67 Calais what is the funny weight dohickey by the right exhaust manifold

[richardbergquist]

I saw today that by the exhaust manifold on the right side there is a little weight gadget with a heat sensing spring. Anyone knows what it does?

[Cadillac Fleetwood]

I saw today that by the exhaust manifold on the right side there is a little weight gadget with a heat sensing spring. Anyone knows what it does?

It's called a heat riser valve. It operates thermostatically with a bi-metallic spring, and with a weight, and allows heated exhaust gases to be used to warm a cold engine.  As the engine warms, the valve opens, ending the diversion of exhaust gases and allowing them to exit through the rest of the exhaust system.  Normal vehicle maintenance requires periodic lubrication of the pivots on this valve, so that it moves freely at all times.

-Charles Fares

[richardbergquist]

Thank you Charles, that was very interesting information. I doubt anyone has lubricated it on my car for many years but it moved freely nonetheless.

[35-709]

Make sure that doohickey stays loose too, and that the spring that opens and closes it isn't broken.  They can cause all kinds of expensive problems if they rust or seize in the closed position.

[35-709]

That is big problem with those heat riser valves, many people don't even know they are even there or what purpose they serve, leading to neglect which leads to problems later.

[Mike Josephic CLC #3877]

It important that you use the proper lubricant on
these.  You cannot use just any oil.  An oil will
turn to sludge at those temperatures and make
the unit stick -- the opposite of what you want.

Use graphite in alcohol -- sold under the name
"Lock-ease ".  The alcohol evaporates off quickly
and the graphite stays put and does it's job. Once
per year is enough.

Mike

[tripwire]

This is the stuff you want to use.

https://www.amazon.com/Genuine-GM-88862628-Penetrant-Inhibitor/dp/B00BK7MLKE

Wes in VT

[cadillacmike68]

At what temp are these supposed to actually close? when I had my engine apart for rebuilding, that valve was fully open at 80F. The spring and everything worked fine, but it was open. I didn't put it in the freezert to see when it would close, but am wondering.

[Glen]

The manual does not give a temperature it opens at, but I would think it would be closed at 80 degrees.  You may have to tighten the spring a turn. 

[cadillacmike68]

I'll just leave it open, the car gets plenty hot pretty quick enough as it is.

[fishnjim]

Just an artifact of carburetion.    That's supposed to restrict only when it's "cold", so the choke side warms up faster so it doesn't stay choked and foul out.   Carbs atomize by air passing through venturis, and that takes heat to partially evaporate for good starting.   Today's gas is different than what it was designed for.   Your choke spring should be holding choke near open when the riser is open.   Unless you live in frigid snow country, not really needed.  Many take them off during exhaust change.   
More harm, if it doesn't open at all.  Usually the springs corrode off with time, so check.

[savemy67]

Hello Richard,

I needed to replace my exhaust system.  I also removed my exhaust manifolds.  Given the age of the car, a lot of corrosion, rust, and broken studs were encountered, including at the manifold heat riser.

One of your posts indicated that the heat riser valve moves freely.  As fishnjim notes, corrosion can hide the fact that the valve may not be operating properly, even if the weight moves freely.  If you have a temperature gun, you may want to aim it at the manifold just above the heat riser while the car goes from cold to normal operating temperature.  If the valve is working properly, the temperature should go from ambient to maybe close to 400 degrees, then it should decline a few tens of degrees when the valve is fully open, and the exhaust flow rushes out the manifold carrying away some heat, and the temperature settles in the mid 300s.  If the temperature does not drop, your valve may be stuck in the closed position, which is not good.

You can also verify that the valve works by removing the exhaust cross-over (Y) pipe, and looking at the valve in the end of the manifold while operating it.  This task risks damaging the heat riser valve.

You can get new heat riser valves ($100 or more), or you can remove the valve.  If you decide to remove the valve, I suggest you consider replacing it with a spacer.  This will maintain proper alignment of the exhaust cross-over pipe.

Respectfully submitted,

Christopher Winter

[Cape Cod Fleetwood]

"dohickey"...

I LOVE IT!

After all the $hit I take for using "thingy" and "gizmo"!

LOL!

such fun

\m/
Laurie

[35-709]

   Puhleeze, it is doohickey 

doo·hick·ey
/ˈdo͞oˌhikē/
nouninformal•North American
noun: doohickey; plural noun: doohickeys

    a small object or gadget, especially one whose name the speaker does not know or cannot recall.
    "a garage filled with electronic parts and other valuable doohickeys"
    synonyms:   thing, so-and so, whatever it's called

[Cape Cod Fleetwood]

  Puhleeze, it is doohickey 

doo·hick·ey
/ˈdo͞oˌhikē/
nouninformal•North American
noun: doohickey; plural noun: doohickeys

    a small object or gadget, especially one whose name the speaker does not know or cannot recall.
    "a garage filled with electronic parts and other valuable doohickeys"
    synonyms:   thing, so-and so, whatever it's called

I sit corrected, LOL!

\m/
Laurie

[Jeff Rosansky CLC #28373]

The 55 has one but it is the older style. Instead of it being a dohickey it is a thing-a-ma-jig.  It is stuck open which ia fine by me but I still check to be sure the exhaust output is the same on the left vs right.
Jeff

[David Greenburg]

If you are looking to remove/disable it and a spacer is not available, you can either weld it open, or, as I did, remove the valve plate from the shaft and reinstall.  Added benefit of maintaining original appearance in the event you are concerned about such things.

[cadillacmike68]

"dohickey"...

I LOVE IT!

After all the $hit I take for using "thingy" and "gizmo"!

LOL!

such fun

\m/

en espanol we refer to them as dettos or desos.

Laurie

My nieces over used the term so much I had to dig out my Detto Pietro cycling racing shoes, and show them that Detto is actually an Italian shoe company.

http://www.dettopietro.com/en/scheda_prodotto.php?ID=6