Is it the water pump now?

[sleam]

Hello - any advice welcome! My 72 Series III is running hot, touching the red but not quite. In the last few months I've changed the hoses, thermostat and radiator, flushed the system etc. Today I drove 40 miles up at 7000ft altitude, close to my own altitude and home and it went to red...I slowed down on a dirt road at that point and the temp went back to mid range. Up at 40 plus mph and it's in the red. What could it be? Help! Please!

[superstator]

Have you checked the voltage regulator or the sender? Could be you're getting a false reading... Otherwise I'd try taking the thermostat out completely and see what happens. These engines are usually over-cooled if anything.

[sleam]

On the way back I took out the thermostat and still running hot. I was wondering if it was a bad sender but would it still change readings at different speeds if that was the case? How do I check the voltage regulator or the sender? I don't have many tools though...

[superstator]

Easy check would be to get it warmed up where it's reading hot, and play with the throttle a little and see if you can make the needle move. Higher engine RPMs should raise voltage coming out of the alternator's regulator, and if the instrument regulator is dying those spikes would leak through and change the reading. Are you having any similar problems with the fuel level sender?

Otherwise, beg borrow or steal a nice DMM and start checking everywhere. You should see 12 - 14v at the battery and a steady 10v going into the sender, and something below 10v coming out.

[SafeAirOne]

Easy enough to figure out what temperature the sender thinks the coolant is, using an ohm meter:

http://siteground237.com/~gunsandr/showthread.php?1871-Temp-Sender-Ohm-Values-vs-Coolant-Temperature

[artpeck]

Check the ground on the regulator. And get a cheap IR thermometer and check various places on the engine. Block, head, etc. Then at least you will know what you are dealing with and whether it is running hot or just showing hot. I chased this one for a year before finally resolving it was a ground issue.

[sleam]

I'll try to get a hold of a friend with the thermometer. It feels to me that it's running hot, when I open the hood the ambient air is hotter than it used to be...but I don't really know! I checked the connections a few minutes ago and all seems good. I'm going to find a hill and burp the antifreeze a little then I have to drive to work and thought I'd take the Landy and see how it does. I'll be in touch!

[sleam]

Okay, the latest - yep it's damn hot and not my imagination or a bad sender unit. Too hot for its own good. I've cleaned and flushed the system FIVE times today before it came out clear and clean. I'm off to get coolant. The water pump is ordered and a new fan belt since I'm at it. Anything else you can think of? A friend of mine thought it was some kind of block in the engine since it had been fine and suddenly wasn't so I'll be interested to drive it tomorrow after all this cleaning. Oh, but it's running rich too so I need to take care of that too.

[SafeAirOne]

Is the ignition timing correct and is the fuel mixture correct?

[sleam]

I dont think so! I checked the plugs later on and found them black and sad to say, wet with oil. I'm going to a friends in the morning and we can check timing etc then. He knows what he's doing and I don't...

s

[SafeAirOne]

Might want to do a cylinder compression test also...

[sleam]

Shall do, thanks Mark.