I put a 97 4.0L into a 96 body, and this has no corresponding plug on the 97 engine.

The plug is part of the wiring harness on the 96 body, and the old 96 engine has the matching plug on the head, but this new (to me anyway), 97 engine does not have the mate on the head.

What's it for, and if I do need it, is there a fix other than swapping heads?

 

Dashboard temp gauge. In '97 they switched to a single temp sensor that feeds the PCM, which in turn drives the dashboard gauge among other things.
There is a flat area on the thermostat housing you can drill and tap for the sender (1/8" NPT), or you can spend $32 and get this:
http://hesco.us/shop.asp?action=deta...247&catId=7969

 

Radi seems to be more familiar with it than me. When I looked at it I thought maybe where I have the white tape here. Mounted of course there are limited angles for adding the sensor. Since the aluminum seems no thicker than the iron I guess I'd be inclined to tap an iron one if I had a choice. (or sender, that grounds the gauge wire?)

 

...I'm stealing your picture for a moment.... Here is where I've seen it done:
Measure first to make sure the sensor + connector clears the fan in front. If not, a right-angle pipe adapter will make it fit.

 

No prob on the pic. I figure once you post something on the web..

So I took a few more minutes. (I might need to do it myself someday) All three housings I have here have differences. One thing in common though is I didn't see any "sweet" thick area.

Being that the seal is achieved from the taper of the pipe thread, (as opposed to bringing a gasket, or washer "Home", that affects what is going on. It looks like ether way would work, and having on a flat sounds nice. It seems having it up on the heater hose outlet would work, but it would be sticking out, and I don't know how much obstruction the business end of the sensor would offer to the flow to the heater. The passage inside seems large enough, but not by allot. Placed on the large hose outlet positions it snugly out of the way..(of what! Lol)

Was me I might take a housing to my local welder/magician and have him make me a little glob there on the large pipe I could then file flat, drill & tap. Not sure I have the pipe thread tap though!

I have a gas rig, but aluminum or cast....this guy makes his own tranny gears and takes a shot at the piston driven land speed record every now and then. Maybe he could handle that.

IIRC there was a post....can the head it's-self be drilled and taped right where the sender goes? I think maybe it can.

 

cwfinlayson,

Just curious...

Do you have a coolant temp indicator in your instrument cluster?

Did you reuse the coolant temp sensor from your '96 in the t'stat housing or did you use the sensor from the '97 engine?

Is the wire to that connector in your pic a single Violet with Yellow tracer wire?