I have an 1986 300sdl with 120,000 miles. My mechanic used to recommend not changing the tranny fliud. He has recently passed away. My new MB mechanic says I should change the oil and have the tranny flushed. What do you guys say? Thanks

My old 90 dodge van had 279,000 miles and I took it to have the fluid and filter changed. The trans shop wouldn't do it. They said over 200,000 not to touch it anymore. I followed their advice.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

The shops don't like to touch 'em, because they're old enough that they could fail at any time, and if you're the last one who worked on it, you're going to get blamed.

Do change the fluid and filter, don't flush it. Use the same fluid as has been used is preferrable, a new formulation with different seal swell characteristics can cause problems.

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Gone to the dark side

- Jeff

I had attempted to have the fluid changed on the '86 about one year ago. If you are going to change the fluid, it's mandatory to drain the t/c in the process. However, we could not find a drain plug on the t/c for the SDL and, therefore, I had to resort to the flush.

So, if you are going to drain it.........see if you can locate a drain plug on the t/c. There is another member who also failed to find a plug on this vehicle.

If you cannot find the plug, you're forced to flush it. Leaving three quarts of old fluid in the system is not what you want to do.

Recommend changing trans oil and filter. Do not know about flushing. Oil is easy to drain using pan plug. Some quick oil changes can help take the place of t/c drain if not done. I found trans maintenance records scribed in pan.

256k on my tranny so far....had it re-sealed at 213k and they said it had very little wear inside. I changed the fluid around 225k to synthetic, and will be changing it again in a few weeks. Full drain, pan, filter, torque converter, 8 new quarts of Mobil 1 Synthetic ATF and filter kit.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Note t all about the T/C drain plug. If the T/C is not the original, for some reason, or another, it may not even have a drain plug. Very often, aftermarket units, or even factory replacements, do not have this feature. I don't know why, but I do know I've seen it, first hand on a lot of occasions. If the car has ever had the tranny, or just the torque converter changed, for whatever reason, there's a high probability it won't have one.

Maybe that explains it. The trans on the '86 has definitely been replaced at some point in its life. We searched for that plug for 15 minutes and never found it.

I have had difficulty in finding the Torque converter drain.....but....I found that it "on my car" is located at a point that is never visible at points where the engine rests......I removed the glow plugs, and only then could I rotate the engine and get the plug at a point where it is visible and removable.....

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

Clearly, that's certainly true.

We pried the engine around twice, using the teeth on the t/c, and never found it.

My views on having the trans "flushed". I don't work on auto trans as such but I get a lot of them from transmission shops (including some AAMCO's) that say they have computer problems. I see a lot of NO SHIFT problems and a lot of cases where the trans was just FLUSHED. I have talked to my local trans shop and he says since the FLUSH machines came out, he has cleaned or replaced more valve bodies than ever. So please don't have a transmission flushed but please do service it including the filter. If you can't drain the converter than double the service interval.
Just my $.02 based on experience.

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84 500 SEL (307,xxx miles)

A note:
I have not yet found a reputable auto-tranny shop which recommends tranny flushes, I'm told that they have potential for trans damage. It is preferred to just change the pan fluid a couple of times instead.

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Gone to the dark side

- Jeff

What's the potential for damage? Fluid goes in one side and comes out the other side.........very low pressure system.........engine is not running.

I don't know, contamination? Overfilling? I've asked the question of transmission techs and that's something they actually seem to agree on. I guess I should have spent more time and asked why.

__________________

Gone to the dark side

- Jeff

I definitely agree on overfilling, however, that problem is not unique to a flush. They can just as easily overfill it with a conventional pan drop and refill.

Contamination is certainly a possibility........but.........the oil comes from the same 55 gallon drums that they use for the conventional fill..........