In the thermostat housing there are two vacuum switches. The one on the p.side is for the EFE system (correct me if I'm wrong!) & the other one on the d.side is for the purge cannister (although it's got EGR in raised letters on it?). The p.side one fits into a 1/2"? NPT hole (3/4" diameter thread) & the other has a smaller diameter thread. The switch for the purge cannister is broken (I had a slight, er, accident :rolleyes: ) & I tried to buy a new one. A switch for the EFE arrived! I tried to order again, saying "not the EFE switch, the other one in the housing" & in due course a switch for the EFE arrived. I now have 3 switches for the EFE system, which isn't even connected! Has my car been Bubba'd or is the d.side switch on an L81 actually for the purge cannister (even though it's got EGR embossed on it)? My supplier has faxed a copy of the L81 350 emission controls & I can see the EFE switch on it - but not the purge canister switch (explains why he had problems). There is something called the evap cannister purge switch, but in the diagram it doesn't look like what I want.
So, what have you other L81 owners got in your thermostat housings regarding switches/sensors? Does the d.side one have 2 vac pipes going to it, one of which goes to the purge cannister stuff? Anybody know the part ordering number for it? And, last question, why is it always the simplest things that cause the most grief :confused: ?
TIA
Paul (who will never, ever again let a socket wrench twist when the head shears off of a thermostat housing bolt next to a vacuum switch when trying to undo it :( )

 

:lol:

OK, Paul, I'll let you know in a few minutes. That's how long it will take me to stroll out to the office parking garage and look under my hood. That's because I drove the Vette to work AGAIN today... :D

 

Paul - I busted mine as well a while back...check out Dr Rebuild....hes got some great pics.
Its also where I got my new switch from :)

I really want to go check for you , but cant right now.

If I remember correctly the drivers side on has 2 hoses..one goes to the carb..the other to the vacuum canister..

Ill have to check later for you though

Kevin

 

looks like gator is going to beat me to it...I drove mine as well to work today - ha

 

OK, Paul, here's what I've got. The p.side piece is the "EFE TVS" (thermal vacuum switch), and the d.side piece is the "PURGE TVS".

I can't tell you the exact vac hose routing for the EFE TVS because I no longer have the EFE. I just put a piece of hose on the two nibs on that TVS to keep the dirt out of it in case I ever have to hook it back up. I removed the butterfly from the p.side exhaust manifold, so there is no EFE to hook anything up to, right now.

On the PURGE TVS, the lower hose goes to the front of the carb, just under the electrical connector at the d.side front corner of the carb. The upper hose from the TVS goes to the evap cannister, tucked away under the d.side fender.

The vacuum hose routing is described pretty clearly on the under-hood emissions sticker - is there not one of those under your bonnet? It's about 3"x8", under the d.side of the bonnet. That's a required piece for US emissions testing, so I suppose it's considered expendable in the UK... :D

As for a replacement PURGE TVS.... none of the catalogs I've got show it. The ZIP book has the EFE TVS, but doesn't show the PURGE TVS. Perhaps you could call or e-mail them and ask?

I don't know exactly how the mechanical functions of the two TVS's differ. As the coolant temperature rises, they can either open or close, and they can be activated at different temperatures. So I doubt that they are functionally interchangeable. I seem to recall vaguely, from when mine were out, years ago, that there is an activation temperature number stamped into the bottom of the TVS's, where they dip into the coolant.

I would presume that the function of the PURGE TVS is to control at what temperature the hydrocarbon fumes in the cannister are allowed to be sucked into the carb for combustion. I may have it completely backwards, but I would expect that the TVS would be open when cold, allowing the engine to pull the fumes through the TVS, until the engine warms up and the fumes have been consumed, at which time the TVS would close. If that's the case, then you would have little to lose by simply plugging the purge hose and capping the inlet nib to the carb with a rubber cap. If I have it backwards, and the TVS is closed when cold and open when hot, then you could bypass the TVS by connecting the purge hose directly to the carb nib. Make sense?

Let me know what you run into. Glad to help if I can. :flag

 

I broke mine a while back, autozone had it, but it didn't look right, so I went to the chevy dealer and they had an updated part # for it. I think at the time they told me it is a standard TVS

 

Hi,
Thanks for the help - now I know that I'm not going mad (clumsy, maybe, but not mad!) & the TVS is for the purge function (even though it has EGR written on it). I think the EFE TVS switches vacuum to the butterfly until it hits 100 degrees (100 written on the bottom of it) & I think that the purge TVS doesn't switch vacuum to the purge cannister until a certain temp (unreadable) has been reached, at which point the engine can burn the vapour/fumes without affecting emissions? I could be wrong (it's not unknown for my logic to be completely inverted!). But that would explain why the switch has EGR written on it - the EGR system only kicks in at a certain engine temp (doesn't it?) so the EGR TVS can also be used as the purge TVS?
I've now removed the EFE TVS & plugged the hole with a Moroso chrome plug (woohoo!) which means that I can't break that TVS now! I could connect the purge cannister directly to the carb (good idea, Gator) but would that weaken the mixture slightly when cold?
Gator & Kevin: I hope you're taking the long route to & from work? :D
Kevin & Stickboy: Have you still got the reciept (Bill of Sale?) with the part number for the TVS on it (especially the GM number)? If I can give my supplier the actual part number then he'll be able to get it OK. I think the problem getting these bits is that nobody in this country seems to have an L81 with the computer still hooked up, so the suppliers never get asked for these things - until I break something ;)
Thanks again for your time & help - it's comforting to know that I'm not alone in breaking things (it just fell off in my hand, honest!) :lol:
:cheers:

