I am wondering if someone can help me out...Here is my problem. I just installed my new rebuilt 327/350 in my 65 Conv. I was setting the timing 36 degrees total (vacuum advance disconected), and messing with the idle mixture screws. When I went back in to shut the engine down, I noticed the temp gauge was almost pegged at 240 degrees. I immediately shut the car down. My confusion is in that the coolant in the expansion tank is reading about 160-180 when the car was running, but the heater in the car seems to be blowing unusually hot heater air. The entire cooling system is brand new....Dewitts radiator and hoses. New expansion tank, ect. I used the upper heater hose (larger diameter) to tee off of the expansion tank, and it runs to the water pump. The lower heater hose is a direct shot from the firewall to the intake manifold. This is the way it was when I took the car apart. The cooling system is filled with 50 percent distilled water, and 50 percent dexcool......I am baffled. Any ideas would be greatly appreciated. The temp sender is also new.....Thanks.....
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Re: Temp Gauge Reading Too High..
Before you panic, verify the temp reading with a thermometer, IR gun, etc. The fact that you installed a new temp sender makes me very suspicious that you have a miscalibrated one. Most of the "correct" temp aren't worth melting down. -
Re: Temp Gauge Reading Too High..
Dave,
The most likely reason is the temp sender. Replacement senders are infamous for having the wrong response curve. If your gauge was really pegged your radiator ould have been spewing coolant. I went through a fist full of sensors to find one that worked right. You can test the sensor without putting in your engine, just heat the sensor in your oven at 180 degrees and the resistance should be about 115 ohms give or take a few. Several people have reported an Autozone sensor to be very close. I belive the number was TU5, but you can check the archives to find the number.
Regards, John McGrawComment
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Re: Temp Gauge Reading Too High..
gyper(generic, aftermarket tiawan sensors ) are junk. judge poorly in ncrs and don't come close to informiong you of the actual temp of the coolant. go junk yarding next wekend( take son or grandson to introduce them to the joy of junk yarding) , find an old 50-60 Gm AC delco sending unit( nearly all the GM Pass cars of these eras had em), pay a buck or 2 for your day of junkyard delight, go home, install the ac delco sender and discover that the small block's operating temp is (and almost certainly was) within normal limits. good luck, mikeComment
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Re: Temp Gauge Reading Too High..
Thye Autozone sender, which has been reported to work well in most cases, costs $6, and is a Wells TU5. A junkyard sender would be better, but many jurisdictions have long ago mandated that the junkyards rid themselves of "scrap" motors and older cars.Comment
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Re: Temp Gauge Reading Too High..
It sounds as though the sender might be the culprit. I sure hope so!! Is it possible for a temp sender to be so out of limits out of the box to produce a reading of 240 degrees, even though the engine is well within safe operating temps? And these companies still continue to sell these senders??Comment
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Re: Temp Gauge Reading Too High..
It is simply a matter of quality control. I have found generic sensors that were fight on the money all the way up and down the curve! It is just a crapshoot as to whether it will be correct and you just have to test it. Letric Limited advertizes a sensor that they say has the correct curve, but I have never tested one of them. If you pull your existing sensor and heat it to 180 degrees in the oven and it reads pretty close to 115 ohms, then you need to start looking at your gauge or charging voltage. If the charging voltage is substantially above 14.2 volts, it can really affect the gauge reading. If you stop the engine and the gauge still reads high with the key on but engine off, you can remove that item from the list.
Regards, John McGrawComment
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