DailyLeggy

So, checked the car after letting it sit from my last post to today. Coolant has been sucked down from the overflow below the mark I made on Tuesday. No pressure on the hoses still. Any thoughts on which way I should lean? Head gasket, water pump or radiator?

After 5 min of the engine being shut down, little to no pressure on the hoses. Coolant level in the overflow not sucked back in and was able to take cap off radiator After 20 min, coolant level in overflow has not moved. So now, common sense tells me it's either blown head gasket or water pump is toast. Could be clogged radiator as well, right?

Today's tests include: 1. Running engine atvidle with radiator cap on. 2. Monitoring coolant level in overflow. 3. Combustion gas testing So, after work, I make sure coolant is just below the lip of the neck, place cap on radiator and mark the coolant level in the overflow with a Sharpie. Start the car and let idle with HVAC off. Lower hose heats up about 190* on scanner. Hoses have pressure on them. As the coolant flows through the engine, I monitor the overflow and see its rising ever so slightly. I watch the scanner as temps slowly...and I mean slowly...start to rise. At 209* on the scanner, relay fans kick on. They shut off at 201*-203* and when the scanner levels off, ECT is at 197*-198*. Coolant level in the overflow does not drop, which is opposite from when I was running the car with the bleeder funnel. Would rise and when fans kicked on, it would drop. I mention this a few posts above. Pic attached shows two dark Sharpie lines. Lower one is where level was when I started, upper one is where it's risen to and holds steady. However, after 15-20 minutes of the fans cycling on and off, the coolant level in the overflow stays put. As for combustion gas testing, in theory, if gasses were escaping/being pushed into the cooling system, when the radiator cap vents coolant to the overflow, those gasses should go there too, correct? I tested for about 5 min and the test fluid never changed color. So, here shortly, I'm gonna shut down the engine and check the overflow level periodically and see if the cooling system sucks down the coolant to the level it was at cold start. I'm also going to see how long the hoses retain pressure to see how long they do so. Will update tomorrow.

DrD - I pressure tested the system last night after work. Pressurized up to 15psi. It dropped 1psi over 20 minutes then held at 14psi for over 30 min. This was done with engine cold. I did not get a chance to try and do so after engine was up to temp. That may be tonight. Plan is to ensure coolant level are good and run the car with radiator cap at idle for a short while to monitor and very fan operation again (on at 210*; off at 196*) and also to see how long pressure can be felt on the hoses after shut down.

Would that mean then I am losing pressure somewhere? Common sense would dictate as much, correct? But, either the coolant is boiling over (causing pressure in the system) and dumping into the overflow, which in turn vents pressure (in theory), or the pressure is venting somewhere else and not properly circulating coolant. My thoughts are 1 of two things causing the lack of pressure to happen. 1. The brand new radiator cap is bad (unlikely, but not out of the equation) 2. I'm losing pressure somewhere else To be fair, though, I don't remember if there was pressure on the system after I purged the cooling system of air yesterday and ran at idle for a while with the cap on. I'll double check today after work and find out I'm also going to call my dad and ask if he can bring me thevpressure tester and test the cooling system. DrD123 stated possibly a bad water pump. I hope not as I really do not want to tear the front of this engine apart again. Replaced the timing belt, tensioner, idler pulleys and water pump 39k miles ago. Really don't want that hassle again. Any other thoughts?

Welp...back to square one it seems... TL/DR version: 1. While bleeding the cooling system, HVAC fan was OFF. 2. While bleeding the system, the coolant in the spill proof funnel was holding steady between the two lines in the above post. 3. Take the car for a drive with the HVAC turned off and we're back to where I started. Took my son with me to monitor the coolant temps. HVAC was off. The road I live on is a 35mph road and there is a gas station about 2.5 miles. Start driving and get up to speed and set the cruise while my son watches the temps. Starts off doing fine getting up to about 205 then starts coming down to about 190. Then, about 3/4 of a mile from the gas station, temps start to climb so I turn on the fans to 3 and turn on the AC compressor to get the fans running. Temps start to climb up past the 220 mark. I hit the hazard lights and pull off into an access driveway and as I come to a stop, the temp warning light comes on. Shut the car down leaving the IGN in the OP position and temp is showing 235. Open the hood and the coolant level in the overflow is about 1/4" below the top. Let it sit for a few min with IGN in the ON position so the fans can pull some heat off the coolant in the radiator. Wait about 5 minutes check the hoses. There doesn't seem to be any pressure on them. Carefully remove the radiator cap and get no hissing or no pressurized coolant coming out (hoses didn't feel pressurized). Take the cap off and there's no coolant visible at the neck. I pour coolant from the overflow back into the radiator using a makeshift funnel and it takes about 3/4 of the contents. Let the car sit for a few more minutes while we monitor the temp and when it hits about 185, I start it up and get turned around to head home. Get about halfway home and the temp starts to climb again above 210. Put the car into neutral to take the load off the engine and it drops slightly while I coast but then comes back up. Pull off the road again and check the coolant level in the overflow. Has come up a bit, but not too much. Sit again for a few minutes and once the temps get about 185, I make another attempt at getting home, this time successfully. Get the car into the garage, kill the engine and turn the IGN back on to monitor temps. Sitting at 230 but dropping as the AC is still on so the fans are running. Pop the hood and overflow is about 3/4 of the way full now. I again carefully take the cap off (again, no pressure on the hoses) and put the spill proof funnel on and place some coolant in it. Temps dropped down to about 185 before I came into my computer to type this post. Here's what's now confusing me... At idle, fans kicked on and off while I was again bleeding the cooling system. As soon as I take it for a driver, never getting over 40 mph or more than 2000 RPM, the cooling system is either getting to boing point being under pressure, the fans aren't kicking on at 210 like they did while sitting, or there isn't enough air flow through the radiator fins (with the AC condenser sitting in front of it). I'm done for the day. I'll get back to it tomorrow after work. I'm gonna jump on the Harley and go clear my head. Troubleshooting and thinking you got things sorted only to find out you didn't SUCKS....

