Coolant temp sensor in head

[Jeepking1995]

So I have a jeep 4.0 that had the coolant temp sensor in the head, I swapped engines and the new one didn't have a spot for it so I tapped a hole in the side of the block and spliced the wire, was having issues years down the road with my wire harness and decided to swap it, didn't want to cut any wires on the harness so I decided to drill the head for the temp sensor, go for a test drive and the coolant temp slowly creeps up to the redline and sits there, I could here my electric fan turn on at 195 degrees and the temp gauge was at around 220, I think I drilled the hole too close to the exhaust runner maybe 1/8 of an inch closer to the exhaust, made sure the sensor doesn't contact any part of the head, fit nicely in there, is it possible it's too close to the exhaust runner and that's why it's reading hot, it seems that way to me

[mpgMike]

I'm running a 2004 TUPY head on a '96 block based 4.6 stroker in my '95 ZJ. I had to drill & tap the head for the referenced coolant sensor. At least on my 2004 head, there was a clearly defined boss as a reference. Don't know what head you have or where you drilled/tapped. Mine works flawlessly.