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Discussion Starter #1
another overheating post, 68 302, usually runs halfway on the gauge(stock). last week it just jumped up to right aqll the way. didnt boil over. had some problems over the years(owned for 20years) . but sorted them out. this has me stumped. first off i changed stat, 195. checked the gauge grounded the wire, pegged needle, have an old cluster, wired up that gauge and warmed up the engine and needle run up same as the cars did. radiator is ten years old, three row, very clean.water pump is stock, 12 years old. i do have afr 165 heads on. no smoke out the pipes. car runs well.this just happened at once. bought an cheep thermal gun and had 206 in the upper tank and hose lower hose was much cooler. unless the water pum p is making noise or leaking i see no reason to change it out. complete overhaul of engine 12 years ago, block was cleaned out. trying not to overthink this but i thought i would try everything i know before posting this. any ideas? get a mechanical; gauge to see hot how hot its getting? i dont know.
 

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Ever consider that you have a bum sending unit? You could pull the sender and boil it on the stove and check resistance with an ohmmeter to verify its operation.
764062
 

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Well, you already know its running a bit hot, and you know the gauge is right, and since it's running 205° the sender is, too. You should see about a 30° drop between the upper and lower hose.

Beware of "new" senders. They are all crap. Apparently manufacture of this simple item is a lost art.

That leaves us with a slightly hot engine. Tell us about your radiator, fan, and shroud.
 

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Discussion Starter #6
three row rad, ten years old, have correct fan shroud, have a clutch fan bought 8 years ago and i have the fan halfway in the shroud. rad cap is a 13lb one. like i said before everything has been fine for a number of years up until two weeks ago when it started sending the needle way over. is there a good way to check if i have a head gasket issue? crank oil is clean.thinking of getting a mechanical temp gauge. just doesnt tell me why my gauges are showing hot all of a sudden. did all the normal changes the first few years to get it running well so i believe im just missing something here.
 

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after looking for more answers i pulled all 8 plugs. two were clean six were black. put them back in and got the engine real warm and shut it off, pulled plugs and all 8 cylinders were 180 to 190. thought mayber if gasket was leaking one or two together would be low. plugs have been in for three years, time to get a new set. going to get a thermometer or a mechanical temp gauge and see hoe how its getting. any ideas let me know, thanks, rich
 

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Do you have a plain fan clutch or the thermal type?
 

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another overheating post, 68 302, usually runs halfway on the gauge(stock). last week it just jumped up to right aqll the way. didnt boil over. had some problems over the years(owned for 20years) . but sorted them out. this has me stumped. first off i changed stat, 195. checked the gauge grounded the wire, pegged needle, have an old cluster, wired up that gauge and warmed up the engine and needle run up same as the cars did. radiator is ten years old, three row, very clean.water pump is stock, 12 years old. i do have afr 165 heads on. no smoke out the pipes. car runs well.this just happened at once. bought an cheep thermal gun and had 206 in the upper tank and hose lower hose was much cooler. unless the water pum p is making noise or leaking i see no reason to change it out. complete overhaul of engine 12 years ago, block was cleaned out. trying not to overthink this but i thought i would try everything i know before posting this. any ideas? get a mechanical; gauge to see hot how hot its getting? i dont know.
Question.... Do you have an oil pressure gauge or light? The reason I ask is that if your IVR is going bad and you didn't notice the fuel gauge going high that might explain the erratic temp gauge operation...
 

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Some comments/things to consider. I would consider a 180 high flow stat and something like a Flowcooler pump. If there is that big of a drop between the upper and lower hose, sounds like water is not moving through the motor quickly enough. Make sure the spring is in the lower hose (I've had the hose get sucked down and stop flow), it's possible the motor/radiator/fan combo is just on the ragged edge of being ok, a little water pump wear and sediment down in the radiator..all it takes to push you over the edge..let us know!
 

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Discussion Starter #13
as i posted before i have a couple of gauge clusters and i hooked one up and ran it off my new sending unit in the engine, it ran up to hot the same as the cluster i have in the car. i have an oil light as i have the tach dash cluster no place to put an working oil gauge. i bought a new lower hose and put a sriing in it today. new set of plugs and took some of the richness out of the carb. road test sAme results. drove it a bit hard but back to the garage with needle next to h, shut engine off, no steam or boil over, from the rad. short of buying a new mechanical gauge how can i get an accurate temp from my engine to see what im actually running. also what are the accepted temps for this engine. seen numbers all over the place. what would be to hot? thanks
 

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Discussion Starter #15
cant say that i do, will get the sales in voice out and call the place i bought it from and if there still in business hopefully be able to see if it is working. thanks
 

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I am sure others will chime in, but I believe 200-210 is the typical range these engines like to run and I don’t know of any other method to get an accurate reading other than a mechanical temp gauge or thermometer. There are some that will use an infrared thermometer, but a lot of debate as to how accurate the moderate to low end ones actually are.
 

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What does IVR stand for ? I am have similar issues. Fuel gauge pegged out above F and oil pressure excessively high all of a sudden.
Thanks
 

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IVR= instrument voltage regulator. It is designed to put out 5 volts to the gauges.

 

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Thanks a bunch. All three started acting up at some time it seems.
Even took 7 gal out of full tank. Same thing.
 
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