86 question!
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
86 question!
I was checking my spark plugs and noticed something that I guess I had overlooked before. 
I don't have any pics, but I'll describe it. It looks like a sensor between the #1 & #3 spark plug. It had what looks like a place that a connector should be. It is threaded into the head with teflon and has a round place for a one wire connector to go. I looked and didn't see any loose wires in the area. I haven't looked through the FSM yet and was just wondering. Any help? 
I don't have any pics, but I'll describe it. It looks like a sensor between the #1 & #3 spark plug. It had what looks like a place that a connector should be. It is threaded into the head with teflon and has a round place for a one wire connector to go. I looked and didn't see any loose wires in the area. I haven't looked through the FSM yet and was just wondering. Any help?
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
That's a fan switch. If your car has one main fan, there should be a plug there. If you got two fans, then you should have it there. If you got one fan, then someone must have added it in and did not wire it in since you don't see the wire.
I added one on my single fan 86 to turn the fan on at 200, and it wires into the fan relay green w/white wire. So do you have one cooling fan or two?
I added one on my single fan 86 to turn the fan on at 200, and it wires into the fan relay green w/white wire. So do you have one cooling fan or two?
Last edited by 86PACER; Mar 31, 2006 at 07:10 PM.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Since we are talking 86 here, I'll post the single fan configuration. There are several small changes thoughout the years, and a past thread on this topic turned into a complete disaster.
Last edited by 86PACER; Mar 31, 2006 at 07:25 PM.
Race Director
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From: The Top of Utah
On your 1986, the gauge temp sender is in the corresponding hole in the right side cylinder head. The left head carries the auxiliary fan switch.
86PACER,
I think a good many of us learned about the "one off" set up in the 1985 without an auxiliary fan. I know *I* did. Your schematic is just an little small, dark, and fuzzy for me to read. Can I assume it is different than the 1985 and looks as one would expect?
RACE ON!!!
86PACER,
I think a good many of us learned about the "one off" set up in the 1985 without an auxiliary fan. I know *I* did. Your schematic is just an little small, dark, and fuzzy for me to read. Can I assume it is different than the 1985 and looks as one would expect?
RACE ON!!!
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Originally Posted by RRT vette
My vette has one main fan. My temp guage does work. Then this is o.k. for it not to be plugged in? Thanks fellows.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Originally Posted by CFI-EFI
86PACER,
I think a good many of us learned about the "one off" set up in the 1985 without an auxiliary fan. I know *I* did. Your schematic is just an little small, dark, and fuzzy for me to read. Can I assume it is different than the 1985 and looks as one would expect?
RACE ON!!!
Last edited by 86PACER; Mar 31, 2006 at 07:29 PM.
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Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by RRT vette
My vette has one main fan. My temp guage does work. Then this is o.k. for it not to be plugged in? Thanks fellows.
RACE ON!!!
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
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From: Louisiana
Originally Posted by CFI-EFI
This post showed up while I was typing my last post. All C4s have only "one main fan". The question is whether you have an auxiliary fan or not. The auxiliary fan will be in the front side of the radiator in your '86, if you have one. The unattached switch is for turning on the aux fan at the designed temp. If you have the fan, the switch should be hooked up. If you don't have the fan, one must wonder why you have the switch.
RACE ON!!!
RACE ON!!!
Thread Starter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Alright guys, I was wrong. There is a secondary fan I remember seeing. It is a small fan just behind the front bumper infront of the radiator and a/c condensor. I looked and I don't think it is working or al least it doesn't look like it. The front bumper is so low to the ground that I need to put it on ramps to see it good.
Melting Slicks
Joined: Apr 2002
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From: St. Charles, MO Route 66 Corvette Club
RRTVette......I can not speak for other year vetts, but my 89 came stock with a 5/16 square plug in the left head, between #1 and #3 cylinders. I installed a secondary sensor in that location to turn on the fan at 192 deg F and I bought the assembly from Mid America Direct. My vette has two fans as it has the AC option. Perhaps the previous owner of you car performed a similiar modification. Just a suggestion for your question. Do you want my old plug 
Team Owner
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The Aux fan in 86 wont trigger until 238F, so its not a surprise that yours doesnt seem to be working, if your temps hang around 180F.
Mine is triggered by a new switch to come on at 185F.
Mine is triggered by a new switch to come on at 185F.
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Uriel, It was in the Electrical Diagnosis Manual Supplement ST-364-86S.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by vader86
The Aux fan in 86 wont trigger until 238F, so its not a surprise that yours doesnt seem to be working, if your temps hang around 180F.
Originally Posted by RRT vette
It looks like a sensor between the #1 & #3 spark plug. It had what looks like a place that a connector should be. It is threaded into the head with teflon and has a round place for a one wire connector to go.
The wire that connects to that "round place for a one wire connector" on the switch in the left head is circuit #335. It is a .5 Dk Grn/Wht wire just to the right of center, near the top of, the schematic Ray Quayle provided. Find the .5 Dk Grn/Wht wire at the "B" terminal of the AUXILIARY fan relay and start tracing. Eventually, you want the other end of that wire connected to the switch in the left head.
RACE ON!!!
