I managed to check every vacuum actuator, and they all hold vacuum. The temperature knob is within spec when I check the resistance. The AC is working beautifully. I've still got vacuum leaks somewhere, and I can't get heat no matter what I do.
When I turn the knob all the way up, the hoses in the engine compartment are hot, both going into the firewall and coming back out. The auxiliary pump works like it's supposed to.
So the questions:
1) If the diaphragms are all holding vacuum, what else could be leaking?
2) Where is all my heat going?
3) Is the set point for the aux. fan lower with the AC on?
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When I die I want to go quietly, in my sleep, like Grandpa.
Not screaming, like the people in his car.
Do you have heat with the setting at defrost? Have you checked the bit of hose up to the temp sensor on the dash ( I assume it's on the dash, it is on my 116 but honestly I haven't looked that closely at the SLC yet)? Not sure if that's any help, I'm just trying to think of ideas here. How about the servo itself, is it in good shape?
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John
'80 500SE Euro '5.0 AMG'- 5.0 AMG engine, Gleason rear diff (still trying to find the ratio) and full aero kit. Stock interior. BBS RS133 8x16 3 piece wheels with Michelin XGT Z4 245/45-16 tires.
'78 450SLC milan brown metallic/bamboo leather
'80 300SD
Have you checked the bit of hose up to the temp sensor on the dash ( I assume it's on the dash, it is on my 116 but honestly I haven't looked that closely at the SLC yet)?
It's on the dash, and yes I checked it. It could be replaced, but it's still there and holding itself together. That's more than I can say about the rubber bit going to the center vents. That part is more the idea of what should be there.
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How about the servo itself, is it in good shape?
It seems to be. It clicks and whirs to itself when I adjust things. The actuator that was snapped off went back on, and now it's holding vacuum the way it should (these things are more sturdy than they look). I singled out the line feeding each one (or each side of one, in the case of double actuators) and used a hand vacuum pump to check them. They held vacuum without the needle moving. But somewhere the line feeding the leg vents has a leak - after that actuator - and it won't open up for lack of vacuum. Ditto with the line after the defrost flaps, and they stay open all the time.
If it turns out to be the servo, I'm upgrading to that digital one. I can spend $500 for an OEM part or $700 for a digital upgrade, and the upgrade seems like the better deal.
Scott, take a look at the photos of my servo bypass in the w116 forum. I don't know if the 107 is set up the same but in the SD the supply hose for the system is the one on the drivers side, which means it is going into the firewall and then connecting to the servo and then going somewhere (sorry I can't remember, lots of hoses that i disconnected). Anyway is it possible that the hoses you feel heat in are both before the servo? Just an idea, I just know that when I lost heat it was the servo, not a vacuum issue.
Scott, take a look at the photos of my servo bypass in the w116 forum. I don't know if the 107 is set up the same but in the SD the supply hose for the system is the one on the drivers side, which means it is going into the firewall and then connecting to the servo and then going somewhere (sorry I can't remember, lots of hoses that i disconnected). Anyway is it possible that the hoses you feel heat in are both before the servo? Just an idea, I just know that when I lost heat it was the servo, not a vacuum issue.
I found the thread you're talking about - thanks.
I don't actually need heat. With the hard top on or the soft top up it stays warm in the car - my outside temperatures only drop below 50 in the middle of the night. I just want it to work the way it's supposed to.
There's a part of me that would really like it to be the servo, because what I've been able to find about the digital upgrade sounds like it's a much better product than what the car came with originally. I'm also looking at the digital replacement for the warm up regulator, but it has a disclaimer that it may not be legal in California. I'll have to find out why.
Linear Mode
