Phoenixilva Posted March 10, 2019 Share Posted March 10, 2019 (edited) Hey all, I have a 1998 Subaru Outback Limited with a 1996 EJ22 and 5MT (based on the serial from the 5MT, I'm assuming the engine came with the trans). I noticed an issue with the coolant level in the overflow and rest of the system after I did the timing belt last summer, but this issue may have existed before hand. I used an Aisin kit, with Aisin waterpump and Six Star thermostat, the t-stat looked identical to the one from Subaru, had the jiggle pin, and similar dimensions. When I have the climate control switch pushed over to heat, I notice that there will be a lot of coolant in the overflow after driving and that more often than not it will not return back into the radiator. After the car warms up or right after I've driven it, I've notice air bubbles in the overflow, usually a few small ones every so often. I replace the radiator cap with a new one from Subaru, and the problem has not really changed, although the level stayed closer to where it should be for a week or so after I replaced the cap, before continuing to do the same thing as before. Recently I've switched the climate control back over to cold and I've noticed the past few days that the coolant level in the overflow is where it should be after its cooled down. I have not noticed any leaking from the heater core, nor any of the heater hoses on the top of the engine in the engine bay. I have not noticed any leaking coolant externally at all. Coolant doesn't smell of exhaust either, and the car consiently gets 22-25mpg mixed in mountainous, high elevation Denver, CO. Closer to 22 in the winter, and 25 in the summer. Never once has it even considered overheating, even at high RPMs up hills, or at idle. Always sits consistently in the middle of the gauge once warmed up. Sometimes might actually cool off if idling for a bit if it's cooler out. Anyone have any ideas as to what to check? Upper and lower rad hoses are new, though I did not replace the bypass hose off the water pump when I did timing, but it looked serviceable and have not noticed leaks. Thanks in advance! Edited March 10, 2019 by Phoenixilva Quote Link to comment Share on other sites More sharing options...
lmdew Posted March 10, 2019 Share Posted March 10, 2019 You may have a small leak in the heater core that allows air to be pulled back into the system instead of the coolant. Larry 2 Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted March 10, 2019 Share Posted March 10, 2019 Check the seat on the radiator filler neck. If that's not it, then I would suspect the coolant cross over o-rings. Pressure test it well above operating pressure. Like 20 psi or even 25. You'll find the leak.... GD 1 Quote Link to comment Share on other sites More sharing options...
Phoenixilva Posted March 10, 2019 Author Share Posted March 10, 2019 Ok, I will pressure test the system and see what that shows. Thanks for the insight guys. Quote Link to comment Share on other sites More sharing options...
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