OK, after having "freed up" the heat riser plate/shaft I noticed it didn't move when I warmed the engine up. I took a heat gun and warmed it up and the loop end of the spring moves away from the pin and the hear riser shaft, of course, does not move. I purchased a new NOS heat riser spring ( GM# 838573) , installed it and again tested with the heat gun. Same problem. I've attached pictures of both the old spring and new spring at 74 degrees F and 120F. Any suggestions? [img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/35676/filename/IMG_1846.jpg[/img]
Last edited by Dusty53; 10/07/20217:30 PM.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
More information to consider. I tried "turning the spring around" and didn't work. So I took a pair of vice grips and "secured" the "tang" to the pin. I heated it up with the heat gun and the heat riser opened like its supposed to, I cooled it off with an air gun and it closed. So what should I make of this ?? I looked at a Youtube video where "Uncle Brad" has posted a video showing the heat riser operate on a 55.2 AD Truck and that spring had a "loop" that wrapped around the pin. Do I have the wrong spring? I've attached pictures of my "clamped" spring . All input appreciated! Thanks.
Last edited by Dusty53; 10/07/20218:23 PM.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Kevin, I did and it didn't move when I heated it up. I put it back on same orientation as the old one and clamped it to the pin and it operates like it should. See my later post......
Here's pics of the spring "turned around". The spring has no tension on it when the riser is in the closed position and doesn't touch the pin when in the open position.
Last edited by Dusty53; 10/07/20219:02 PM.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I turned it around and.....nothing. I reinstalled like the original, which matches this reference photo and a page from a GMC manual and then clamped it to the pin and the heat riser operates like it should. What am I missing ?
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Did you check your bushings? The flap should fall open on its own without the spring. From your pictures, it looks like the spring is moving around the shaft rather than the shaft being moved by the spring.
Did you check your bushings? The flap should fall open on its own without the spring. From your pictures, it looks like the spring is moving around the shaft rather than the shaft being moved by the spring.
Yes, it operates very freely. When I "clamped" the tang against the pin ( see earlier post and pics ) it opens and closed as it should using a heat gun ( opens around 115 / 120 degrees) . I "cycled" it several times and it operates as one would expect. I'm stumped. I'm kinda hung up on the fact that "Uncle Brad" youtube video shows a spring that has a loop that wraps around the pin. I checked and rechecked the spring wind direction and orientation and its sure looks correct.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Does your spring not have a tang in the center that fits in the slot of the shaft? Your photos make it hard to tell.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Does your spring not have a tang in the center that fits in the slot of the shaft? Your photos make it hard to tell.
Yes it has a tang. Here's pic of it "turned around" and pulled out a bit to see the tang in the slot. What ya think? Uncle Brad's youtube video has a spring with a "loop" that goes around the pin. Your thoughts?
Last edited by Dusty53; 10/07/20219:17 PM.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Well, here's an interesting observation. With the spring installed and "heated up" the riser / counterweight can be moved to the open position with virtually zero force. I suspect the engine exhaust would open it easily and it would stay open until the engine was shut off and cooled off. As soon as I get the heater core replaced, I'll start it up and give it a whirl. Stand by for future updates.....thanks everyone.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I thought I saw something in the service manual about "winding up" the spring a bit, so that it's preloaded and starting to move the riser valve when cold. But I just looked and can't find it. In other words, put the tang in the slot on the shaft 180 degrees from where you show it in your last photo, and then pull the outer tang over the stud. The spring doesn't really push that hard, which is the reason for the counterweight.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Up front, I am not an expert. Having said that when I was fiddling with mine I ran into the same thing. Near as I can tell the spring is for closing the valve as it cools, not forcing it open as it warms. What appears to happen is, as it warms the spring relaxes it's push toward closed and the force of the exhaust pushes the valve open. When you shut the engine off and the spring cools it pulls the valve closed.
Last edited by Tiny; 10/08/20213:09 PM.
