havasumark

Ok, I have a strange one.. Just took my 62 for its first ride since I restored it. Temp gauge rises when I accelerate, then goes back down when I slow down. I checked the temp with a heat gun and its running at normal temp, so it does not appear the be running hot. What could be causing this? Could it be a ground issue?
Any suggestions would be appreciated,

Thanks,
Mark

AZDoug

Possibly, or bad battery connections. Do any other gauges rise and fall? If not, it proably isn't electrical
Are you running an alternator or generator?
You don't say how much it rises.
Doug

havasumark

Hello Doug,

Just the battery gauge but it's just charging I believe. Checked battery connections, clean and tight. I'm running a generator. When I accelerate temp gauge rises quickly to full, then at idle its normal. When I place a infrared gun to the head and raise the rpms, it stays between 168 and 171 deg.

Thanks, Mark

AZDoug

Disconnect the temp gauge at the temp sender and see what happens. Does the gauge still rise?

Is the harness ground to the engine connected? it should connect at either a valve cover bolt, or maybe the coil bracket, IIRC.

Doug

havasumark

Doug,

I tested it again with the infrared gun. This time I pointed it directly at the sending unit. This does show the temp rising to about 220 Deg when I increase the rpms by manually moving the throttle linkage..

bj1k

I had the same exact problem with my temperature gauge in my 57 . The gauge was saying over 200 and the infared heat gauge was showing normal around 170 .I just replaced them with Auto Meter " Old Tyme " 2 1/16 gauges from Summit for the temp and gas gauges . The temp gauge comes with the correct sender and it works great . The gas and temp gauges are totally accurate now . I'm going to order the matching gauges for the oil and charging gauge . All of the gauges are a direct fit .

havasumark

Doug,
When I disconnect the temp sender gauge is off.. I have the harness grounds connected to each valve cover bolt. With engine at operating temp at idle, infrared gun reads about 170Deg. When I increase rpm's it seams to max out at 215 Deg.

Mark

BLUE1972

just some thoughts:

- is the temp gauge sender going too far into the head and almost touching / bottoming out on the sensor-head
- is there an air pocket in the sensor area
- poor water flow when the engine is idling (allowing a hot spot in the engine) - drill a 1/16 - 3/32 hole in the thermostat to keep it flowing while the stat is closed. ( this will not affect the operation of the stat.)
- relocate the temp sender to the intake manifold and note if there is a greater / less change
- pump is caveating when the motor revs
- return hose is collapsing when the motor revs and the pump pulls more water from the rad
- incorrect temp sending unit

If it's the gauge - could be overvoltage from the generator.

AZDoug

Where is the sending unit, in the head?

I always use manifold mounting locations.

If your IR guns reads 215 at the sending unit and the gauge reads the same, well, you know it is correct. IMO, head mounted sending units are only good for idiot light senders.
Doug

SDVette

This caught my eye too.. If your regulator is not working, it may be stuck in 'charge' mode.. so when you rev the motor, you're getting a very high voltage in the system, causing the gauges to fluctuate.
Does the fuel gauge move around at the same time?
Or, if you have a volt meter, check the voltage when revving.

BLUE1972

I would also check the engine to frame ground, which can also cause other bad things to happen.

68hemi

Are you using the complete gauges and faces or were you able to use just the back of the gauges and you original needles that keep the gauges looking correct?
I replaced my tach with an Auto Meter unit that fits the "can" and was able to use my original needle.

havasumark

Doug,.
Sending unit is in the stock location in the aluminum intake manifold. BTW, motor is a 327 340HP. All stock except cam. Its a crower 0320.

65GGvert

Post back your answer to the question above about battery voltage when revving.

havasumark

Ok, I may have a over heating issue. I pulled the thermostat and running without one at the moment. When the car is at idle it runs about 180 deg. As soon as I start to rev the motor, it goes up quickly. I measured the temp with an IR gun at the temp sending unit. It tracks fairly close to the gauge (all gauges are original), At Idle, its 178 to 180, then as soon as I start the rev the motor it climbs quickly. It got to 226 deg on IR gun in less than a minute.
Perplexed,
Mark

havasumark

Voltage rises as revs increase. At about 2800 rpms the voltage climbs to about 17.9.

65GGvert

Bingo

65GGvert

Fix that before you run it much more, or you'll be replacing at least the battery. You're at least 4 volts too high for a max.

havasumark

Thanks, 65GGvert,

Just ordered a new Voltage regulator. No more test driving till it's replaced.
Thanks to all of you for your assistance. I will keep you posted after I install new regulator.

Mark

havasumark

All My gauges are the original ones..