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01 Forrester 5spd
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Discussion Starter #1
Need some troubleshooting help on my '01 forester S (Man. Trans, 154k miles).

Noticed I was overheating the other day on the way home. Driving in town on a 60 deg. F day. stopped & let it cool and limped home with the heater cranked, made it home without putting the gauge in the red. As soon as I got home I popped the hood:

-Radiator fans Not running
-Checked oil, proper level & no coolant or coolant smell - oil didn't smell 'hot' or burned
-Coolant overflow tank was bubbling right when I got home with the engine off and almost in the red on the temp gauge
-Coolant in the OF tank looks & smells clean (i.e. no oil or oil smell)
-No visible coolant leaks
-after it cooled I checked coolant level in the Rad and it was full - no air

My first thought was the HG since its a common issue (I just did a HG job on my '04 OB a year ago) but I wanted to start simple and work up. visual inspection of the HG shows it is seeping oil from the rear but I have know that for awhile and I just keep an eye on the oil level. no visible coolant leaks on the exterior of the HG.

- I replaced the coolant sensor (on the crossover on Pass. side of inlet) and the thermostat

After the sensor & the Tstat I flushed both block & Rad and refilled with coolant, (warmed up with the heater on, Burrped the upper Rad. hose, refilled through Rad as needed, according to your walkthrough above) Here’s what I observed:
Start the car and run at 2500ish RPM with heat on full
- Temp gauge rises to normal and stops for about 2-3 min.
- if I sustain a 2500-3000 RPM, after about 3 min gage will begin to climb past normal. It climbs continuously and looks like it would hit the red if I let it.
- If I let the RPM drop to idle when the temp first hits normal, it will only climb to about ¾ on the gauge and stabilize (with the Heat cranked, if I turn the heat off at this point temp begins to climb again)
- No bubbles in the Overflow tank (any RPM, even up in the 3’s)
- Rad. Fans do not come on unless I hit the A/C switch
- Lower Rad. Hose does not warm up (cool to the touch when the engine is at ¾ on the temp gauge or above
- Not Consuming coolant

This of course leads me to believe I have circulation problems. I put a new Radiator in it tonight, re-filled and burped and I’m getting the exact same behavior.

My only other good idea now is Water pump. I replaced the WP on this car about 20k miles ago when I did the Timing Belt. I am not hearing any noises or anything else to indicate the WP bearing is bad, could the pump fail without creating any timing belt issues? Is there any way to check the pump beyond what I have done without tearing the whole time cover off?

Sorry for the long post, I’ve been annoyed at not being able to figure this one out.

Thanks in advance for any help.
 

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Premium Member
2004 Forester 4EAT
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5,458 Posts
So to answer your last question first; no. There is no way to check the WP without removing it. Now if it were me.....
1) compression/leakdown test to make sure HG's are good.
2) remove t-stat completely, refill, and test.
3) pressure test cooling system
4) flow test the cooling system with the t-stat still out.
 

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1999 Forester Automatic
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82 Posts
I would be surprised if it was the water pump. The lower hose being cold after a drain and fill would seem to be air trapped in the system, or a a bad thermostat. Did you use a Subaru t-stat?

Another option would be to take the t-stat out completely and see how the temps do. But it really seems to that the fans are not coming on. Does the temp stay down with the a/c on? If so, I'd check/replace the fan relay, rock auto shows it has one.

2001 SUBARU FORESTER Radiator Fan Relay

I wouldn't think it would be a fuse since you said the fans work when you turn the a/c on, but I suppose it never hurts to check?
 

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2004 Forester 4EAT
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5,458 Posts
Ok, so I re-read your post. I would start by first removing the t-stat. It's quick and easy. I know it's new, but it is a known problem, especially if it's not OEM. The temp sensor you changed, did it have one wire or 2/3 wires going to it. The one-wire one talks to the ecu, which tells the car to turn on the fans, stop choking the car, etc. The 2/3 wire one goes directly to the gauge. (BTW, our cars have 2 temp sensors.)
 

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2019 Crosstrek 2018 XT
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13,414 Posts
I'm confused on how the oe Tstat would change anything?
There are differences in the two. OE and non-OE. There was a post some time ago that showed both..they are different and there was information that non-OE did not work or not as well.
 

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2012 Forester 4 speed auto
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999 Posts
Pressure test

Pressure test the cooling system. You can borrow a coolant system tester at Autozone. See if the system can handle 15PSI. If it cannot the coolant will boil at 225. Then look for bad hose clamps, bad hoses, cracked housings.
 

