Posted by David Sherman on Monday, May 14, 2007 at 01:33:56 :
In Reply to: Re: stalling m37 posted by KenW on Sunday, May 13, 2007 at 22:52:55 :
"Missing", as in you split the manifolds apart and it wasn't in there? That would be really strange. I think it's about a 16 gage piece of flat steel spot-welded to the shaft. Sometimes there's a thermostatic coil and a weight on the outside that's supposed to turn it depending on the temperature. Other times there's a pointer that you move manually between the "summer" (miniumum heat) and "winter" (maximum heat) position. I found the pointer on one of my sno-cats had been set in the "summer" position a long time ago and that was why the carb kept icing up. Why you would ever set the carb heat to "summer" on a sno-cat is beyond me.
Anyway, if it's stuck or broken, you'll have to pull the manifolds off the engine, then remove the 4 bolts that hold the manifold sections together, in order to see what's wrong. Clean all the soot out of the heat passages under the carb while you have it apart. I suspect the thermostatic kind tend to not get stuck as much as the manual kind, because they're always vibrating a bit. When putting it back on, bolt the manifolds together with a new gasket, then have the assembly milled or ground flat prior to mounting it to the block. If you mount the manifolds separately to the block and then bolt them to each other, you risk cracking them. It's definitely a chore to fix a stuck or broken heat riser. There's nothing to it technically, but it's a lot of rusty stuff to take apart and put back together.
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