66 insturment cluster in 65 question
 

Oil pressure gauge works fine. Gas gauge works. Gave up on amp guage. Temperature gauge is the problem. When engine starts to warm up guage goes all the way to hot. Stays all the way to cold until engine warms up. Tried different sending units and two gauges. Short the wire to the sending unit to ground and it goes all the way to hot. which indicates gauge is ok per shop manual. Pull the sending unit from the engine, hook up the wire to the gauge and ground the sending unit and it stays on cold until you heat it up. Hold the sender between my fingers and as soon as it warms up to body temp it goes all the way to hot. The fact that the gas guage works tells me that the constant voltage regulator is working. What am I missing here? Tried two used sending units and a new one. Same results. Sending unit seems to act as an on off switch.

Re: 66 insturment cluster in 65 question
 

I think your sending units are for a light and not a gauge or if your getting new ones they are Chinese knock offs that don't work

Re: 66 insturment cluster in 65 question
 

While that makes sense it doesn't compute. The 65 cluster had a gauge and I started with the sending unit that worked with it. It wasn't acurate but it didn't go straight to hot. The last one I tried was a new unit from one of the Mustang parts people. That doesn't necessarily mean it is good though. I keep thinking I am missing something simple. Wiring on the gauge is similiar on the 65 and 66. Wire to sending unit from gauge. Wire from constant voltage regulator to the gauge. Ford ran gauges for several years and I tried several used sending units that came from gauge cars.

Re: 66 insturment cluster in 65 question
 

It would be nice if you had another gauge to try. You mentioned the new gauge came from a dealer, it may be the issue

Re: 66 insturment cluster in 65 question
 

Since you mentioned a Mustang incidentally in one of your posts, I would presume it's a Mustang, then? Doesn't matter to me, but it's possible that there haven't been as many responses to your question as there could be because you haven't clearly specified a model of car. Just want to see you get your questions answered, because I know how frustrating these mysteries can be.



My recommendation is to abandon the largely inadequate '60's era Ford factory gauges in place and use a decent quality mechanical temperature gauge. I can empathize with those who like originality - I do to - but I'd rather have gauges that can relay accurate and pertinent information. One issue with a mechanical gauge, however, is that you may have to hunt for an adapter for the sensor to fit the location the existing sending unit is in.

Re: 66 insturment cluster in 65 question
 

Sorry I wasn't clear but it is a 65 Mustang with 66 Mustang gauge pannel. Yes I am aware of the shortcomings of the orignal Ford guages but I am sore of anal retentive about orginal stuff working if I can get it to work. My '57 T Bird has all the orginal gauges working, not necessarily accurately, and Stewart Warner oil and tempreture gauges under the dash also. Already have mechanical oil pressure gauge on the Mustang with working factory gauge. I consider geting it working a challange.

Re: 66 insturment cluster in 65 question
 

Did your 65 have what I call the Falcon dash? If it did there are two different wiring harness. The 65 GT had the 5 gage cluster, but still had its own wiring harness, 66 had its own, along with senders. Could be some of your problems.

Re: 66 insturment cluster in 65 question
 

It had the Falcon Dash. Temp gauge wiring is about the same. Next question. Now looking into adding a mechanical gauge. Problem is the capilary end on the gauge I have is 3/8" pipe thread. The hole in my '65 Shelby itake is 1/4" pipe. Don't want to drill out the Shelby intake. Any other place to install the mechanical Temp gauge at the engine?

Re: 66 insturment cluster in 65 question
 

That is a very early Cobra intake to have the 1/4 water sending unit hole. I sure would not drill it either! The only other hole is the heater hole.

Re: 66 insturment cluster in 65 question
 

It came off of a '65 GT 350 Mustang out of a junkyard in the late '60s. It was on a '66 Sunbeam Tiger that I had for a couple of years. The guy I bought the Tiger from scrounged parts off of a wrecked Shelby. I took all the Shelby stuff off before I put it up for sale. Intake, aluminum oil pan, hi po distributor, hi po fan. Neat stuff on the Mustang now. I wonder if anyone makes a temp gauge with a sending unit that will fit? Wonder what Shelby used? I'm thinking they had an after market guage under the dash on the Shelby. I have no recolection of what temp gauge was in the Tiger but it worked. Thats another one of the cars I wish I still had today,

Re: 66 insturment cluster in 65 question
 

Finally figured it out. There are 3 black wires with green stripe in the gauge harness. Had one in the wrong place. Finaly figured it out by comparing the 65 wiring diagram with the 66 wiring diagram. Gauge calabriation is still off so I ordered a new gague. Success!

Re: 66 insturment cluster in 65 question
 

You can have your amp gauge converted to a volt meter. Rocketman classic cougars do them. 2 types of cores. Last time I looked it was 60 or 65 with core and 135 without.

Re: 66 insturment cluster in 65 question
 

Thanks for the info on the amp meter. Will think about it. Now have the idiot light hooked into a red LED light mounted in a hole on the bottom edge of the dash.