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01 Forrester 5spd
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Discussion Starter #10
the saga continues:

Took the Tstat completely out today and ran the car without it. Guess what? SAME BEHAVIOR!!!!

One exception, the lower radiator hose DID get hot this time (it better with no Tstat right?). Given that and the fact that the heater works well I think I can rule out the WP.

Is my dash gauge lying too me?

I noticed that with the dash gauge at three quarters and the Tstat removed the cooling fans on still did not kick on. (they do come on with the A/C, so its not the relays).

am I denying the obvious and it is the HG after all? even though it doesn't show the signs?
 

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01 Forrester 5spd
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Discussion Starter #11
To Summarize, at this point this is what I have:

-New Radiator
-New Tstat (or no Tstat!!)
-New coolant temp sensor (3pin ECU one)
-New Rad. Cap
-Flushed block with clean water (from upper rad hose out W/P)
-No signs of coolant sys. being pressurized by combustion gasses (no bubbles/exhaust smell in O/F tank at any RPM)
-No visible leaks or cracks in the coolant sys.
-No sign of coolant in oil, or oil in coolant
-Not obviously consuming coolant (I have been doing 3-5 min test runs and it is not consuming during those, I haven't driven it)

after all this, STILL getting the O/H. temp climbs to normal, and slowly but surely creeps past it. Whoever figures this one out I owe you a beer, a good one:Banane35:. Im completely stumped
 

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2002 S-turbo Manual 5sp
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72 Posts
Fans have to kick in...If they don't then that's the problem....Try to connect the green test connectors under the dash, turn the key to ON, but don't start the engine, fans should start switching on/off constantly....
 

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01 Forrester 5spd
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Discussion Starter #13
I'll check that with the fans, but when I turn the ac on and the fans do kick on the temp still doesn't drop
 

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I'll check that with the fans, but when I turn the ac on and the fans do kick on the temp still doesn't drop
I know this was a while ago but did you ever figure out what happened this is the same issue I’m having with my 01 forester m trans 139k miles
 

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2009 Legacy
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808 Posts
@Subiedobiedoo I'd start making sure you have enough coolant in the system. That may seem obvious but Subarus require 'burping':
Park the car nose up on a slight incline, like on ramps or a curb. Take the radiator cap off (car being cold) and add coolant (50/50 mix, subaru coolant). Squeeze the top radiator hose, watch the bubbles come out. Start the car, turn on the heat, squeeze the top hose some more, watch the temperature climb and add coolant as necessary. Do NOT let it overheat. If goes above normal, stop. Turn the car off. If so you are having a different issue; maybe thermostat, maybe something more costly. Let's hope burping helps.
This tool comes on really handy for burping.
 

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I di
@Remco So the thermostat is wide open (not there) and I did this last night it stayed normal for 45 min with ac on and reving it to 2500 3000 rpms and it was solid but when I decided it was good I took it on a 12 mi test drive it started to over heat the last mile it didn’t go red but when I made a turn right before my house a check engine light came on and it stayed hot right below red I think I’m gunna do a jdm swap to the 2.0 EJ20 with less miles with a 6 month warranty
 

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2009 Legacy
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808 Posts
@Subiedobiedoo You may want to burp it again. It can be a real challenge to get all the air out. I usually pull the top radiator hose, pour as much coolant in there as possible, quickly attach it and do another burp.
Is it losing coolant? What was the code it threw?
I like EJ20 engines. They are pretty much bulletproof but you may not need to yet.
 

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@Subiedobiedoo You may want to burp it again. It can be a real challenge to get all the air out. I usually pull the top radiator hose, pour as much coolant in there as possible, quickly attach it and do another burp.
Is it losing coolant? What was the code it threw?
I like EJ20 engines. They are pretty much bulletproof but you may not need to yet.
It is loosing coolant and I haven’t had time to check the code yet I have been away from home since that day visiting family. I just think it around the same price to replace the ej25 with a ej20 or to get the head gasket and heads done my engine has 139k the new one obviously will be somewhat lower
 

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2009 Legacy
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It is loosing coolant and I haven’t had time to check the code yet I have been away from home since that day visiting family. I just think it around the same price to replace the ej25 with a ej20 or to get the head gasket and heads done my engine has 139k the new one obviously will be somewhat lower
Yeah, time to do the HG. If you're losing coolant, no amount of burping will help you.
 

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2018 2.5i Premium CVT
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18,116 Posts
I sailed through the emissions test with a previous (non-Subaru) car whose head gasket was just beginning to fail, jacking the temp up a good bit. A serendipitous side effect it was. :)

Despite all the warnings, I never blew one on a Subaru. Timing belt? That's a different story. :mad:
 
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