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Veteran
Posts: 147
 
| hi friends.
I've had my car for 7 years and have driven it 25k so far. I knew my hr was stuck from the beginning but the passenger side exhaust (dual) was always emitting fumes so I wasn't worried about that.
Now i wanted to take a look at the hr so i recently demounted the downpipe and saw that the hr was not completely open, but closed 3/4. The shaft is extremely tight, but I was able to turn it with a grip wrench until the flap was fully open.
The car always ran smoothly and I never had any problems with the engine running. Can damage still have occurred? |
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Expert 5K+
Posts: 9654
  
Location: So. Cal | I think the damage from excessive back pressure is clogged piston oil rings, carbon build-up, degraded oil, weakening gasket seals. So as long as you don't notice excessive oil burning, and you do an oil change, I wouldn't expect any significant long term effects from it - especially if you were driving it more casually, not aggressively. Also, when the heat riser is closed, the exhaust can still exit through the intake to the left side of the car, so the exhaust isn't fully shut down. But it would cause your intake to always be quite hot while running.
Edited by Powerflite 2023-07-05 2:27 PM
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Expert 5K+
Posts: 9900
Location: Lower Mainland BC | .
I think Powerflite gave you the answer(s) you need. If you wanted to learn more, you could read pages 15 to 24 in this pdf:
https://www.mymopar.com/downloads/mtsc/082.pdf
Or watch this video from 10:15 to the end:
https://mymopar.com/mtsc-1954-volume-7-10-automatic-choke-and-heat-c...
Edited by 56D500boy 2023-07-05 3:01 PM
 (HeatControlValveFunctionSchematic.jpg)
Attachments
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 HeatControlValveFunctionSchematic.jpg (146KB - 47 downloads)
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Extreme Veteran
Posts: 350
| When I was on the bench, 60 years ago, we had a Heat Riser Solvent. We found those darn HR’s stuck up on many of the cars. I have no idea what that solvent was. I squirt WD40 on mine regularly. It stinks until it burns off. If someone out there has an alternative it will make Todd and myself happy.
Del |
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Extreme Veteran
Posts: 580
| https://www.yearone.com/Product/1967-1968-1969-1970-1971-1972-1973-1...
0-1981-Pontiac-Firebird-Trans-Am-Parts/2627N/view#prettyPhoto
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Veteran
Posts: 147
| Thanks guys for your thoughts on this.
@dels56 : https://paceperformance.com/i-10086466-88862628-gm-ac-delco-rust-pen...
https://www.summitracing.com/int/parts/ado-10-4020/overview |
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Veteran
Posts: 147
| Here's a probably stupid question: in case of a frozen open heat riser - Would it be possible and would it make sense to close the tail pipe on the passenger side on cold days (with a rag, for example), and then let it idle for 5 minutes and then remove the rag and go for a ride? :).... so to speak kind of manual heat riser )))
Edited by Todd 2023-07-07 8:22 AM
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found heat riser stuck 3/4 closed
