My heater core hose has a plastic piece in the middle with a screw-top... is that normal? What would be the purpose of having that?


I'm asking because it's leaking coolant where the plastic piece connects to the hose closest to the firewall (you can actually see a drop in the picture).


1983 300D w/ ~325k miles.


Thanks.

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I doubt if it is stock. It looks like one of the items I have seen as a setup to flush the cooling system. Do a google image search and look up some flushing kits and you might see something similar.

I would be more curious to know what condition it is in considering plastic might not hold up.

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84 300D, 82 Volvo 244Gl Diesel

I have a similar kit to the one in the attached pic that I have never used for anything (it was on a barging table at some cheap tool outlet place and I bought it because it was cheap and might have some future use). I don't think they are made do be mounted in the system permanently. However, someone else is going to have to comment on that.

Is there another one someplace in the system along the passenger side of the Block?

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84 300D, 82 Volvo 244Gl Diesel

I doubt it.

I have never seen what is in your picture as stock on any of the 617 engines I have encountered. Nor have I seen it shown in a factory diagram.

I agree with Diesel911's previous two posts in this thread.

Definately an aftermarket flush kit fitting. I mounted mine in the same location. After 10 years the plastic softened and it began a slow leak. I bridged it with a brass pipe nipple until the replacement hose arrived.

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Gwizzer
'82 300D

Ah, it being an aftermarket flush piece makes sense.

Could not find another one on the passenger side, or anywhere else.

ill be replacing it soon with a stock hose, so i'll take pics and report back.
i tightened the clamp, but it still leaks. my guess is it's developed a crack.

it's been in the car since I've owned it (~8 years).

Those Prestone flush tees always crack as they age. I used one when I was young and dumb on my 1969 Dodge Dart. You can replace it with a 5/8" copper tube. I don't know if that hose is still available. If you fab your own like I did, note that the side at the engine is much larger OD. I used 2 sizes of silicone hose.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

turns out yes, the flush piece developed a crack along one of the necks (see pics).

i replaced the entire thing (plastic flush piece + 2 hoses) with one genuine mercedes hose. no more leaks.
(the hose closest to the firewall wouldnt come off and was very stubborn... had to cut it off with a razor blade.)

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It is good that you caught it before it caused real trouble.

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84 300D, 82 Volvo 244Gl Diesel