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June 26, 2010 6:03 AM Subscribe
YANMM but: how hot is too hot for an engine?
I drive a 1996 Ford Escort. I've noticed over the past few weeks that the temperature gauge climbs higher than it normally does...it takes perhaps 10-15 minutes to reach somewhere between 1/3 to 1/2 of the way up. I've never seen it climb that high. Last week I drove a 45 minute trip back and forth in a day and again it climbed that high, to about half way, but no higher.
Normally I've never seen it climb more than 1/8 of the way up, even after the end of a longer (1.5 hour) trip.
Oil is fine, coolant was a bit low but not exceedingly so. I topped it off but it hasn't made much difference.
Is this worth getting checked out? I drive very little, normally only around town with occasional longer trips. Also, I was thinking of taking a trip today that takes about 1.5 hours. Would that be a dumb risk?
I drive a 1996 Ford Escort. I've noticed over the past few weeks that the temperature gauge climbs higher than it normally does...it takes perhaps 10-15 minutes to reach somewhere between 1/3 to 1/2 of the way up. I've never seen it climb that high. Last week I drove a 45 minute trip back and forth in a day and again it climbed that high, to about half way, but no higher.
Normally I've never seen it climb more than 1/8 of the way up, even after the end of a longer (1.5 hour) trip.
Oil is fine, coolant was a bit low but not exceedingly so. I topped it off but it hasn't made much difference.
Is this worth getting checked out? I drive very little, normally only around town with occasional longer trips. Also, I was thinking of taking a trip today that takes about 1.5 hours. Would that be a dumb risk?
Is it actually redlining the temperature gauge? I had a 1995 Escort when I lived in Florida, and the temperature seemed to always peak at 3/4 of the meter, but I never had a problem.
posted by Cat Pie Hurts at 6:22 AM on June 26, 2010
posted by Cat Pie Hurts at 6:22 AM on June 26, 2010
Probably just a stuck thermostat. It's an easy repair.
posted by Bighappyfunhouse at 6:23 AM on June 26, 2010
posted by Bighappyfunhouse at 6:23 AM on June 26, 2010
By "⅓ to ½ of the way up" you mean from zero? The temperature gauge would normally be calibrated to point at the middle of its range when the engine is at normal running temperature for continuous operation at highway cruising speeds. If you haven't seen it there before, maybe your usual short drives around town haven't warmed up the engine that much, or maybe the weather is warmer than when you've taken longer drives in the past. I wouldn't worry about it much as long as it stays in the lower ½ of its range, but keep an eye on it and if it goes higher get it looked at.
posted by nicwolff at 6:39 AM on June 26, 2010
posted by nicwolff at 6:39 AM on June 26, 2010
Response by poster: Yep, I mean from zero...so no, it's never approached the red line...then again I've gone on mostly short trips lately. So I've been worried I've only escaped overheating or some problem because the car hasn't had long enough to overheat. (I'm not even sure if that thinking is logical...I don't know much about cars, obviously.)
posted by unannihilated at 6:41 AM on June 26, 2010
posted by unannihilated at 6:41 AM on June 26, 2010
How hot is too hot? ... when you see steam coming out of the radiator cap ... when the overflow resevoir is bubbling or pumping coolant out its vent ... when you can hear the coolant gurgling inside as it boils ... when the fan comes on and won't turn off ... then it is too hot.
Check that the fanbelt is tight (really tight), the radiator is free from clogging by bugs, leaves etc, ... the fans come on when the engine has been idling for a while, then turns off after another while ... watch the coolant level, and you should have little to worry about. Guages can play up, so treat them as only one indicator of what is happening.
posted by GeeEmm at 7:34 AM on June 26, 2010
Check that the fanbelt is tight (really tight), the radiator is free from clogging by bugs, leaves etc, ... the fans come on when the engine has been idling for a while, then turns off after another while ... watch the coolant level, and you should have little to worry about. Guages can play up, so treat them as only one indicator of what is happening.
posted by GeeEmm at 7:34 AM on June 26, 2010
Have a look at your radiator cap. It may look fine at first glance, but might actually be gunked up. It is cheap to replace. If it is not working right it can cause your car to over heat.
posted by nimsey lou at 7:34 AM on June 26, 2010
posted by nimsey lou at 7:34 AM on June 26, 2010
If you are out and it gets to hot, roll down the windows and blast your heater. It will temporarily lower the temp. This will let you get it some place safe. Don't do this on a regular basis.
posted by nimsey lou at 7:37 AM on June 26, 2010
posted by nimsey lou at 7:37 AM on June 26, 2010
To elaborate, by 'fanbelt' I mean the one that drives the coolant pump. If the pump is original it might be shot and need replacing.
