85 300D Radiator bottom nozzle leak - PeachParts Mercedes-Benz Forum

Graham · #1 10-24-2015, 04:09 PM

I had noticed a few drips of AF on garage floor. Had a look today and glad that I did!

The leak can be seen in the pic below. Presumably that is a transmission cooler line? As you can see from second picture, the nozzle nut completely split into pieces. This without touching it.

I did a search and found that someone on MBCA site had exact same problem on a 300SD some years ago. He was able to fix it (he was a guest, so no way to contact him)

Questions:
- any one here on Peachparts had this problem?
- How to disconnect transmission fluid flare nut? Seems like I would need to grip the threaded nozzle, which could damage it.

leathermang · #2 10-24-2015, 04:17 PM

I think a transmission cooling line will drip red transmission fluid instead of green engine coolant...... where does the other end go to ?

Graham · #3 10-24-2015, 04:24 PM

Quote:

Originally Posted by leathermang

I think a transmission cooling line will drip red transmission fluid instead of green engine coolant...... where does the other end go to ?

The leak is out of the radiator, not the flare nut.

leathermang · #4 10-24-2015, 04:26 PM

Why do you call it a transmission cooler line..
and a transmission fluid flare nut ?

Graham · #5 10-24-2015, 05:15 PM

Quote:

Originally Posted by leathermang

Why do you call it a transmission cooler line..
and a transmission fluid flare nut ?

Because that is what they are. Probably don't have them on a 240D.

Graham · #6 10-24-2015, 05:19 PM

I was hoping to get an answer from someone who has had same problem, understands it and has fixed it.

Mxfrank · #7 10-24-2015, 05:22 PM

The transmission cooler side is welded to the cooler...it wont turn. If the flare nut isn't frozen, you should be able to get it off with a wrench. If it is frozen, you'll need a new radiator AND a new hose, not that the hose is that big of a deal. You might be able to carefully split the nut with a dremel, but hopefully you won't have to go there. I suspect that if you can find a jam nut that will fit the transmission cooler fitting, you can pack it with teflon or maybe a rubber washer and fix the leak. If it was me, I'd prefer to replace the radiator, as this is probably the first sign of worse trouble coming.

I see no problem with green coolant, but if you post here, you should expect a scolding.

Stretch · #8 10-24-2015, 05:33 PM

Quote:

Originally Posted by Mxfrank

...but if you post here, you should expect a scolding.

Really?

Not from everyone!

cooljjay · #9 10-24-2015, 04:28 PM

Your using green coolant, which is a no no in these cars....

Chances are you'll need a new radiator.....I don't think that can be fixed....

Have you checked the trans fluid, to see if the coolant has mixed with the ATF? That is certain death for the transmission....

Stretch · #10 10-24-2015, 05:20 PM

I'm concerned if you are leaking coolant from the nut for the transmission (ATF) cooler connection. If the leak is coming from that union it should be bleeding red ATF.

If you get coolant in the transmission the transmission dies pretty quickly as the coolant mixes with the oil to form a horrific emulsion that ain't never coming out with out some serious dismantling and scraping.

(If you want to see emulsion damage in a 722.303 I have pictures in this thread 722.303 in bits photo shoot )

Mxfrank · #11 10-24-2015, 05:25 PM

Quote:

Originally Posted by Stretch

I'm concerned if you are leaking coolant from the nut for the transmission (ATF) cooler connection. If the leak is coming from that union it should be bleeding red ATF.

He's bleeding coolant from the nut that holds the cooler in place in the radiator tank, not from the flare nut. From what's been shown here, there's no evidence that the cooler has been breeched.

Stretch · #12 10-24-2015, 05:30 PM

Quote:

Originally Posted by Mxfrank

He's bleeding coolant from the nut that holds the cooler in place in the radiator tank, not from the flare nut. From what's been shown here, there's no evidence that the cooler has been breeched.

I thought the radiators were physically split - top half air : coolant for the engine. Bottom half air : ATF for the transmission.

I don't think the "ATF part" of the radiator is mixed with the "coolant" part of the radiator. There's not some sort of weird three phase cooling relationship going on. The air does the cooling => it goes through fins for the coolant. It goes through the fins for the ATF. I think of the ATF cooler as a separate cooler much like an oil cooler that just happens to be physically attached to the bottom of the radiator.

leathermang · #13 10-24-2015, 05:34 PM

Quote:

Originally Posted by Stretch

.....I think of the ATF cooler as a separate cooler much like an oil cooler that just happens to be physically attached to the bottom of the radiator.

Or to the side....

Stretch · #14 10-24-2015, 05:36 PM

Quote:

Originally Posted by leathermang

Or to the side....

Sure OK but I don't think the two meet. If there's coolant leaking through to the transmission "side" I don't think that's a good thing. Meaning I don't think it is designed that way.

I could be wrong but I don't think the transmission cooler sits in a bath of anti-freeze.

Graham · #15 10-24-2015, 05:41 PM

Quote:

Originally Posted by Mxfrank

He's bleeding coolant from the nut that holds the cooler in place in the radiator tank, not from the flare nut. From what's been shown here, there's no evidence that the cooler has been breeched.

Thank you Mxfrank! That is correct.

In searching net, I have found several posts where owners have had same problem. Dealer even sells the nut and a seal washer. I will order these Monday. Just hope the flare nut comes apart easily. May have to protect threaded nozzle and hold with vicegrips.