Heat Riser Valve Frozen - HELP

[Ed Barrett]

Hello....just joined and this is my first post. I purchased a '41 Special Sport Coupe last fall. I have had the dual carbs rebuilt and have been cleaning the straight eight in preparation for painting....but, noticed the heat riser valves (both of them) are frozen solid. The car was not running well when I got it, attributed it to the carbs needing rebuild and old plug wires. Now I am wondering if these frozen valves could be contributing to the problem, but I dont know when or how long they have been frozen. Anyway...they are both frozen with the extended portion of the weight in the 12 to 3 oclock position on the face of a clock. I'll try to post a picture below...it will be a bit tipped toward the right so you'd need to tilt your head to the right a bit to get the proper orientation of the weight. The question I have for you guys in the know, is the valve frozen open or closed or part way? If I thought it was frozen open I would forget it....but if its frozen closed or mostly closed, I will have to tear off the manifolds I guess and take out the flapper. I'm new to Buicks and certainly not a mechanic so bear with me! Thanks for any help you can offer.

[58 Roadie]

Hi Ed ,

GM has a Heat Riser penatrant ( specific )that I have used on some pretty crusty items . I was suprised at how well it worked . Might check with a Dealer . I don't know the part # though . Give it a few applications , letting it work in and try to get it wiggling .

The valve is designed to aid engine warm-up . Should be a spring along side the counter weight . Should be able to open/close .

Guluk'

Scott

[Ed Barrett]

Thanks....I have heard that, although no dealers have it here locally. I have been shooting both sides of the outside of the shafts with PB Blaster and tapping with a hammer for two weeks......not a budge. I am hoping someone out there with an original manifold set up with a working flapper can tell me what position mine is frozen in compared to when theirs is in full open position with the engine warmed up (and the flapper open to exit exhaust thru the muffler. Thanks for your input.

[theoldguy]

The simplest cure is to pull the exhaust and have someone go in with a cutting torch and cut them out. It makes for a longer warmup, but most of the time they will freeze up again umless you drive the car a lot.

I did this to mine 10 years ago, and the car still runs great !

I have the 41 dual exhaust manifold on my 40

[Spud]

First off nice looking car. I looked at one that I have on the bench for my 38, with the weight straight up warms the carburetor back towards 3 oclock is out the exhaust.

[Bob]

I have used a cutting torch on them to loosen them up. Heat 'em up good to break down the corrosion and once they are moving, use some penetrating lube to really free them up.

[39CENT]

heat riser valves if stuck closed will play havoc with performance, can cause damage to the manifolds. If stuck open to the exhaust pipe they will be ok. but if closed you will need to take off the the manifolds and fix. I would just block them open for good it will just have to run a little longer for warmup.

[Muley Gil]

I had a '52 Super for almost 30 years and the damper would rust on a regular basis. I would squirt it with the GM oil mentioned above and then tap the ends of the rod back and forth. It takes awhile, but will evenually free up. I used an 8 oz ball peen hammer.

Good luck.

[thibay]

My heat control valve is completely frozen.
The valve body is soaking in petrol for 1 week but still don't move even under hammer shocks.

I didn't tried yet to heat it.

Howhever even if I can get this out it'll need to be replaced.
I don't see rebuild kits in cars.inc or bobs catalogs.

Do you know a place where I can order it ?

Thanks,

Thibault

[Al's 52]

I read an article in a machinists' forum that rated 8-10 rust busting products. Believe it or not a mixture of 50% acetone and 50% ATF in an oil can outdid the best by more than 40%. I haven't tried it on a rusty bolt but will asap. I'd run the car, get the exhaust warm to the touch (first application only) shut it off and try that mixture. Keep the shaft assembly wet for a couple of days by squirting this on both sides as it soaks in. After a couple of days, tap (gently) on the end of the shaft with a small hammer and squirt it again. There is a little end play in these shafts (1/8 in or so) . Be careful not to bend and break the weighted piece on the spring side of the heat riser. Patience is the name of the game. My dad taught me that. He probably learned that the hard way. Let us know how you make out.