Decided to fix the broken temp control on my E12 today. In trying to get the half of the broken U joint out of the green head in the water control valve, the green but came out, and some coolant came out with it.
Is there supposed to be an o ring or some kind of seal here? I don’t see any, but something clearly isn’t right. It was secure in the water control valve and now it’s not - the u joint and shaft will hold it in but that’s not enough. What’s missing, and is there an easy way to fix this?
Edit: God help me I’m never going to figure out the right way to attach photos
Theotherotter wrote: Mar 09, 2024 5:29 PM
This is on the other end of the water control valve, though - where the temperature adjustment knob linkage attaches.
Go to the ECS Tuning link - I’m talking about a seal between the green piece and the body of the heater valve
OK, it seems to me that it does not have an seal/o'ring and that it is an internal wear of the rotating part. Based on the photo of the piece, it appears that it can be disassembled and checked to see if a seal can be placed.
It’s part #1 shown in the first realOEM diagram - the water control valve comes as a unit and isn’t supposed to be disassemblable. When the green bit popped out it seemed straightforward to reinsert it…except it now has no retention at all. Previously *something* was retaining it - I just have no idea what. I tried going to the FLAPS and getting an assortment of O rings so that I could try to seal the back side of the green bit against the valve. Maybe it would seal, but there’s still no retention, so when I turn the control it just back out a mm or two and starts leaking. Sigh.
Looking at the part and thinking about it, I think the answer is no - I’d expect a retention groove of some kind of there were an O-ring. So I’m then left with 1)how was this thing retained? And 2) why is the valve leaking?
According to this video, the valve is sealed and if it leaks it is because it broke internally....and there seems to be no solution except a new one that is NLA....I would try to look for some used ones out there, and if there is no success, I would open it somehow and try to reseal it. Internally it must have a worn part that must be able to be repaired in some way.
I'm fairly certain there's an O ring in there that leaks. And yeah it's not replaceable. I've done at least half a dozen of them and tried like hell to figure out a way to fix them but never came up with anything. And contrary to what the U tube guy says, they can be replaced without pulling the heater out. A pain, but they can be.
Yeah, I have found some threads on firstfives.org about replacing them - and even removing the heater core - without pulling the dash. It does look doable, and it does look like a PITA. Looks like a job that would benefit from a lot of planning for what could go wrong on each step and coming up with mitigations or contingencies (e.g. having a magnetic stick to hold the nut, or stuffing a cloth somewhere to keep it from disappearing if it falls off - that kind of thing.) Also, it looks like pulling the pedal cluster would help with access.
Before I started this job on Saturday, I could see there was just the slightest evidence of weeping from the green bit - there were the dried remains of a couple of dribbles on the tunnel carpet, but no staining down by the pedal. What I'm really baffled by, and would like to understand, is how the green part is normally retained and what happened when it came out.
I procrastinated on this job for a long time and prioritized some maintenance on my 911 for a while, until I finally started this job last weekend. I decided the tear-things-out approach would suck less, and started taking the console out, etc. Once I got the AC out I was pleased to find that I could get to the two remaining hidden nuts on the back of the water valve without taking the heater/blower assembly out - I got to one from the passenger side and the other from the driver side after dropping the steering column to get enough room to swing the wrench. Old valve is out and new one will go in this weekend. I'll clean up the AC assembly some and put some new foam sealing on it, and I need to figure out a solution to the two broken plastic swivel joints. I have one good replacement but that leaves me with one more. I'm researching DIY solutions involving parts available from McMaster-Carr and/or robotics catalogs that use the broken joints, or RPing something. I'll update this thread with photos or start a new one when I'm done.
You got to one nut from the passenger side? Never tried, but I can't imagine how, but as long as it worked, more power to you.
The U joints. They do now appear to be NLA. MM Carr does have an amazing amount of stuff, but I think I'd try to kludge something. Maybe wire loops thru the area that acts as a hinge? Maybe something like vinyl that is flexible glued to both parts of the joint? Both sides? Not sure how you'd attach it, but perhaps something like a speedo cable or a flexible 1/4" socket extension? Not sure if you could get anything as free of play as the original, but I see lots of options.
Mike W. wrote: Jun 21, 2024 7:43 PM
You got to one nut from the passenger side? Never tried, but I can't imagine how, but as long as it worked, more power to you.
The U joints. They do now appear to be NLA. MM Carr does have an amazing amount of stuff, but I think I'd try to kludge something. Maybe wire loops thru the area that acts as a hinge? Maybe something like vinyl that is flexible glued to both parts of the joint? Both sides? Not sure how you'd attach it, but perhaps something like a speedo cable or a flexible 1/4" socket extension? Not sure if you could get anything as free of play as the original, but I see lots of options.
With the AC unit out, I had clear line of sight of the upper right nut from the passenger footwell. The shroud that connects the AC unit to the ductwork inhibited getting the wrench on there well so I pulled the fasteners out and was able to move it out of the way enough to get the wrench on there.
Ideas I’ve considered as possibilities include a flexible extension and RPing a receiver based on half of the flex joint with a 1/4” drive on the other end; bolting a small U joint as used in robotics to the half of the flex joint and bolting a suitable rod to the other end (if it’s a genuine U joint I don’t think it will need to telescope) and adapting E21 parts. IN the short term I’m going to install the one good U joint I have and try to find a second one. If I can’t, I’ll probably leave the heater control unconnected (not gonna need heat for a while) and figure out a solution later.
A few more notes on getting the nuts back on the new heater valve:
The two nuts that you can see easily from the driver's footwell are not hard. With the steering column dropped, I had enough access to the upper left stuf to have little trouble threading the new nut on. The upper right was the hardest. I could get my finger tip on it, but I couldn't get two fingers holding a nut back there. I tried putting some tape on the back of the wrench to hold the nut and slide it in from the passenger side - close, but no cigar. I could get the nut located, but not started. I tried putting some grease on my finger tip to hold the nut on it while I guided the nut in with that finger and kept my other finger on the stud for reference - close, but no cigar. What worked was using my telescoping magnet stick to hold the nut. Working from the driver's footwell, I put a finger on my left hand on the stuf to locate it, and used my right hand to slide the nut on the stick in - you have to hold it almost right up against the heater box. I finally got it located (confirmed with other finger) and used the finger on my left hand to hold it on and rotate it - it only takes half a turn or so to get it started. To tighten it, my regular 8mm open/ratcheting box end wrench wasn't quite working - the body was hard up against the heater box and I couldn't get enough swing. I got an old, very thin 8/9mm box end wrench that I had, maybe left over from the E21 we had when I was a kid, and that had no trouble tightening the nut because of how thin it was.
Don't forget new O- rings, and to grease the new O-rings before you put the new valve on.
