Bubbling in overflow, many repairs to fix it

[novakdesolation]

Hello, I just got my 2000 Outback 2.5 with 185k miles and the previous owner had issues with the car's overflow bubbling, here's what she replaced and when last year to make it easier to diagnose.

August:
-Timing belt
-Water Pump
-Shift solenoid replaced
-New head gaskets
-Cylinder heads rebuilt
-New plugs and wires

October
-New radiator
-New Thermostat
-Replaced coolant
-Redid the head gaskets [were installed improperly]

at this point, she has sunk over 3k into this problem, and it is still slightly bubbling, and decided to move onto another vehicle. Now, does this seem like a problem with the head gasket again? luckily, the place of repair has a 12 month repair warranty if so, but are there any other ideas on what may be happening here? she's no overheating at all, she stays within normal operating temps and has about a bubble a second when at idle, meanwhile it disappears when above 2k rpm. sorry if this is lengthy but i wanted to be thorough in my approach to better get the problem resolved without wasting everyone's time lol. thanks for any assistance in advance!

[grossgary]

1. Was Subaru Coolant Conditioner added? It is required for that engine. At the beginning of headgasket signs it often clears them up. Two bottles can be used as well on existing leaks. Buy it and follow the directions on the bottle.

That step alone stops most Phase II EJ25 headgasket coolant leaks at onset....but that being said, the headgaskets should not leak immediately after installation so that's a red flag.

Sounds like headgaskets....though that is a nontypical headgasket symptom for that phase EJ25, but it's often the case that nontypical failure modes occur after a headgasket replacement so it's hard to guess what's going on.

Was the engine ever overheated?
What does it mean that headgaskets were "installed improperly"?
Were the heads resurfaced and what headgaskets were used?

Should use the Subaru EJ25 Turbo headgaskets on that engine....too late for that but if they were ever done again that's good to know.

It's possible the block has issues - but that's very rare and would usually only happen if it's been overheated in the past, run hot.

[novakdesolation]

Yes, one 4.4 oz bottle was used at time of radiator replacement, and she said it did overheat one time, but she pulled over and had it towed to the shop and they were unable to reproduce the overheat even with a/c on, but installed a new radiator and thermostat along with replacing the coolant. And my apologies they put replaced defective head gaskets

Also thank you for the quick response! Please let me know if I did not address anything

[cardoc]

The bubbles would be dependent on how long since the last repair involving the cooling system, whether it was properly burped and the condition of the radiator cap itself.

A couple things to ask the shop that did the work are, was a Subaru thermostat used and is the radiator cap a Subaru cap. And I don't mean a thermostat or cap that fits a Subaru. Aftermarket stats don't work we'll in any car, especially a Subaru and he caps don't seal right.

A few bubbles in the reservoir would be normal since the coolant coming from the radiator would be pushing air out of the reservoir tube. It's the massive amount of bubbling that would be a concern.

[novakdesolation]

Well besides the replacement of the radiator in October, it did have a pressure test done on the second of this month, and had the coolant replaced again.

The cap does look new, but I do not see that it was replaced at the time of radiator replacement, and pressure tests put each cylinder at 170 lbs, although that could have changed I know.

Also while its not massive, it is constant, and the overflow is full, but does not have anything pulling out [as far as I can tell at least, I'm going to mark the cold level when I leave to have emissions and registration done, and check tonight on what the level is] and I will call the shop when it opens in a bit to see what they used for parts

Also just want to check, I will try burping the system, but do these types of engines require different techniques, or the same as a regular engine?

[cardoc]

Pretty much the same burp.

Get a new Subaru cap while out.

[novakdesolation]

Also, I got it warmed up and it only does a little bubble every second or so unless I rev it then it stops after a few seconds, and there were some bigger bubbles if I reved while cold, but those stopped once it reached about 120. I will try burping later and get that cap while I'm out, thanks!

[novakdesolation]

Quick update, when getting off the highway it did get hot when I stopped to read the sign to see what lane to go to, I reved the engine to flow coolant through quicker and temp went down and is staying at 215 degrees f at idle.

Edit: stable at 190

[1 Lucky Texan]

the rad fans have also been confirmed to work right?

[novakdesolation]

Correct, it is sitting at idle at 222 f and rad fans are on right now. Temp has been stable for a few mins