It happened today for first time. I have a 1996 Volvo 850 GLT wagon. I went to few places; the vehicle took few seconds to start than usual, RPM went to 2000 for few seconds without hitting a gas pedal, then back to 1000 - idle. It did same thing when I got home and started 3 times, figuring it out why. I noticed my cooling fan was on while the engine is off. It didn't turn off for over 5 minutes, so I unplugged it, and plugged it back on, it's off. My coolant gauge was normal and fluid level is fine, but I do have a leak from the heater core that make the carpet wet. I checked my oil dipstick; it has white & light tan milky on it... Most likely I need a new head gasket right? Can't think what else could be with these two issues at same time. Thanks.

 

It is possible, but before you think head gasket do some checks first. With the car running after it is started carefully remove the coolant bottle cover. Is the coolant bubbling like it is being put under pressure? Does the coolant have oil in it? Is there a lot of white smoke coming out the exhaust? If so to any of these three, then yes it is possible you might need a head gasket.

More than likely the cooling fan issue and RPM issue is caused by the coolant temperature sensor. It is a sensor that is located just below the thermostat on the coolant flange. I had one go bad and experienced the same symptoms. Temp gauge read normal too. Try that first.

The milky oil could be nothing more than a lot of condensation in the oil. I have that too from time to time in the cold weather. A good run on the freeway (hour or so) usually clears it up.

Don't panic or think the worst yet!

Glenn

 

These cars are nuts with the milky dipstick. Mine all do that when it's cold out.

As for the heater core, these cars have the easiest heater core to get to of any car I've ever seen. Fix it. I've been using the russian ones on ebay for $35, but you do need to remove that weatherstripping. It stinks terribly.

I have seen cars do the fan on thing, but I am not sure what it is telling you. I bet somebody knows.

 

I can believe some of this:
http://www.matthewsvolvosite.com/for...hp?f=1&t=59522

You'll have to ignore the "thermodynamic semantics ****" stuff. Don't see that much on the internet.

If you don't have a CEL, it's important to consider the engine coolant temperature can be wrong, as long as its not intermittently going totally out of range, and not set a CEL. It doesn't have anything to double check.

 

It was under 20'F, so yeah. The faulty coolant temperature sensor makes sense as I started it shortly after warm up and the gauge did nothing for some seconds plus what you said about your experience. It never stall out, but sometime rough idle since I got that problem. I have a engine light on when I bought it. Checked it at autozone once; it was oxygen sensor (have a exhaust leaks) and I bet I have another code. I can take it there tomorrow. The previous owner told me he replaced the heater core.. I doubt they put new o-rings in - that's where the leak come from and I have another leak somewhere outside as I saw it dump small amount of antifreeze on the ground once a while.. Yes, my vehicle stinks because of that lol. The heat works fine though. My Volvo is falling apart, the timing belt is due, and have 330,000+ miles on the body :/ I can't afford everything, but it's still a beast.