RE: IML: temp gauge shows overheating

[RandalPark@xxxxxxx]

If the temperature gauge suddenly registers hot, I stop the car. The next thing I do is determine if it really is hot. This is not that hard to do. We see/hear hot water on the stove just about everyday.

If it really is hot, the cause of the overheating is usually obvious (broken hose, belt, water pump), but if it isn't, the thermostat could have failed and closed. It is possible to buy a "fail-safe" thermostat that opens when it fails instead of closing and causing the car to boil over. Whenever I replace one I buy this type.

If it really isn't hot, I check everything anyway, resume my trip, and pay VERY close attention to what is going on under the hood. If nothing happens I replace the sender.

On '65 and '66 Imperials (and many others after that) if the car really is hot, the Sentry Signal will also light up. The Sentry Signal has separate sending units for oil pressure and temperature.

Paul W.

In an email dated 2/5/2005 8:26:40 pm GMT Daylight time, "Pete Engel" <peter.engel@xxxxxxxxxxx> writes:

>Rich,
>
>Wow, I'm glad you're not working on MY car! ?Go for the EASY stuff first.
>
>I'll bet that your temp sending unit is the culprit and it's easy to check.
>When the rubber molded plug is disconnected from the sender the gauge will
>drop to cold. ?When you ground the metal terminal inside the molded plug the
>gauge will peg at hot. ?Don't keep the connector grounded for more than 15
>seconds or so.
>
>Years of hot/cold cycles and some corrosion inside the sending unit are
>probably causing the guts to short to ground periodically. ?I've seen the
>sending units get pretty crusty at the threaded terminal and that's a sign
>that all is not well.
>
>You can get away with replacing the sender WITHOUT draining any coolant.
>Loosen the sender and unscrew it almost all the way out. ?Then squeeze the
>upper radiator hose closed, remove the radiator car, reinstall it, and
>release the hose. ?If you quickly unscrew the sending unit and get the new
>one in place there will be little or no coolant loss.
>
>Pete in PA
>
>From: "Woolf,Richard T(Contractor)" <richard.woolf@xxxxxxxxxxxx>
>Subject: IML: temperature gauge showing over heating
>Date: Mon, 2 May 2005 13:23:32 -0400
>Reply-To: mailing-list@xxxxxxxxxxxxxxxx
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>Hello List,
>
> I have a problem with my '66 Crown. I was driving one night coming back
>from a car show when all of a sudden my temperature gauge went all the way
>over to right which showed me it was over heating. I quickly stop the car
>checking the belt to see if it was broken. Everything under the hood looked
>normal so I waited for about a half hour and starting to drive the car home
>when it did it again. After getting home I decided it probably was the
>thermostat which jammed such, and changed that first which as many of you
>know is no picnic if you have AC. After completing the job the problem was
>still there. So I decided to change the water pump since it was original
>with over 115,000 miles on it. I took the water pump off, and found nothing
>wrong with it. As a matter of fact it looked like brand new inside. I pulled
>the radiator out and used a hose to put water in the top of the radiator
>inlet to see if it would flow out of the bottom freely, and it did. I'm
>wondering if it's the temperature sending unit. I ordered one today from
>NAPA, and will have it by Wednesday. If the problem is still there then I'm
>out of ideas. ?Does anybody have any thoughts???
>
>
>
>
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