High coolant temp at idle with A/C off
 

I just had the 22.5K mile oil change done an hour ago on my stock (no mods) BRZ. This is the last of the "free" service visits. After leaving the dealership I noticed Torque is showing the coolant temp at 188-190F while driving, but it immediately shoots up as high as 210F at idle. My idle coolant temp usually doesn't go above 195F even on the hottest days and even when I've been romping on it. My other vehicle has a history of temp problems, so I'm in the habit of monitoring my temps religiously, so I'm certain it wasn't doing this prior to the service visit.

This high temp is happening with calm driving in traffic. Ambient temp here is 55F. Oil temp is running 203-210, not out of the normal range. No CELs or warnings. The car's own temp gauge shows no movement (but of course it wouldn't).

Any thoughts?

Could be sampling variation.

I wouldn't worry about it ...... unless it goes higher.

However, if you want to do something ..... you may wish to check the fuse for the cooling fans.....;)


humfrz

I actually wrote that while I was in the waiting area at the dealership. Once I saw what the car was doing, I took it back to get them to check it out. The tech said it was operating within normal range. He also checked the fans and said everything was operating normally there as well. He said until something actually failed, there wasn't much more he could do about it.

So I guess this is "normal," and I should now take a drink. But really, a 20° swing in coolant temp is "normal"? I guess that wouldn't be the weirdest quirk of this car.

Check to ensure there is enough oil in the car.

Motor oil is also used to help cool the engine.

First thing I did was pull over, pop the hood and check the oil, considering that I had just had the oil changed. My first thought was that they didn't fill it or hadn't tightened the plug. The oil level is fine. As I said above, I'm also monitoring the oil temp on Torque, and it has been staying between 200° and 210° in traffic, well within normal range.

It appears to be only the coolant temp that has been affected. What's weird is that the coolant temp actually exceeds the oil temp at idle, which is completely different behavior from usual. It has me completely stumped.

What's your coolant level at in the overflow tank when the engine is fully warm after a little while?

It's at the top line hot, exactly where it should be. I did have the coolant drop people were talking about over the summer. I topped it off in August with Subaru blue, and it hasn't dropped since.

They could have put super thick oil in which would flow and thus cool less.

Coolant t is supposed to climb pretty fast at idle. Maybe 1.8F per 5-10 sec.

If it shoots up from 194 to 210 in a couple of seconds there's something else going on.

Eye opening thread as I am considering a BRZ... I just did a random Google search on "coolant loss Subaru". Yikes - plenty of reading. Seems it is a well known problem with Subie flat engines.

meh. More of us DON'T have an issue than those who do. I've never had to touch my coolant.

The coolant drop has nothing to do with it. That happened a few months ago, and the temp was never a problem. Apparently that's "normal" (take a drink) for these engines. I only discovered it because I noticed it was low when I was checking my oil.

I have discovered an additional piece of this puzzle. The day I got my oil changed was the first cool day I have driven the car in a long time and the first time in months that I have driven it with the A/C off. The oil change was just coincidental timing, because I have been able to confirm that if I turn the A/C back on, the temp drops back to normal. It appears that having the A/C on is forcing the fans to come on earlier. I can turn the A/C off, watch the temp go up, turn it on, watch the temp go down.

The tech said that the fans were operating normally when he checked them. So now I'm curious if other people's cars are doing this same thing. Anybody monitoring your coolant temp, and if so, does yours do this? What's your normal coolant temp at idle with the A/C off?

Perhaps it should fall under a new thread.. As a prospective BRZ owner doing a little research on Subarus I found the following. Usually presents around 100,000 miles. No mention of the Subaru FA20 engine but perhaps they haven't accumulated enough miles yet.

http://allwheeldriveauto.com/subaru-...ained-part-ii/

There was a thread here about a BRZ owner with head gasket leaks but I can't seem to find it now.