You might want to check with Holmesuser01 from Asheville. I am pretty sure I read a thread he just recently did one on a 1984 201. I am not sure if they mirror a '91 or not.

Hey guys.

The dash is not as horrible as one other car I did a core on, but it's close.

The whole dash basically has to come out so you can loosen and remove 4 bolts, and basically lift out the heater box. This is after disconnecting vacuum lines, etc, and in the case of my car, figuring out what the heck the previous owner did when they replaced the same core in 1999.

I put everything back the way its shown in the service manual.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

I can see exactly where the leak is. its coming from the driver side metal pipe connector which appears accessible from the driver side. My question is do I still need to remove the entire dash to take off the pipe and also is there a gasket or something in there that needs to be replaced?

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1990 190E 3.0L

+1, it's your heater core! Both sides of the heater core are plastic, they do crack. Most likely the crack is near the pipe, that's why you think the o-ring have failed.

Coolant flows from the engine's driver side into the heater core & out to the aux water pump. So if you want to bypass the "LEAKING" heater core, you either have to install a ball valve on the engine's driver side too or run a hose from there to the aux water pump.

I did mine 5 years ago. Yes, looks pretty scary...but actually not too bad, just time consuming.

Like Holmesuser01 said, you have to remove that metal bracket & nylon divot, before the pipe can be loosen (see pic#2).

Pic#3 shows the pipe on the right side attached to the heater core, notice the sides are "PLASTIC".

Pic#4 shows the pipe removed from the heater core, pipe inserts into core ~1/2". Also shows the evaporator (after the heater box is removed) on the other side of the fire wall. NOTE: Evaporator can only be removed from the engine bay.

Pic#5 shows the heater box removed, you have to take apart the heater box to replace the heater core.

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85' 190E w/collector plates

Cypress, Good pictures. I know these views!!!

And when you take the heater box apart, be aware of the locations for all of those little clips that hold the heater case together, and make sure they are all put back correctly.

Label where the vacuum lines go on the heater box, too. Will save time, later.

I took the trouble to clean the inside of the heater box thoroughly, though I didnt take any pictures of it. Removed smoke and general filth that flowed through the system over the years.

It's worth the extra work.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

If you do decide to replace the heater core, replace the rotted foam seals on the heater box as well. Also the vacuum pods should be replaced at this time, otherwise you'll regret it later.

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85' 190E w/collector plates

I didnt replace the foam. I DID replace the vac motor on the top of the heater box, and the one on the left side above the instrument cluster.

Should-a replaced the foam. The only foam I replaced came with the new core.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.