TCCoA Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
Hi, I just purchased the 96 bird listed under my username, and I wanted to know what you all thought of this odd behavior of the temperature gauge. It takes quite a long while to show it getting to temperature, but when it finally reaches the N in NORM it slightly moves down behind the N, then back up to it and does this constantly for the remaining time that I drive it. It never shows it overheating, and there is no evidence of the head gasket being blown. I just wonder if it is a trait caused by the car's past. It was my grandmother's car, and she was never much of a driving person, but had no choice but to drive herself places once my grandfather passed away in 2001. She never drove it more than 1-3 miles(one way) from her house so I doubt the car reached full operating temperature for a good percentage of its drives. The last 10k miles were put on it this way. The car still puts out good heat quickly when I take it out from a cold start, so is this even worth looking into?
 

·
Super Moderator
Joined
·
9,262 Posts
Every car has a different character with the temperature gauge. My car's normal range is between 1/3 and 1/2 on the gauge. A friend's is between 1/2 and 2/3. Same operating temperatures, just different positions on the gauge.

The oscillation you speak of is likely the thermostat opening and closing to accommodate cold coolant inside the radiator, this is normal in cold weather. Once the coolant hits 200-205 degrees the thermostat pops open and the cold, near freezing temperature coolant inside the radiator cools the engine down to 190 very rapidly. This causes the thermostat to close (or mostly close), allowing the radiator to cool the hot coolant inside very effectively. Once the coolant inside the engine warms up again the thermostat opens once again, repeating the cycle.

At least, this is what I have observed occurring with my car.
 

·
Registered
Joined
·
1,170 Posts
Hi, I just purchased the 96 bird listed under my username, and I wanted to know what you all thought of this odd behavior of the temperature gauge. It takes quite a long while to show it getting to temperature, but when it finally reaches the N in NORM it slightly moves down behind the N, then back up to it and does this constantly for the remaining time that I drive it. It never shows it overheating, and there is no evidence of the head gasket being blown. I just wonder if it is a trait caused by the car's past. It was my grandmother's car, and she was never much of a driving person, but had no choice but to drive herself places once my grandfather passed away in 2001. She never drove it more than 1-3 miles(one way) from her house so I doubt the car reached full operating temperature for a good percentage of its drives. The last 10k miles were put on it this way. The car still puts out good heat quickly when I take it out from a cold start, so is this even worth looking into?
Its probably ok BUT....
When was the coolant changed? I would change the coolant, flush the system and get a new OEM thermostat.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #4
Its probably ok BUT....
When was the coolant changed? I would change the coolant, flush the system and get a new OEM thermostat.
I honestly don't know. I looked at it and the coolant looks fresh, but I don't have a tester to see exactly how fresh it is.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #5
Every car has a different character with the temperature gauge. My car's normal range is between 1/3 and 1/2 on the gauge. A friend's is between 1/2 and 2/3. Same operating temperatures, just different positions on the gauge.

The oscillation you speak of is likely the thermostat opening and closing to accommodate cold coolant inside the radiator, this is normal in cold weather. Once the coolant hits 200-205 degrees the thermostat pops open and the cold, near freezing temperature coolant inside the radiator cools the engine down to 190 very rapidly. This causes the thermostat to close (or mostly close), allowing the radiator to cool the hot coolant inside very effectively. Once the coolant inside the engine warms up again the thermostat opens once again, repeating the cycle.

At least, this is what I have observed occurring with my car.
That makes sense. Every car has its own little quirks that make it unique, some to make/model, some to individual cars. I guess this is just one of those little quirks, and as long as I don't have to worry about a larger problem looming I am ok with it.
 

·
Registered
Joined
·
7,758 Posts
Every car has a different character with the temperature gauge. My car's normal range is between 1/3 and 1/2 on the gauge. A friend's is between 1/2 and 2/3. Same operating temperatures, just different positions on the gauge.

The oscillation you speak of is likely the thermostat opening and closing to accommodate cold coolant inside the radiator, this is normal in cold weather. Once the coolant hits 200-205 degrees the thermostat pops open and the cold, near freezing temperature coolant inside the radiator cools the engine down to 190 very rapidly. This causes the thermostat to close (or mostly close), allowing the radiator to cool the hot coolant inside very effectively. Once the coolant inside the engine warms up again the thermostat opens once again, repeating the cycle.

