Overheating

[johnfin]

My 2002 ws6 is overheating on surface roads, especially with the a/c on. When on the freeway the gauge is half way and ok........ on surface roads the gauge pegs out and check gauge light comes on. Fans are working and they come on for a while after the car is off. Is this a common problem and what should I check?

[35th-ANV-SS]

If the gauge pegs out I wouldn't be driving the car at all until you fix the problem as you'll warp the heads and can do other damage to the motor. A few different possibilities. Stuck thermostat, low on antifreeze, clogged/dirty radiator, air pocket in the line, and a bad or poor performing water pump.

[johnfin]

The coolant was low so I put a dye in it and used a Uv light. Dont see any leaks. Water pump was replaced 2 years ago. So i was thinking where is the coolant going. Then I remembered the inline cooler. I am thinking about pulling the small lines off and seeing if there is coolant in them. The heater core could be another source, where is it located?

[35th-ANV-SS]

Usually if the heater core goes bad you'll have a front passenger side wet carpet as it's located on that side.

[pajeff02]

At highway speeds the fans are really not needed as there is sufficient air flow through the radiator. However, at low speeds the fans are what moves air through the radiator. Are BOTH fans working, or maybe only one? Is your radiator blocked up with road debris (look up in at it from the front with a flashlight). Have you verified temps with a laser temp gun or anything to see what is really going on? Only '98s had working temp gauges. From then on, think of the temp gauge as an "estimator" at best.

[johnfin]

Coolant is low so I think I need to start there. I see a faint stain mark (not dye or liquid) on the back on the pump under the bell pulley(typ place where they leak). Its only 2 years old but I have a feeling its leaking. I need to get the car up on ramps and look up there.

[2002ssslp]

Good luck.

[pajeff02]

Make sure you get all the air purged out when you refill the system - these engines can air lock the thermostat.