The Stovebolt Site Forums The Shop Area Engine Shop Bi-metal spring on heat riser

I have a new spring but cannot install it such that it opens when hot. Anyone offer any help on this?

Can you move the heat riser manually to verify that it's not stuck? Most that haven't been used for a while are stuck in whatever position they were in.

yes it moves - but I do not know what position is for heat off and what position is for heat on

Exhaust manifold heat riser on what engine?

http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0605.html

I had the same problem, I even bought 2 just in case I had a bad one somehow, I just think they aren't really calibrated to anything, just some wound up bi-metallic material that is made to look similar enough to the original to get 10 or 15 bucks out of them. Whatever the case, when the counterweight is down the heat is off, when the counterweight is up (the spring is cold) the heat is on. I don't think mine ever had one since I have had it. And I have had it for 30 years, it started and ran just fine at 15 below. So I don't know how important the spring really is. The exhaust is bolted directly to the intake, so conduction is pretty good in that situation, not to mention the flapper inside is far from a tight seal. Also the intake sits over the exhaust for the full length allowing convection on top of all that. I do know if you force the flapper to remain in the heat on condition, the engine runs horribly.

Looking from engine front rotate weight ccw for heat off. If you click on Tim's link above and go to previous page there is a great cross section picture. On my 216 the spring doesn't actually hold the flapper open but is relaxed enough to allow it to open under acceleration.

when you're looking at the spring the closed part of the hook should be facing you ,and to calibrate it you have to hold it and use a long nose plier on the center section and twist it tight or lose so it just opens the flap than when it heats up it will move the flap closed.

Pete

Interesting. Mine ('38 car) is just opposite. I verified that when I had mine apart. Maybe they changed somewhere along the line???? It couldn't be that I made a mistake. If I did it sure runs fine when hot.
Heat off position.

As Pete posted, it's hooked over the stop from the front.
From the driver point of view, the theromstate spring is
counter clockwise closed, winds clockwise open the butterfly:
http://www.pbase.com/dennygraham/image/112537676
Looking from the front to the back the counter weight is down in
a clockwise position and counter clockwise it's nearly straight
up and down:
http://www.pbase.com/dennygraham/image/112537670
DG

Thanks for the help. On my 1948 216 the heat is off with the weight up rotated toward the engine (from the front of the engine CCW) and heat on with weight down. It was flooding real bad after I stopped hot, and I found out the heat was always on. Runs much better on todays 95 degree day with heat off.

As shown in a link above:

Orientation of the heat control valve thermostatic spring.

Orientation of the heat control valve from the other side of the manifold (open/cold and closed/warm)

It is interesting to me that GM refers to that spring as an "anti-rattle spring"?!

the flapper is in the position to heat the intake manifold when the weight is in the uppermost position, (clockwise standing at the front of the engine), the flapper is in the position to bypass the intake when the weight is down, or the counterclockwise orientation standing at the front of the engine. I can determine this because I have the exhaust manifold in my hand looking at it. If I knew how to post pictures I would. But you are just going to have to take my word for it.

...click...

...click...

Nice video
DadEEo

Danke Schoen

Any suggestions on how to free a rusted flapper assembly, or how to remove and replace one?

Hi DocFin,

I just finished rebuilding my heat riser. I followed Achipmunk's instructions. Read through the thread he started:

Achipmunk's thread

Good luck,

Mine is stuck in the "heat on/ open" position. How much run time (say...minutes) would it take to produce enough excess heat to affect how well the engine runs?

Look at the last item in the left-hand column.
Harold

Once upon a time I had a locked thread on how to post links to images as a sticky in the 'Bus but it's disappeared.

yes Harold, but even that assumes even a rudimentary understanding of what is outlined. I don't have that. Peggy tried to help me before. Maybe soon I will figure it out.

The link pointed to on the left doesn't show HOW which is why I had the locked thread that I could point to when necessary. Harold, if you can't figure it out PM me and I'll step you through it. It's not difficult but the process isn't very intuitive.

Here you go Harold. I wrote up V2.0 of the tip. If you still have questions give me a holler.