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Master Tech Matt
Master Tech Matt, ASE and Chrysler Master Technician
Category: Car
Satisfied Customers: 1608
Experience:  20 years automotive experience, Factory trained by Chrysler, Jeep, Dodge, and Toyota
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Temperature gauge shot up in car. What do I do?

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My temp gauge shot up today in my car despite only driving for 20 mins. Never happened before. Levels are fine. Drove home with heater on and gauge went back down.

Master Tech Matt :

The most likely cause of your concern would be a stuck or sticking thermostat. This will cause the engine to overheat fairly quickly, but in cool enough weather running the heater will provide enough engine cooling to keep the engine temperature down.

Customer :

That's what was already said to me. I did think though if the thermostat stuck it would only run cold? What are the chances of it being a head gasket issue?

Master Tech Matt :

The thermostat can stick closed in which case the engine will overheat, or it can stick open, in which case the engine runs too cold. If running the heater cooled the engine off, and you have no coolant loss, or coolant in the oil it is unlikely a head gasket.

Customer :

The car has been running fine, the on board computer did show up to check for cool and last week and I topped it up but the coolant level today was fine. I have to drive the car to my garage tomorrow or Tuesday, will I do damage if I do this? It isn't a big journey 15 minutes maximum.?

Master Tech Matt :

As long as running the heater keeps the temperature in the normal zone, and you are not noticing any engine misfire or rough running conditions, then driving it a short bit will not harm anything.

Customer :

Great Matt, really appreciate your help. Hopefully you're right, it seems to be what a few others said to me but they aren't experts. Thanks buddy

Master Tech Matt :

You are welcome, can I help you further?

Customer :

Oh, some times it takes a few seconds to start in the morning, am presuming its because its a diesel automatic...mate of mine has an E220 and has same issue...

Master Tech Matt :

Assuming this only happens when ambient temperatures are cooler, then yes this is a normal characteristic of the diesel engine.

Customer :

No problem Matt sorry was on the phone there. Mostly in the mornings its like that, when I start and stop regularly there is no problem. Thanks again for all your help. Is there anything else in particular that you would advise with my car? Its a 2003 but the mileage is high, 176000, I normally get it serviced every 8-9k miles is that often enough?

Master Tech Matt :

Normal service including oil, air filter and fuel filter changes are the most important thing you can do for engine life. I would change the oil every 5K unless you allow the engine to come up to operating temperature every time it is ran, this usually means a trip of at least 15 miles. The more stop and go type driving, and short trips you do the more often you need to change the oil.

Customer :

Yeah I do change the oil fairly often. I do a mixed bag between short and long distance. Short is all city driving. Thanks for all your help.

Master Tech Matt :

You are welcome.

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