98 Forester Thermostat

Tiny
JPREWITT
  • MEMBER
  • 1998 SUBARU
Subaru, Forester, 98, 182K, 2.5L
I just bought the car with alot of miles on it because I am a poor college student. After driving it for a week I noticed that when it idles (when being driven the temp is fine) the temp goes up to the red, sits there for a few minutes then goes down. I was told by a mechanic to replace the thermostat, but I dont have the money to have him do it, so I want to try it myself. First of all, does it sound like a thermostat problem? If so, could I get some very detailed instructions on how to make this repair in that it doesn't sound like the thermostat is very accessible on this vehicle. Thanks.
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Wednesday, March 21st, 2007 AT 12:12 AM

12 Replies

Tiny
POCONOSDEWEY
  • MEMBER
Give me a couple days, I'm going to put one in my 98 Forester. When I figure out how to do it I'll let you know.
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Wednesday, March 21st, 2007 AT 12:14 PM
Tiny
JPREWITT
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Did you have any luck with the thermostat? Any advice for changing it? Thanks
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Tuesday, April 3rd, 2007 AT 9:26 PM
Tiny
POCONOSDEWEY
  • MEMBER
Hi,
I'm so sorry I completely forgot about posting this for you.

Here's how to do it. You will need a large pan to collect the antifreeze that will come out. Go to Wal-mart or some such place and buy some kind of tupperware. On the lower left side (passenger) side of the radiator you'll see a petcock that you can open to drain the radiator. Open the radiator cap first, but not while it's hot. After you have it drained you have to climb under the car. On the lower right (drivers) side of the car you'll see where the radiator hose comes out and goes into the bottom of the engine block. Where the hose goes into the block you'll see a flange with two bolts. Remove these two bolts and pull the hose assembly away from the engine. You'll get a green shower here. Be CAREFUL with that flange it's plastic. After you have the hose off you can see the thermostat inside the block. Grab it with pliers and pull it out, Second green shower now. This is a messy job so if you have to do it "on the street" you'll want to make sure you have a big enough pan and maybe some cardboard under the car. If you get one of those tupperware containers that the stores sell for christmas wrapping paper that may be perfect. If you have any questions post here and I'll answer.
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Wednesday, April 4th, 2007 AT 6:22 AM
Tiny
JPREWITT
  • MEMBER
Thanks for the post it should help me a lot and I appreciate it. Just out of curiosity, what problem were you having that made you replace the thermostat, and did replacing it fix the issue?
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Wednesday, April 4th, 2007 AT 10:38 AM
Tiny
POCONOSDEWEY
  • MEMBER
I was having an overheating problem. I'm still in the lets see if it worked point of the problem.
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Wednesday, April 4th, 2007 AT 9:04 PM
Tiny
SCUBARU
  • MEMBER
Hey guys I really hope you have looked into the proper procedure for purging the air out of the cooling system. You can easily create an air pocket that will cause the vehicle to overheat. It is important on any vehicle to know the entire repair procedure and not just one aspect of it prior to trying it yourself. Also on a Subaru I really must stress the importance of using an OE t-stat. Most aftermarket T-Stats do not have the flow through valve which can cause a no coolant flow condition until the thermostat it self starts to open. Which is not what Subaru had intended.I have seen a lot of problems caused by aftermarket t-stats so please make sure it has the flow through valve prior to installing it.

Justin
All Wheel Drive Auto
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Friday, April 6th, 2007 AT 9:40 AM
Tiny
JPREWITT
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What would you suggest is the best way to refill the radiator after replacing the thermostat?
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Friday, April 6th, 2007 AT 4:57 PM
Tiny
SCUBARU
  • MEMBER
1998 was a split production for the Forester meaning it can have either the 2.5l SOHC or the 2.5l DOHC. The DOHC should have a radiator air bleed screw. Next invest in a coolant fill funnel, you should be able to find one online. The funnel installs on the radiator neck in place of the radiator cap. Here is the proper procedure.

1. Remove air bleed screw
2. Install fill funnel
3. Fill vehicle with a 50/50 mix anti-freeze and water
4. Fill until coolant starts to come out of bleed screw
5. Place supplied stopper in funnel
6. Install bleed screw
7. Fill funnell up 1/2 way and remove stopper
8. Run vehicle until the thermostat has opened
and the cooling fans have cycled on and OFF twice.
9. Monitor fluid level in funnel at all times watch for air bubbles when there are no more tiny bubbles coming to the surface the air is out of the system
10. Place stopper in funnel and remove funnel
11. Install radiator cap
12. Set the coolant level in the overflow bottle to below the max line
13. Test drive vehicle verify heat out of heater vents
and tempature gauge readings are normal
14. Shut off engine and note level of overflow bottle

Justin
All Wheel Drive auto
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Friday, April 6th, 2007 AT 6:24 PM
Tiny
JPREWITT
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Where is the air bleed screm located?
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Friday, April 6th, 2007 AT 6:32 PM
Tiny
JPREWITT
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Where is the air bleed screw located?
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Friday, April 6th, 2007 AT 6:33 PM
Tiny
JPREWITT
  • MEMBER
I flushed the system last night and changed the thermostat. When I was refilling the coolant in the radiator with the bleed screw out, then when coolant started coming out the bleed screw, I put it in. Then let the car idle with the top off the radiator. After a while (20 min) air was still burping little bubbles. I went ahead and put the cap on just thinking it would cycle them out. After a few minutes on the road the temp spiked. I had to park and turn off the car to let it go down. How can I get those stubborn air pockets out the system? Thanks so much.
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Saturday, April 7th, 2007 AT 9:36 AM
Tiny
SCUBARU
  • MEMBER
You really needed a coolant fill funnel. Otherwise its a tough task. We wouldnt try it at our shop without one. As Subaru cooling systems are very fragile

Justin
All Wheel Drive Auto
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Monday, April 9th, 2007 AT 6:31 PM

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