Long time 2.2 subbie owner - been in a 2.5 for about 9 months. The 2.5 I am driving is a 99 outback (DOHC). About 10-9,000 miles ago a subbie shop in town here changed the HG's, timing belt, t-stat, radiator, and all the associated parts with that maintenance. The HG's were bad at this change and the heads were checked at a local machine shop (all OK).
Last week (when the whole Nation was freezing cold) I was headed back from Portland (4.5 hour drive). At about 3.5 hours into the drive I noticed my temp gauge was slightly higher than where it normally resides (It was only a few tick marks about the middle). I found that if I accelerated (higher RPM's), it dropped to normal operating temp. In the morning I finished my drive and noticed the same symptoms (lower RPM's and the temp would creep up just a bit, higher RPM's and the temp would reside in it's normal spot). I finally had time to plug my scan gauge into it tonight and while fusing at highway speed (55 mph, 2,000~ RPM's) I would get a constant temp of 104-105 deg C, If I'd push a higher RPM it would drop to 100 deg C, or even get in around 97, 98, or 99 deg C. Cursing through town it would ride at 105 deg C (25 mph) and sitting parked in my driveway it would ride back down to 97 deg C. Both radiator fans are running just fine.
Any thoughts? HG's, again? T-stat? Was it the single digit temps that pushed it over? 105 deg C is too warm for me, hope it's not too warm for this car. It bounced up to 107 deg C briefly and returned to 105. Thanks in advance.
177K on this engine, HG's changed about 10K ago (heads checked too)