slow heater core leak - PeachParts Mercedes-Benz Forum

mechanicalman · #1 05-03-2008, 11:45 PM

i've got a super slow coolant leak (took 2 months to loose a noticeable amount) and i've noticed a slight glycol smell when i open the heater core valves. the smell isn't always there and it seems to go away after a few minutes of running the heater. i expect the leak is swelling back shut as the metal expands.

i'm not ready to pull out the dash to change the heater core since i've looked at the diy article and the problem just doesn't bother me enough to warrant such an effort.

question: are there any radiator stop leak products that you guys would recommend to stop such a leak? some seem like they'll just clog up the heater core without fixing anything.

/shiftless

Stevo · #2 05-04-2008, 10:11 AM

Dont see allot of heater core problems. Take a real close look at the double heater valve on the fire wall. I wouldn't use any "stop leak", its hard enough keeping these engines running at the right temp

mechanicalman · #3 05-05-2008, 07:35 AM

cool, i'll do that, but why would a leak on the engine compartment side of the firewall cause me to smell coolant inside the cabin?

winmutt · #4 05-05-2008, 09:59 AM

Done use any stop leaks. Despite the other memebers assessment, heater core leaks are quite common. More because of the labor involved to replace it vs just leaving it be. It is a SERIOUS PITA to replace the heater core. You pretty much have to remove everything down to the firewall.

Stevo · #5 05-05-2008, 10:11 AM

The heater valve is above the exhaust header pipe, not likely to be the answer but something to check before ripping into the dash

, especially since leaking heater cores in W123s isn't a real common problem. Just wipe your finger under each side if the valve and check for moisture. Good luck

Stevo · #6 05-05-2008, 11:17 AM

Quote:

Originally Posted by winmutt

Done use any stop leaks. Despite the other memebers assessment, heater core leaks are quite common. More because of the labor involved to replace it vs just leaving it be. It is a SERIOUS PITA to replace the heater core. You pretty much have to remove everything down to the firewall.

I hardly think leaking heater cores could be considered a"common" problem, matter of personal opinion of course , oh, and the high number of posts about "leaking heater cores"

winmutt · #7 05-05-2008, 12:53 PM

Quote:

Originally Posted by Stevo

I hardly think leaking heater cores could be considered a"common" problem, matter of personal opinion of course , oh, and the high number of posts about "leaking heater cores"

The instances of them happening, infrequent. The chances of it being repaired, very infrequent. I have seen many that had that special smell.

DieselAddict · #8 05-05-2008, 02:35 PM

I will have to dissent here and personally I'd recommend Bar's Leaks Radiator Stop Leak (I think that's what it's called). However I'd also recommend only running it through the heater core and nothing else. The way you do this is by using an additional aux. water pump (the electric kind, get one from a junkyard) and temporarily connecting some hoses to circulate the Stop Leak / hot water mix only through the core for at least 15 minutes, then flush it with clean water. It worked in my 240D and fixed the problem completely (system maintained perfect pressure afterward) and the heater continued to work just as good as before. I got this recipe from LarryBible. Do a search and you might be able to find his original post with more detail. He's stated that even after 10 years this "fix" was still holding up well.

winmutt · #9 05-05-2008, 02:46 PM

Oh ah. Now that is a good idea. I think I will do this on my wifes car. I started pulling the core from my parts car and gave up about 4 hours into it.

Stevo · #10 05-05-2008, 03:07 PM

Quote:

Originally Posted by DieselAddict

I will have to dissent here and personally I'd recommend Bar's Leaks Radiator Stop Leak (I think that's what it's called). However I'd also recommend only running it through the heater core and nothing else. The way you do this is by using an additional aux. water pump (the electric kind, get one from a junkyard) and temporarily connecting some hoses to circulate the Stop Leak / hot water mix only through the core for at least 15 minutes, then flush it with clean water. It worked in my 240D and fixed the problem completely (system maintained perfect pressure afterward) and the heater continued to work just as good as before. I got this recipe from LarryBible. Do a search and you might be able to find his original post with more detail. He's stated that even after 10 years this "fix" was still holding up well.

GOOD info..Thanks

mechanicalman · #11 05-06-2008, 08:06 AM

Quote:

Originally Posted by DieselAddict

I will have to dissent here and personally I'd recommend Bar's Leaks Radiator Stop Leak (I think that's what it's called). However I'd also recommend only running it through the heater core and nothing else. The way you do this is by using an additional aux. water pump (the electric kind, get one from a junkyard) and temporarily connecting some hoses to circulate the Stop Leak / hot water mix only through the core for at least 15 minutes, then flush it with clean water. It worked in my 240D and fixed the problem completely (system maintained perfect pressure afterward) and the heater continued to work just as good as before. I got this recipe from LarryBible. Do a search and you might be able to find his original post with more detail. He's stated that even after 10 years this "fix" was still holding up well.

this is the kind of solution i was looking for. i'll let you guys know how it turns out. (after inspecting all the pertinent hoses).

jkoebel · #12 05-06-2008, 09:58 AM

Awesome tip about aux. water pump + heater core circulation for stop-leak.

DieselAddict · #13 05-06-2008, 12:39 PM

I'm glad I could help.

mechanicalman · #14 12-12-2008, 01:25 PM

allright, this is kind of old now, but just to close the thread; i got an electric aux pump and was ready to do the fix, but when i touched the hose going from the engine block to the heater core, it was entirely too loose.

turned out, the coolant smell was from it leaking into the tiny opening between the firewall and the heater core line entering the engine compartment.

dieseladdict had the best idea, but steveo had the solution. thanks for the help guys

DieselAddict · #15 12-12-2008, 01:35 PM

Good to hear you solved your problem. Solutions are only good if the diagnosis is correct.