I was driving the car last-night (to work) and the temp gauge shot up to OVER RED LINE for about 5sec and then went back to normal temp and about 25 miles later it shot up to OVER RED LINE!!! For the rest of the trip it was ok. This started after about 2 1/2 hrs into the drive. This happened on Sunday on my way home also but only one time. That I know of. Is my pump going bad, the sensor, or the thermo. It scared the hell out of me!! I was miles from anything or anyone, at 10:00 pm. I have a 195 thermo in now, is this one giving me the problems?? My water level is good and had good heat all through the trip. I do have a manifold leak around the area near the temp sensor. The motor was running at 65-70mph all trip. Temp out side at 47-50. Any ideas any one???? Help!! Will my car crap out on me? I need it for about 2 to 3 more weeks, and I will start riding one of the motorcycles. This just started last week I think. I have driven it for 22,000 miles with no over heat problems, the last year.

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1930 Jordan Great Line "90", 1951 Chrysler Saratoga,1953 Plymouth, 1971 Honda CB 500 "4", 1973 Honda CB 350, 1975 Honda CB 500 twin, 1988 Honda Shadow 1340, 1975 Dodge Dart Custom, 1992 Dodge 2500 turbo truck,1975 Schwinn Collgate 5sp.

I've had my temp gauge jump around like how you described a few times. Nothing else was wrong, and I wrote it off as a wire moving a bit, making the signal jump, and/or the block temp sensor sending a wrong signal, just because those sensors crap out after awhile. If I play with the connection at the temp sensor, I can make the gauge jump around.

I do know that the block temp sensor and the thermostat are inexpensive to replace, so that may be a place to start. I plan on replacing my sensor, and NAPA sells one for less than $10. My gauge currently only moves up to the first line on the gauge, and never reaches the "normal" range. I figure that the sensor isn't sending the correct signal (sending probably isn't the correct term. I think it works with varying resistance inside the thermo resister). It's a cheap and easy first step.

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63 Dart GT Convertible

Since you have a leak, steam pockets can cause the gauge to spike. Fix the leak and purge all the air out of the system with your coolant tank and a good double gasket reverse flow radiator cap.

Hopefully the sender didn't take a dump yet. If they get a good dose of steam for any length of time they will not be accurate after a major overheat.

SL6 Dan can probably elaborate on the correct sensor for the different year gauges. They are not universal through out the years! and if you get the wrong one it will not read correctly.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Check the wire that goes from the temp sender to the temp gauge -- if its insulation is failing anywhere, and it shorts to ground, it'll spike the temp gauge.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The Temp gauge works by controlling the ground resistance. Touch the sender wire to ground, anywhere along it's path and the gauge pegs at "Hot".

Check the wire going to the sender to be sure it is not cracked, "rubbed thru" and touching ground at any point. Also check the connections where the wire goes thru the bulkhead connector, if the connection(s) there get wet or corroded, that can cause the problem.
DD
(SL6 Dan beat me by a few minutes... I need more coffee)

Not as much more as Chuck needs; he got rung out of bed at 6:30—four hours after he finally stopped work and went to bed—when it was discovered the site was down!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Watch the gas gauge also-see if it goes up when the temp gauge does. If they both are going up and down it is the 6 volt instrument regulator. Remember before you play around with the gauges disconnect your battery first!
Lynn

Hay thanks for the help. I will go through the wires and see what they look like. Tonight I checked some things out while waiting for the warm-up. I think I found a very small wet area on the bottom right side of the radiator core. I know I have fluid because I check it twice every week, and it was up to pare the night before. I will check this before I go home this AM. I think that I will also flush out the block one more time, I did it kind of half assed when I did it last December (2008) when I got the car. It was kind of cold then, and I never went back to do it right. The car sat for about 10 years before I started to drive it. So there still might be crap in the block. I had a problem with the carb last AM I did not let it warm-up and it started to flood like a river was running through it!!! I put a new fuel inlet fitting on and this seams to have helped, but time will tell. I just have to go through the carb and see if something is wrong. rebuild it. one more time.

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1930 Jordan Great Line "90", 1951 Chrysler Saratoga,1953 Plymouth, 1971 Honda CB 500 "4", 1973 Honda CB 350, 1975 Honda CB 500 twin, 1988 Honda Shadow 1340, 1975 Dodge Dart Custom, 1992 Dodge 2500 turbo truck,1975 Schwinn Collgate 5sp.

Hi hydrive1953. You could take the opportunity when you replace the thermostat to use a known brand radiator cleaner and really flush out the whole system, before running the engine hot and changing the water a couple of times. Yes, it's boring, dirty and time consuming, but it sure beats the buildup of a local hot-spot that can ruin your engine. Often small rust flakes from inside the water channels in the engine can lodge themselves in the thermostat and temporarily prevent it from opening. It may also clog the tubes in your radiator. If you have the time and place to do a really thorough cleaning of your cooling system, you should also remove the radiator and turn it upside down and flush it backwards from normal flow direction. You may be surprised at the amount of crud from inside your top tank! Use a high quality coolant when finally filling it up again, it is just as important as picking a good oil, and also use a high quality thermostat that react only on temperature and not on pressure. Also check the surface of your temp sender, it may be covered with rusty sludge to give a false reading. Good luck!
Olaf.

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Aspenized