I purchased my 2015 OB about two months ago. I couldn't recall a time when I had heard the fans run. I turned on the AC and popped the hood to ensure they were operational-check. I then connected my OBD scanner and took the OB for a spin to warm it up. Now I have the car in park idling, no AC on and wait....and wait. The scanner slowly rose past 211F and made it to 220F. A moment later both fans kicked on low speed and quickly brought the ECT back to 210F and turned off. Repeated one more time-numbers the same. My question: is this normal for this engine? Has anyone checked this and can confirm? Seems a tad high to me, but the engineers on these new vehicles seem to extract maximum efficiency out of the engines- maybe a hotter engine does that.
According to the copy of the 2015 FSM I have, with the AC off, as the coolant temperature rises, the fans should come on at "Low" speed around 210 F, and then switch to high speed at around 221 F.
However, I had a similar question about my 07. ( http://www.subaruoutback.org/forums...3-what-temperature-do-your-rad-fans-turn.html ). What was being experienced is the ECM choosing which "fan mode" (post #8) to use under particular conditions. Obviously, Subaru built in a higher trigger point mode that begins around 212 F. What remains a question is what criteria it uses to select the higher temperature table.
I can't say this is the case, but wouldn't be surprised if your 2015 has a similar set of "fan mode" tables in the ECM ROM, and at the time you did the test, the ECM was using a higher table.
Edit: On further thought, the 220 F start up does seem high.
How did you determine that the fans were on at low speed, rather than high speed?
If the FSM is correct (and, perhaps, there's only one fan "mode"), it's possible that the ECM did call for the fans to come on at around 210 F, but there's a problem in the fan circuit so the fans didn't spin. Then, when the temperature reached 220 F, the ECM called for high speed operation, and that worked.
The fan low/high speed control is effected by using three relays to connect the two fans in series for low speed, and in parallel for high speed. A bad connection through a relay in the low speed mode could prevent both fans from running. But when the relays are switched for high speed, each fan motor is powered separately, and might have worked as expected.
Plain OM-Thank you for the information from your earlier thread. Re: low speed fan- that was my assumption. They were very quiet.
I was going to replace the sensor with a new one and check again. Very cheap. Now think I should check those relays. I will have to do some research as I am a novice at electrical diagnosis.
I haven't specifically checked ECT vs fan operation. However I do routinely monitor temperature. Never have I seen any coolant temperature over 205°. That's city driving, short periods of idling .... 6% 5 mile plus long grade @65 mph in 90°F + ambient temp. Typical temp. is 198° - 202°. I've owned the car since Oct 2015 so it included an Arizona desert summer operation. CVT fluid temp is another thing however generally hasn't exceed 200 for any prolong period.
Have you monitored coolant temperature during your general driving? Have you observed temp. in the 210+ range?
Ok I checked out the 3 relays. They were fine. Found the FSM and read thru the rad fan info. I don't believe changing the temp sensor is going to change anything. The temps I'm reading thru OBD are from the ECU. It must be seeing the higher temps and not acting on it until 220F. My scanner hasn't shown a temp higher than 92C during any driving conditions other than very long idles. AC definitely keeps engine temps down and it is almost a daily requirement now in Georgia. I think I'm going to roll with it but run the scanner periodically.
If anyone does any logging of their ECT on the FB25, I would definitely like to hear from you. Thanks everyone. Love the Outback ( I recently did the buyback on VW Sportwagen TDI.)
Those numbers may seem high, but modern engines are designed to run that high (compared to engines from 40 years ago) for emissions and efficiency reasons. Aluminum engines (block and heads) cool so efficiently they need the hotter thermostats to maintain combustion efficiency.
I recall my old cars typically had a t-stat in the 192-195 range for stock and I might put in a 180 or 160 'stat to make it run cooler so I could squeeze more ignition advance out of it.
And as we all know, the cooling system is pressurized so the boiling point will typically be in the 250F range. 220 sounds about normal to me.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Subaru Outback Forums
1.9M posts
188.3K members
Since 2003
Welcome to the Subaru Outback Owners Forum, we have tons of information about your Subaru Outback, from a Subaru Outback Wiki to customer reviews.