'72 sbc engine wont get warm
Thread Starter
Racer
Joined: Jun 2017
Posts: 495
Likes: 85
'72 sbc engine wont get warm
Hello,
My stock 1972 sbc corvette engine never really gets above 140-160 degrees on the temperature gauge (about 1/4 from the left on the gauge). I just purchased the car, and have been bringing it on only shorter trips, but even when i am in traffic, it doesn't really even get to 160.
I brought it on the freeway a few times, and it heats up to about 160 on the gauge (the rpm's get pretty high on the stock 3 speed auto), and it runs better when it is warmer. This is still only about 1/3 from the left on the temp gauge.
Of course, since the fan is mechanical, it runs all the time, so that doesn't help my problem.
I have one of those IR temperature sensor guns; should I measure the temperature on the thermostat housing to verify the gauge is reading correctly?
Could there be an issue with the thermostat staying open?
Should i get a thermostat rated at a higher temperature?
Should I just be happy it is cool rather than hot and just richen up the carb?
My stock 1972 sbc corvette engine never really gets above 140-160 degrees on the temperature gauge (about 1/4 from the left on the gauge). I just purchased the car, and have been bringing it on only shorter trips, but even when i am in traffic, it doesn't really even get to 160.
I brought it on the freeway a few times, and it heats up to about 160 on the gauge (the rpm's get pretty high on the stock 3 speed auto), and it runs better when it is warmer. This is still only about 1/3 from the left on the temp gauge.
Of course, since the fan is mechanical, it runs all the time, so that doesn't help my problem.
I have one of those IR temperature sensor guns; should I measure the temperature on the thermostat housing to verify the gauge is reading correctly?
Could there be an issue with the thermostat staying open?
Should i get a thermostat rated at a higher temperature?
Should I just be happy it is cool rather than hot and just richen up the carb?
Team Owner
Joined: Sep 2006
Posts: 31,278
Likes: 4,372
From: Westminster Maryland
Hi m,
Your 72 originally had a fan that had a temperature controlled 'clutch' on it.
The clutch didn't engage until the air coming through the radiator reached a certain temperature.
The fan turned, but at a much lower rpm, when the engine was cold. The clutch engaged when it's temperature reactive coil or bar pushed on a valve in the clutch causing the clutch to engage and the fan to spin more rapidly.
When you engine isn't running can you turn the fan easily? You should be able to.
When you shut the engine off how long does the fan spin after the engine is off.
Might this be the cause of the 'cold'?
Maybe?
Regards,
Alan
You can see the fan bolted to the clutch on the front of the water pump.
Your 72 originally had a fan that had a temperature controlled 'clutch' on it.
The clutch didn't engage until the air coming through the radiator reached a certain temperature.
The fan turned, but at a much lower rpm, when the engine was cold. The clutch engaged when it's temperature reactive coil or bar pushed on a valve in the clutch causing the clutch to engage and the fan to spin more rapidly.
When you engine isn't running can you turn the fan easily? You should be able to.
When you shut the engine off how long does the fan spin after the engine is off.
Might this be the cause of the 'cold'?
Maybe?
Regards,
Alan
You can see the fan bolted to the clutch on the front of the water pump.
Last edited by Alan 71; Jun 28, 2017 at 05:03 PM.
Thread Starter
Racer
Joined: Jun 2017
Posts: 495
Likes: 85
Hi m,
Your 72 originally had a fan that had a temperature controlled 'clutch' on it.
The clutch didn't engage until the air coming through the radiator reached a certain temperature.
The fan turned, but at a much lower rpm, when the engine was cold. The clutch engaged when it's temperature reactive coil or bar pushed on a valve in the clutch causing the clutch to engage and the fan to spin more rapidly.
When you engine isn't running can you turn the fan easily? You should be able to.
When you shut the engine off how long does the fan spin after the engine is off.
Might this be the cause of the 'cold'?
Maybe?
Regards,
Alan
You can see the fan bolted to the clutch on the front of the water pump.
Your 72 originally had a fan that had a temperature controlled 'clutch' on it.
The clutch didn't engage until the air coming through the radiator reached a certain temperature.
The fan turned, but at a much lower rpm, when the engine was cold. The clutch engaged when it's temperature reactive coil or bar pushed on a valve in the clutch causing the clutch to engage and the fan to spin more rapidly.
When you engine isn't running can you turn the fan easily? You should be able to.
When you shut the engine off how long does the fan spin after the engine is off.
Might this be the cause of the 'cold'?
Maybe?
Regards,
Alan
You can see the fan bolted to the clutch on the front of the water pump.
The fan doesn't spin at all after the engine is off. I figure this could attributed to the engine not getting hot enough, though.
I'll check to see how difficult it is turn the fan while the engine is off.
Is there any other way to tell if the fan clutch has a problem other than just feeling how tough it is to turn the fan?
Team Owner
Joined: Sep 2006
Posts: 31,278
Likes: 4,372
From: Westminster Maryland
Hi m,
The fan should make at least several revolutions on it's own after the engine is stopped.
The fact that it doesn't might indicate the fan clutch is 'locked-up' and so is spinning at crank speed continuously. I believe this would contribute to an engine not reaching normal operating temperatures.
This may not be what's causing your situation, but might be part of it.
Regards,
Alan
The fan should make at least several revolutions on it's own after the engine is stopped.
