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2001 Forester
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26 Posts
Discussion Starter · #1 ·
So here's what I've replaced so far...

-water pump
-thermostat (failsafe)
-hoses
-radiator cap
-radiator
-head gaskets
-outlet manifold o-rings

I thought the problem was solved, let the car sit for a week while I attempted to install a new starter. Went to drive it yesterday and sure enough it overheated. This time was different than the others it didn't overheat as badly and it wasn't consistent. Something else I noticed is the heat completely went out as soon as it started overheating. Seems like driving it at high RPMs for about 10 seconds and then letting it sit at 2-3k rpm does the trick. Suspected it could be the heater core but didn't think it would impact the cooling system that much. If anyone has any suggestions or thoughts I'd greatly appreciate it.
 

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2007 2.5XT Limited 4EAT
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343 Posts
It sounds like you may have air trapped in the system. Which usually also means not enough coolant in the system as well. Pretty common when replacing all of those bits at once. You could try letting the car idle with the radiator cap(s) off and periodically squeeze the upper radiator hose after the T-stat opens. This can help expel air out of the system. Sometimes it takes a while. I would start here.

Not sure if it is even possible on these engines, but could the head gaskets have been put on opposite sides, upside down, or in some other manner that they are blocking the water passages? Long shot, but worth asking.

As far as the heater core goes, it is possible that a sever clog could contribute to the issue, but probably not the root cause. Usually when heater cores fail they either puke coolant onto the passenger side floor or spew a mist of coolant through the defroster onto the windshield. If you don't have those symptoms the core is probably ok.

Does the car overheat if you are not running the heater?
 

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2001 Forester
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26 Posts
Discussion Starter · #3 ·
All of the parts were installed one at a time, since I was trying to solve the problem with the least amount of money... which didn't happen. I've tried burping the system several times to ensure it was free of air. Also when I open the cap it's full every time.

As far as the gaskets go I made sure I put them on the right way and that no passages were blocked. They are FelPro MLS not the original from everything I've read I thought they were pretty good. .

Could my new radiator have gotten clogged like the old one? It's been about 12 months since I changed it out the old stuff was pretty gross so I put new coolant in as well.
 

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2007 2.5XT Limited 4EAT
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343 Posts
@SubaDrew87
Interesting...it seems like you should be good to go from what you said. I suppose your newish radiator could be clogged, or perhaps a clog somewhere else. Considering coolant is fairly cheap, why not try flushing the system? You could also bypass the heater core to see if that makes any difference. A few bucks in antifreeze and a few hours labor to at least rule those out, or maybe solve the problem.
 

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2012 Forester 4 speed auto
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1,152 Posts
Coolant

Make sure your coolant is Silicate Free. Silicates will precipitate out and can clog the radiator.
 

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2001 Forester 4EAT
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41 Posts
Hey, just wondering what you've figured out with the problems you posted.

I was doing the HGs, TB, and all the little stuff at around the same time you were posting about your HG project. I just wrapped up the project last week and took it on a serious test drive (500+ miles up to 11,000 ft elevation at highway speeds) and seems like I was successful... not a drop of leaked fluids and no overheating... so I was curious how and why it wasn't successful for you. I also used the Felpro MLS gaskets, had the heads machined and sanded the block by hand the best I could (with the block still in the car).

I made an effort to 'wash down' the engine with oil and coolant before I filled it up with fluids for the testing. What I did was: with both heads back on, and that cast aluminium connecting piece on the top of the engine (coolant passage) removed, I just poured water through the opening on each side. My hope was to wash out any debris from the work and I noticed that it ALL ended up coming out at the hose that connects to the oil cooler on the passenger side. I expected some water to come out the water pump opening but to my surprise there is a coolant passage internal to the block that takes coolant from the drivers side head to that small hose at the oil cooler. I'm wondering if maybe that passage is blocked for you, especially if you are noticing leaks in that area. I also dumped 2 old qts of oil in at the oil filler and simply let that drain out to wash out anything else before I did a final filling of fluids.

What I noticed about the coolant passages in my case was, they were all fairly spotless and clean like new. The radiator was new when I installed it back in 2014 and I never used a coolant additive to stop leaks. Due to that, I was confident the cooling system was not obstructed. However I did just bite the bullet and get a new rad anyway. It sounds like this may have been more of a problem in your case. I'm guessing there is still a blockage somewhere.

Also, it's not clear, was the radiator replaced before you did the HG job, or was that replaced at the same time?
 
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