Good luck!
posted by GeeEmm at 7:38 AM on June 26, 2010
Good luck!
posted by GeeEmm at 7:38 AM on June 26, 2010
Those gauges usually indicate the spectrum of reasonable working temperatures. If it isn't in the red zone, it's not *too* hot.
But as for why it is hotter than normal, the radiator cap is a good thing to check.
I sort of doubt it is the thermostat; if it is stuck open, the car will eventually reach its normal operating temperature anyway. And if it's stuck closed, it would overheat pretty quickly. I guess it is possible to be stuck in the middle, but I kind of doubt that.
Other things it could be:
-dirty radiator, inside or outside.
-low charge on AC refrigerant, creating more external heat than normal, which leads to poorer engine cooling.
-the car is malfunctioning in some subtle way that is causing it to run slightly warm.
-is the weather simply hotter or more humid than you are used to? humidity makes it a lot harder for a car to reject excess heat.
posted by gjc at 8:25 AM on June 26, 2010
But as for why it is hotter than normal, the radiator cap is a good thing to check.
I sort of doubt it is the thermostat; if it is stuck open, the car will eventually reach its normal operating temperature anyway. And if it's stuck closed, it would overheat pretty quickly. I guess it is possible to be stuck in the middle, but I kind of doubt that.
Other things it could be:
-dirty radiator, inside or outside.
-low charge on AC refrigerant, creating more external heat than normal, which leads to poorer engine cooling.
-the car is malfunctioning in some subtle way that is causing it to run slightly warm.
-is the weather simply hotter or more humid than you are used to? humidity makes it a lot harder for a car to reject excess heat.
posted by gjc at 8:25 AM on June 26, 2010
Many new cars run around 90C or between 180 and 200F. Your older Escort might run a little cooler than that.
As noted on many gauges, "normal" is generally anywhere below the big red H. Many late model cars have an electronically dampened temperature gauge or a program in the instrument cluster that prevents normal fluctuations in engine temperature from moving the needle. They don't want owners to panic when they see the needle move. So, as long as it's in the normal range, the cluster just sets the needle in the middle. On a late model car, I can watch the coolant temp value with a scan tool fluctuate over 20 degrees without seeing a corresponding variation in the gauge. The needle won't move until the coolant temp starts to climb above normal.
Older vehicles like yours don't usually have that function. The needle will move in direct unbuffered correspondence to engine temperature. I've seen some older Saturns that have such sensitive temp gauges that you can watch the needle climb and fall as the electric cooling fans cut on and off.
So, you're saying that you've never really seen the coolant gauge show the needle at half-way? If that's so, it sounds like the thermostat in your car has been stuck open. The thermostat is designed to regulate engine temperature. At a cold start, the thermostat is closed and effectively blocks the flow of coolant through the radiator. This assists in quickly warming the engine up to its optimal temperature. Once that temperature is reached, the thermostat expands and opens, allowing coolant to flow into the radiator. If a thermostat malfunctions and remains closed, the car will overheat. If it malfunctions and remains open, the car will take a long time to warm up.
If your thermostat is sticking in any way, you should get it replaced. It might stick open today, but it could stick shut tomorrow. A stuck closed thermostat can overheat a car within just a few blocks of driving. And the same principle applies to the water pump. If it's flowing, it's cooling. If it's not, it's overheating. A faulty water pump will usually be accompanied by a leak and a shopping-cart wheel noise coming from the engine as the bearing wears out. The car will also usually overheat as the coolant and pressure leak out of the pump. On other cars, like the notorious VW, the plastic impeller can separate from the water pump shaft and cause a no-flow situation without any noise or leaking. But that's not going to be the case on your Escort. And if the water pump was bad, the needle would almost certainly be going over 1/2 within a few miles of driving, the same as a stuck shut thermostat.
