1986 EGR Switch
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 21
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From: Parsonsfield Maine
1986 EGR Switch
How would you check the EGR switch that is screwed into the EGR tube for proper operation. Is it an open and closed switch or a varible resistor? I would like to check it out on the bench with a heat sorce if I could. I have meters to checks for proper operation, just don't know what to I should be looking for. Thanks All
Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
It's a bi-metalic strip that is in open cold and is supposed to make contact when it heats up. I adjusted mine to cure a code 32 problem & posted a thread. The link in my first post may answer your testing question:
http://forums.corvetteforum.com/c4-g...djustment.html
The switch is available for sale again.
http://forums.corvetteforum.com/c4-g...djustment.html
The switch is available for sale again.
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 21
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From: Parsonsfield Maine
I see how the switch is threaded into the porcelain/metal holder that is then screwed into the EGR tube. Somehow some part of that switch has to make contact with ground. Here's my idea on how it may work, please correct me if I'am wrong, You would screw the switch into the porcelain/metal holder a couple of turns off the bottom where it would come in contact with ground when it expands or you screw the switch untill it hits the metal bottom and the switch connects to ground internally. Do you really have any adjustment?
Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
The wire goes to the ECM. The ground is the housing screwed into the egr tube. The electrode connected to the wire is threaded into the ceramic and you can adjust it by turning it. Turn it in and it closes at a lower temperature, turn it out and it connects at a higher temperature.
When I did my I was very surprised how little force it took to turn it. The wire connection seems fragile, though, so be careful. I disconnected the wire to turn it more than one or two revolutions and the hardest part was reconnecting the wire.
Look at the thread link I posted and the chevy thunder link (which I just updated at the end of my thread).
When I did my I was very surprised how little force it took to turn it. The wire connection seems fragile, though, so be careful. I disconnected the wire to turn it more than one or two revolutions and the hardest part was reconnecting the wire.
Look at the thread link I posted and the chevy thunder link (which I just updated at the end of my thread).
Melting Slicks
Joined: Aug 2001
Posts: 2,516
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From: Lockport NY
I googled the relevant words and got...this URL...which has too many periods in it, which is what is screwing up the link (Chevy Thunder mistake)...
http://chevythunder.com/fuel injection egr temp sw..htm
Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
The extra periods is certainly part of the problem, but I couldn't paste the address into my post without the url code getting messed up. I couldn't find the article browsing within the chevythunder web site either. Googling chevythunder and egr led me there eventually & I immediately created a pdf using cutepdf so I'll have it if/when this happens again.
On the other hand my engine was pulled this week so I won't actually need this again.
On the other hand my engine was pulled this week so I won't actually need this again.
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
I commented in the other thread - "I looked in my spare parts bin and found 84 - 89 EGR TEMP SENSOR SWITCH 1408 7415 which Google shows as still a good number, and which is listed at GM NOS Parts at $125.00." Looking at my receipts, the new one I bought 10 years ago from Jeff Kopp at Superior Chevy cost $115.00...Seems to be holding its price...
Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
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Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
Also see:
http://forums.corvetteforum.com/1578426348-post14.html
and, from agent86's stash:
http://members.shaw.ca/corvette86/EGR%20System.pdf
Look at the third page, figure c7-5
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
Hmph...So that's where it goes! 
I had labeled all these things when I put them away, but the labels dried up and fell off most of them...
I wonder if that crenelated hose behind it goes on over the tube???
I actually have a couple of the crimp-on connectors to install this tube, and I found that an oxy-acetylene hose crimping tool works great on them...
I had labeled all these things when I put them away, but the labels dried up and fell off most of them...
I wonder if that crenelated hose behind it goes on over the tube???
I actually have a couple of the crimp-on connectors to install this tube, and I found that an oxy-acetylene hose crimping tool works great on them...
Last edited by Rich B.; Dec 17, 2011 at 08:07 PM.
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
Yup, that's it - looks different from yours...
14087579, SHIELD EGR PIPE (1986)
This one pushes on from the bottom...Yours looks like it wraps around (better idea)...
My Vette has never had one since 1998 (when I bought it)...and doesn't seem to have any problems...No codes, no lights...My tube is actually connected to the [new Random] catcon...The one with the spigot...
14087579, SHIELD EGR PIPE (1986)
This one pushes on from the bottom...Yours looks like it wraps around (better idea)...
My Vette has never had one since 1998 (when I bought it)...and doesn't seem to have any problems...No codes, no lights...My tube is actually connected to the [new Random] catcon...The one with the spigot...
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
That's really interesting about the EGR switch "adjustable" feature. I replaced one because it was loose. I thought it was broken, even though it seemed to work OK.
I bought one of the aftermarket EGR tube wrap around heat shields. I thought it was kinda iffy with the Velcro to attach it. Sure enough, the Velcro couldn't take the heat and basically turned into dust. I also recently found out that the earlier cars with the Oetiker clamp at the bottom take a longer heat shield. The short one I bought melted the flexible looms on the spark plug wires. My latest plan is to put header wrap on the EGR tube with hose clamps to hold it in place. I had this idea quite a while ago and then I saw a picture on the Forum where somebody else did this. I also plan on putting KoolSox on the spark plug wires, just for added insurance.
I bought one of the aftermarket EGR tube wrap around heat shields. I thought it was kinda iffy with the Velcro to attach it. Sure enough, the Velcro couldn't take the heat and basically turned into dust. I also recently found out that the earlier cars with the Oetiker clamp at the bottom take a longer heat shield. The short one I bought melted the flexible looms on the spark plug wires. My latest plan is to put header wrap on the EGR tube with hose clamps to hold it in place. I had this idea quite a while ago and then I saw a picture on the Forum where somebody else did this. I also plan on putting KoolSox on the spark plug wires, just for added insurance.
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 21
Likes: 0
From: Parsonsfield Maine
EGR tube
My origimal heat shield measures 14 1/2 inches long and is in bad condition, I am going to rebuild it with exhaust header tape, a double or triple wrap of aluminum foil and sew it onto the EGR tube with fine stainless wire. I think that heat from the EGR tube is transferring to the valve seals for number 8 cylinder, resulting witrh premature failure of the valve seals. I think that the purpose of the shield, is to stop the heat transfering to the valve cover and inside over time. ???
Melting Slicks
Joined: Feb 2011
Posts: 2,322
Likes: 6
From: Los Altos CA
That's really interesting about the EGR switch "adjustable" feature. I replaced one because it was loose. I thought it was broken, even though it seemed to work OK.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
This is what a wraparound heat shield looks like after a couple of years. The Velcro is toast. buzzlightyear said the original is 14-1/2" long. The ads I've seen for this guy say it's 11-1/2" long. That's part of the problem, as the bottom 3" of the EGR tube is exposed and caused the split looms on the spark plug wires to melt. I put the aluminum foil on the bottom as a heat shield. One other problem I had with the wrap is that the Velcro is on the "wrong" side and the seam is exposed and visible. If they had switched the positions of the two Velcro pieces the wrap would have covered up the seam.
Here's my fix, header wrap and hose clamps to hold it in place. I might put one of the wraparound heat shields over this. I think it would look better, as I expect the header wrap to get dirty over time. My hope is that the header wrap will cut down the heat enough that the heat shield Velcro won't be damaged.
Here's my fix, header wrap and hose clamps to hold it in place. I might put one of the wraparound heat shields over this. I think it would look better, as I expect the header wrap to get dirty over time. My hope is that the header wrap will cut down the heat enough that the heat shield Velcro won't be damaged.
