Hello.
I'm hoping that someone would be kind enough and maybe shed some lights.
I finally had to bite the bullet and replace the heater core on my 91 190E 2.6 baby.
Using the awesome "How to" from Pelican + lots of cussing i was able to get it it in the end.
Took the replacement Nissen 72002 out of the box and proceed to put it back in the box and this is where i got stumped.
The original core (a Behr going by the inscription on the side) has 2 openings with 2 holes per each opening. The replacement core has 2 openings with 2 holes per each opening as well BUT one of the openings has, what appears to be, a plastic tube connecting the 2 inside holes.
Now is that plastic tube some sort of "guarantee" that the part is brand one and i need to pull it out or somehow did i end up with a wrong part, even though it just like the original ?
I attached 2 pics of the replacement core which shows the 2 openings. Thank you

Attached Thumbnails

   

I'm guessing it's like that to prevent too much force. Also notice the plastic spiral inside other end. Seems like that too is there to break up the amount of force/pressure flow of coolant. However, I could be wrong about it's purpose, but bottom like is that it is normal. Mine also had it.

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1990 190E 3.0L

Thing is that the original one doesn't have anything that "blocks" the holes, two holes on each side, coolant flowing from one end to the other, at least that what it looks to me.
In any case thank you for your input
I'd RMA this one and should get another one, will update once that one arrives.

The spiral is to slow down water flow in the heater core and make it give off more heat. It's a common thing in heat exchangers, some are made of metal. You RMA'ed a functional part. Don't complain when pricing goes up to cover the restocking fees of parts RMA'ed for no reason.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
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Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

The original one ( i say original because it hasn't been changed since 1991) that i pulled didn't have anything ,not even a shred and the "how to" didn't mention anything.
Assuming your statement is correct and the replacement will have the same spiral, where will it go ? Towards the engine or towards the pump ?
Thank you.

My son has done EXACTLY that job, but on a 190D 2.5.

We noticed that strange thing. We placed it on the inlet side, for reasons I cannot recall.

But all is working well, heating, cooling, no leaks etc.

Interesting. Looking forward to other comment on this.

RayH