Not sure if I put it in my opening post but I did buy a new cap with the t-stat and hoses from the Subaru dealership. Have been letting it run with the cap on and watching the overflow and not seeing any rise in level at the moment. Think I'm going to take it for a quick test drive while keeping the scanner plugged in so my son can monitor the coolant temp. Update to follow.

Ok, here's a 40-ish second video of the bubbles coming up. https://youtube.com/shorts/GnQ8NGyJVxw?feature=share

@silverton Thank you for the info. Your tip about leaving the HVAC fan off seems to have helped me out. So, here's a little update after about 45 minutes of letting the car run at idle with the HVAC fan in the OFF position. As I mentioned earlier, I filled the funnel to just below the vertical section. Started the car and monitored the coolant temp with my OBD II scanner. After about 15 minutes or so, the thermostat seemed to open as the lower hose got hot. Temp on the scanner showed 190*. Cool. At least I know now that the T-Stat is working which makes some sense since the coolant temp sensor is at the top of the engine and the warmer temps up there could differ a few degrees from the temp at the T-Stat. So, as the engine was idling I noticed that the level of coolant in the funnel did come up a bit and leveled off. I made a mark with my sharpie marker on the funnel. I continued to watch the temp on the scanner and positioned myself on the driver side so I could also see the fans. I noticed as the temperature began to rise, the level above the sharpie mark also rose but also leveled out so I made a second mark. (See attached picture.) After about 35-40 minutes, the temp on the scanner showed 210 and the fans kicked on!!! WOOOT!!! They turned off when the scanner showed about 201 but when the temp leveled out it was at 196, which if I read the bulletin that was posted in the link above correctly, that's what it's supposed to do. I also noticed that the coolant level in the funnel never went below the bottom mark or above the top mark. I let the fans cycle on and off about 4 or 5 times and the coolant level stayed right where it needed to be. I also have a video that I took after about 25 minutes being at idle and there are air bubbles that do come out here and there. But, common sense would tell me that if I had a bad head gasket that breached at the cooling passages from the combustion chamber, the bubbles would be coming up a lot more than what I saw. (Will post video of the bubbles I was seeing shortly.) I think I am making progress here and maybe all hope is not lost!!!

**UPDATE after 5 minutes from below. Lower hose got hot now and some air bubbles came up through the funnel. Temp was at 190 then dropped to about 180 for a moment. Currently sitting at 189.** So, filled up bleeder funnel to just below the vertical section before starting. Here's the level now after about 15 min stvidle with interior heat off. Scanner says coolant temp is at 183*. Lower hose still cold.

Regarding the rattler on the tstat, yes. It is at the 12 o'clock position. I made sure of that when I took the old one out but appreciate you bringing that one up as I did not mention that. Right now, after letting the car sit for a couple of days with the bleeder funnel on and covered (lots of bugs here in the midwest) and it is currently sitting about halfway between the neck and the vertical portion of the funnel. Should I fill it to the point where the vertical section is? As for bleeding the air with interior heat off, do you mean having the fan in the off position or having the temp range set to cool air vs. warm. Im guessing the former. As for the blend doors, is it something that's easy to fix or diagnose without tearing the interior apart? Just seems weird that if the AC is on, all vents blow hot butbifbibturn on AC, two blow cool. It's probably something that does make sense and I'm over thinking but, that's what I do. I'm gonna try again here shortly to see if I can get this sorted but if the fans don't come on after an hour of being at idle, could it be a bad Coolant Temp Sensor? Are those easy to swap without taking the intake manifold off?

