E-bay

 

YES----VERY VERY MUCH!
( sorry for the hijacking of this thread on this).

DUB

 

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

 

Thanks Dub, I just checked the inside of the thermostat housing. The green one has a broken off sensor inside the housing, so it is no good. I could probably cut out the yellow one. I found a yellow one online, is there any difference functionally between the green and the yellow one, can I replace the green one with a yellow one.
Thanks

 

Nope

 

Thank you I think I found the part # for the green one, 3031386. Called local dealer.

 

Had another question, what is different between each Thermal vacuum switch :
1. Purple
2. Yellow
3. Green

 

I expalined/answered that in POST #11. That post must not have been read.

DUB

 

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.

 

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

 

Thanks Dub that helps, appreciate it. I am doing my best to cut the yellow one out of the thermostat housing.

 

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

 

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

 

Green one screws into the thermostat housing. looks line one line goes to distributor.

 

Thought so. I will get back to you on this.

DUB

 

Thanks dub, here is assembly pic with arrow pointing to the efe switch.

 

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

 

Yes you are correct, thanks a bunch

 

This is FYI but this GM # is an OEM part number...whereas

This GM # is a service replacement. The number sequence indicates when numbers were assigned...I mean this is totally useless to R16678 queries.

 

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