So today I went to change the fan switch, since its inbetween the 6 and 8 cylinders like I was told. I have a replacment low temp fan switch and all. When I pulled this (see photo) from the bottom of the block on the passanger side, it looks nothing like my fan switch, someone please tell me what this is! If this is not the fan switch, where can it be found. I have an 86z28 but someone has change the engine before. Its a 305 tpi, I assume the same engine as stock. Help please!

 

sorry about the poor picture quality

 

knock sensor

 

This is the aftermarket low temp switch I bought, as you can see it looks nothing like the other one!

 

Cannot be a knock sensor since it was in the block and knock sensors deal with air correct..

 

A knock sensor goes in the coolant port in the block. That is a knock sensor.

 

So where is the fan switch then?

 

the fan switch is in the right side(pass) head between cylinders number 6 & 8 just under the exhaust manifold.

 

They are correct, your picture is of the knock sensor. The fan switch like already said is above the knock sensor under the exhaust manifold.

 

How come when I was under there I could not see the fan switch, and I did look right above the knock sensor.So, just take off the exhaust manifold and I will be able to get to the fan switch??

 

if you look at the left head(drivers side) between cylinders 1 & 3 you should see the sending unit for your temp gage, now imagine if you were to take the left head & put in on the right side, that is were the fan switch is on the right head. 1 of the past owners may have removed the switch, so there maybe a screw in plug were the switch is suppose to be at.
it's pretty much dead center between the #6 & #8 spark plugs & almost dead on the same level with them
you shouldn't need to pull the exhaust manifold to get at it.

 

thanks for all the replies, tomorrow im going to take a second stab at the fan switch, thanks again!

 

No, the fan switch is between cyls 6and 8. The knock sensor goes into the side of the block, a couple inches above the oil pan.

 

There was a threaded plug in place of where the fan switch goes. HOw could the fan have ever came on if there is NO fan switch at all? Ive seen it run before...

 

The wiring may have been modified by the previous owner.

 

They might have tied it into the main power. I know that on my car, they apparently didn't like how hot it ran or something like that, so they just hooked the fan directly up to the ignition so that whenever you engaged the ignition, the fan would start up, and as soon as you shut the car off, so would the fan.

I don't like that however, since there are times when the fan needs to stay on after the car is shut off. So that's on the fix list.

 

'86 LB9 motor did not have a thermostatic fan switch as only a single fan was the factory setup and it was controlled by the ECM only. In '87 the dual fan setup came into existence and the thermostatic switch to control operation of the secondary fan was placed in the passenger head.

 

Ya know i thought about that. But i figured a dual setup must have been added to his car because he knew about the switch and all. After you said that, i figured i wasn't the only one thinking that. Good Call.

Z28, do you have dual fans? If not, you don't need a fan switch.

 

I have a single fan setup.. I was misinformed about the fan switch. I am really lost, lol I just want my fan to work!!! I checked the fan it does have power, I replaced the relay and thermo (180 degree). It still doesnt work!

 

So if you put power to the fan, it doesn't work? My 86 did that. Sometimes it'd come on, but not usually. Ended up replacing the fan motor, was only like 25 bucks at AutoZone.

 

Apparently, the temp. sending untit was bad and that was messing up the whole system. Thanks for all the help though.. My fan works!! just a bit excited..