Heater Intake Valve Leak

[Coastal220]

Hi All,

I recently performed a coolant flush (no citrus cleaning) but many water flushings of the radiator, block, and heater. What I think of as a heater intake valve at my bulkhead (I don't know the exact name for this part) has developed two small leaks. The leaks originate from underneath the two slotted screws which attach the cables and control arms.

I did clean the exterior of this unit during my coolant change. It was filthy and I took a toothbrush and a bit of degreaser to it with a toothbrush...

How should I address this problem? Anyone know the kind/size/source of seals?

What is the replacement procedure? Car is a W115 1970 220


Cheers!

[Mike D]

Pull it (three hoses, two cables and two screws), take it apart, clean it, replace the o-rings and re-assemble. Nothing fancy or tricky about the job. Just pay a bit of attention to how the cable levers are mounted.

[Coastal220]

Thanks Mike.

Does anyone know offhand what size o-rings I'll need? I'd like to have them lined up before I take the thing apart.

[meltedpanda]

they will be pesky to source , most likely metric in all dimensions. Take care to remove and then a trip to the parts store or lowes type to match

[Coastal220]

Here's what I came up with:

Four o-rings total, two sizes. It's hard to tell exactly what size they should be based on the existing rings and their seating locations, but I'm about 90% sure they are as shown in the picture and listed:

13mm (ID) x 2.5mm

8mm (ID) x 2mm

Does anyone know if MB was using odd sizes of o-rings? For example, I see some ring widths sold at 1.6 and 1.9 mm; it seems like dimensions to the nearest .5mm should be far more common. Is anyone here an o-ring engineer?

Finally, I'll check at the local hardware store but chances are that I'll just order them from McMaster-Carr. They have Viton® fluoroelastomer which is used in applications requiring chemical and oil resistance. Temperature range is -40° to +400° F. Durometer hardness is A75. Meets ASTM D2000/SAE J200.

The way local hardware stores have become, they would probably charge me the same amount as if I purchasing packs of 10 and 25 from McMaster (I won't even bother going to Lowes/Home Depot). Anyone here need these sizes?

[Mike D]

If you do end up buying a 10 pack then I could use 2 of each size.

[meltedpanda]

good luck, I have been in your posistion and they really have to be exact. IT may be a bit of trial and error as well since there will be some internal wear on that brass
Mine was difficult to get apart, gotta soak it

[Pooka]

If you live in the SF area then you might just check to see if there is an O-ring shop in town. Many large cities have companies that deal in only O-rings and all you have to do is find one, call, and ask for the City Sales desk.

You can then take the entire part in and they should be able to help you measure and spec out the rings so you get the exact ones necessary.

Sometimes there is a minimum sales amount like $5, but I doubt that amount will kill you. You are really paying for their experience with this minimum charge.

And most of the time the City Sales guys love to see these weird projects come in since it lets them use their brain and it breaks up the everyday routine.

And the best part of all? You will get to post here the correct size and type of O-ring. Type? Yup. Some are flat on one side, some are oval.....

And be careful when taking the valve apart. The little cylinders are set-up in a specific way and need to be assembled in the same positions or you will never get it to work again. There's not much to remember here, but be sure to mark them anyway. They are a lot easier to get out of position than you might think.

[Coastal220]

Good point on the local guys. Look who is literally down the street from me:

O Rings l Parker O rings l Metric O Rings l Spiced & Vulcanized O Rings l kalrez - Darcoid

Of course I'll let you know the details.

[Coastal220]

To close out this thread: the o-rings required are:

13mm (ID) x 2.5mm

8mm (ID) x 2mm

The valve unit requires two of each. I cannot say for sure that these are the original MB sizes, but they match the o-rings that were removed from my unit, and so far, no leaks. If I have any trouble I'll update this thread.

[meltedpanda]

always good to follow up with the resolve , makes the forum stronger... Thanks