Expect this repair to be relatively cheap and quick. The mechanics will want to pressure test the system, check for leaks, check the coolant level and quality, replace the thermostat and gasket, refill with new coolant, and then test drive the vehicle. I think the thermostat housing is under the ignition coils and the air intake, so some labor might be involved in removing it, but it shouldn't be that bad.
posted by Jon-o at 8:31 AM on June 26, 2010 [1 favorite]
As noted on many gauges, "normal" is generally anywhere below the big red H. Many late model cars have an electronically dampened temperature gauge or a program in the instrument cluster that prevents normal fluctuations in engine temperature from moving the needle. They don't want owners to panic when they see the needle move. So, as long as it's in the normal range, the cluster just sets the needle in the middle. On a late model car, I can watch the coolant temp value with a scan tool fluctuate over 20 degrees without seeing a corresponding variation in the gauge. The needle won't move until the coolant temp starts to climb above normal.
Older vehicles like yours don't usually have that function. The needle will move in direct unbuffered correspondence to engine temperature. I've seen some older Saturns that have such sensitive temp gauges that you can watch the needle climb and fall as the electric cooling fans cut on and off.
So, you're saying that you've never really seen the coolant gauge show the needle at half-way? If that's so, it sounds like the thermostat in your car has been stuck open. The thermostat is designed to regulate engine temperature. At a cold start, the thermostat is closed and effectively blocks the flow of coolant through the radiator. This assists in quickly warming the engine up to its optimal temperature. Once that temperature is reached, the thermostat expands and opens, allowing coolant to flow into the radiator. If a thermostat malfunctions and remains closed, the car will overheat. If it malfunctions and remains open, the car will take a long time to warm up.
If your thermostat is sticking in any way, you should get it replaced. It might stick open today, but it could stick shut tomorrow. A stuck closed thermostat can overheat a car within just a few blocks of driving. And the same principle applies to the water pump. If it's flowing, it's cooling. If it's not, it's overheating. A faulty water pump will usually be accompanied by a leak and a shopping-cart wheel noise coming from the engine as the bearing wears out. The car will also usually overheat as the coolant and pressure leak out of the pump. On other cars, like the notorious VW, the plastic impeller can separate from the water pump shaft and cause a no-flow situation without any noise or leaking. But that's not going to be the case on your Escort. And if the water pump was bad, the needle would almost certainly be going over 1/2 within a few miles of driving, the same as a stuck shut thermostat.
Expect this repair to be relatively cheap and quick. The mechanics will want to pressure test the system, check for leaks, check the coolant level and quality, replace the thermostat and gasket, refill with new coolant, and then test drive the vehicle. I think the thermostat housing is under the ignition coils and the air intake, so some labor might be involved in removing it, but it shouldn't be that bad.
posted by Jon-o at 8:31 AM on June 26, 2010 [1 favorite]
When the engine is cold, remove the radiator cap and start the engine. If you see bubbles coming up through the coolant, you have a bad headgasket. Do not run it too long or you will have coolant spilling onto the ground.
Headgasket= `$700 from a shop and ~$250 if you DIY
posted by WhiteWhale at 4:41 PM on June 26, 2010
Headgasket= `$700 from a shop and ~$250 if you DIY
posted by WhiteWhale at 4:41 PM on June 26, 2010
To add to Jon-O - if it's been a while since your upper and lower radiator hoses have been replaced, have them done while they've got your car down. It's not a massively expensive repair item, and since they'll be draining the coolant anyway, this is a really good time to have them done. These hoses deteriorate structurally over time, and need occasional replacement as a preventative maintenance item.
posted by azpenguin at 7:05 PM on June 26, 2010
posted by azpenguin at 7:05 PM on June 26, 2010
Response by poster: I just wanted to say thanks for the answers, all. I ended up taking my trip and drove the 70 miles and back with no issue. The needle went up to about 1/3 of the way from zero after about 10 minutes and stayed that way for the rest of the trip and didn't move. It must be my new normal. No other problems, but since this is new I'll investigate the other options.
posted by unannihilated at 5:16 PM on June 27, 2010
posted by unannihilated at 5:16 PM on June 27, 2010
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posted by unannihilated at 6:07 AM on June 26, 2010