Possible cooling system issue

[07outback12]

Hello everyone. I have an 07 outback. It has about 124,000 miles on it , bought it last year. I replaced the radiator recently  now I'm experiencing a  fluctuating temp gauge , the radiator pushes the coolant into the reservoir tank and then the heater blows cool air. The thermostat is new from Subaru. I can't figure it out , I am assuming there is air in the system but I have no clue how to solve this issue ..please an help is appreciated .

[el_freddo]

Welcome to the forum! 

Why did you replace the radiator? 

If you’ve been for a drive at highway speeds this will sufficiently bleed the cooing system if you’ve got enough coolant in the system already. 

When you top up the radiator, run the engine up to temp with the cap off, then watch for bubbles in the radiator. If these show up there’s a high possibility that you’ve got a blown head gasket. 

Cheers 

Bennie

[montana tom]

As Bennie asked why was the rad replaced ? 

Fill the engine from the upper hose , then attach and finish  by topping the radiator.

Strong chance you may need head gaskets.

Edited May 20, 2019 by montana tom

[07outback12]

Hey thanks guys, the radiator was replaced because I started seeing bubbles in my over flow tank sonic figured because it was the original rad , that they might be blockage. I was afraid that it might be a head gasket issue. How difficult is it to replace without taking the engine out of the car? 

[GeneralDisorder]

Rent an engine hoist and pull the engine. Bubbles in the overflow and the temp gauge fluctuations tell me you have a head gasket failure. It is not common for them to fail like that - usually they just leak oil externally. But it's possible. Just replace them with 642's or 770's.

GD

[FerGloyale]

4 hours ago, 07outback12 said:

Hey thanks guys, the radiator was replaced because I started seeing bubbles in my over flow tank sonic figured because it was the original rad , that they might be blockage. I was afraid that it might be a head gasket issue. How difficult is it to replace without taking the engine out of the car? 

 

Everybody always hopes "maybe it's the radiator."  It almost never is.  

Can't tell you how many cars I've been brought for HG's that the owner say's, "yeah we just replaced the radiator x months ago."

Don't try to do them in the car.  Just as hard if not harder than pulling engine.   It's possible, but way more likely to screw something up.  If you aren't a pro-level mechanic, I can guarantee you that you'll end up doing one of three things in car

1) Scratch the hell outta block trying to finangle the heads in along the rail with the bolts already sticking through.

2) Drop, fold or damage the new HG's as you are making that same move.

3) Assuming 2 and 3 are avoided, you're likely to screw up the torque. It's impossible to make full 90 degree rotations with the handle of breaker/ratchet used to set the head bolts.  It's not simply a torque procedure, there are specific rotations and to do it right in this case you need a torque wrench with a angle calculator.

Doing them out of car, on an engine stand, gives you the best platform for doing a successful, long lasting job, the first try.

Subaru engines are light and easy to handle in and out of the car.