Question on Thermal Switches
12-03-2016, 12:54 PM
#21
12-03-2016, 03:58 PM
#22
Race Director
DUB, you are an asset to this forum and all of us trying keep these cars on the road. Your support helped me learn how my '81 carb and emissions worked to the point everything operates correctly. Otherwise I would have gutted it and taken what seemed like the easy route. Now I just have to get the HVAC system working correctly. BTW, I hope you're enjoying the mini C2 dash I sent you.
( sorry for the hijacking of this thread on this).
DUB
12-03-2016, 04:07 PM
#23
Race Director
Thanks Dub the purple one broke off at the head, so I have to try to get that one. The other two are locked into the old housing and have a bunch of build up around them inside the thermostat housing, I can trying cleaning them up and see if I can reuse them. I appreciate the guidance. Thanks again for all your help.
The CLR stuff will work but being pipe thread design..I seriously doubt it can wick into these threads.
In my opinion. If I had a customer who wanted me to address these two TVS' in the thermostat housing and wanted me to take them out. I would either cut the thermostat housing and get the TVS' to come out and get a new one....or possibly apply heat the the thermostat housing and get it to expand some and then try to take the TVS' out.
If I was finding that I was beginning to round off the hex head portion of the TVS....I would sacrifice the thermostat housing...and NOT think twice about it. And this is becauase you can buy the thermostat housing readliy. And the cost of the thermostat is less than me farting around for hours on trying to get two TVS' out.
DUB
12-03-2016, 06:05 PM
#24
Racer
Thread Starter
If you can post a photo of the amount of 'build up' you are referring to would be helpful.
The CLR stuff will work but being pipe thread design..I seriously doubt it can wick into these threads.
In my opinion. If I had a customer who wanted me to address these two TVS' in the thermostat housing and wanted me to take them out. I would either cut the thermostat housing and get the TVS' to come out and get a new one....or possibly apply heat the the thermostat housing and get it to expand some and then try to take the TVS' out.
If I was finding that I was beginning to round off the hex head portion of the TVS....I would sacrifice the thermostat housing...and NOT think twice about it. And this is becauase you can buy the thermostat housing readliy. And the cost of the thermostat is less than me farting around for hours on trying to get two TVS' out.
DUB
The CLR stuff will work but being pipe thread design..I seriously doubt it can wick into these threads.
In my opinion. If I had a customer who wanted me to address these two TVS' in the thermostat housing and wanted me to take them out. I would either cut the thermostat housing and get the TVS' to come out and get a new one....or possibly apply heat the the thermostat housing and get it to expand some and then try to take the TVS' out.
If I was finding that I was beginning to round off the hex head portion of the TVS....I would sacrifice the thermostat housing...and NOT think twice about it. And this is becauase you can buy the thermostat housing readliy. And the cost of the thermostat is less than me farting around for hours on trying to get two TVS' out.
DUB
Thanks
12-03-2016, 06:58 PM
#25
12-03-2016, 07:28 PM
#26
Racer
Thread Starter
12-04-2016, 12:28 AM
#27
Racer
Thread Starter
12-04-2016, 06:56 PM
#28
Race Director
12-04-2016, 07:17 PM
#29
Racer
Thread Starter
Dub I understood what you said in post #11, but was not sure what the difference is between green & yellow TVS that sit in my thermostat housing. Do they perform different functions or react to water heat differently? My purple TVS is in the intake manifold. Thanks again for all your guidance.
12-05-2016, 06:09 PM
#30
Race Director
Dub I understood what you said in post #11, but was not sure what the difference is between green & yellow TVS that sit in my thermostat housing. Do they perform different functions or react to water heat differently? My purple TVS is in the intake manifold. Thanks again for all your guidance.
The purple one may operate BEFORE the coolant temperature actually gets high enough for your thermostat to open. It has been a very long time ago....but in the past I checked them and knew what temp they basically 'switched' at. But that was LONG time ago and I have forget that. As long as they 'switch' is all I am usually concerned about.
The thread sizes of the TVS' is also specific so it can only be threaded in the thermostat housing where it is supposed to go.
YES...it is possible that the TVS can 'switch' at different times due to the sensor itself and the range of temperature it is set-up to switch at.
DUB
12-05-2016, 09:04 PM
#31
Racer
Thread Starter
YES...your green and yellow TVS' perform different tasks because that are directly plumbed to specific parts on your engine. SO...they DO make a difference in where the vacuum hoses go.
The purple one may operate BEFORE the coolant temperature actually gets high enough for your thermostat to open. It has been a very long time ago....but in the past I checked them and knew what temp they basically 'switched' at. But that was LONG time ago and I have forget that. As long as they 'switch' is all I am usually concerned about.
