heat getting into cabin with center lever off after SSI upgrade

[sbrown.nw]

Hi everyone. Did a quick search for this issue but I did not find anything obvious as a match. About a year and a half ago I upgraded / backdated my exhaust on my 3.2 euro to SSI's and a 2 in 1 out muffler. My chassis is a 72 T, so it only has one heat lever by the e-brake if that is relevant. My first drive with the car after the shop did the work (a very skilled air cooled mechanic that is an SSI dealer) resulted in excessive heat in the cabin, even with the heat lever in the down position, especially with the targa top on. I brought it back and they did some adjustments and it got better, but never resulted in a 100% no heat situation when the heat lever was in the down position. Lately, the issue seems to be getting worse / more noticeable but nothing like the first time I drove the car after the SSI install. I recently had the car in the shop for new soft brake lines and I asked them to adjust the connections / heat coming into the cabin when the lever is off. Unfortunately, they said there was nothing they could do.

Is anyone else experiencing this issue? What can be done to address / fix this issue or it is a given as part of the upgrade on some of our cars?

TIA,

Scott

[ClickClickBoom]

The heater boxes are mis-adjusted. My 3.2 with SSIs work exactly as required. With the heat levers full down, there is 0 heat coming out of the vent system. With a single heat lever, logic would dictate if there are 2 heaterboxes, the cable has to somehow split to activate both heat boxes. My thoughts are either one segment of the heater cable is either broken, leaving one heater box on and one shutting off. The reason you might be noticing the heat now, is the SSIs are incredibly effective and when you put them on, the broken heater box control became evident.
You don't need a mechanic to check your heater boxes, jack the car up, jack stands and look at the end of the heaterhoses for a star looking opening in a box. Verify both boxes are in the same position.

[jpnovak]

pull the hoses that connect the SSIs to the heater valve. Look inside the heater valve and make sure the valve actually closes with the lever down. If it does not close then loosen the cable catch and close valve. Then tighten the cable.

You may find that the heater valve is sticking and the return spring is not strong enough to get it to close. IN this case, you can disassemble and clean them or just replace so that they work properly.

Its a very simple system. lever moves cable. Cable opens valve so heat goes into cabin.

[ClickClickBoom]

https://www.pelicanparts.com/More_Info/91121101300M124.htm?pn=911-211-013-00-M124&bt=Y&fs=0&SVSVSI=804

Not rocket surgery...

[theiceman]

Originally Posted by jpnovak

pull the hoses that connect the SSIs to the heater valve. Look inside the heater valve and make sure the valve actually closes with the lever down. If it does not close then loosen the cable catch and close valve. Then tighten the cable.

You may find that the heater valve is sticking and the return spring is not strong enough to get it to close. IN this case, you can disassemble and clean them or just replace so that they work properly.

Its a very simple system. lever moves cable. Cable opens valve so heat goes into cabin.

this .. but be VERY careful if you are replacing those heater boxes, they are on studs out of the body and nuts go on the end, you do not want to break a stud, spray and soak liberally.

[frankc]

If you discover that the heater valve is indeed all the way closed and heat is still getting through, it's possible that the sealing material used on the butterfly has melted, allowing some of the heated air to bypass it:

Heater Control Box Meltdown

[911pcars]

Originally Posted by frankc

If you discover that the heater valve is indeed all the way closed and heat is still getting through, it's possible that the sealing material used on the butterfly has melted, allowing some of the heated air to bypass it:

Heater Control Box Meltdown

Slight correction. When the heat control valve (under the chassis, next to engine) is closed, hot air is directed to the cabin.

S

[frankc]

Originally Posted by 911pcars

Slight correction. When the heat control valve (under the chassis, next to engine) is closed, hot air is directed to the cabin.

S

Sorry for any confusion - when I mentioned the valve being closed, I was referring to the butterfly valve within the control unit that, when open, allows hot air to flow to the cabin - not the exit vents on the bottom of the control unit where the hot air is re-directed when the butterfly valve is closed. The exit vents are closed when the butterfly valve is open, and vice-versa.