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Old 05-26-2003, 05:24 PM   #1
latinskllz
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Default MY00 RS Overheating only when at a stop light...

hey guys,

I have done a search but all have come up with differing overheating problems.

First here's the story:

I have a WRX Waterpump that I repleaced along with a timing belt about 2000 miles ago...no problems whatsoever until this weekend.

I took a trip to Miami from Orlando (about 250 miles one way) and when I got to my destination in Miami, the car was idling and immediately noticed the temp needle climbing rapidly. Therefore I shut the car off and left the key in the ON position so the fans would come on as well as turning the heater on to cool it down.

When I opened up the hood, I noticed that the coolant reservoir tank was overflowing, topped out etc....Therefore I poured the excess coolant from the tank into a container I had in the trunk. Then I let the car sit there for five minutes, turned it on and back to normal...Continued driving in Miami.

When heading back on the turnpike all is well...Arriving home in Orlando at a stop light, I noticed the car started overheating again, stopped for a couple of minutes and then started driving again.

The car is fine when being driven, the problem only happens when I am at a stop light.

I am thinking of starting off with a new radiator cap, thermostat, flush/fill the coolant system. Perhaps the coolant reservoir being overflowed caused a pressure in the system, causing air pockets...

Any inputs on this? I want to know if there are other things I should look into. Thermo is the original one.
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Old 05-26-2003, 07:08 PM   #2
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If the water pump is still good (can't imagine why one would die in 2k miles) you may need to flush the system - maybe the inside of the radiator is covered in crud - also, look around for any leaks in the system. Given the symptoms, it does sound like the typical bad waterpump issue (cools well when you are moving, and have good airflow over the radiator, but not when stopped) - also, check and make sure the cooling fans are working properly. Wouldn't be a bad idea to change out the thermostat while you are in there (which could also be the problem)
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Old 05-26-2003, 11:05 PM   #3
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Thermostat, rad cap, head gasket.. some factors.

Mine used to overheat on long treks when at a stop, and it was a crack in the block.

"Found the engine block leaking coolant internally, diagnosed and replaced the engine block, reassembled and tested ok"
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Old 05-26-2003, 11:38 PM   #4
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Don't forget to check the fans also.
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Old 05-27-2003, 12:13 AM   #5
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Default hmm...

Thanks for all the replies guys!

I don't think it's the block...I mean, could a stock motor crack? I rarely drive it hard, hell I even warm up the freaking car before taking off in the morning.

I would think that it had something to do with the coolant reservoir tank overflowing because that's when it started overheating.

There are no leaks coming visually from outside and the fluid is actually clean green...

What I will do tommorow is change the thermostat, radiator cap, flush/fill the coolant again and take it from there...

The thermostat and the cap are 65k miles old, so hopefully it will be simple as that....

Any other input here? I mean, would it pull a CE light code if the thermostat was stuck closed perhaps?

Thanks guys,
Kevin

Last edited by latinskllz; 05-27-2003 at 12:37 AM.
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Old 05-28-2003, 02:08 AM   #6
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Quote:
I would think that it had something to do with the coolant reservoir tank overflowing because that's when it started overheating
That's probably the symptom of it overheating.
Just curious -- did you use a Subaru OEM water pump or an aftermarket water pump when you replaced it? I've heard that the aftermarket pumps (at least for Japanese cars) are often of much lower quality than the OEM parts, and people have had them rub and sieze within hundreds of miles after installation.
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Old 05-28-2003, 08:58 AM   #7
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Hey guys,

Replaced the thermostat and all is good now...Hopefully no more overheating problems now...

The waterpump is OEM.....

Keep you guys updated if anything happens.....

Thanks again....

Kevin
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Old 05-28-2003, 04:31 PM   #8
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This is a 2.5, bubbling coolant is one of the first signs of a leaking head gasket.
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Old 06-02-2003, 09:38 AM   #9
latinskllz
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Default Update...

Quote:
Originally posted by latinskllz
Hey guys,

Replaced the thermostat and all is good now...Hopefully no more overheating problems now...

The waterpump is OEM.....

Keep you guys updated if anything happens.....

Thanks again....

Kevin
Hey guys,

Car is not overheating anymore, but something is pressurizing the system again. I am starting to notice the coolant reservoir bottle starting to fill up again.

Is it safe to dump out the excess coolant off the bottle to its normal level?

