metalhead8711

Hello everyone, as the title suggests I ran into an issue after my engine rebuild. I found that the fan switch was not connected but i noticed another another connector that looked the same as the fan switch. Some research into the manual led me to the conclusion that one connector with the white wire is for the knock sensor and the connector with the green wire is for the fan switch. However when I removed the sensors for the engine to go to the machine shop. My engine did not have any knock sensor installed but the fan switch was installed on the block on the passenger side near the oil pan and dipstick. What's bothering me is if the coolant switch was Mickey moused in the wrong location and they just removed the knock sensor. I'm confused because I dont want to risk my rebuild on sensors that are mounted in the wrong location. And some photos or descriptions on where the knock sensor and coolant fan switch are supposed to go would he very helpful.

Drew

iTrader: (58)

There really have never been really great diagrams explaining what is what. The GM diagrams were/are artist's drawings, that aren't always all that clear. The closest you can usually get beyond those drawings are photos members have posted. Those photos have their own issue, photo hosts tend to go down, or photos are deleted over time. Best bet is to get a copy of the service manual for your specific car, and learn to use it.

TBI cars don't have a fan switch. The fan is controlled entirely by the ECM. The only time you have a dedicated fan switch is on dual fan cars.

In the block, you'll have a knock sensor just above the oil pan rail on the passenger's side. Dual fan cars have a fan switch in the coolant jacket port in the passenger's cylinder head. All have a temp GAUGE sender or idiot light switch in the driver's head. Then there's a coolant temp sensor for the computer in the front of the intake near the thermostat housing.

sofakingdom

iTrader: (1)

The hole that the KS goes in, was originally the coolant drain for the pass side of the block. I like to think that the engineers at GM were SO clever, they were preparing for the introduction of EFI in 1955 when they designed the block... they built the KS location into it, but disguised it as the drain so their evil competition at Frod and Xler would be fooled and wouldn't recognize it.

In any case, just go buy a new one and put it in that spot. Seal it with Teflon tape, only about 3 - 4 wraps, and DO NOT overtorque it!!! That makes it too sensitive, and the ECM will constantly be pulling out timing, which will make the car run lazy and probably warmer than it should and use more gas.

I have no clue about TBI cars and the fan switch, never had one. But my L69 car has the fan switch in the pass side head, the same hole in that head that's for the temp gauge sending unit in the driver's side head. Install the fan switch the same way as the KS, if your car uses one. The fan switch and KS both use the same connector type; fan sw wire is green w/ white stripe, KS is black if memory serves, in my car. Green no stripe wire on the driver's side is for the temp gauge.

metalhead8711

I removed this sensor from the bottom hole that I highlighted red.

sofakingdom

iTrader: (1)

That's a fan switch. It belongs in the head, if anywhere. NOT in the block. Somebody efffed up your sh...tuff.

You need something else to go in the coolant drain port down near the oil pan. It'll be called a KNOCK SENSOR. It'll look somewhat different from that.