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Heater valve leaking internally?


Dudeland

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Good afternoon folks. 

 

I am getting heat out of my heater even if the valve is closed.   I took it apart when I did the heater box, and did see that it had new plastic guts, which tells me that at some time it had been rebuilt.  When I got the car it was installed backwards, I installed it facing the right way. 

 

I adjusted the cable to make sure that it would be good and closed.  It doesn't leak externally at all, is there a way of assembling it in a way that would allow the water to flow?  Kinda stumped and I don't really want to take it out until i have a diagnosis.   I did get the heater box rebuild kit and rebuilt it with the appropriate grommets gaskets and the reinforcing bracket to hold the heater valve. 

 

Any help would be appreciated. 

 

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"Goosed" 1975 BMW 2002

 

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Sorry to say but I think your in a remove and diagnose situation. I never understood whey BMW assembled this in such a way that you can't service the dang thing without removing the heater box. They are tricky at best. If you don't get it complete closed you are going to get heat. 

You can always plug of the hoses to stop the heat I guess until you get it fixed. 

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If everything is stock and assembled correctly the flow should cut off.  It all focuses on the valve.  When the alignment of the guts completely inhibits the flow, your heater blows cold.

 

I would open the front cover of the valve to confirm that the plastic guts are aligned correctly when open and closed.  The operation is a bit mind boggling with the lever on the dash, the lever on the valve and the cable.  Just maybe it is not functioning (adjusted) as expected OR is there a chance that the cable is being pinched or restrained under the dash?  The lever operation on the dash should be a smooth arc from cold to hot without ( or little) resistance.

 

Good luck.  Not one of my favorite jobs.

 

Tip: when removing the slot-head screws from the valve, stuff drop clothes inside the bulkhead.  You don't want to lose those screws down the drain tubes. ☺️

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73 Inka Tii #2762958

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Coupla thoughts:

  • Late cars (75 and 76, possibly 74s) had heater valves with a small hole drilled in the valve, allowing a small coolant flow even when the heater valve was in the off position.  The factory found that folks living in warm climates who rarely used their heaters were discovering the cores plugged up with crud due to no coolant flow...but normally it isn't enough to allow the heater output to be warm.
  • Are you sure you installed the bellcrank on the heater valve correctly?  It's really easy to install backwards so that when your dash control is set to cold, you have full coolant flow into the heater--i.e. heat.  You can determine this without dismantling anything by setting the dash control to cold and see if you have heat, then set to hot and see if it cools down.  
  • You can remove the valve without removing the heater; however it's much easier to reinstall if you unbolt the bellcrank from the valve, leaving it attached to the control cable.  Then when you reinstall, set the dash control to hot, the valve fully open, and fasten the bellcrank to the heater valve without disturbing either setting.  

Happy tinkering

 

mike

 

 

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'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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If the valve has new plastic plug (guts), I assume it’s been rebuilt with a Blunttech kit. If the valve operation is stiff and requires a high force to rotate, it is possible for the metal valve stem to deform the sides of the depression in the plastic plug such that you don’t get full rotation of the plug when you pull the cable to close the valve. 

 

Unscrew the valve cover cover with the cable pulled to the fully close position. Then remove the plastic plug, carefully noting its orientation. Then compare it to the orientation of the valve shaft seat, and check the condition oval depression in the plastic plug where the shaft sits. Check for the possibility that the stem is over-rotating due to the plug binding. If that’s the case, the valve body may need to be honed and polished to minimize the binding. 

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49 minutes ago, 2002 said:

 

I looked closely at this article before I posted.   it seems as though you could not put it together incorrectly. 

 

I anticipated the not fully closed thing before i posted as well.  I shortened up on the cable so it would bottom out at the valve, just in case it wasnt adjusted properly to shut completely. 

 

Also when I set it to hot, I can feel the air get hotter. 

 

The only thing that makes sense is that i have a crack in my valve.   Anybody have one close to me? 

 

"Goosed" 1975 BMW 2002

 

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16 minutes ago, Schon '02 said:

If the valve has new plastic plug (guts), I assume it’s been rebuilt with a Blunttech kit. If the valve operation is stiff and requires a high force to rotate, it is possible for the metal valve stem to deform the sides of the depression in the plastic plug such that you don’t get full rotation of the plug when you pull the cable to close the valve. 

 

Unscrew the valve cover cover with the cable pulled to the fully close position. Then remove the plastic plug, carefully noting its orientation. Then compare it to the orientation of the valve shaft seat, and check the condition oval depression in the plastic plug where the shaft sits. Check for the possibility that the stem is over-rotating due to the plug binding. If that’s the case, the valve body may need to be honed and polished to minimize the binding. 

When I did the heater box i pulled the valve apart and it looked great.   It operated smoothly, no binding. 

"Goosed" 1975 BMW 2002

 

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My brass valve core (09/71) has a slit to allow minimal flow all the the time.  Had it out this past summer to replace orings.  With the valve in hand, check for tightness by blowing thru the closed valve on the plastic ones.

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A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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There are two different length of levers (that i know of). One is 25.5 mm (c to c) and other is 27.5 mm (c to c). So maybe your rebuilt unit have wrong one and it doesn't close fully when everything is connected?

Edited by tzei

2002 -73 M2, 2002 -71 forced induction. bnr32 -91

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2 hours ago, tzei said:

There are two different length of levers (that i know of). One is 25.5 mm (c to c) and other is 27.5 mm (c to c). So maybe your rebuilt unit have wrong one and it doesn't close fully when everything is connected?

It definitely is bottoming out on something.  I will check just what it is. 

 

1 hour ago, Guy Cocquyt said:

What year is your car?

Sent from my STH100-1 using Tapatalk
 

It is a 1975

"Goosed" 1975 BMW 2002

 

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Does this look right?.  I think it is.  The cable engages the lever on the bottom of the valve, so the lever is oriented strait down when closed.  Not sure why I put the glue there.  Perhaps to hold something in place while I got a screw in it.   I think it may have been the washers that go between the housing and the bracket. 

 

IMG_7976.thumb.JPG.70db5d3b1f62b53a0bee13561929d61b.JPGIMG_6536.thumb.JPG.b8f75d8c62963a1dc5472bbd994b61db.JPG

"Goosed" 1975 BMW 2002

 

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It is a 1975
I had another line of investigation if it was an earlier model single lever hot/cold lever.

My thoughts are adjusting the cable length at the valve to ensure it is closing properly when your lever is positioned to cold at the dash. Several have already suggested this and I concur.

Sent from my STH100-1 using Tapatalk

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