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1998 forester
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3 Posts
Discussion Starter #1
My 1998 forester is overheating lately with the over flow tank overflowing fluid. The top rad hose is hot while the lower hose is not, so I changed the thermostat but still same problem. I hear a whistling sound while driving, Do you think I should replace the water pump? Thanks for any advice.
 

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NA No more! :(
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8,529 Posts
have you tried replacing the radiator cap first? the whistling could be coolant steaming out like kettle. a bad cap will not hold pressure and the system will overflow to the bottle. but i wonder if there's a block in the system with the lower hose being cold...
 

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1998 forester
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Discussion Starter #3
A while back, I used a few bottles rad leak thinking it was losing coolant because of a leak. Will that block the flow?, because the temp difference between the upper and lower hose could be a block in the system. Maybe I should flush the system.
 

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NA No more! :(
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it's possible, definitely not the first i've heard of such happening. usually people flush the system after using something like Bars. have you checked for exterior leaks at the pump, hoses, and such? the worst possible scenario is a head gasket issue, but let's not assume the worst yet.
 

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03X MT
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847 Posts
That's exactly what my 03X did last year. The coolant in the expansion bottle was being blown out from overheating caused by a leak internally between the exhaust and coolant ports.

The lower rad hose was cold so I just assumed the t-stat was not opening (wrong) I also change the rad cap (wrong)

Adding the Subaru coolant conditioner solved the over heating problem.

To this day I cannot understand the design of the t-stat on the out flow of the radiator and furthermore it is under the rad in the cold part of the loop.

THis seems wrong to me.

If your coolant systems has not used the conditioner try if b4 you replace a bunch of expensive parts.

Not sure about other things like "Leak Stop" etc. Stay with the Subaru brand.
 

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2003 forester
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2 Posts
once again same prob all exactly the same syptoms i got my radiater looked at they pulled the top tank of and found that it was 80% blocked with what looks like corrision from the alluminium coils they are only small rad's and block very easy. i also tried t-stat rad-cap before hand with no luck diffently worth getting checked
 

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1998 forester
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Discussion Starter #7
So I flushed the rad, good flow when I removed the bottom drain screw, the I disconnected the bottom hose and top hose. I put a plug in the bottom hose and turn the water on into the top rad hose and water seems to be coming out out the thermostat housing, so I guess no blockage in the engine section. Fill with antifreeze taking care that all air is out of the system using the top air screw.
I let it idle for about 15mins, temp gage is about little below 1/2, took it for a 15min drive, temp gage same, but the overflow tank is full and overflowing. Top hose is hot and bottom hose is cold.
So problem not solved, what should I do next? Thermostat is brand new.
 

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03X MT
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It's not unusual for the bottom hose to be cold after a short or a longer drive. It will depend on how warm the outside temp is. Also if you start out with a full rad and a full expansion bottle then the coolant in the bottle can be driven out as the car warms up.

Keep the rad full but have the bottle empty and then let it idle for as long as it takes for the fans to come on. At this point the bottle should have an amount in it say around half. The bottom hose should be warm/hot showing that the t-stat has opened.

If the coolant is being blown out then this points to a leak internally in the engine where the exhaust is leaking into the coolant port and causing the coolant to become "superheated" blowing out of the bottle.

Also if you didn't add the the Subaru recommended "coolant conditioner" then this might help. It cured the overheating in my 03X.

Keep us posted
 
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