Hello,
I have a 1972 2+2. The temperature gauge needle usually reaches the 'L' of "NORMAL" on the gauge and seems to stay there during a short (20 mile of less) run. I have flushed radiator, changed hoses, replaced antifreeze, replaced thermostats and added 2 bottles of "water wetter" but that has made no difference.
It seems to be the same in stop-and-go traffic or when moving.
When I check the engine temperature with a laser thermometer it is around 215 degrees F.
I think I am down to 2 options: 1. new gauge (if 215 degrees is normal) or 2. new radiator.
The radiator was professionally acid cleaned several years ago so I'm leaning towards a new one instead of another acid treatment.
Is 215 degrees a normal operating temperature?
Do you guys have any other ideas I can try?
Thank you for any advice!
Curt
Operating Temperature
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Chickencoupe
Topic author - Posts: 10
- Joined: Mon Apr 21, 2014 1:29 am
- Location: North Carolina--United States
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Chickencoupe
Topic author - Posts: 10
- Joined: Mon Apr 21, 2014 1:29 am
- Location: North Carolina--United States
#3 Operating Temperature
Thank you Ian.
The thread is very informative. It mentions that 225-250 degrees are normal readings on the cyl heads and mine seems to stay around 215 degrees.
My fans seem to be working as they should so I guess there is a chance that I don't have a problem.
Maybe I should have the gauge calibrated?
Curt
The thread is very informative. It mentions that 225-250 degrees are normal readings on the cyl heads and mine seems to stay around 215 degrees.
My fans seem to be working as they should so I guess there is a chance that I don't have a problem.
Maybe I should have the gauge calibrated?
Curt
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#4
It could be a case of needing a new temperature sender. You can also check the gauge by pulling the lead to the sender and grounding it - it should give you full deflection if you do that.
Steve
Steve
Steve
1973 S3 v12 2+2 1S52113BW
1973 S3 v12 2+2 1S52113BW
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Chickencoupe
Topic author - Posts: 10
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- Location: North Carolina--United States
#5 Operating Temperature
Oh, okay Steve. I'll try a new temperature sender and check the gauge.
Thank you!
Curt
Thank you!
Curt
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Chickencoupe
Topic author - Posts: 10
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#6
Hello again,
I have finally had a chance to work with the car again. I checked the gauge by grounding the lead and it seemed to work fine.
I replaced the temperature sensor with a new one today and unfortunately that did not seem to make a difference.
The temperature gauge needle still stays on the 'L' or close to it after 20 minutes or so of normal operation. The engine seems to stay around 215 degrees F when checked with a laser thermometer.
The fans are working properly.
A temperature gauge reading on the high side of normal can really take the enjoyment out of a run...
The car has been in our family since 1976. It has about 75,000 mile on it.
I'm wondering if the temperature gauge needs to be calibrated or if I should consider a new radiator?
Any advice would be greatly appreciated.
Thank you,
Curt
I have finally had a chance to work with the car again. I checked the gauge by grounding the lead and it seemed to work fine.
I replaced the temperature sensor with a new one today and unfortunately that did not seem to make a difference.
The temperature gauge needle still stays on the 'L' or close to it after 20 minutes or so of normal operation. The engine seems to stay around 215 degrees F when checked with a laser thermometer.
The fans are working properly.
A temperature gauge reading on the high side of normal can really take the enjoyment out of a run...
The car has been in our family since 1976. It has about 75,000 mile on it.
I'm wondering if the temperature gauge needs to be calibrated or if I should consider a new radiator?
Any advice would be greatly appreciated.
Thank you,
Curt
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#7
Dear Curt,
There is no knowing what the L of normal actually means, since you are dealing with a voltage which is simply split between the gauge and the sender and so you need to just go back to basics to correlate this to the real world.
Whilst a laser thermometer might sound high tech, I'd just remove the sender, place it in ice and measure its resistance and then warm it up all of the way to boiling and make a table of resistance versus temperature.
You can then run your car from cold up to operating temperature and you'll have a measure of the water temperature on the right hand front manifold housing. If you want to extend this analysis, drill and tap the other three housings and repeat. You'll now have an accurate view of the temperature of the water at the four exit points and whether the one measurement was representative of the whole picture.
The Otter switch also gives you a couple of reference points as to temperatures at the bottom of the radiator as it has hysteresis. The fans cut in at one temperature but cut out at a different temperature.
Effectively, you are calibrating your gauge with real numbers from the water temperature, not from the external body temperature of where your laser thing is pointing.
A couple of things to look at:-
Thermostats were available in 72-88'C so you can set the lower bound of the operating point of the engine lower or higher if you wish. If set lower, then you have more headroom for peace of mind regarding overheating. The fuel injected v12s ran with 88'C thermostats and so will always be 6'C closer to overheating than the carburettored cars.
The cooling capacity of the engine is probably adequate because the temperature does not run away upwards to infinity, so a new radiator is unlikely to be necessary.
The engine cover will have had a foam cover over the shroud to help dirtect cooling air through the radiator rather than around it.
No mention is made of all of the crud which will have accumulated around the cylinder liners over the years.
If you suspect that your thermostats never fully close off, then drop them into a pan of boiling water and measure how much the foot extends and verify that this exceeds the depth to the base of the front castings from where the thermostats sit.
You can find plenty of healthy discussion of the topic on the jag-lovers.org website and picture illustrating some of these points in some of the photo albums on that site.
kind regards
Marek
There is no knowing what the L of normal actually means, since you are dealing with a voltage which is simply split between the gauge and the sender and so you need to just go back to basics to correlate this to the real world.
Whilst a laser thermometer might sound high tech, I'd just remove the sender, place it in ice and measure its resistance and then warm it up all of the way to boiling and make a table of resistance versus temperature.
You can then run your car from cold up to operating temperature and you'll have a measure of the water temperature on the right hand front manifold housing. If you want to extend this analysis, drill and tap the other three housings and repeat. You'll now have an accurate view of the temperature of the water at the four exit points and whether the one measurement was representative of the whole picture.
The Otter switch also gives you a couple of reference points as to temperatures at the bottom of the radiator as it has hysteresis. The fans cut in at one temperature but cut out at a different temperature.
Effectively, you are calibrating your gauge with real numbers from the water temperature, not from the external body temperature of where your laser thing is pointing.
A couple of things to look at:-
Thermostats were available in 72-88'C so you can set the lower bound of the operating point of the engine lower or higher if you wish. If set lower, then you have more headroom for peace of mind regarding overheating. The fuel injected v12s ran with 88'C thermostats and so will always be 6'C closer to overheating than the carburettored cars.
The cooling capacity of the engine is probably adequate because the temperature does not run away upwards to infinity, so a new radiator is unlikely to be necessary.
The engine cover will have had a foam cover over the shroud to help dirtect cooling air through the radiator rather than around it.
No mention is made of all of the crud which will have accumulated around the cylinder liners over the years.
If you suspect that your thermostats never fully close off, then drop them into a pan of boiling water and measure how much the foot extends and verify that this exceeds the depth to the base of the front castings from where the thermostats sit.
You can find plenty of healthy discussion of the topic on the jag-lovers.org website and picture illustrating some of these points in some of the photo albums on that site.
kind regards
Marek
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Chickencoupe
Topic author - Posts: 10
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#8
Very good points Marek.
Replacing the radiator would be an expensive mistake if that is not what I need to do. Sounds like the actual temperature readings are where I need to focus my attention at this point.
Thank you!
Curt
Replacing the radiator would be an expensive mistake if that is not what I need to do. Sounds like the actual temperature readings are where I need to focus my attention at this point.
Thank you!
Curt
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