212 Exhaust manifold Heat Control Valve issue help needed

Bitburger

I have a 47 series 171 with a 212.  I'm having an issue with excessive heat from the exhaust manifold which after warm up seems to make the Choke assembly quite hot. It appears that the heat control valve is stuck, not sure in what position.

 The Mechanical Procedure Manual section 16 page 284 does not list series 171 re the Heat Control Valve.  It does show for series 172,173 and. 178 for one remedy and series 173 and 174 for another. The difference being service with or without removing the manifold.

Can anyone tell me if I remove the Heat Control Valve assembly and do not replace it would there be any problems. I'm in North Carolina so not sure if I even need it anyways.

Are replacement Heat Control Valve Assemblys available anywhere ?

Any help appreciated

Huddy42

If you don't need it where you live I would removed it, they are prone to stick in the closed position.

Bitburger

Huddy42 said:

If you don't need it where you live I would removed it, they are prone to stick in the closed position.

If stuck in the closed position would that account for the heat issue ? Removing it would not affect the automatic choke operation correct ?

barrysweet52

There is a W for winter and a S for summer cast on the ex manifold, so easy to see what season it is stuck on. This heat control valve is brittle if you use a knockometer. Club members do have spares.

Bitburger

barrysweet52 said:

There is a W for winter and a S for summer cast on the ex manifold, so easy to see what season it is stuck on. This heat control valve is brittle if you use a knockometer. Club members do have spares.

Per the manual aren't the S and W on 20 and 28 models with single barrel carbs and manual chokes ? Which I think would be pre 1942 applications. My 47 series 171 has a two barrel carb with the automatic choke setup.

Bitburger

Attached is a pic from the carburetor side

Toddh

The flap forces hot exhaust around the intake barrels to heat the fuel mixture back when gas was less volatile.   It uses a coil spring element that opens and closes the flap based on engine temperature that appears to missing on yours.  Not really necessary these days. You should pull the exhaust manifold and hose it down with a penetrating oil and let it sit until you can move the flap open. You may also find that the heating chamber on your intake manifold is full of crap too

Bitburger

Can the entire valve assembly be removed by removing the nut and bolt and the cover (shown in the picture) that appear to hold the assembly in place ?  I'm not sure why the cover is secured by a bolt and a nut/stud vs two studs with nuts. Perhaps an earlier fix.

If possible I would like to attempt to fix with the manifold in place vs removal.  My guess is that both the bolt and nut/stud will break but if all I'm doing is welding the cover back on it won't matter.

Toddh

The advise always given to me was to not mess with that oval cover and to just take the whole manifold off so I’ve never done it. My thoughts are that you’ll be putting a lot of stress on the manifold trying to remove it on the block.  

Maybe another can chime in here on their experiences. 

Huddy42

Bitburger said:

Huddy42 said:

If you don't need it where you live I would removed it, they are prone to stick in the closed position.

If stuck in the closed position would that account for the heat issue ? Removing it would not affect the automatic choke operation correct ?

Bitburger said:

Huddy42 said:

If you don't need it where you live I would removed it, they are prone to stick in the closed position.

If stuck in the closed position would that account for the heat issue ? Removing it would not affect the automatic choke operation correct ?

Bitburger said:

Huddy42 said:

If you don't need it where you live I would removed it, they are prone to stick in the closed position.

If stuck in the closed position would that account for the heat issue ? Removing it would not affect the automatic choke operation correct ?

Huddy42

Yes, if stuck in the closed position it will cause heat issues as the heat is trapped in the front section of the manifold, no need to remove manifold to remove oval plate, but, be careful as the bolts make break.

Bitburger

Huddy42 said:

Yes, if stuck in the closed position it will cause heat issues as the heat is trapped in the front section of the manifold, no need to remove manifold to remove oval plate, but, be careful as the bolts make break.

Based on the condition of the bolt and the nut/stud I believe they both will break.  I'm considering cutting off the head of the bolt and cutting away the nut from the stud so at least there will be something left to reattach the oval cover to. 

Does the valve/butterfly plate come out with the oval cover as one unit ?

JACK356

I have overcome mine. Well watered with gripping especially in the center. The axis deboite once the oval is removed. There are two small rings. One in the collector; the other in the oval piece. The bolts are broken. Retarauded and placed two helicoil. I am looking for the tube that goes from the small heater to the carburetor choke.

JACK356

On mine eight 34 we can clearly see the piece that it is above. With w and s;the piece that fits on the axis and the spring. All original

Bitburger

Huddy42 said:

Yes, if stuck in the closed position it will cause heat issues as the heat is trapped in the front section of the manifold, no need to remove manifold to remove oval plate, but, be careful as the bolts make break.

So now the oval plate is off. The valve/butterfly plate is jammed solid.  Shown in the pic, is that open or closed ?   My guess is where the shaft goes through the other side of the manifold is rusted in place. I am lubing with PB Blaster and hoping I can drive it out from the backside of the manifold.  Any ideas ?

BigSky

Bottom line, get rid of that stupid diverter plate inside the exhaust manifold they are nothing but problems. Mine was rusted closed on the inside so I removed the manifold & got rid of it.  I’ve driven my 37’s 212ci engine down into the low 40’s without any warming issues what so ever after removing mine, & I’m in Montana.  On mine hot exhaust can still go around the intake manifold as before but it’s not all forced to only go around it now.  Soak the nuts/studs well & you should be able to get the nuts off.  

As you can see in the photos below, I put a gasket behind the plate to seal it.  I have a stainless steel bolt & washers going all the way through the middle to fill the two holes on each side. 

If you were dead set on keeping it in place, I’d find someone to machine a brass bushing to be put on both sides of the manifold in hope it wouldn’t get rusted shut again with infrequent use.  

Val

The one on my 39 212 is welded in the open position. Works well that way. 

Bitburger

BigSky  nice clean finished look on yours and I will follow.  Where did you get the gasket or did you make one ?

Geoff

Just one suggestion, rather than a bolt right through, I would use a short bolt and nut on the inside, and make a flat plate for the outside.  

BigSky

A retired mechanic had some old asbestos sheet, the “good stuff” & I made it from that.  I have seen exhaust sheet on Amazon not long ago.  Otherwise the new Permatex high temp is a good option.  https://www.amazon.com/Permatex-Right-Minute-Temperature-Gasket/dp/B08CRY9WHC/ref=mp_s_a_1_7?dchild=1&hvadid=73598718293386&hvbmt=be&hvdev=m&hvqmt=e&keywords=the+right+stuff+permatex&qid=1631642853&sr=8-7

Geoff’s recommendation is definitely an option one could do. 

Bitburger

BigSky said:

A retired mechanic had some old asbestos sheet, the “good stuff” & I made it from that.  I have seen exhaust sheet on Amazon not long ago.  Otherwise the new Permatex high temp is a good option.  https://www.amazon.com/Permatex-Right-Minute-Temperature-Gasket/dp/B08CRY9WHC/ref=mp_s_a_1_7?dchild=1&hvadid=73598718293386&hvbmt=be&hvdev=m&hvqmt=e&keywords=the+right+stuff+permatex&qid=1631642853&sr=8-7

Geoff’s recommendation is definitely an option one could do. 

Ok thanks for the info and the link. Since my original mounting studs are not usable for the short bolt route I think the long through bolt is best for me. 

Bitburger

Looks like assembly should be easier than removal. Thanks to all who responded and helped. Much appreciated