 

You know, I have to quit working so much. I've been neglecting the forum lately. I don't see these important topics until I'm a day late. :crazy: But, as usual, Gator81, the L81 expert, comes through in a pinch. We can always count on you to get us straightened out Gator. :cheers:

p.s. That business of rubbing in the fact that you drove the vette to work has got to stop though. ;)

-Justin

 

Justin - right you are , Gator has helped me more than a few times...good guy, that Gator :D

Paul - I keep all that stuff , so its just a matter of finding it.... I will do my best...
dont let me forget...

"take the long route...." every chance I get...you reminded me of one of my favorite songs
"Take the Long Way Home" by Supertramp......:)

Kevin




[Modified by ksems, 10:32 AM 4/4/2002]

 

geez... you guys are making me all warm and fuzzy. Stop it. :rolleyes:

 

UKPaul,

Haven't seen photos of your car since you were working on the rear under-carriage.

How's it looking?

 

Paul,

sorry this took so long, heres what I got:

Drivers side -
EGR switch
I replaced mine with NAPA Part# 2-1029 The replacement is Blue and has the code J10
My original one was mostly black with a green top on it.
It is labelled EGR and has a number on the top that reads 303 1549, there is also some numbering on the side that says 21 HRD.

Passenger Side -
EFE switch

I replaced this with an AC delco part that I believe I got at NAPA.
There are a couple numbers on the box
one of them is EH-388
the other is 14007803
Actually I may have gotten this from ZIP - sorry cant remember

The new one is black and has the number 7803 down the side of it and a 6
near the top.....I checked the old one and it has the same numbering.


Hope this helps - its all I can find

Kevin

 

I just looked for 2-1029 on the NAPA website and it didnt come up
:confused:

thats weird because I have the box in my hand with the part number on it

found this for you at Car Parts .com
here is the part you need:
http://www.carparts.com/parts/compon...link=0-0-0-0-0

the first one is the Purge valve ( or EGR )
the second one is the EFE valve

both AC Delco :D

Kevin





[Modified by ksems, 9:04 PM 4/4/2002]

 

Hold it Paul !!!

I just saw the other one on there

Part # EC19
It has an OE number of 303 1549, exactly the number that is on the top of our EGR switches - Id go with that maybe...

Good Luck

Kevin

 

Kevin:
A huge "Thanks". That's the part I need. I'll pass the part number to my supplier & wait for it to arrive. Thanks again - this forum is excellent :)
Justin:
Hi there. How's it going? We've got clear blue skies & temps of 70F (dunno what's happened to our weather, winter stopped one morning & summer started - we seemed to have skipped Spring, but I'm not complaining) & I keep getting emails from people here, who are blasting around with their tops off. No sympathy, some people, they know mine is in bits :lol:
Gator:
Good link - where can I get one of those keyboards? ;)
67:
It was looking really good. Then 2 things happened - the 1st was that I started taking more bits off :rolleyes: & the 2nd (& this one really p'd me off) was that each time I filled my daily driver up I stuck an extra gallon in a can & poured it into the Vette. One day I went to the garage (to pull some more bits off!) & there was a strong smell of petrol. The fuel tank had sprung a leak all on it's own! There's a tiny little mark in the bottom of it & the fuel is seeping out of a minute little hole in the middle of it (it was in the place that had the only bad rust on the whole tank - which is why I pulled it off & painted it). The fuel has seeped out & melted the zinc paint (that was looking really good), run down onto the freshly powder coated fuel tank xmember, along the xmember (depositing silver paint all over it), then dripped down into the spare tire tub, where it melted & lifted the satin black Smoothrite that I'd painted it with. It then dribbled all over the garage floor. I'm taking it very philosophically - I've got real :mad ! If that wasn't bad enough, I'm now getting earache from my Mother because her house stinks of petrol & her pristine garage floor has a rather fetching black & silver paintjob under the back of the car (she hasn't seen what the state of the floor is like under the front of the car yet - I dunno, 41 years old & still getting nagged by my Mother!). Things like this just seem to happen to me.... I must have done something really bad in a previous life (I can only hope I enjoyed doing it :D ). When I've got it all cleaned up (the floor that is ;) ), I'll post some pics.
:cheers: