—- 1999 Subaru Legacy Outback 2.5L H4 AWD Automatic —-
Hello everybody!
So I did a few posts about a year ago about this car sitting for 2 years in Montana after it overheated. Everyone was worried about the HG being bloated, I was skeptical even though everything pointed to a bloated HG.
After fixing the car I saw that where the upper radiator hose connected to the radiator itself was brittle and turned to dust when I touched it and was losing coolant.
I bought a new radiator and hose, OEM T-stat, T-stat gasket. we exchanged them and all went well!
While burping the system, there was a bit of an exhaust smell coming through the coolant reservoir and some bubbling.
The car has run fine with ice cold A/C with no problems during the hot summers here in Vegas for the past year and a half.
I was at a red light recently and noticed that the temp gauge started to climb pretty quickly at almost 3/4 of the way to the H mark on my temp gauge. I immediately pulled into a parking lot and turned off the car and opened the hood.
I checked my oil which read below the L mark on the dipstick (mind you I just turned the car off so it didn’t have time to cool when I checked), there were bubbles running through the coolant reservoir and some smoke that smelled like exhausted.
I let it cool, put a pint of oil in it and took it home and it didn’t get too hot on the way back.
I bought some coolant and swapped out the OEM T-stat and gasket from last year for a new one (from Autozone), when I drained the old coolant I noticed it looked like coolant someone had put dirty water in, it wasn’t ” mixed” rather it looked like distinct green coolant with dirt or debris thrown in there, almost like dirty sandy stuff and what looked like little pieces of blue rubber (most likely HG) and I’m crossing my fingers that the coolant system just it wasn’t flushed properly when the original HGs were swapped out for MLS and I’m hoping it’s just parts of the old parts and not the “newer” part – (last 3 years) MLS. So part of me is hoping it’s a clogged radiator, (I haven’t flushed the radiator properly, nor bought a new one since last year)
I filled the system with fresh coolant, and the system has burped constantly since 2 years ago after it comes to temp, I burped it for over an hour and still every 5-10 minutes it would burp some air and it never seemed to end. it ran fine for a few days until the problem reappeared. Red light, idled for about 5 minutes and the temperature started to climb to 3/4 of the H, the light turned green and as I hit the gas and almost in proportion to the amount of gas I gave it, the temperature quickly dropped back to normal . This behavior continued for a week or so as I continued to drive it (doing Doordash, constant stopping and turning the car on and off and lots of stop and go traffic)
The car would heat up intermittently again after about 2 hours of driving, sometimes I could idle for 20 minutes with no problem and sometimes it would overheat after a few minutes but the problem would continue more and more often the longer I drove it same period of time but whenever i started moving the temperature dropped immediately and was fine as long as i was moving above about 20 mph.
I then got a block tester from AutoZone to test for hydrocarbons, nothing showed up on that test. so i took it to kaiju motorsports (subaru experts in vegas) and they ran a compression test and a head burst test. Halfway through their diagnosis they discovered my radiator cap was not holding pressure, they put a new one in and continued testing and testing for hydrocarbons and compression. It passed all their tests at the time and showed no signs of exhaust leaks or loss of compression. They also noted that the car ran at normal temperatures.
They informed me that if it continued to overheat to try getting new fans and if that didn’t fix the problem, it was most likely a HG.
The car overheated about an hour later I just drove it for a test drive with the same problems.
So I got new fans and changed them…Same issue!! Intermittent overheating stopped after about 2 hours of driving.
Additional info: I have some electrical issues like the lights go dark when I hit the brakes, sometimes I won’t turn the key (absolutely nothing happens) and it would take a few seconds for the car to try to turn over, but no problems starting once it tried.
I was driving and flashed my headlights on someone whose headlights were off to be friendly, the car started overheating about 3/4 into H (while going about 40 mph) <---up to this point it wasn't never overheated while going over 20mph.
I pulled over and turned the car off, then went back to the accessory position with the heat blast to get rid of the heat. As I sat there I turned the lights off to save the battery, the second I turned the lights off the temp gauge went down by half, I turned it back on and off again and the temp gauge went down drastically in unison with me turning the lights back on sometimes.
The gauge immediately returned to a normal temp after turning my lights on and off.
(this is all in a span of about 2 minutes) I turned my car back on to verify the actual temperature and it read normal.
I kept driving and everything was fine.
So now I suspect my gauge is not even reading the correct temperature?
So the car is overheating sporadically and I’m hoping and praying it’s not HG, if I’m correct and it’s not HG.
There are 4 things left that I think could be before I can 100% confirm it’s HG: blocked radiator, bad temp sensor, bad power relay, or air in the system
