Heater Valve Rebuild Woes

[npdw]

Before installation I made a setup in my shower with a garden hose etc to check if it would function properly without leaks. I learned to do that because I had to remove and disassemble the heater box 3 times. That was not a nice experience

[SydneyTii]

3 hours ago, Schon '02 said:

The width of the teflon plug is equal to the internal width of the brass valve body. The stainless steel shaft and its seat is designed to be sandwiched between the side of the Teflon plug and brass valve body. It’s important that the internal brass valve body be free of any corrosion preventing the full insertion of the teflon plug. The plug and stem should then smoothly rotate, but not have any wobble or radial movement. Polishing the inside of the valve is helpful IMO.

 

Note that there are various versions of brass heater valves, so your version may be more susceptible to issues. You made no comment on where your valve leaked (at the stem or the cover). Pictures would be helpful.  

Ok so a bit more info, my valve is the later valve, the inside and outside of the valve has been cleaned and polished., absolutely no crud anywhere. The leak is on the shaft which visibly moves, the o ring in the kit is I believe to small/thin, if the o ring protruded from the recess in which it seats a bit it would sandwich the Teflon body and stainless plate/post better, hence the others who have used a 2mm o ring to prevent the leak issue.

I took another same model old valve apart and noted the post which passed through the body and which has the lever attached to it, is plastic or similar material, and actually has a step in it, this step sits in the recess that the new o ring uses. this step prevents any movement. I have new o rings coming so will try the thicker 2mm one to see how I go.

Failing that it’s a new valve, but I can’t see me doing that!!

[SydneyTii]

3 hours ago, npdw said:

Before installation I made a setup in my shower with a garden hose etc to check if it would function properly without leaks. I learned to do that because I had to remove and disassemble the heater box 3 times. That was not a nice experience

Great idea!

[Highnote1]

This worries me. I just rebuilt my entire heater box and it’s sitting in the garage waiting to go back in car after paint. I don’t want to do this twice. I have a 76 and it does not appear to have extra movement or anything.  Do I need to hook up a hose to test it? Not sure how to do that without getting everything soaking wet. This is lame. That kit was not free!

[SydneyTii]

It seems to be hit and miss, some find it ok, others find it leaks, hopefully yours is ok.

its interesting as the old “collar or step” on the original post/pivot doesn’t seam to use an o ring.

Because the new o ring seems to be too small it allows the pivot post to move which must be where the leak originated from.

Edited August 22, 2020 by SydneyTii

[SydneyTii]

Has anyone had any recent clever ideas to fix this issue?

[02Les]

17 hours ago, SydneyTii said:

Ok so a bit more info, my valve is the later valve, the inside and outside of the valve has been cleaned and polished., absolutely no crud anywhere. The leak is on the shaft which visibly moves, the o ring in the kit is I believe to small/thin, if the o ring protruded from the recess in which it seats a bit it would sandwich the Teflon body and stainless plate/post better, hence the others who have used a 2mm o ring to prevent the leak issue.

I took another same model old valve apart and noted the post which passed through the body and which has the lever attached to it, is plastic or similar material, and actually has a step in it, this step sits in the recess that the new o ring uses. this step prevents any movement. I have new o rings coming so will try the thicker 2mm one to see how I go.

Failing that it’s a new valve, but I can’t see me doing that!!

 

Ok, here's my take.

I believe the seal on the shaft was originally a square/rectangular section seal. Mine started leaking at that point and, pictured below, is the seal that was in there. Difficult to get a good focus, but I think you can see it's not an o'ring (the bleached out picture shows it best & I don't think I could have got an o'ring to stand up against the pencil). I guess there's no obvious reason why an o'ring seal won't work, but it does seem it's hit or miss.

If I ever get a replacement for it, I'll post the info. I looped the hoses to by-pass the heater, so it's become a 'back burner' job.

 

[tech71]

Yeah, a square ring, not an o ring. I took something similar out of an I think original valve on a 76.

It seems to be a lot stiffer/firmer than a Buna o ring, a lot. Teflon maybe or something similar.

That stiffness along with the increased bearing surface provided by the square/flat aspect would provide better support on the pivot shaft.

Sorry mate, no clever ideas at this time, I'm still experimenting.

I have a few heater valves, some are all brass including the internal parts, no plastic. They appear to be much better .

I'm wondering... at some point did BMW cheap out and switch to cheaper/crappier plastic internals?

 

I pressure tested my valve by blocking the outlet, attaching to an air source with little regulator on the inlet side set to 15 PSI. Stuck it in a bucket of water and looked for bubbles.

Second time was the charm for me? 

Edited August 23, 2020 by tech71

[Schon '02]

2 hours ago, SydneyTii said:

Has anyone had any recent clever ideas to fix this issue?

I had a similar issue with a slight weep from the shaft. I soaked my shaft o-ring in power steering leak-stop for a day to swell the o-ring a bit for a tighter fit. I’ve had no leakage since doing so. 

[SydneyTii]

My internal part is the new Blunt type kit, my old internal parts are good except the tiny pin/rod between the black centre piece and the white rotating part is gone.

So as an update, I changed the o ring which I got from a plumbers supply shop, and is for hot water systems, covered everything in suitable grease, closed it all up again, and then connected the heater box up to the water main, and my mains has high pressure, I blocked off the exit side of the box and opened / closed the valve like 20 times. NO LEAK !!!!!!

i will leave this for a few hours, but my experience of plumbing is if is gonna leak then it pretty will under pressure straight away.

The pivot post still moves but less as obviously it’s up tighter against the o ring, I’m still going to look for more o rings, but this maybe a win similar to what others have had.

The highlighted o ring size is what I used, I measured the thickness to 2mm.

I don’t find removing the heater box to arduous as it’s 2 nuts, 2 jubilee clips, and a few wires, I will leave the console out as well until I know it’s ok under the cars Cooling system pressure.

Will report back once it’s been under load in the car.

 

[tech71]

Cool, thats a square ring isn't it? looks perfect  as long as it plays well with coolant.

[SydneyTii]

6 minutes ago, tech71 said:

Cool, thats a square ring isn't it? looks perfect  as long as it plays well with coolant.

Yes good point re coolant! 
Time will tell...

[tech71]

Is it soft, pliable, squishy like rubber? or denser like nylon?

 

[SydneyTii]

Bit in between, I will try and get some more o rings that I’m sure are ok for coolant.

[SydneyTii]

Ok so I’ve run it up to operating temp a few times, opened and closed the valve and no leaks! 
I have viton o rings coming and did some research re hot water, it seems they can withstand higher temps than our cooling systems generate and also stand up to coolant/chemicals, I will do more research. 
im going to try and find the more squared off o ring which is suitable for the environment, I will update this thread when I get some more details.

Thanks everyone for your help.