I cannot think of anything that can cause this. What I will tell you is that the only two things I can think of cause this is:

a) the waterpump (WRX one)
b) the CLT Sensor from the TEC-II (mounted on the hose coming out the block going into the heater about 3" from the pipe on the back of the block)

I don't know why either of these two may be contributing to the problem as they have been used and proven.

Any other suggestions why the system may be getting pressurized?

Or perhaps is just excess coolant the engine does not want since I flushed and filled and maybe I didn't drain all of the old one?

I don't know what else to think,
Kevin
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Old 06-02-2003, 01:20 PM   #10
Subie Gal
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get the car looked at by a professional subaru mechanic.

you have all the signs and symptoms of blown head gaskets....

my car did this.. and it was blown cylinder #4.....

have them do a hydracarbon test.
dont delay or you could cause more damage.

cheers
Jamie - www.subiegalracing.com
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Old 06-02-2003, 01:53 PM   #11
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Quote:
Originally posted by Subie Gal
get the car looked at by a professional subaru mechanic.

you have all the signs and symptoms of blown head gaskets....

my car did this.. and it was blown cylinder #4.....

have them do a hydracarbon test.
dont delay or you could cause more damage.

cheers
Jamie - www.subiegalracing.com
Correct me if I am wrong, but does the Hydrocarbon test shows wether a mixture of exhaust gases exist in the coolant pressurizing the system?

I will look into that...

Thank you,
Kevin
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Old 06-05-2003, 03:42 AM   #12
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Your car is done blow'ed up.

Yes the Hydrocarbon test measures for exhaust gases in the coolant. Usually its just a blue fluid placed in a tube over the filler neck that turns green (or yellow if its really bad)

A bad thermostat will make the car run hot or over heat ALL THE TIME.. wether stopped or driving on the freeways since the coolant just isnt flowing.

If it ONLY heats up when NOT moving it probably has something to do with a cooling fan failure since the coolant is flowing but it cant be cooled since there not alot of air flowing over the fins of the radiator.

A blown head gasket will also cause it to over heat..but usually when driving it.but not when stopped.

Removing the thermostat all together is bad. It lets the coolant flow too fast where it cant pull the heat out of the engine and cant disapate the heat in the radiator.

Now..being low on coolant will ALSO show a normal reading on the gauge and still over heat..no water touching the sensor and the sensor has nothing to read..only the surrounding metal around the sensor.

Check the fans..but it might be too late for this engine.
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Old 06-05-2003, 03:24 PM   #13
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I'm guessing head gasket too.
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Old 06-05-2003, 09:30 PM   #14
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Yo Kev, they're right, we've seen your symptoms way too many times.
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Old 06-05-2003, 09:34 PM   #15
latinskllz
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Default yeah afraid so...

what i do notice now is this:

1) daytime, the cooling system gets pressurized.

2) nighttime, the cooling system sucks up the coolant from the coolant reservoir.

I still haven't had the chance of having the hydrocarbon test done, but I will get done within the week.

I just hope it's not too serious....
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Old 06-05-2003, 09:45 PM   #16
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Default Re: yeah afraid so...

Quote:
Originally posted by latinskllz
what i do notice now is this:

1) daytime, the cooling system gets pressurized.

2) nighttime, the cooling system sucks up the coolant from the coolant reservoir.

I still haven't had the chance of having the hydrocarbon test done, but I will get done within the week.

I just hope it's not too serious....
Just make sure its not mixing water and oil. Check the dipstick.

Just thought about another thing..check the radiator cap when you get a hydrocarbon check.
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Old 06-05-2003, 09:48 PM   #17
latinskllz
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Default Re: Re: yeah afraid so...

Quote:
Originally posted by Kudagra


Just make sure its not mixing water and oil. Check the dipstick.

Just thought about another thing..check the radiator cap when you get a hydrocarbon check.
I did buy a new stant rad cap that i haven't used...should I replace it now?
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Old 06-05-2003, 10:38 PM   #18
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Boiling over then sucking back in is EXACTLY what happens when the head gasket leaks. Do yourself a favor, bad news is better than letting the problem get worse and worrying.

On my third blown headgasket (supra) I melted the area between two pistons, and that wasnt going to be cheap!

On the second I damaged the cylinder wall slightly because the water would be sucked into the combustion chamber on the intake stroke.
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Old 06-06-2003, 01:42 PM   #19
latinskllz
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Default here's something i never thought about

Maybe this is not relevant to my situation but worth considering:

When I changed the waterpump,timing belt, clutch etc., my car shocked me a couple of times when my hand rested on the intake manny.

