I am close to completing Sandy's car. I haven't driven more than around the block but I noticed when I turn on the key the temp gauge pegs over to hot. It stays there when I run the engine. I was thinking I may have a bad CHT sensor. I believe it works as a warp switch and if it fails it would short to ground and peg the gauge right?

Also I noticed the exhaust pipe is sooty. It may be running rich in an attempt to correct the CHT reading? It runs nice I just noticed these faults.

Anyone have any thoughts on where to start looking?

Rick, What gauge are you talking about? Stock oil temp gauge, or after market head temp gauge?

if the wire coming from the oil temp sensor is shorted to ground somewhere it will read max temp even with a cold motor. I had this problem and reached under the car and wiggled the wire and it started to read correctly. I still need to find the bare spot on the wire and provide some insolation.

Bad ground somewhere.

It was late when I posted this and I was kind of brain dead by then. Yes, the stock oil temp gauge. Nothing to do with the CHT sensor. duh.

I'll check the wiring but I have a refurb'd Bowlsby harness on the engine. So it's likely someplace along the chassis harness. This really sucks cause I have the full interior in the car now including the console.

Maybe I'll track it down after coffee.

rick, are you using the stock wire that runs behind the fan housing?

k

Hi Kevin,

I'm not sure where it runs yet. If I read into what you posted the wire for the oil temp runs behind the fan housing. Maybe a common place where it could get pinched or chaffed?

My wire has a conection from the sensor that runs behind the fan housing up thru the tin by the throttle cable with a conection to a wire that goes to the wire harness. You can disconect it there. if it still reads max temp the problem is in the wire harness to the gage. If temp goes to 0 then the proble is with the wire to the sensor.

Cool! I'll check there.

Disconnected the wire above the fan shroud. Same thing. Gauge pegged when I turned on the key. I'll try connector under the console and see what happens.

with others. Mine did the same thing with an aftermarket VDO gauge/sender when the ground wasn't properly attached.

This JUST happened to me with my fuel gauge. As soon as the key was turned the gauge pegged. I had the ground and sender wires switched. The wire post with the descriptive pic that looked like a transmission signal was actually the ground, and the post that had a "G" next to it actually was the sender wire (probably stands for "gauge" Geber ). I took G as "ground". Check it out. either that or the sender wire is shorted somewhere.

I think that if the temp gauge pegs to max, then that means a short to ground in the sensor wire that goes to the taco plate.

I unplugged the wire coming from the sender through the cooling tin and the gauge still pegged.


Q) If the wiring is good from the engine bay to the gauge should expect to see the gauge lay on the cold (no reading) side of the gauge?

I'll have to take a continuity test on the chassis wiring to see if I have a grounded (shorted) wire.

Are you sure that gauge itself is wired correctly?

"G" on the gauge is *not* ground!
It stands for "Geber" which means sending unit. The ground on those gauges should either have a "-" or that "stick in the ground" symbol.

Yuppers, look at that first.

I don't recall any screws that you could have fired into the wiring under the console, but it may have happened.

Rich