The thread sizes of the TVS' is also specific so it can only be threaded in the thermostat housing where it is supposed to go.
YES...it is possible that the TVS can 'switch' at different times due to the sensor itself and the range of temperature it is set-up to switch at.
DUB
The purple one may operate BEFORE the coolant temperature actually gets high enough for your thermostat to open. It has been a very long time ago....but in the past I checked them and knew what temp they basically 'switched' at. But that was LONG time ago and I have forget that. As long as they 'switch' is all I am usually concerned about.
The thread sizes of the TVS' is also specific so it can only be threaded in the thermostat housing where it is supposed to go.
YES...it is possible that the TVS can 'switch' at different times due to the sensor itself and the range of temperature it is set-up to switch at.
DUB
12-06-2016, 07:45 AM
#32
Racer
Thread Starter
I found the GM part # for the purple one and the yellow one, but can not find the part # for the green one. Anyone have an idea what the green TVS part # is
Purple EGR - part # GM 373510
Yellow EFE TVS - part # GM 14009008
Purple EGR - part # GM 373510
Yellow EFE TVS - part # GM 14009008
12-06-2016, 06:11 PM
#33
Race Director
What is the green one going to????
I know one hose is from a vacuum source...but where does the other hose go to???
I will look IN my GM parts book and see if I can find it.....but knowing what it is doing will help.
DUB
I know one hose is from a vacuum source...but where does the other hose go to???
I will look IN my GM parts book and see if I can find it.....but knowing what it is doing will help.
DUB
12-06-2016, 06:38 PM
#34
Racer
Thread Starter
Green one screws into the thermostat housing. looks line one line goes to distributor.
12-06-2016, 06:42 PM
#35
Race Director
12-06-2016, 06:45 PM
#36
Racer
Thread Starter
12-06-2016, 06:49 PM
#37
Race Director
Just so we are on the 'same page'...You are NOT pointing to the EFE TVS switch....you are pointing the 'TR SPK TVS'
I will look into it for you tomorrow.
DUB
I will look into it for you tomorrow.
DUB
12-06-2016, 07:23 PM
#38
Racer
Thread Starter
12-07-2016, 04:00 PM
#39
Safety Car
Purple EGR - part # GM 373510
Yellow EFE TVS - part # GM 14009008
12-07-2016, 04:04 PM
#40
Safety Car
Your red arrow is pointing to the transmission spark TVS switch...not the EFE...as DUB points out.
So the TVS switch hose routes to the distributor; through the TVS switch; and then onto the carb port. Engine manifold vacuum is controlling or managing distributor spark advance...kind of an interesting "vacuum" emission management technique.
The attached document shows the hose routing of a 1978 L48 to the carb port less the transmission spark TVS switch (#3). All you are doing is inserting the TVS switch into the distributor to carb port hose circuit. In my 78, I don't have the TS TVS switch so it connects directly. What you may be missing is the "F" which is a three-port check valve. The hose from the distributor routes to the front port of the check valve. From your AIM Schematic, you can see that two ports route to the TR Spark TVS switch. The back side of the check valve routes to the carb port per my schematic below.
Supposedly, you 79 gets 5 HP more from all this emission hose configuration...but, as you have learned, it gets much more freakin complicated. We should have recognized that this was a premonition of an Obama administration.
Frankly if you wanted to make your Corvette life less complicated, configure it like my 78. Get a thermostat housing with only one inlet port for a TVS switch. You're down to purple and yellow...drop the green and route the hose directly from the distributor to the lower carb port as shown in the schmatic.
TVS Switch_1979.pdf
So the TVS switch hose routes to the distributor; through the TVS switch; and then onto the carb port. Engine manifold vacuum is controlling or managing distributor spark advance...kind of an interesting "vacuum" emission management technique.
The attached document shows the hose routing of a 1978 L48 to the carb port less the transmission spark TVS switch (#3). All you are doing is inserting the TVS switch into the distributor to carb port hose circuit. In my 78, I don't have the TS TVS switch so it connects directly. What you may be missing is the "F" which is a three-port check valve. The hose from the distributor routes to the front port of the check valve. From your AIM Schematic, you can see that two ports route to the TR Spark TVS switch. The back side of the check valve routes to the carb port per my schematic below.
Supposedly, you 79 gets 5 HP more from all this emission hose configuration...but, as you have learned, it gets much more freakin complicated. We should have recognized that this was a premonition of an Obama administration.
Frankly if you wanted to make your Corvette life less complicated, configure it like my 78. Get a thermostat housing with only one inlet port for a TVS switch. You're down to purple and yellow...drop the green and route the hose directly from the distributor to the lower carb port as shown in the schmatic.
TVS Switch_1979.pdf
Last edited by hunt4cleanair; 12-07-2016 at 04:50 PM.