The fact that it doesn't might indicate the fan clutch is 'locked-up' and so is spinning at crank speed continuously. I believe this would contribute to an engine not reaching normal operating temperatures.
This may not be what's causing your situation, but might be part of it.
Regards,
Alan
Last edited by Alan 71; Jun 28, 2017 at 06:00 PM.
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pull your thermostat and check it to see if its sticking open. While its out check and see what temp its rated for. Theyre cheap and you could just buy a 180* one if its a 165* model
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
Thanks for your reply Alan,
The fan doesn't spin at all after the engine is off. I figure this could attributed to the engine not getting hot enough, though.
I'll check to see how difficult it is turn the fan while the engine is off.
Is there any other way to tell if the fan clutch has a problem other than just feeling how tough it is to turn the fan?
The fan doesn't spin at all after the engine is off. I figure this could attributed to the engine not getting hot enough, though.
I'll check to see how difficult it is turn the fan while the engine is off.
Is there any other way to tell if the fan clutch has a problem other than just feeling how tough it is to turn the fan?
Check the thermostat.
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
1. above 30 mph the ram air effect negates anything your fan does.
2. your thermostat regulates the water temperature of water in your engine block. if the temperature of the water in your engine block is below the thermostat rating, the water does not leave the engine block until it does.
3. your gauge is not calibrated correctly
4. your temperature sending unit is not mated correctly to your gauge. ( ask Willcox about this one )
5. the wire from the sending unit to the gauge has too much resistance and is too old. causing false readings.
6. there is no such thing as an over capacity radiator, or fan coming on too soon, or staying on too long. the thermostat regulates the engine output temperature.
if you were running hot then you might have issues similar to what they are telling you here but you are running cold so throw out the capacity, water pump, fan, water/glycol mixture issues.
2. your thermostat regulates the water temperature of water in your engine block. if the temperature of the water in your engine block is below the thermostat rating, the water does not leave the engine block until it does.
3. your gauge is not calibrated correctly
4. your temperature sending unit is not mated correctly to your gauge. ( ask Willcox about this one )
5. the wire from the sending unit to the gauge has too much resistance and is too old. causing false readings.
6. there is no such thing as an over capacity radiator, or fan coming on too soon, or staying on too long. the thermostat regulates the engine output temperature.
if you were running hot then you might have issues similar to what they are telling you here but you are running cold so throw out the capacity, water pump, fan, water/glycol mixture issues.
Instructor
Joined: May 2017
Posts: 100
Likes: 5
From: I don't do cities N/W Montana & Nor California
My 72 is the same way.... After it's initial warmup, the temp gauge stops and doesn't move... I had it checked and it's normal, the over sized radiator that came with the AC equipped cars, seems to work well.
Now that the motor is being Bored & Stroked, Im interested to see the difference...
Now that the motor is being Bored & Stroked, Im interested to see the difference...
Thread Starter
Racer
Joined: Jun 2017
Posts: 495
Likes: 85
My 72 is the same way.... After it's initial warmup, the temp gauge stops and doesn't move... I had it checked and it's normal, the over sized radiator that came with the AC equipped cars, seems to work well.
Now that the motor is being Bored & Stroked, Im interested to see the difference...
Now that the motor is being Bored & Stroked, Im interested to see the difference...
Or do you mean the gauge was reading normally, and the car didn't warm up?
Instructor
Joined: Feb 2017
Posts: 145
Likes: 6
From: Roswell, Georgia
I just went through this process with a '71 and discovered that the temperature sending unit was faulty. The original unit would only register to around 150 degrees. I ended up purchasing 2 new ones until I was able to find one that measured correctly in boiling water (about 85 ohms was as close as I could get). The unit that worked for me was a BWD WT203.
Instructor
Joined: May 2017
Posts: 100
Likes: 5
From: I don't do cities N/W Montana & Nor California
Good or bad, it has a very consistent low temperature...
I live in a very cool climate, so, that probably adds to it's constant cool temps.
Instructor
Joined: Oct 2002
Posts: 223
Likes: 20
From: jim thorpe pa
I vote for the thermostat
thermostats are a bi metalic spring, they open and close as sensed by temperature, it constantly opens and closes
If it never reaches operating temp,it is stuck, if you put another one in and it does the same thing, it has to be your temp gauge not reading correctly
putting a thermostat in is a very simple task, I siphon the radiator for about a gallon, take out old stat, fill block to bottom of stat housing, drop in new one, put rest of water back in radiator, and recovery tank if needed
and on another note, if the engine does not get to 180/190 the engine oil never gets hot enough to burn off condensation
If it never reaches operating temp,it is stuck, if you put another one in and it does the same thing, it has to be your temp gauge not reading correctly
putting a thermostat in is a very simple task, I siphon the radiator for about a gallon, take out old stat, fill block to bottom of stat housing, drop in new one, put rest of water back in radiator, and recovery tank if needed
and on another note, if the engine does not get to 180/190 the engine oil never gets hot enough to burn off condensation
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
If your gauge is accurate, then your Thermostat is either missing, stuck or is too low a temperature rating.. your fan clutch is not the issue, the engine will warm to the rated temp on T-stat required to open and flow coolant, regardless of fan function ... $12 fix
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Either your gauge is reading low (old/bad sending unit or just poor calibration) OR you have no thermostat installed. The stat could be stuck OPEN, but I think that is not very likely with 140* running temps.