Engine running temps very wide range, normal?

Post by **rguzz** » 25 Dec 2019, 12:09

96 855t, very variable operating temps, is this normal? Long uphill climb, 36 degrees out, 200+F degrees, downhill same climb temp drops to 150 degrees, in a very few minutes. Gauge drops down from middle position. General cruising temps 180's, again about 40 degrees outside, pretty consistent. T stat is OEM Volvo, CTS new OEM, Nissens rad is maybe 5 years old. I assume this is all pretty normal, comments? Happy Holidays. BTW, readings are from my OBD2 reader.

Post by **FlyingVolvo** » 25 Dec 2019, 13:23

Once warmed up, even on long descents, the coolant shouldn't really drop below the temperature rating of the thermostat. Sounds like yours may be broken (stuck open). It's more normal for temperature variance above that rating, commensurate with load (AC, hills, weights, ambient temp, etc).

Post by **rguzz** » 25 Dec 2019, 18:20

I've been away from the car for a few months and don't recall these fluctuations in the past. Temp gauge always has been in the middle, with no memory of it ever dropping below that.T stat is maybe 2-3 years old, max. OEM Volvo. Heat appears somewhat to be erratic and dependent on what kind of driving I'm doing, ie warmer when I'm on a long, hard drive. Sounding more like a bad thermostat, doesn't it.

Post by **polskamafia mjl** » 25 Dec 2019, 21:40

For sure, if its getting so low that its affecting blower temp then its definitely a stuck thermostat.

Post by **bmdubya1198** » 25 Dec 2019, 21:53

One more for a bad thermostat... the heat being affected is almost a dead giveaway, given the other issues.

Post by **abscate** » 26 Dec 2019, 03:43

My 1999 sits at 87C coolant temp while driving, at idle it will cycle between 87c and 105c as the engine heats up, radiator fan comes on, temp goes back, Maybe 2-3 minutes to creep up,then 30-60 seconds to come back down.

The temp gauge isn’t a precision device.

I logged the temp vs tick mark positions on one of my cars in a thread, it basically a

Cold - correct- Overheat measurement device

Post by **RickHaleParker** » 26 Dec 2019, 03:58

Thermostat response time is slow. Replace Thermostat before it gets really bad and does damage.

Post by **rguzz** » 26 Dec 2019, 07:40

Thanks, will do, absolutely. Disappointed in life of the last replacement. I do carry a spare, time to fish it out. Have a great holiday, everyone.

Post by **RickHaleParker** » 26 Dec 2019, 07:59

rguzz wrote: ↑26 Dec 2019, 07:40 Disappointed in life of the last replacement.

What brand did you use and where did you source it?

Post by **rguzz** » 26 Dec 2019, 14:17

Volvo OEM as seen in this video. Mine broke in exactly the same way. Replaced it today with a Wahler, whose internals appear much more robust. Maybe Volvo should no longer be the go to for thermostats anymore. 2 years for me. Looks like a design flaw.