through the dipstick tube. Overfilling will not hurt the trans in this short time.
3. Disconnect drivers side transmission cooler hose from radiator
4. Find a bucket that is deep enough and can fit under your raised car. You are going to mark out 3 quarts and if you can, a 6 quart line.
5. Place drivers side trans hose in bucket
6. With an assistant observing, Start car and drain old dirty fluid in 3 quart increments. Idea here is to not run the trans dry, not good if you do.
7. Stop engine and refilling with 3 quarts through the dipstick tube.
8. Continue cycle until transmission fluid runs out clean
9. Drain and drop fluid pan
10. Replace filter, reinstall pan and add correct amount of fluid.
11. Bring to operating temp and run through gears.
12. With it at operating temp and on level ground. Check the fluid level add if necessary.
13. If overfilled disconnect the drivers side transmission cooler hose from radiator and drained in small increments until correct level.

I've done this several times for years with my various w123 and w126 models I've had for my standard trans maintenance. Just remember you don't want to run the trans dry.

.

dieselworks · #9 07-01-2019, 07:46 PM

I saw a video on your tube that explains when it isn't wise to flush the transmission. It's when the transmission fluid is very dark. If dark the fluid has clutch particles that when removed will allow the clutches to slip. Otherwise you'll be having to rebuild the transmission.
I've also heard about dislodging crud in the valve body and the transmission won't shift properly.
But if the transmission fluid is still pink you needn't worry about a flush.
Back in the old days you would pull the transmission stick and look and smell to check the condition of the fluid.
My experience...i have yet to find a transmission with dark/burnt fluid. But one should always check.
Roddy

Sent from my SM-G900I using Tapatalk

ROLLGUY · #10 07-01-2019, 08:33 PM

Quote:

Originally Posted by DeliveryValve

I guess I am in the minority. I am a big fan of flushing, I think it's the best and quickest way to get all the old fluid and particles out of the system.

My procedure..

1. Get 16 quarts (4 gallons) of desired new ATF
2. Slightly overfill transmission by 3 quarts through the dipstick tube. Overfilling will not hurt the trans in this short time.
3. Disconnect drivers side transmission cooler hose from radiator
4. Find a bucket that is deep enough and can fit under your raised car. You are going to mark out 3 quarts and if you can, a 6 quart line.
5. Place drivers side trans hose in bucket
6. With an assistant observing, Start car and drain old dirty fluid in 3 quart increments. Idea here is to not run the trans dry, not good if you do.
7. Stop engine and refilling with 3 quarts through the dipstick tube.
8. Continue cycle until transmission fluid runs out clean
9. Drain and drop fluid pan
10. Replace filter, reinstall pan and add correct amount of fluid.
11. Bring to operating temp and run through gears.
12. With it at operating temp and on level ground. Check the fluid level add if necessary.
13. If overfilled disconnect the drivers side transmission cooler hose from radiator and drained in small increments until correct level.

I've done this several times for years with my various w123 and w126 models I've had for my standard trans maintenance. Just remember you don't want to run the trans dry.

.

Sounds like a lot of unnecessary waste of fluid. Once the pan and filter are off, and the converter drained, all that is left is blowing out the cooler. There is not much more fluid left in the transmission to be gotten out.

Sugar Bear · #11 07-01-2019, 10:00 PM

The OP changed the filter 15K miles ago so it should be ok to leave it in.

My $0.02 is exchanging the fluid using the cooler lines is fine IF you don't damage the threads on the radiator whilst removing the cooler hose. It is essentially no different than how the fluid moves during everyday operation of the car.

Flushing in my opinion/understanding is sometimes done with a chemical cleaner, under pressure from a machine and with the possibility of pushing the fluid in the direction opposite normal flow. This flushing scenarion could cause problems and is different than a simple fluid exchange.

Since this Benz has a pan drain plug and a converter drain plug I'd probably just drain them and not mess with the transmission cooler lines.

Good luck!!!

party · #12 07-01-2019, 10:16 PM

I'm with those who say to drop the pan and drain the torque converter and not deal with a flush. I've done the cooler line flush method on a car that didn't have torque converter drain and it does go by quickly. But I'm of the mind that since you have to go under the car you may as well just let gravity do its work.

I feel the same way about oil changes, in that while I generally prefer to use vacuum method, for cars that require getting under to change the filter I drain the pan from the plug while I'm down there. On cars with oil filters that can be accessed from under the hood or wheel well I rather use the extractor.

greazer2b · #13 07-02-2019, 07:13 AM

Thanks for all the Great reply’s

This tranny has 367,000 on it & religiously has filter and fluid done at 25,000 miles during my ownership these past 10yrs.

Tranny fluid is only $20-25.00 cheap insurance for peace of mind, I’m currently making a run of 750 miles a week for the next 4 weeks and just thought about doing a flush or extraction method while changing oil, before the 25000 mile comes up.

I would never consider a power flush like is done a chain stores for these cars

Maybe I’m just being to picky but I Love my Benz

and can’t help wondering if theres not another way to take care of Alfred.

You have given me a lot to mull over today as I make my second run today back to STL.
You guys are best

greazer2b

DeliveryValve · #14 07-02-2019, 11:25 AM

Quote:

Originally Posted by ROLLGUY

Sounds like a lot of unnecessary waste of fluid. Once the pan and filter are off, and the converter drained, all that is left is blowing out the cooler. There is not much more fluid left in the transmission to be gotten out.

Point here is "washing" down the interior of the trans with new fluid to remove the contaminated material that coats interior of the system. You'll never remove that with a simple drain and blowing out the cooler line, it'll just contaminate the newly installed fluid. My stated 16 quarts is probably overkill but it's just to cover yourself just in case you run out of fluid while flushing.

In reality I generally use about 9 to 10 quarts for the service. You can save yourself some fluid by draining the pan first. Or first doing the filter change and cleaning the pan, then do the flush.

I've also flushed at a 20k interval, dropping and changing out the filter every 40K. When you don't change the filter, you can get away with less than 2 gallons.

But if you know your trans is dirty and don't want to waste your expensive fluid, I've done flushes where I used a $12 per gal Walmart Supertech ATF as the initial flush to push all the old fluid out. Then you continue to flush with the desired fluid you want to run.

Like I said earlier, I am in the minority and it has worked very well for me. And your procedure has been good for you and that's cool too.

vwnate1 · #15 07-02-2019, 11:36 AM

Most Mechanics get to see and smell, a LOT of burned ATF ~ few people ever service their slushboxes until it fails .

In addition to running a repair shop I used to build low co$t used cars as my shop was in a College town, every slush box that came in had the tranny pan dropped because all the flusing in the world won't get that thin coating of black crud off .

Doing a preemptive fluid and filter change is the smart money .

When it comes to high mileage vehicles, no fault in doing overkill .

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