Ok...so I had to go out of town last week for work and I got back to work yesterday when I got back. What's weird is at first idle, after the temp got up to around 185 - 190 (verified with OBD II scanner) the lower radiator hose never got hot, like the t-stat never opened. It wasn't until I started revving the engine to try and work any more air pockets out that I finally got some heat in the lower hose. Coolant temp during this process would get up to about 210. During this whole scenario, I kept the heat on with the fan either on the second setting or the third setting and kept the A/C off. The fans never once kicked on. Had engine temps at one point around 214. What is also strange is during the time I was revving the engine, keeping it between 2000 - 3000 RPM, the coolant level in the spill-proof funnel would start to rise. Even if I stopped revving, it would continue to rise up but more slowly. Only when I would shut off the engine would the coolant get sucked back in after gurgling a bit. Then, over the course of a few hours, more coolant would get sucked back in. Also, and this is weird, when I don't have the A/C button on, I get good hot heat out of all the HVAC vents, however, when I press the A/C button to turn the compressor on, still having the heat turned up, both passenger vents start to blow cool air while the driver side still blows hot. If I sustain RPMs around 1800 - 2000 the passenger vents blow slightly warm air but i cannot get it to blow out any hot air at all. I'm to the point where my skill level is maxed out on any further diagnosing of this issue but I really can't afford taking this to a dealer to find out what's wrong. I really wish someone here on the forums was near me that could come over and help me try and figure this stuff out...

Update: This morning, after letting the car sit overnight, I checked the coolant levels and everything was good. Just at the base of the radiator cap neck and at the full mark for the overflow. Started the car with heat still on and AC off and started a timer. After 30 minutes of just idling, the lower hose never got hot. The fans never kicked on. The fluid level in the overflow, previously at full, was starting to creep up. Good hot heat was coming out of all HVAC vents on the dash. I siphoned out some of the coolant in the reservoir to get it between full and low and let it run a few more minutes. After another 5 or so minutes, still no change in level in reservoir and still no fans. Also, just to see if the fans were still working, I pushed the AC button and the fans kicked on however, what is weird, is when I did that, the two passenger side vents started blowing cooler air (not cold) while the driver side vents still blew hot. Pushed the AC button to turn it off and the passenger side vents still blowing cooler air. I took it for a 10 minute drive around my neighborhood never exceeding 40mph and everything seemed fine. No lights, still had heat coming out the driver side vents but not the passenger side vents. As I was coming back up my driveway and parking, the temperature light came on red and I shut it down in front of my garage. Opened the hood and the overflow was completely full and it looks like some coolant had vented out the little hole at the top and from around the overflow cap. As a side note, yesterday before I drained the existing coolant to do my t-stat and hose change out, I did a combustion gas test on the radiator. The radiator was already low so I didn't have to siphon any out. I started testing about 10 - 15 minutes after the car was running and continued doing so for 20 minutes and the fluid never changed color. Then, the coolant started to rise (which I did not notice at first) and coolant got in the tester and contaminated the fluid. But, those 10 minutes I was testing, I never got any change in color. Oil doesn't show any signs of coolant in the system, either. It's a clean as it was 7 weeks ago when my son got the oil changed. I'm at a complete loss here. Either I have one hell of an air pocket in the cooling system that is wreaking havoc on my car and my patience or I have something else way larger going on.

Update for the below post - Let car run for close to 30 min and fans never cane on. No warning lights either. So, back out letting the car run with the funnel on. Been running about 25 minutes. Heat is on, no AC, and lower hose is hot. Coolant in the reservoir still getting some bubbles out but...the fans have yet to kick on and coolant level in the funnel is slowly rising. Thoughts?

Hey there, everyone. Long time gone but back again with another topic. Will try to keep it short and to the point but I'm at my wits end and am not wanting to have to spend too much money so trying some self diagnostics here. Replaced my t-stat/gasket and both radiator hoses today on my car however, I'm noticing something that is quite odd during the cooling system bleeding. (Had front of car jacked up in the air and using a spill proof funnel). I'm noticing that the radiator fans don't seem to be kicking on even after letting the car run for quite a while. When I turn the A/C on with the button, the fans instantly kick on. I let the car fun for a good 15-20 minutes while up in the air and was revving the engine between 1500-2500 off and on to get the water pump to try and force more air out of the system, which it seemed to do, but the fans never kicked on without the AC on. I also noticed at one point that when I was revving the car to help bleed the air, the coolant level in the spill-proof funnel was rising. It started getting close to the top of the funnel so I shut the car off and it started sucking back down into the radiator. To be fair on this, my son usually has this car with him at college but he doesn't really drive it that much. When he brought it back from school a couple weeks ago, it started having some issues with the cooling system. Not sure if the radiator fans not coming on without AC was a thing before today as I haven't been driving it while he's overseas (i have another car and a motorcycle.) This is why I replaced the t-stat/gasket and hoses as I've had the car for 5 years and wasn't sure what condition the t-stat was in. (Did timing belt in 2020 but can't remember if the kit came with a t-stat or not. It did have the water pump!) I've searched online and in multiple different forums and there are multiple scenarios from bad fan relays to bad coolant temperature sensor. And, since this particular generation doesn't have a temperature gauge, and I don't have anything to read the temp from the ECU, I'm kinda stuck. Any suggestions on what I can do here? Thanks in advance, all!