any one ever replaced the heater core? - PeachParts Mercedes-Benz Forum

JDmills · #1 01-12-2005, 09:39 PM

I think I have a hole in my heater core. There is a sweet smell when I first turn on the heat in the morning. Any one ever done this job? I cannot even immagine how to get to it. Of course the Haynes manual does not even mention such a job in it's pages.

Also, does any one know how to drain ALL the coolant out of the engine block? I drained the radiator, and replaced the thermostat last month, but only got a little more than a gallon of coolant out. seems like there should be almost another gallon in there, but I cannot figure out how to get it to drain. It needs to be done, as I later discoverd that the car had green antifreeze in it, and I refilled it with the G-05 stuff... the coolant had so much rust and sediment in it that it looked, well rusty but pinkish, until the rust settled out a couple of days later. Now I have to drain and flush, the mixed junk out. All adivce welcomed
Thanks,
Jason

mplafleur · #2 01-12-2005, 10:23 PM

There is a drain plug on the side of the block. Drain and flush with water first.

I've replaced the heater core on a w201 body and a w115 body. Neither were easy as it means taking the whole dashboard out. Makes sure it's really yhe heater core as it could be a leak in a line or at the connection to the heater core. Try to find where the leak is. Look for coolant under the floor mats or under the car.

boneheaddoctor · #3 01-12-2005, 10:49 PM

Quote:

Originally Posted by JDmills

I think I have a hole in my heater core. There is a sweet smell when I first turn on the heat in the morning. Any one ever done this job? I cannot even immagine how to get to it. Of course the Haynes manual does not even mention such a job in it's pages.

Also, does any one know how to drain ALL the coolant out of the engine block? I drained the radiator, and replaced the thermostat last month, but only got a little more than a gallon of coolant out. seems like there should be almost another gallon in there, but I cannot figure out how to get it to drain. It needs to be done, as I later discoverd that the car had green antifreeze in it, and I refilled it with the G-05 stuff... the coolant had so much rust and sediment in it that it looked, well rusty but pinkish, until the rust settled out a couple of days later. Now I have to drain and flush, the mixed junk out. All adivce welcomed
Thanks,
Jason

there is a block drain about the level of the starter just behind the pass side motor mount, but just above it on the horizontal plain. get a flashlight its there but tough to see.

JDmills · #4 01-13-2005, 10:36 AM

Ahh, I got the drain plug in my sights thanks. ... Not in a hurry to play with the heater core!! Just afraid that it may be the culprit. would doing a low PSI pressue test while it is on the car be an option? And is there more than one heater core? seems as if there should only be two tubes for a single heater core, but these cars have four options where coolant flows into the firewall.. How confused am I?

leathermang · #5 01-13-2005, 12:13 PM

"the coolant had so much rust and sediment "

I don't believe that just finding the drain plug is going to do what you need/want to do.

In the old days... car engines would need rebuilding every couple of 100k.... and proper rebuilding was understood to be Vatting the block before starting back up with replacing stuff... This is a full immersion caustic bath and then cleaning that off the block... all done WITH THE CORE PLUGS REMOVED.... ( also called freeze plugs ).... This would take care of the rust sediment in the coolant cavity until the next rebuild.

Many of us are driving cars which the engines have never been rebuilt (with twice the number of miles old gas engines used to go )...and even many of those rebuilt were done without stripping the block and Vatting it...

I think what you need to do is take out the core plugs... and get a wand which will alllow you to blast the recesses of the coolant cavity while using a wet vacuum to get it out fast enough to allow plenty of unobstructed blasting in the corners...

When you just open the drain plug the flow is not fast enough....and the opening is not big enough to get that sediment out....and you have no way to ' excite' the sediment in the area away from the drain plug.

It might even be helpful to make your own nozzle if you can... their is a design in one of " The Home Mechinist's Bedside Reader" would be a good design.

dmorrison · #6 01-13-2005, 02:16 PM

You don't want to replace the heater core if you don't have to. The job requiers removing the center dash, dash and the heater/evaporator box. taking that apart and replacing the heater core. a large job. I know I had to replace the evaporator in my 82 300TD.
chack all the connections in the engine bay. at the fire wall are 4 tubes that the hoses are connected to. Make sure the clamps are tight. And make sure the tube the firewlal seals are tight. Hopefully the clamp is loose and the antifreeze is leaking into the heater box.

Part 2. If the core is leaking then try this method to repair it before you remove the dash. Find a pump and mix some water in a large container. Add radiator leak stop and pump the mixture JUST thru the heater core. Isolate the core form the rest of the car/engine system. Hopefully you wil be able to seal the core this way and not have to replace it. The leak stop works by drying and hardening when exposed to air. So as it leaks out the heater core it will dry and plug the leak. Larry Bible tried this method with success. It's worth a try. Your heater core is divided into 2 halves. That is why you have 4 tubes. You may try to determine which half has the leak by isolating the halve over time and seeing if the smell goes away. then you can try the pump method on the leaking half.

To see what's involved in getting to the heater core search for my post on replacing the evaporator in my 300TD.

Here is the car with the dash out, scroll down.

Order for installing evap box in a W123.

Dave

rwthomas1 · #7 01-13-2005, 10:07 PM

If the car is not running hot and has never given that kind of trouble then tearing it apart to get the crap out of the cooling system may not be worth your time. I flushed the cooling system in my truck over a period of a month last summer. I would flush and refill with fresh water every other day for a month or so. Lots of crap came out with the method but it takes a while. I would do this and then add your prefered coolant and a 1/2can of Bar's Leaks. Put the Bar's Leaks in and drive around with the heat on max for a 1/2hour or so. No more leaks. Worked for me. Oh yeah, I also run a 7psi rad cap. Less pressure on the old cooling components is a good thing. RT

Tirebiter · #8 01-14-2005, 02:32 AM

I would rather wear Rosanne Barr's panties like a ski mask than have to replace another Mercedes heater core

Use a cooling system pressure tester to test it first. I pump in about 15 pounds of pressure and I expect it to hold for five minutes.

Through the years I have been lucky enough to save a few by running a warm water stop leak solution through them and then flushing an hour later.

rwthomas1 · #9 01-14-2005, 01:41 PM

[QUOTE=Tirebiter]I would rather wear Rosanne Barr's panties like a ski mask QUOTE]

Wow, how big is your head? Would have to be at least 3ft wide.... RT

JDmills · #10 01-15-2005, 06:29 PM

I really like that Idea about hot water/radiator stop leak!!! that will be my first attempt. (and the second)

The car used to overheat, but a new thermostat fixed that.

tomorw I will try and flush the cooling system. as well as replace the modulator valve... my heater fan, quit, does that mean the climate control system is done?? If so it is my own dang falt..

what would happen if i was to bypass the modulator valve? Actually I had better check the fan, as I recall there was some heat comming out of the defroster vent, through convection, thus the modulator valve must have been open. Any way, thank you for the help.
Jason