656 Exhaust Manifold Heat Control

Wicksfield · Apr 17, 2018

What is the operation of the heat control valve and spring in the exhaust manifold? Mine is free and spring is in good shape. I put a heat gun on the spring which I anticipated would coil tighter and turn the valve. Nope. The spring does coil when hot but it moves away from the pin in the manifold and does not move the valve. Turning the valve with a screwdriver moves the coil spring away from the pin. It appears the spring is useless. Is it installed wrong?

Thanks for your response.

pete 23 · Apr 17, 2018

The spring , if installed correctly, hold the counterweight straight up and down in cool positon. This positon directs the exhaust gases inside by using a plate so that the hot exhaust goes around the internal stove inside intake manifold. When engine gets warmed up really well, the spring loses it's tension and allows the weight to fall forward and then the internal plate directs the exhaust right on out the manifold.

If that weight is not straight up and down when cold , or if weight will go farther toward back than straight up, there is a problem inside with plate or shaft or both.

Wicksfield · Apr 17, 2018

Pete, thanks for the info. Went out and checked with a cool engine. The weight is resting all the way forward...hot engine position. What are my choices:

1. Leave as is since this tractor does not get used in cold weather.
2. Install new spring
3. Bend current spring allowing for more tension moving the weight vertical
4. Or, none of the above...Ha!

Thanks for your response.

pete 23 · Apr 17, 2018

Ahh, hate to say this but maybe just leave it alone. But on the other hand. If the weight does travel to vertical with no problem and stops there, in other words, doesn't go back ward beyond vertical, you could pull spring and turn it around, if spring is any good. Lot of springs just play out on right or wrong. New springs are kind of spendy now days.

Wicksfield · Apr 17, 2018

You're not kidding kinda spendy. Found them from $24.50 up to $40. Absolutely ridiculous.

Thanks again for your help.

feverpuller · Apr 17, 2018

The spring should be wound counterclockwise and if I remember right it's gonna be about around to round and half. I just did this a month ago on my 560.

povertyknob · Apr 18, 2018

I fixed mine as well on my 560 after I got the engine overhauled
I had to heat the spring up a few times with a bottle torch gently to get it right, but it works, also I had to replace the weight as mine was broke

povertyknob · Apr 18, 2018

More pictures

Wicksfield · Apr 18, 2018

Thanks for the reference pictures, Poverty. Looks good.

656 Exhaust Manifold Heat Control

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