Wooooo! Let's talk about Flare! - PeachParts Mercedes-Benz Forum

1983/300CD · #1 04-11-2017, 06:30 PM

Model 1982 300CD Turbo
Engine 617.952 12 016925
Transmission 722315 02 178022

The transmission was running perfectly. Was. So, I thought I'd drain the oil and replace the filter. Now it flares between 1-2 and 2-3 when cold. After it warms up, it's back to being perfect.

From all I've read I have learned that the o-ring seal between the filter and valve body could let air in, being above the fluid line. Sounds plausible. I don't remember what brand filter I used the last time.

So my question is about what brand of transmission filter is best, and what sort of preparation should be done to the o-ring seal other than simply wetting it with ATF. And while we're on the subject, is synthetic recommended?

Anybody with any experience with this? Thank you in advance.

Diseasel300 · #2 04-11-2017, 06:52 PM

Did your filter actually have an O-ring? When I did mine I used an OEM filter and it had a cork gasket, not an O-ring. What kind of transmission oil did you use when you filled back up? How is the fluid level? High or low?

1983/300CD · #3 04-11-2017, 07:33 PM

I thought it was a square rubber o-ring. I wouldn't bet my life on it, though. Standard Dexron III / Merc ATF. Fluid level above low, below high, so correct. In park, level, running, hot.

I think it is more correct to say that the problem is resolved after a certain number of shifts from 1-2 and 2-3, rather than the temperature change from cold to warm. This leads me to believe in the fluid-leak, air infiltration theory. I can go gingerly to the main road, and drive for quite a while. When I stop and start going again, it will flare again. If I goose it from the start, it will flare bad that first time, but that will end the problem. I suspect this is doing some damage to the transmission, though.

Diseasel300 · #4 04-11-2017, 09:16 PM

If it wasn't doing it before you did a fluid/filter change I'd plan on dropping the pan and changing that filter and refilling again. Driving it with flaring gear changes will do nothing good for your clutch packs. A filter and fluid for peace of mind is a hell of a lot cheaper than a replacement transmission.

Did anything else get done to the car in the mean time? Is it possible you have a stuck vacuum valve or something causing high vacuum at the modulator all the time?

Mxfrank · #5 04-12-2017, 07:15 AM

The most elementary question is, did you install enough fluid? Low fluid levels would cause a flare.

Maxbumpo · #6 04-12-2017, 08:06 AM

Mann transmission filters seem to be very consistently good (especially for 124 cars), or you could by an MB filter from the dealer.

I've used the Mobil 1 synthetic ATF, and I think it does fine. I would NOT use a generic ATF, only the Febi ATF that meets the spec or M1.

strelnik · #7 04-12-2017, 09:12 AM

Quote:

Originally Posted by Maxbumpo

Mann transmission filters seem to be very consistently good (especially for 124 cars), or you could by an MB filter from the dealer.

I've used the Mobil 1 synthetic ATF, and I think it does fine. I would NOT use a generic ATF, only the Febi ATF that meets the spec or M1.

The guy who rebuilds the transmissions for the local MB dealers rebuilt the trans in a 240D I plan to sell soon.

He puts Dexron-Mercon in the ATs used with the 616 engines. That mush I know.

VT220D · #8 04-12-2017, 09:15 AM

Quote:

Originally Posted by Mxfrank

The most elementary question is, did you install enough fluid? Low fluid levels would cause a flare.

I can attest to that. I got my 85 300d out of winter storage and experienced flare for the first time. I have a small leak that over time left the transmission down a quart. I topped it off and all is well.

Mercedes transmissions are more sensitive to fluid level variations than most other automatics. If your fluid level is OK then I would suspect filter restriction or aeration from a leaky filter seal.

If fluid and filter are OK you might have problems with the vacuum system/modulator. You may want to go through the adjustment procedure to rule out any external cause. Bad shifter bushings and linkage could leave you between detents causing a cross leak between circuits.

There is a valve body repair kit to reduce flare. I have no experience with that kit or how to determine if it's needed. The kit does offer a step between adjustment and overhaul that might solve your problem if all else fails.

Good luck.

Maxbumpo · #9 04-12-2017, 10:38 AM

Mercedes-Benz Specifications for Operating Fluids: Engine Oil, Gear Oil, ATF, Coolant, Brakefluid

According to sheet 231.0 (General Gear Oils), it looks to me as if sheets 236.1, 236.6, and 236.7 would all work with the OP's transmission. All of those ATF's correspond to "no longer valid GM specification Dexron II-D."

Additionally, sheet 236.1 ATF's also correspond to GM specification Dexron III.

Looking at sheet 231.1, for 722.3/4/5, sheets 236.9, .10, and .81 can also be used.

Maxbumpo · #10 04-12-2017, 10:44 AM

Interesting, looks like my favorite Febi ATF is no longer listed. I guess they didn't want to pay to be tested by MB.

1983/300CD · #11 04-13-2017, 10:21 PM

Thank you for the replies, but the fluid level is good, and if it were a vacuum issue, it wouldn't straighten out after the first few shifts. I will do a filter change and report back.

I did replace the pan at the same time that I did the filter change. Though it didn't leak, I felt the bolt holes could sit a little more flush against the transmission. That's a lot of pan for so few bolts, and the gasket is pliable. The new pan came with a plug that has a copper washer painted to it, making it basically one piece. Problem with that is that the washer bites down and creates a good seal the first time. The second time, not so much. Third time? That rucka fricka stupid piece of... So, I guess I'll be getting a plug and washer while ordering a new filter.

1983/300CD · #12 04-29-2017, 09:32 PM

Yeah, that seems to have done it. The filter that didn't seal was a Mann filter (regular cork seal), and the new is a Meistersatz. I wet the new filter with ATF for an hour or so before installing. Don't know exactly why the old one wasn't doing its job, but it's fixed now.

1983/300CD · #13 05-08-2017, 08:54 PM

Well, I spoke too soon. First to second shift is nice and jarring, a good clunk like I wish it wouldn't. But second to third, and even third to fourth are flaring for the first couple of exchanges. What the heck is going on here? Is it possible I have gotten some dirt into the system? Why would the problem resolve itself after it warms up?

Mxfrank · #14 05-08-2017, 10:14 PM

The k1 and K2 accumulator springs may be weak. It's worth pulling the covers to inspect. Do a search on the procedure.

1983/300CD · #15 05-09-2017, 06:46 AM

I changed a couple of springs a couple of years ago with those from the European shift correction kit, whichever few could be gotten to without actually dropping the valve body. It was running fine until that fluid and filter change last year.

If that were the problem, would it straighten itself out after the first few shifts? I'm no transmission expert and this is just a guess, but it seems that fluid is leaving a part of the system where it should stay.