Heater Valve

[timjshanahan]

Hello all, when I purchased my 69 280SL, the heater core was bypassed. I did a smoke test on it today and found the O ring was leaking. I was able to manually open and close the valve, so I'm hopeful that all I need to do is replace the O ring. The Sealing ring, heater valve O ring is available from Authentic for a few bucks. I'm sure that I'm missing something here, but where are the gotchas when replacing this O ring. Would you consider this a difficult process? Is the heater core removal a difficult process.

Thanks again for the knowledge transfer.

Tim

[ja17]

Those with experience and skill can replace the o-ring with the heater core and valve still in the car. There are many pit falls, the biggest of which is dropping small parts into the "dark abyss" never to be seen again.

Removing the whole assembly from the car is tedious and difficult also it involves removing the heater controls, glove box, ac evaporator unit, and more.

In the car replacement of the o-ring is the best option. Get familiar with all the parts and get good advice every step of the way.

[timjshanahan]

Thanks for the reply ja17. This process might be too much for me, so hopefully my mechanic can manage this. My car is a non AC car, so if the heater core needs to come out, it might be a little easier otherwise. Thanks again.

Tim

[lowpad]

FWIW, I just took out the fan box on my 230SL due to a cranky blower motor (somewhat easier with no A/C and no radio). After reading the many helpful posts here on the subject, I felt informed enough to take it on. It is tedious, but it's not an impossible task as long as you don't move too fast and document every step. I thought that extricating the blower would be it, but once the heater core was uncovered, I discovered that it had come loose from its brackets and that it, too, now needed to be removed to be resoldered. Haven't started that yet, but it looks fairly straightforward.

The one thing that would be helpful in all of this would be detailed photos of all the added foam that pervades the system. Like most of our cars, I suspect, my foam turned to dust as I was taking it apart and it would be really helpful to have some photos of the correct foam installation for all the relevant components -- as well as specs for the type(s) of foam to use.

[timjshanahan]

Thanks lowpad, I'm hopeful that the valve is the issue and my efforts will be localized to the o ring. As with most projects, it will most likely be deeper and more complex.

[timjshanahan]

One more point, Authentic also sells a Heater Valve Core for $45. Would your suggestion be to replace the existing valve with the new valve or just replace the O ring for the valve? Does the valve have to come out to replace the O ring?

[WRe]

Hi,
Replacing the sealing ring in the heater valve is no rocket science. Use a spark plug to pull the valve out: https://www.sl113.org/wiki/Electrical/HeaterControlValve.
I recommend using an X-ring instead of the O-ring as it allows the valve to move more easily and still safely (17,6 x 12,3 x 2,62mm; https://lelebeck.de/17501.htm).
Dismanteling the entire heating system is a tremendously unpleasant job: https://www.sl113.org/forums/index.php?topic=36270.msg265019#msg265019.
...WRe

[timjshanahan]

Thanks again WRe, this helps and thanks for the advice.

Tim

[rwmastel]

Tim,

Search, search, search.  There should be posts from others doing this same work.  Maybe you can find something good in the Tech Manual (wiki)?  These forums have been around 20 years, so your answers are probably out there.

[DavidAPease]

Tim,

I have done this job twice.  There are a couple of things to be aware of.  One is that if it has been frozen in place for a long time, the valve may be very difficult to remove.  Several of us have built extractors using a long (IIRC 4mm) bolt, some nuts, and a socket or short length of pvc pipe.  (I gave my first setup to my mechanic, kept my second.) 

The reason that I have done this twice is that the first time I didn't realize that there are different materials used in "rubber" o-rings, and using the wrong one will cause the o-ring to swell and bind.  Of course, buying the o-ring from Authentic Classics will avoid that problem.

Unless your valve is scored or otherwise deformed, there should be no reason to replace it. 

There is good information on this site about how to orient the valve and the actuating arm attached to it so that it works properly.  (I did this wrong the first time, too.  Nothing like learning from your mistakes!)

            -David

[timjshanahan]

Excellent David, thanks Tim

[timjshanahan]

Thanks guys for all of the help. This project was very easy and took about 10 minutes given your excellent directions and details. Thank you very much for all of the information and direction. One project down several more to go.

Tim

[rwmastel]

Awesome!

[yves]

For LOWPAD i have just fitted my "new" heater core in the car.... Bracket and plate welded , i have fitted a adhesive foam of 8 mm and in some place 20 mm
PANASORB ref : 1345608 and 1345311 . Quite easy after degreasing the surfaces.