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RX Overheating


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I just acquired an 87 5sp D/R RX Turbo and its overheating. It has about 180,000 miles.

 

The coolant is boiling out of the resevoir into the overflow tank....and some is spilling out also.

 

Is this a common issue? I am just not sure what is causing it. The car appears to be running fine otherwise......although I am quite sure it needs a good tuneup.

 

Radiator needs to be cored?

Bad Thermostat?

I dont want to replace the radiator to find out that does not solve the problem.

 

Thanks,

Gregg

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It overheats at highway speed after about 15 minutes.........I havent let it idle long enough to overheat but it stands to reason that it would overheat at idle too. The temp gauge needle doesnt reach redline but its fairly close.

 

My heater works fine........if the thermostat were stuck closed wouldnt that make my heater useless?

 

Also, doesnt the water pump leak if it is no longer working? My understanding of water pumps is that if too much pressure builds up they blow a seal (by design) of some type and leak profusely.

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I have the same problem on my 86 GL-10 turbosedan. Its the start of a cracked head or a bad headgasket. This is the sign that it needs heads and/or headgaskets. Normally the passenger side head is the ones that crack easiest. If you don't fix it soon, it'll start getting worse and worse to the point where it'll use ALL the water in about 20 miles, overheat and die. It happened to me already and now I need a new head.

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it is possible the start of a bad head gasket can blow COMBUSTION gases into the cooling system, causing the cap to puke out coolant, because the pressures from combustion will exceed the capacity of the radiator cap.

 

is your car puking? try running with the cap off, and see if it runs cooler

 

check the oil for milkshake lookin foam, check under oil fill tube, pcv lines on the valve covers

 

use a compression tester to see if it has consistent readings

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take tha radiator cap off, and start it.. give it a few revs.. if it blows water out like old faithful then you got a blown HG or cracked head..

 

compression check would be a good way to go as well.. low compression in 1 cylinder by a drastic amount would = blown HG..

 

could also take it in and have the coolant checked for exhaust gases..

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Come on you guys.. You're probably scaring this poor guy.

 

Yes, subarus do blow headgaskets.. Its never happened to me, so maybe I'm doing something wrong:D

 

The only symptoms you say you have had so far is the overheating and coolant boiling back into the recovery tank.. That can be as simple a thing as an air bubble in the coolant( you didn't mention whether it was diong it while the car was running, or after its shut off) .. Soob radiators do get old and crap out.. So do their water pumps. And no, just because a water pump quits does not mean its going to leak. Something as small as a bad radiator cap can cause cooling issues.

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ya, it could be a loose hose, just as easily as being a head gasket or a cracked head, but if you dont have to add water, then its not going out the tail pipe, unless very slowly.

it could be your thermostat, same thing happened to me in my wagon, and your heater will still work just fine, even better.

could also be an intake manifold gasket, happened to morganm.

lotsa possibilities.

 

my bet is a sticky, not broken thermostat.

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Thermostat outta cost ya about 6 bucks too.... not a bad part to have new anyways... My philosophy is start with the cheapest part you can replace and work your way up. Might not always work... but at least you have elimintated one option... and maybe you'll just happen to find something disonnected or leaky, or just plain MIA in the process.

 

Good luck

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I think the easyest parts swap is the Rad cap. if it does not hold pressure you will boil coolant into the overflow.

 

another stupid question what percet anifreeze to watter are you running? I had straight coolant do the same thing. water transfers heat better than straight anifreeze. 50/50 is best

 

to check when the T stat opens without needing to remove it. start car cold. put hand on upper rad hose. it should stay cold untill T stat opens. at time of opening you will feel a little pressure and some heat.

 

if all this fails check for the head gasket or other problem by doing a compression test and a cooling system pressure test.

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I swapped out the thermostat and also put in a vented radiator cap. The problem of overheating persists but the symptoms have changed.

 

1. I checked for bubbles in the radiator while the engine was running..........no bubbles.

 

2. The car will NOT overheat sitting at idle. I let it run for about 45 minutes and it was still at the normal operating temperature.

 

3. I run it around the block (about 1 mile driving fairly hard) and I get all types of steam coming from under the hood. I cant find the source but it appears to be coming from near the upper coolant hose feeding the turbocharger. So, I replaced the upper hose. The same problem continues.

 

4. I drove it home about 20 miles with the vented radiator cap open and I didnt lose enough coolant for it overheat but upon arrival I am getting a gurgling sound (and steam) coming from near the turbo.......but the upper turbo coolant hose is not leaking. I cant really see the lower turbo coolant hose.....but I dont really think it is coming from there. It may not be coming from the turbo at all but it is definitely in the vicinity.

 

The big question is now. Where is the coolant coming from? I only know of 9 possible locations to get a coolant leak of that magnitude.

 

1. Upper radiator hose

2. Lower radiator hose

3. Upper heater hose

4. lower heater hose

5. Upper Turbo Coolant hose

6. Lower Turbo Coolant hose

7. Radiator

8. Thermostat housing

9. Water Pump

 

Is there something I am missing? Help.......my car is hot and it wont stop overheating.

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take off the turbo heat shields, run it, use a mirror and flashlight to check out under the turbo when you can get it to leak. make sure the coolant's full first. I'll bet it's the lower return hose, and you can search for lower turbo coolant hose and find a few methods of repair there. good luck!

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The Good News - I found the source of the overheating. I was blowing coolant right out the intake manifold gasket......but only when it was running under a load.

 

The Bad News - Now I have to figure out how to get the intake manifold off.

 

Thanks to everyone for their help.

 

Gregg

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Also check the metal coolant line that runs from the t-stat housing to the rubber hose to the turbo. Mine had a very small crack in it and coolant hissed and bubbled out. I thought it was the coolant hose but it was actually the hose itself and the metal tube...stop leak fixed my situation...

I had the same problem with overheating when driven but not at idle and it was the radiator...it had crap all clogged up in there...

If you think about it, (considering the t-stat works), if your car stays cool sitting there, your pump is probably ok, and at 900rpm or so, your radiator doesnt need to be very efficient to work. but when you drive, the few rows that arent clogged in the radiator arent efficient enough to keep it cool under load...just a thought to consider...hope it helps...good luck

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Gregg,

 

I have some aftermarket intake manifold gaskets, still in the package. You can have them if you want. I will mail them to you.

Let me know if you want them. When you take it apart, make sure that the lower turbo coolant hose is the heat shielded OEM part. I replaced the one on my wife's turbowagon with a section of hose from NAPA, it promptly blew out, and I had to replace it a second time. The second time I used the genuine Subaru part, no problems since then. The previous owner of the car said that he replaced the hose, but I suspect that he probably did not use the genuine Subaru part. I'm glad to hear that you figured out the problem. Good luck.

 

toybuilder

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The sage continues. I installed the intake manifold gaskets....and that was a chore.

 

But now it wont run!!!

 

I turn the key, and it cranks for about 10 seconds before it starts. Then it runs perfectly for about 4 seconds......and then it dies out. Its as if the fuel pump isnt working right.

 

I did pull the gas line to see if it was being primed when I turn the key on (but not starting it). Gas shoots in a big stream.

 

Obviously it is something I did when I removed/installed the intake manifold.............any ideas????

 

 

PS. Toybuilder....thanks for the offer but I already got the gaskets. They were only $3.50.

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