Cooling system/temp unit questions.

Dsertdog

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In my 66 Polara 383, I recently did a timing chain replacement and installed a new water pump hosing which I cleaned thoroughly and replaced the temp sending unit with one from a1967 and up application, which the stud connector instead of the spade. This also eliminated the jumper wire from the factory to adapt the two harnesses. See photo...
20220827_093451[1].jpg


I used a 180 degree T-stat (gates) which came with the used housing but did the hot water test and it opened at 180 degrees.
The car seems to run hotter than normal by the gauge
See photo...

20220827_093401[1].jpg

Before all the swapping, the car ran with the temp setting on the R and rarely over the A, now it runs between...well you can see it. Sometimes it gets hotter. It never gets below the A

I checked the antifreeze temp at the top of the radiator with an instant read thermometer, and it reads 160 degrees. There was some air in the system, but a lot has been bled off.

So...is there a resistance difference between the 1966 and 1967 temp sensors?

Is my T-stat working correctly or... ?

The car runs great, but it could it be a timing issue? I have not checked that.

You can see the "top" lettering on the water pump so it should be correct?
Thanks!

Edit: Checked and adjusted timing slightly...seems ok
 
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CBODY67

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I agree that the gauge needle should be more vertical (i.e., mid-range) in the Normal band, but if you know that the radiator is running at or below 180 degrees F and you know the old thermostat is openning at 180 degrees F, then you know those two things are working normally, in spite of the inside gauge reading.

So, keep that heat gun handy to do more checks after you drive the car more. Also check the radiator core temps after the drives (idling in "P"), too, to see if there might be some clogs/restrictions in the core, too. KEY thing is that you know everything's working as it should and the gauge reading is now a bit off, compared to prior times.

If the ignition timing is set to spec, there shoudl not have been enough difference between the timing chains/sprokets to make a real difference in running temps, But, you might try advancing the base timing 2 degrees BTDC and see how that might affect things.

You did ensure that the centerlines of the camshaft bolt and the crankshaft bolt are in perfect alignment, with the "dots" on the timing chain sprokets in that same line, too? Just curious, no more, no less.

Just some thoughts,
CBODY67
 

volksworld

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dumb question...any chance the thermostat you removed was a 160?...do you have access to an ohmeter and can compare the resistance between the old and new senders?
 

Dsertdog

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I agree that the gauge needle should be more vertical (i.e., mid-range) in the Normal band, but if you know that the radiator is running at or below 180 degrees F and you know the old thermostat is openning at 180 degrees F, then you know those two things are working normally, in spite of the inside gauge reading.

So, keep that heat gun handy to do more checks after you drive the car more. Also check the radiator core temps after the drives (idling in "P"), too, to see if there might be some clogs/restrictions in the core, too. KEY thing is that you know everything's working as it should and the gauge reading is now a bit off, compared to prior times.

If the ignition timing is set to spec, there shoudl not have been enough difference between the timing chains/sprokets to make a real difference in running temps, But, you might try advancing the base timing 2 degrees BTDC and see how that might affect things.

You did ensure that the centerlines of the camshaft bolt and the crankshaft bolt are in perfect alignment, with the "dots" on the timing chain sprokets in that same line, too? Just curious, no more, no less.

Just some thoughts,
CBODY67

dumb question...any chance the thermostat you removed was a 160?...do you have access to an ohmeter and can compare the resistance between the old and new senders?
CBody...to best of my abilities, yes, everything was aligned.

Actually, I screwed up. The car HAD a 180 stat and that worked pretty well. When I put the car back together, a 160 stat was installed.
Thus the 160 degree tank temp. The gauge should not read hot.

I'm beginning to suspect the sender.
 

Dsertdog

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WELL...this was enlightening!
So I grabbed an Ohmmeter, right? The original '66 sender shows .11 on the reading, the new '67 sender shows .22 on the reading! I've checked this 3 times and the readings are consistent!

I'm beginning to highly suspect the temp sensor! I'm going to swap in the old sensor and the bogus wiring adapter and see what occurs!
 

1970FuryConv

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Agree that sensor is problem. Not sure if sensors are matched to gauge, but if 66 and and 67 sensors have different resistance because of different gauges, the 67 sensor maybe acting as it was built to act.
 

Dsertdog

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It must've been the sensor. I changed it for the original and put my 180 stat back in.

Car barely gets above the first E in Temp.

Thanks to all who responded!
 

70bigblockdodge

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You can "calibrate" the gauge. They are all volt gauges and have a small port on the back that rotates the whole guage works one way or another.
 

marty koirtyohann

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In my 66 Polara 383, I recently did a timing chain replacement and installed a new water pump hosing which I cleaned thoroughly and replaced the temp sending unit with one from a1967 and up application, which the stud connector instead of the spade. This also eliminated the jumper wire from the factory to adapt the two harnesses. See photo...
View attachment 554621

I used a 180 degree T-stat (gates) which came with the used housing but did the hot water test and it opened at 180 degrees.
The car seems to run hotter than normal by the gauge
See photo...

View attachment 554622
Before all the swapping, the car ran with the temp setting on the R and rarely over the A, now it runs between...well you can see it. Sometimes it gets hotter. It never gets below the A

I checked the antifreeze temp at the top of the radiator with an instant read thermometer, and it reads 160 degrees. There was some air in the system, but a lot has been bled off.

So...is there a resistance difference between the 1966 and 1967 temp sensors?

Is my T-stat working correctly or... ?

The car runs great, but it could it be a timing issue? I have not checked that.

You can see the "top" lettering on the water pump so it should be correct?
Thanks!

Edit: Checked and adjusted timing slightly...seems ok
check the temp with a non contact thermometer to verify themp & go from rthere
 
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