Apparently, when cranking i could see the coilpack sparking on coil for cyl. 1...

So i prompted to take out the spark plug wire, and that damn wire was like burning hot on the boot that connects to the spark plug.

I immediately also noticed that coilpack 1 & 4 tips were corroded. so I put the magnecores I have for the tec-ii, and voila, no more sparks.

Prior to this, i noticed the car would constantly feel like it would misfire....so maybe cyl 1 may have played a role in this...

I am just trying to trace back to the nature of this problem....

Any input?

Kevin
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Old 06-06-2003, 03:45 PM   #20
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What's happening is when you're driving the car it's forcing exhaust gasses into the cooling system, displacing the coolant - causing it to overflow. When you're not driving it the gasses seep out and the coolant returns to it's previous level minus any that evaporated or spilled.

If you've got plenty of cash on hand, keep driving the car until the head gasket dies completely, then swap an STi engine and tranny in.
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Old 06-06-2003, 08:19 PM   #21
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Kevin

Just replaced my coilpack on my 98 GT because it was degrading and losing spark punch to the plugs. Corrosion/carboning is one of the first indicators that this is happening. You should also have a CEL if it misfires enough.

If it is misfiring a lot, you may or may not notice it on the Subaru because the engine management system is pretty sophisiticated. I noticed it on mine because the engine seemed to "burble" at low RPM (off idle) and higher RPMs under load (freeway speeds). Left like this for a while and the engine misfire causes the cylinder to overheat and that can lead to all kinds of problemos as mentioned previously.

Under these conditions, and particularly on the 2.5 DOHC (but some of the SOHCs experience this too), the head gasket 's gonna let go. FWIW, DOHC typically blow internally (across cylinders/water jackets) while the SOHCs typically exhibit external coolant "bleeding" at the head gasket joint itself.

Get a hydrocarbon sniff test done as soon as possible or, if that is not available, get a coolant system pressurized leak-down test. If there's a blown headgasket, and it sure sounds like it to me, then you'll want to get that repaired ASAP so you don't do any internal damage to you car. The last thing you want to have happen is for it to set over night and fill one of the cylinders with coolant. Water lock is not pleasant.

Technical thought: Believe your 2K 2.5 RS is SOHC. The WRX is a DOHC so it's possible that water pump "pulley" may be smaller than the SOHC to accomodate the different "angle" of the timing belt and therefore turns at a different speed. I've not had to replace one, so I have nothing to compare it to. Just a thought but might be worth exploring too.

Br, Dale
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Old 06-06-2003, 11:40 PM   #22
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the water pump is the same....so i don't think it's that i have visually compared both....i don't know if the internal assembly of the impeller is different but i see no difference...

Kevin
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Old 07-09-2003, 12:49 PM   #23
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Quote:
Originally posted by Subietonic
Kevin

Technical thought: Believe your 2K 2.5 RS is SOHC. The WRX is a DOHC so it's possible that water pump "pulley" may be smaller than the SOHC to accomodate the different "angle" of the timing belt and therefore turns at a different speed. I've not had to replace one, so I have nothing to compare it to. Just a thought but might be worth exploring too.

Br, Dale
OK so I had the dealership replace both headgaskets, no visual problems with the heads and such.

Three weeks later which is today, the car started overheating at idle again. I am starting to think that the WRX waterpump is bad.

I just don't understand about the pulley being a different size but I guess I will have to compare that.

The reason I put this waterpump was because I will be installing my turbo kit soon and need this to clear the WRX headers. I am beginning to think that this turbo kit was not meant to be.

Can anyone help me find any specs on both pumps? People have been using the legacy turbo waterpump with no problems and even though the legacy turbo IIRC had SOHC heads, i compared the pulleys visually with no differences in pulley sizes.

Hmm, now I am wondering...Crap...

Kevin
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Old 07-11-2003, 02:01 PM   #24
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bump any more suggestions?
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Old 07-11-2003, 02:48 PM   #25
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If no other ideas come up , I'd say put back on the oe 2.5L unit (actually, if I had to open that timing cover back up I would install a brand new oe pump).

Rest assured there are many 300+hp 2.5T's running around with the oe water pump with no problems.

If cooling is a concern look into an oil cooler, lower temp t-stat, sti radiator cap, or a larger core radiator.
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