At least, this is what I have observed occurring with my car.
A properly operating thermostat should not cycle the temperatures. Based on the coolant temperature the thermostat varies how much it opens. A thermostat is not an open/closed device but rather a temperature based, variable orifice that limits the amount of coolant flowing to the radiator.

Couple of questions (we’ll assume it doesn’t have a chip):
How long is “quite a long while”?
Are you describing the time to get warm while idling or driving?
How many miles are on it?

This is just my .02, but whenever I buy a used car, the first thing I do is:
Complete tune-up, including plugs, wires, filters, belts and hoses.
Replace all fluids (coolant, power steering, oil, transmission fluid, etc.)
Check the suspension/brakes and replace/repair as necessary.

Based on what you’re describing, I would replace the thermostat just to be on the safe side. An engine that rarely gets up to operating temperature is really hard on the thermostat.

But again, just my .02. :thumbsup:
 

·
Registered
Joined
·
11 Posts
Discussion Starter #7
A properly operating thermostat should not cycle the temperatures. Based on the coolant temperature the thermostat varies how much it opens. A thermostat is not an open/closed device but rather a temperature based, variable orifice that limits the amount of coolant flowing to the radiator.

Couple of questions (we’ll assume it doesn’t have a chip):
How long is “quite a long while”?
Are you describing the time to get warm while idling or driving?
How many miles are on it?

This is just my .02, but whenever I buy a used car, the first thing I do is:
Complete tune-up, including plugs, wires, filters, belts and hoses.
Replace all fluids (coolant, power steering, oil, transmission fluid, etc.)
Check the suspension/brakes and replace/repair as necessary.

Based on what you’re describing, I would replace the thermostat just to be on the safe side. An engine that rarely gets up to operating temperature is really hard on the thermostat.

But again, just my .02. :thumbsup:
This car is bone stock, but my daily commute to/from work is 12 miles one way, and I don't see the engine reaching full operating temperature till about half way through that drive. Just seems a little long for me considering my other cars were always completely or nearly warmed up in half that distance. The car only has 42k miles on it, and the oil looked like it had been changed recently along with a healthy looking green color to the coolant.
 

·
Registered
Joined
·
563 Posts
I have a one range colder thermostat in my PI 4.6L. I also did the "head coolant mod" on the rear of each head, and use a custom hose system (that I think came out very well) which drastically improved cooling system by increasing water flow considerably. Now, in cold temperatures, my temp needle when fully warmed up (which takes some time, especially just idling) barely goes into the N range - like 1/8th up the gauge. In the middle of summer with spirited driving and occasional WOT the gauge will go to 3/8 through the Normal range.

I need to spend more time datalogging after I finish overhauling the suspension.
 

·
Registered
Joined
·
59 Posts
my car did this too found out that the thermostat was replace and when they did it bc of it stand up designe it sliped down a lil bit alowing the coolant to constantly be flowing around it my car on a warm winter day(35degrees) it would never warm up on a 5 mile drive on a 20 mile drive it would come up just a hair above the blue cold square fixed it and now it heats up in 10 mins idling
 

·
Registered
Joined
·
369 Posts
I would do 2 things 1 is change the thermostat. I dont know if it has its original one or if O.E does this, but some aftermarket ones stay open when they fail. Also you could be missing it entirely. If grandpa or any old school shade tree mechanic did any work its fairly common to see them chuck the thermostat.

2 do a fluid exchange at a shop because they can also take out any air in the system. Trapped air can make it stay cool. If you do it yourself just make sure you dont leave room for it to have air in it.
 

·
Registered
Joined
·
369 Posts
This car is bone stock, but my daily commute to/from work is 12 miles one way, and I don't see the engine reaching full operating temperature till about half way through that drive. Just seems a little long for me considering my other cars were always completely or nearly warmed up in half that distance. The car only has 42k miles on it, and the oil looked like it had been changed recently along with a healthy looking green color to the coolant.
looks can be deceiving.
 
1 - 11 of 11 Posts
Top