99 XC AWD Overheating??

twncty · Post by **twncty** » 26 Jun 2012, 18:53

Perplexing problem with my 1999 V70 XC/AWD. Last summer intermitently the outside tempeture gauge would read higher than actual outside temp. The temp would seem to increase during heavy traffic. At about 95-100 degrees the AC would shut-off and then the actual temp gauge would start to rise. I flushed the system and cleaned the radiator seemingly problem sovled. Through the fall, winter and spring it drove fine. Well its back doing the same thing now that the weather is warm again. Any suggestions on where I should start to diagnose this would be greatly appreciated. Thanks!

Post by **rspi** » 26 Jun 2012, 19:14

There is a difference between the ambiant "outside temp" gauge that tells you how hot it is outside and the motor temp gauge that tells you how warm the motor is.

The ambiant temp gauges means nothing to the operation of the car. It's just a friendly notice to let you know how hot or cold it is outside in case you are very comfy inside the car. The sensor is under the car in the lower front section of the air scoop. So, when you are in traffic and driving very slow, the heat from the road, motor, etc., will cause the reading to raise, because it's telling you how hot it is under the car. Don't worry about that. If your ac wasn't cooling the car well, it likely needs serviced but to be honest with you, Volvo's ac system are not the greatest and don't do well over 95 degrees. It's just to hot.

Now on the other hand, if you are seeing your engine temp needle rise, let us know.

twncty · Post by **twncty** » 26 Jun 2012, 19:28

Yes the temp gauge goes up. I turn off the AC and it goes down. Is it possible its registering excess engine heat? Once the outside temp shows 100 degrees (on a 75 degree day) it starts to overheat.

Post by **rspi** » 26 Jun 2012, 19:37

What starts to overheat?

twncty · Post by **twncty** » 26 Jun 2012, 19:54

The engine temp gauge starts to go up after the outside gauge reads 100+ degrees.

Post by **MoVolvos** » 26 Jun 2012, 20:20

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twncty wrote:The engine temp gauge starts to go up after the outside gauge reads 100+ degrees.

The Engine (Coolant) Temp Gauge with Needle is the measure of Coolant Temp in the Engine

Outside Temp Reading is just a Thermometer which measures the Ambient (Outside Air) Temperature

The 2 are not related but it so happens at this time the Coolant Needle is going up when the Outside Air Temp is 100+ Degrees which makes sense as your car has a problem when it get hot. If you have your AC on the Radiator Cooling Fans stay on till the AC shuts off. This is why your Radiator (Coolant) Temp does not go up when the AC is on.

Although your Coolant is pretty fresh the Thermostat maybe stuck partially open so only when the weather is hotter the Coolant Temp Needle Rises.

Are you losing Coolant anywhere?

Blessings,
BKM
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twncty · Post by **twncty** » 26 Jun 2012, 21:17

No loss of coolant. I am replacing the thermostat tonight. Next couple days are going to be 90+ degrees. I'll see if that works. I have a ODBII that shows the cars temp at idle after a short drive around the block and 10 mins of idle to be 199 degrees. I don't know if that is normal or not. My only reference to the outside temp gauge is that tonight as an example; outside tempature is 73 degrees driveway ground is cool but when I start my car and let the engine idle the outside temp gauge raises in tempature. In this case it registered to 90 degrees before I shut the car off.

Post by **MoVolvos** » 26 Jun 2012, 21:28

twncty wrote:No loss of coolant. I am replacing the thermostat tonight. Next couple days are going to be 90+ degrees. I'll see if that works. I have a ODBII that shows the cars temp at idle after a short drive around the block and 10 mins of idle to be 199 degrees. I don't know if that is normal or not. My only reference to the outside temp gauge is that tonight as an example; outside tempature is 73 degrees driveway ground is cool but when I start my car and let the engine idle the outside temp gauge raises in tempature. In this case it registered to 90 degrees before I shut the car off.

When you begin to drive the Temp should come down a little bit as the heat trapped under the vehicle can raise the Air Temp Gauge. Hope the Thermostat works!

Here is some additional information:

How To Fix An Overheating Car (The Long and Short of it)

He actually answers emails! Albeit, in a week or so.
... re=related

Blessings,
BKM
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Post by **MoVolvos** » 26 Jun 2012, 21:45

twncty wrote: I have a ODBII that shows the cars temp at idle after a short drive around the block and 10 mins of idle to be 199 degrees.

There are several Temp Range Thermostats so the 199 Degrees is normal
http://www.oreillyauto.com/site/c/searc ... vi=1434025

Blessings,
BKM
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Post by **jblackburn** » 26 Jun 2012, 21:45

Your car is fine - don't worry about it. They all do this. I've seen 135 on my S70 before.

The engines operate between 180-220 degrees, which is indicated at the 3:00 position on the dash temp gauge.

The ambient temp sensor is located close to the radiator and picks up heat from that area. The asphalt on the road and the layer of air within a few inches of it CAN actually be 110+ degrees in the summer heat, so that affects it as well.

A bit of preventative maintenance, if you have not, would be to change coolant, flush radiator, and replace all coolant hoses on your car (turbo ones included!). Summer temps are very hard on your car's cooling system, and these hoses will burst in hot weather if they are old.