Heat Riser Question.
Thread Starter
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Heat Riser Question.
The heat riser never seems to open even after a long ride, untill I have time to change it can I just wire it open?
With it staying closed does that lower the MPG?
With it staying closed does that lower the MPG?
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You can wire it open. You can also buy a spacer instead of the heat riser. It will most definitely effect your mpg if it is closed. You effectively cut off the exhaust flow on the right bank which isn't "efficient" to put it mildly. You can try to free it up with some penetrating fluid like WD-40 or PB Blaster. But I would replace it.
Race Director
Joined: Mar 2006
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From: Florida
Thread Starter
Le Mans Master
Joined: Aug 2006
Posts: 7,417
Likes: 1,554
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Thanks for all the suggestions.
I'll try the PB a few times over the weekend and see if that helps. The riser has been in there since I got the car 10 years ago so I'm sure it's past its life expectancy. If I push it down about 3/4 of the way it will pop back up, but if I push it down all the way it gets stuck but than after a ride it is back up again. If the PB does not fix it I'll order a new one.
Looks like a simple thing to change but I know from other cars that those bolts seem to need a lot of heat to loosen up. If the PB doesn't help any I'll order a replacement.
Just wondering, I live in NC and the car leaves the garage in winter at 55*. can I get away with a spacer rather the the heat riser valve?
Would that just take the choke a few minutes longer to fully open?
Thanks again for everyones advise. PG.
Looks like a simple thing to change but I know from other cars that those bolts seem to need a lot of heat to loosen up. If the PB doesn't help any I'll order a replacement.
Just wondering, I live in NC and the car leaves the garage in winter at 55*. can I get away with a spacer rather the the heat riser valve?
Would that just take the choke a few minutes longer to fully open?
Thanks again for everyones advise. PG.
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
In NC, you'll never notice the difference. In Fairbanks, Alaska, you will. Toss it in the trash. Install the spacer.
If PB doesn't work, stop by your local airport- the FBO (if they work on little airplanes) will have a little bottle of stuff called "Mouse Milk". try a little of that, or some Hoppe's #9 Gun Solvent.
If PB doesn't work, stop by your local airport- the FBO (if they work on little airplanes) will have a little bottle of stuff called "Mouse Milk". try a little of that, or some Hoppe's #9 Gun Solvent.
Thread Starter
Le Mans Master
Joined: Aug 2006
Posts: 7,417
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Great Advise!
In NC there is a gun shop on every corner and a few small airports on every few miles. My boss had a meeting last week and stated that if you do not use your 6 sick days before the end of the year we can no longer carry them over to the next year and any vacation days not used will be forfeted when the new year begins, so I'll be calling sick tomorrow and have time to search for the Milk Mouse and Hoppe's #9 gun solvent you mentioned, thanks.
Buy the way he now says we have to pay half the medical on our own which will cast $40.00 extra per week. I doubt that I'm going to be long on this job. PG.
Buy the way he now says we have to pay half the medical on our own which will cast $40.00 extra per week. I doubt that I'm going to be long on this job. PG.
Last edited by Peterbuilt; Oct 29, 2009 at 03:59 AM.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
GM & others sell a high temp rust penetrant and heat riser lubricant. Run of the mill penetrants will burn off quickly.... the correct lubricant will not.
Edit:
AC Delco Part 10-6000
88900415
Rust Penetrant and Inhibitor
Contains a special blend of solvents and lubricants
Dissolves rust and corrosion to loosen nuts, bolts and other fasteners
Lubricates heat valves and removes manifold deposits to ensure correct heat valve operation
Edit:
AC Delco Part 10-6000
88900415
Rust Penetrant and Inhibitor
Contains a special blend of solvents and lubricants
Dissolves rust and corrosion to loosen nuts, bolts and other fasteners
Lubricates heat valves and removes manifold deposits to ensure correct heat valve operation
Last edited by Tom454; Oct 29, 2009 at 10:32 AM.
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Instructor
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From: Waterbury CT.
Your heat riser is vacuum controled. Unplug the vacuum hose at the actuator and see if it opens. If it does you need to change the thermal vacuum switch or just plug the TVS with a golf tee and forget about it. The heat riser usually isn't the problem. It's normally open and is closed by vacuum through the actuator.
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
FWIW: Mouse Milk is used to lube the turbocharger wastegate on light aircraft. Good stuff.
Probably the same as that GM stuff for 2x the price.
Probably the same as that GM stuff for 2x the price.
Burning Brakes
Joined: Aug 2000
Posts: 952
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From: Morgantown,WV USA
Heat Riser Question. Reply to Thread
How do you know if the heat riser is open or closed? On my 78 if I disconnect the vacuum line the thing moves in the opposite direction (that it was in with it applied).
Dan
Dan
Former Vendor
Joined: Apr 2009
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From: Charlotte North Carolina 704-394-5150
Pete,
You engine's heat riser should NOT be vacuum controlled. That came in 1975-79.
Yes you can wire it up...but may take the choke to stay on a little biut longer...if you drive it when it is cold out.
It is an easy replacement...due to the nuts should not be frozen on ...due to your engine rebuild you did a short while ago. I would apply a little penetrating oil on a Q-tip and then apply to the threads of the exhaust manifold..instead of shooting the stuff and making a mess on your clean car....and having it burn off due to being soaked.
It is a part that you can pick up locally...instead of paying for shipping. Just make sure that you also get the gasket that goes between the exhaust manifold and the heat riser. And it would be a good idea to have on hand the donut gasket also.
"DUB"
You engine's heat riser should NOT be vacuum controlled. That came in 1975-79.
Yes you can wire it up...but may take the choke to stay on a little biut longer...if you drive it when it is cold out.
It is an easy replacement...due to the nuts should not be frozen on ...due to your engine rebuild you did a short while ago. I would apply a little penetrating oil on a Q-tip and then apply to the threads of the exhaust manifold..instead of shooting the stuff and making a mess on your clean car....and having it burn off due to being soaked.
It is a part that you can pick up locally...instead of paying for shipping. Just make sure that you also get the gasket that goes between the exhaust manifold and the heat riser. And it would be a good idea to have on hand the donut gasket also.
"DUB"
Burning Brakes
Joined: Feb 2002
Posts: 804
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From: Fresno CA
I just picked up a spacer from these guys for a 72 I'm doing. Looks like a nice piece:
http://store.heartbeatcity.net/store...cer%2C-all-SB/
http://store.heartbeatcity.net/store...cer%2C-all-SB/
Thread Starter
Le Mans Master
Joined: Aug 2006
Posts: 7,417
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Thanks everyone for all the help and suggestions, I'll dab some penetrant on the moving parts for a few days and then get the AC Delco penetrant if that doesn't help.
Some times a day at work is easier than staying home, ended up putting in a new light fixture in the kitchen and than mowing the lawn, got to keep the better half happy if you know what I mean! PG.
Some times a day at work is easier than staying home, ended up putting in a new light fixture in the kitchen and than mowing the lawn, got to keep the better half happy if you know what I mean! PG.