Save a life, adopt a senior shelter pet. The three main causes of blindness: Cataracts, Politics, Religion. Name your dog Naked so you can walk Naked in the park.
Up front, I am not an expert. Having said that when I was fiddling with mine I ran into the same thing. Near as I can tell the spring is for closing the valve as it cools, not forcing it open as it warms. What appears to happen is, as it warms the spring relaxes it's push toward closed and the force of the exhaust pushes the valve open. When you shut the engine off and the spring cools it pulls the valve closed.
Thank you, Tiny. What you just stated is what I read on another site last night and it makes perfect sense as the spring "relaxes" allowing the exhaust gas to "open" the heat control valve. When using a heat gun, the spring relaxed away from the pin and allows the valve to open. When it cools off the spring causes the valve to "close". Thanks for coming on the forum and giving your input, much appreciated!
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I was browsing the service manual today and found the blurb about "Winding up" the spring.
"The tension of the thermostatic spring is very important. When too tight, the heat will not be turned off the intake heat riser as the engine warms up, with the result that the incoming gasses will be expanded several times greater than normal and it will be impossible to get a normal fuel charge into the cylinders. ....... Therefore, is is important that the thermostatic spring be wound up just enough to slip its outer end over the anchor pin (fig. 4) and no more. This is approximately 1/2 turn of the spring from it's position when unhooked."
BTW it looks like you had it the right way, but just didn't have it "wound up" enough. It's not supposed to be wrapped around the anchor pin.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I was browsing the service manual today and found the blurb about "Winding up" the spring.
"The tension of the thermostatic spring is very important. When too tight, the heat will not be turned off the intake heat riser as the engine warms up, with the result that the incoming gasses will be expanded several times greater than normal and it will be impossible to get a normal fuel charge into the cylinders. ....... Therefore, is is important that the thermostatic spring be wound up just enough to slip its outer end over the anchor pin (fig. 4) and no more. This is approximately 1/2 turn of the spring from it's position when unhooked."
BTW it looks like you had it the right way, but just didn't have it "wound up" enough. It's not supposed to be wrapped around the anchor pin.
Kevin, I noted that with the heat control valve closed it takes about 1/2 a turn of the spring to get it over the anchor pin. I'd also read that section and everything seemed to be correct as far as how I installed it. Once I get the heater core replaced I'll give it a real test with the engine running and see if it works properly. Thanks again to everyone who responded with advice and suggestions.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I'm back at it - Started the motor and let it run for roughly a half hour in the garage. The temperature at the exhaust manifold reached 257F and nothing happened. I took my heat gun and pointed it at the spring and at 275 the spring wound up and pulled away from the pin, I flipped the heat riser counterweight up using a screwdriver and it stayed "open" until I removed the heat gun and then it slowly closed (dropped) back. Did the engine not reach the required temperature to operate the spring? I did not increase engine rpm to see if the heat riser would stay open, I guess I should have. I've attached photos , engine was running during my "test" . At what exhaust manifold temperature should the spring operate ??
Last edited by Dusty53; 01/03/20224:57 AM.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Temperature is irrelevant- - - -what you need is exhaust gas volume to push the flap open once the spring tension relaxes. Unless you're willing to rev the engine up to highway cruise speed in the shop, THE VALVE WILL NOT MOVE!
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Temperature is irrelevant- - - -what you need is exhaust gas volume to push the flap open once the spring tension relaxes. Unless you're willing to rev the engine up to highway cruise speed in the shop, THE VALVE WILL NOT MOVE!
Jerry
Thanks Jerry , good information to know. Happy New Year!
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
In the mid-1970's smog-equipped engines went to vacuum operated heat riser valves that got the vacuum motor triggered by a thermal sensor in the thermostat housing. When the thermostat opened, usually at 195 degrees, the heat riser would snap fully open and allow the exhaust gas to go directly down the pipe instead of being routed under the intake manifold. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
