Frozen Heat Riser

[Gary #41345]

If a heat riser gets frozen up the effects on the engine will be?

[Tom D.]

Depends If open, shut, or half open...

If open, not a problem until you start up in winter. Engine warm up will be slower.

If shut, right side exhaust is always forced up and through the intake, even after the engine is hot. This which will overheat your carb. Fuel in the carb will overheat (perhaps boil?) and performance will suffer. How severe? Depends which intake you are running.

If half open, you get half of the above "if shut" problem.

One out of three makes for poor odds. Fix it, or replace it. If you can free it up, wire it open to see the effects of "if open". Weight on the outside should point to the ground when open.

Tom
4889

[Jim T.]

Re: Frozen Heat Riser

The muffler/exhaust system on he passenger side will last longer if the heat riser is wired/frozen open. Heat risers restrict the hot exhaust from removing the moisture from the muffler.

[Gerard F.]

Re: Frozen Heat Riser

Gary,

Try some Tri-flo on the shaft. Not sure how long it will last but it did free up a brand new one on mine from sticking in a half open position. They don't fully open with heat alone, but are supposed to go fully open with exhaust pressure when you step on the gas.

Jerry Fuccillo
#42179

[Wayne K.]

Re: Frozen Heat Riser

Gary,

As Jerry has mentioned it will not fully open from heat alone. At full temp the valve is about half open when idling. As rpm increases the exhaust forces it to full open. You can watch it gradually open as you bring rpm's up and partially close as they decrease.

Wayne

[Bill E.]

Re: Depends If open, shut, or half open...

Hello Tom:

Does the heat riser shaft rotate a full 90 degrees from closed to open? The one on my car only rotates about 45 degress before stopping so the weight isn't pointing straight down to the ground. It sounds like it is hitting something. I wonder if the wrong heat riser was installed.

Thanks, Bill

[Rick S.]

Re: Frozen Heat Riser

Is there a preventive maintainence recommendation to prevent the heat riser from freezing up?
Rick

[John H.]

Re: Frozen Heat Riser

GM "Heat Riser Valve Lubricant" - made specifically for this application.

[Rick S.]

Re: Frozen Heat Riser

John,
Still available at any GM dealer?

[John H.]

Re: Frozen Heat Riser

Yup!

[Stephen B.]

Re: Frozen Heat Riser

this is the best penetrating fluid going even beats pb blaster in my book not just for the heat riser GREAT STUFF my 2 cents Steve