My new 73 has me stumped. When I bought it in May I took delivery in New Mexico and drove it across west Texas to Central Texas. Temp never got above the 210 mark, traveling 75 mph, and without a chin spoiler. I added the spoiler after getting back and that moved the temp down about 5 to 10 degrees. Then it came time to drive my new car to Bloomington. Took off about 5 a.m., put it at 75 mph and the temp went right to 230. Kind of wierd for the whole trip, at 70 mph the temp was 230, at 65 it was 220, and at 60 it was 210. So made the trip running between 60 and 65. At least it saved me some gas. I only made two changes to the car before the trip. One was to set the timing (dist has slipped so had to retime, this was about 3 days before the trip) and the other was to add on can of Freon to the A/C the day before the trip. All seals are present and in place around the radiator. Any one got any ideas of what is happening.
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Re: Cooling Questions for 73 Big Block..
Hello Tom; Cars that have the timing too retarded will run hot. I would double check the timing setting and also check the vacuum and centrifugal advance mechanisms in the distributor. Hope this helps. Chuck Gongloff1963 Corvette Conv. 327/360 NCRS Top Flight
2006 Corvette Conv. Velocity Yellow NCRS Top Flight
1956 Chevy Sedan. 350/4 Speed Hot Rod -
Re: Cooling Questions for 73 Big Block..
Hello Tom; Cars that have the timing too retarded will run hot. I would double check the timing setting and also check the vacuum and centrifugal advance mechanisms in the distributor. Hope this helps. Chuck Gongloff1963 Corvette Conv. 327/360 NCRS Top Flight
2006 Corvette Conv. Velocity Yellow NCRS Top Flight
1956 Chevy Sedan. 350/4 Speed Hot RodComment
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Re: Cooling Questions for 73 Big Block..
Agree. First check timing. Then check temp sender itself.
Originals were 'pinhead' with cylindrical slip-on connector. GM discontinued and many engines of the era are now wearing button head temp senders with notched wafer connector.
Top of temp sender is bakelite insulated. If you have some kind of conductive foreign coating over the bakelite (oil?) it could be giving a partial short to ground, lowering effective resistance of temp sender and raising gauge reading.
If original pinhead temp sender, it may be giving up the ghost. Once they start to leak and admit coolant into body of transducer both high and low readings are possible.Comment
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Re: Cooling Questions for 73 Big Block..
Agree. First check timing. Then check temp sender itself.
Originals were 'pinhead' with cylindrical slip-on connector. GM discontinued and many engines of the era are now wearing button head temp senders with notched wafer connector.
Top of temp sender is bakelite insulated. If you have some kind of conductive foreign coating over the bakelite (oil?) it could be giving a partial short to ground, lowering effective resistance of temp sender and raising gauge reading.
If original pinhead temp sender, it may be giving up the ghost. Once they start to leak and admit coolant into body of transducer both high and low readings are possible.Comment
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Re: Cooling Questions for 73 Big Block..
Hello,
You didn't say whether or not you were running 60-65 MPH with the A/C on. If so, you are preheating the air going to the radiator and it will make a slight difference in the cooling capacity. Hope this helps. JohnComment
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Re: Cooling Questions for 73 Big Block..
Hello,
You didn't say whether or not you were running 60-65 MPH with the A/C on. If so, you are preheating the air going to the radiator and it will make a slight difference in the cooling capacity. Hope this helps. JohnComment
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Re: Cooling Questions for 73 Big Block..
Tom,
I'd suggest systematically checking each item in the system. Since you state the car runs hot at speed, that would probably eliminate the fan clutch. Running hot at speed indicates either airflow or coolant flow could be the culprit.
To start, ask yourself 'what has changed since the temp was normal?'. Undo whatever it is even if it seems illogical & retest the car. This will prevent you from chasing your tail later on. With this done, I'd check the condition of the seals around the shroud, the hoses (they can collapse at speed -- especially if there are no internal springs), the thermostat (it may be partially open-- put it in hot water with a thermostat to see at what temp it opens), flush the cooling system, check the water pump impeller, replace the fan clutch with a known good one or test yours (unlikely the problem based on your symptoms so do this last), check your timing as mentioned by others, etc. Also, your radiator may not be flowing properly. I'd get it checked by a reputable shop.
Be methodical & make sure each component is functioning to spec. I'd also consider Jack's suggestion that your temperature sender may be out of calibration. There is ALOT of tolorance in temp senders -- both original & repro. I've seen as much as a 10 ohm spread in new over the counter senders. This will produce a significant variation in the reading of the gauge. Make sure the connections in the gauge circuit are solid. Even a few extra ohms resistance will cause innacurrate gauge readings.
Finally, see if you can buy or borrow an infrared thermometer (one of those point & shoot jobbies) & make sure the temperature readings by the sender or thermostat housing is the same as the gauge reading.
Hope this helps.
Fred OlivaComment
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Re: Cooling Questions for 73 Big Block..
Tom,
I'd suggest systematically checking each item in the system. Since you state the car runs hot at speed, that would probably eliminate the fan clutch. Running hot at speed indicates either airflow or coolant flow could be the culprit.
To start, ask yourself 'what has changed since the temp was normal?'. Undo whatever it is even if it seems illogical & retest the car. This will prevent you from chasing your tail later on. With this done, I'd check the condition of the seals around the shroud, the hoses (they can collapse at speed -- especially if there are no internal springs), the thermostat (it may be partially open-- put it in hot water with a thermostat to see at what temp it opens), flush the cooling system, check the water pump impeller, replace the fan clutch with a known good one or test yours (unlikely the problem based on your symptoms so do this last), check your timing as mentioned by others, etc. Also, your radiator may not be flowing properly. I'd get it checked by a reputable shop.
Be methodical & make sure each component is functioning to spec. I'd also consider Jack's suggestion that your temperature sender may be out of calibration. There is ALOT of tolorance in temp senders -- both original & repro. I've seen as much as a 10 ohm spread in new over the counter senders. This will produce a significant variation in the reading of the gauge. Make sure the connections in the gauge circuit are solid. Even a few extra ohms resistance will cause innacurrate gauge readings.
Finally, see if you can buy or borrow an infrared thermometer (one of those point & shoot jobbies) & make sure the temperature readings by the sender or thermostat housing is the same as the gauge reading.
Hope this helps.
Fred OlivaComment
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Re: Cooling Questions for 73 Big Block..
You are right, John. I was running with the A/C on. But would not think that adding one can of Freon would make that much difference. The car stays below 210 in traffic and city driving. My thoughts would be some type of air flow problem. Will reset the timing this weekend to see if that will make any difference.Comment
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Re: Cooling Questions for 73 Big Block..
You are right, John. I was running with the A/C on. But would not think that adding one can of Freon would make that much difference. The car stays below 210 in traffic and city driving. My thoughts would be some type of air flow problem. Will reset the timing this weekend to see if that will make any difference.Comment
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