Manifold Heat Control Valve ...

[peter e mark]

Hello everyone, and todays intake manifold replacement question is : AS my repalcement exhaust manifold's heat control valve don't work, or is absent altogether, shall I install a blank plate into what is the bypass between the intake and exhuast manifold? I don't understand how the use of such a valve isn't a bypass to and cosequent reduction of, the carberated mixture being delivered into the cylinders?

[AmarilloCorey]

Hello everyone, and todays intake manifold replacement question is : AS my repalcement exhaust manifold's heat control valve don't work, or is absent altogether, shall I install a blank plate into what is the bypass between the intake and exhuast manifold? I don't understand how the use of such a valve isn't a bypass to and cosequent reduction of, the carberated mixture being delivered into the cylinders?

Peter,

It's been awhile since I've had an M-37 manifold apart so my mental details are sketchy, but the heat control valve is not a bypass between the two manifolds if that's what you're thinking. All the plate does is allow or disallow hot exhaust gasses to "hit" the bottom of the intake manifold. This should aid in warming and keeping warm the intake manifold when you have it in the winter setting.

When in the summer position the plate is horizontal and blocks the exhaust gas from directly contacting the bottom of the intake and when in the winter position it is vertical and allows the hot gasses to warm the intake.

Isn't it just a flat plate that is supposed to be there? That's what I don't remember.

Corey

[monkeymissile]

yes, it's just a flat plate with the corners knocked off welded to the shaft that acts as the diverter of the exhaust. If yours is missing you don't have to do a thing although if the shaft is missing you'll have an exhaust leak. If the valve is stuck in a bad position (most are!) then it can sometimes cause one end of the manifold to get too hot and crack.

[peter e mark]

Thank You all, And yes, one end of my exhaust manifold is cracked ! Big Johnny Midwest sold me a "good " exhaust take out, and a new intake manifold and gasket set, and i am planning to replace it all. I hope i can finnish this job in one work day ...

[monkeymissile]

have fun, I just finished the exact same repair a few weeks ago except my used manifold had a stuck heat riser valve that I had to machine out. Then I did 2 coats of manifold paint. Took me a weekend, but looks and runs great. I am going to use a cable to actuate my riser valve from inside the cab, right now I just have a spring holding it in the summer position.


[img][img]http://inlinethumb62.webshots.com/27517/2235476120103704959S600x600Q85.jpg[/img][/img]

[peter e mark]

Thank You, And I am encouraged by your report of your machine running better...Not sure what I'll do about the valve yet, or the paint, but I do expect to get more manifold vacuum out of it all, which is 17" VAC presently....

[monkeymissile]

my one issue was that three out of the four bolts that held the two manifolds together were broken off in the intake manifold, oh joy! I had to drill out and re-tap them by hand. Then the gasket surface above the heat riser valve on the exhaust manifold was anything but flat. I hit it with a file and made sure the gasket fit well and put a healthy coating of copper spray on it before assembly. So far so good, no leaks.
If your valve is stuck in a bad position, you could just dremel out the diverter plate and leave the shaft in, won't hurt anything, maybe just harder starting in the cold.

[peter e mark]

Thanks monkeymissle, Im sure your description will make more sense to me when I have the manifold in one hand, while I scratch my head with the other ...I'm going to schedule a vacation day from work for this one....

[monkeymissile]

Peter,
sounds like an ideal vacation to me! I have a vacation week coming up and plan to tackle my brakes, hope it's enough time!

[peter e mark]

It seems to me brakes are much more straight forward, you have the brake parts in front of you, the TM manual telling you what to do, the feeler guage, the blanket, knee pads and jacks, your favorite red rags and of course snap on tools ! Just add radio, soda and cookies and your all set !

[monkeymissile]

theoretically straighforward, but I've never had the pleasure of working on brakes so it'll all be new to me. I have all new wheel cylinders and a new MC to install. Like I said, I hope a week is enough!

[peter e mark]

In that case, make sure you have flare nut wrenches, brake fluid, glasses for when you disturb the old master cylinder which will be positioned directly over youyr face, gloves, for when you try to manipulate that bastard master out. a socket set with a variety of extentions and flex sockets, kano kroil penetrant, drop light, someone to pump your brakes when the hydrualics are done, sedatives and a bible.

[monkeymissile]

just need the wrenches and I should be good to go!

[ELBUFO]

Is the heat diverter manually adjusted or is there a bi-metallic spring internally. Mine is stuck in the same position shown in Monkey's picture. So far no manifold damage...John

[AmarilloCorey]

Is the heat diverter manually adjusted or is there a bi-metallic spring internally. Mine is stuck in the same position shown in Monkey's picture. So far no manifold damage...John

Manually adjusted.

Corey