Thermac air sensor
December 18th, 2011, 01:19 AM
#1
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Thermac air sensor
83 delta 88 307 cu.
I've been going over things on the engine and in doing so I came across the sensors in the air cleaner. I replaced the vacuum switch for the secondary pull off. Then i checked the thermac air sensor cleaner, it wasnm't working (not closing the damper to direct warm air during engine warm up). So I replaced the sensor, still didn't work. Turns out the vac lines were reversed. I hooked them up properly and it now works. Problem is the performance of the engine has suffered. For the first 10-15 minutes there is hesitation that seems to come from a lack of air that the engine is calling for upon acceleration. even after the engine is completely warmed up it still doesn't seem right. The car seems to have run a hell of a lot better without it! So before i disconnect this vac line and plug it up, i'm wondering if anyone else has experienced the same???
I've been going over things on the engine and in doing so I came across the sensors in the air cleaner. I replaced the vacuum switch for the secondary pull off. Then i checked the thermac air sensor cleaner, it wasnm't working (not closing the damper to direct warm air during engine warm up). So I replaced the sensor, still didn't work. Turns out the vac lines were reversed. I hooked them up properly and it now works. Problem is the performance of the engine has suffered. For the first 10-15 minutes there is hesitation that seems to come from a lack of air that the engine is calling for upon acceleration. even after the engine is completely warmed up it still doesn't seem right. The car seems to have run a hell of a lot better without it! So before i disconnect this vac line and plug it up, i'm wondering if anyone else has experienced the same???
December 18th, 2011, 04:59 AM
#2
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That part never works.
If you are one of the rare people who have replaced yours and connected it correctly, though, you should not be experiencing the symptoms you are experiencing.
All that valve does is to direct vacuum to the door in the air cleaner snorkel to close the door, diverting airflow from the outside intake to the intake that runs past the exhaust manifold when the engine and the outside air are cold, making intake the air warmer. This will improve cold running and warm-up.
It does not, in any way, restrict the air intake.
It "automatically" disconnects itself under heavy acceleration, because when you step on the gas, the vacuum goes down, and the door returns to the "outside air" position.
- Eric
If you are one of the rare people who have replaced yours and connected it correctly, though, you should not be experiencing the symptoms you are experiencing.
All that valve does is to direct vacuum to the door in the air cleaner snorkel to close the door, diverting airflow from the outside intake to the intake that runs past the exhaust manifold when the engine and the outside air are cold, making intake the air warmer. This will improve cold running and warm-up.
It does not, in any way, restrict the air intake.
It "automatically" disconnects itself under heavy acceleration, because when you step on the gas, the vacuum goes down, and the door returns to the "outside air" position.
- Eric
December 18th, 2011, 09:47 AM
#3
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Well for the 5 years I've had the car it hasn't worked because of the hoses being reversed. I knew it didn't work but I wasn't concerned because it's pointless other than directing warmer air for a few minutes during engine warm up. I don't see why it would create a problem either.. Unless the new sensor has a vacuum leak? When i get a chance I'll cap off the vac port going to that system and see what that does. If it's not sluggish anymore then i guess it was to blame. I'm almost wondering if someone had reversed the vac lines to purposely make it inoperative.....
Aside from the factory air cleaner, does anyone recommend just removing it and going with an aftermarket open air cleaner?? My secondary choke pull off doesn't really pull off the choke much more than the primary anyways and my AIR system is not currently connected. If we dont' care about thermac air warmer, then i don't think anything else would be affected by the open air cleaner.
Aside from the factory air cleaner, does anyone recommend just removing it and going with an aftermarket open air cleaner?? My secondary choke pull off doesn't really pull off the choke much more than the primary anyways and my AIR system is not currently connected. If we dont' care about thermac air warmer, then i don't think anything else would be affected by the open air cleaner.
December 18th, 2011, 05:28 PM
#4
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When I had a daily driver '68 Delta 455, I was darn grateful for that hot air stack and vacuum valve on the day it started and ran flawlessly on a 3 hour trip on a -25°F (-30°C) day.
Your air cleaner probably pulls cool air from in front of the core support through a dryer hose right now (a setup people paid dearly for in the sixties).
If you dispose of the snorkel, it will pull hot air from inside the engine compartment instead, reducing power and efficiency, and effectively do exactly what you said was "pointless" in the preceding sentence.
- Eric
December 18th, 2011, 05:45 PM
#5
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Eric,
I figured the cold air coming from in front of the radiator was better than the open cleaner that just pulled warm air in from around the engine thats why I never went with an open air cleaner. I'd rather have it working as intended thats why i replaced that air cleaner sensor. I just can't see why it's acting sluggish other than the sensor itself creating a vacuum leak?? I've checked the vacuum motor (the actual air door) with a vacuum pump and it held vacuum so i don't think there is a vacuum leak there. Any other suggestions?
I figured the cold air coming from in front of the radiator was better than the open cleaner that just pulled warm air in from around the engine thats why I never went with an open air cleaner. I'd rather have it working as intended thats why i replaced that air cleaner sensor. I just can't see why it's acting sluggish other than the sensor itself creating a vacuum leak?? I've checked the vacuum motor (the actual air door) with a vacuum pump and it held vacuum so i don't think there is a vacuum leak there. Any other suggestions?
December 18th, 2011, 06:04 PM
#6
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It's got to be something else.
Since the vacuum hoses were the last thing you messed with, I'd block vacuum hoses one at a time and see if any of them changes anything. Don't forget that no matter how sure you are that you didn't change anything else, there's always a chance that you dislodged a different vacuum hose or cracked a plastic vacuum tee or knocked an electrical connector off when you were fixing the vacuum sensor.
In almost every case of something not working right after you worked on it, it will be something right in the area that you disrupted and didn't notice.
- Eric
Since the vacuum hoses were the last thing you messed with, I'd block vacuum hoses one at a time and see if any of them changes anything. Don't forget that no matter how sure you are that you didn't change anything else, there's always a chance that you dislodged a different vacuum hose or cracked a plastic vacuum tee or knocked an electrical connector off when you were fixing the vacuum sensor.
In almost every case of something not working right after you worked on it, it will be something right in the area that you disrupted and didn't notice.
- Eric
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