Mysterious Over Heating

[allwheeldriver]

I picked up a 93 legacy na wagon a while back with an "electrical issue"
Turned out it was just a cut wire leading to the fuse box... go figure. Anyway, I fixed the wire, checked fluids, new tranny filter gasket and fluid, and iridium spark plugs. The next day, I drove the 980 miles to idaho (from Washington) where I go to school. I am in a few auto shop classes, so I have the advantage of being able to work in a HUGE University shop. Driving to Idaho, I had no problems. after a few months, the car was great untill...
One day I noticed the temp gauge was higher than normal, then it slowly crept up to the H. So I pulled over, and relaxed for a few minutes to let it cool down. Drove it home, no problems (5 miles) I checked fluids, and fuses, etc. All good. A month goes by, and it never overheated. Until about a week ago, it did the same thing. SO I swapped the t-stat, flushed coolant, new hoses, and replaced the fan fuse as it was toasted. Three says of driving, and no issues until last night, I parked the car (temp was in the middle) and when I got out I noticed a pretty audible "click" that came from the thermostat. I popped the hood, and to my suprise coolant was gushing out the overflow. WTF. When I flushed the system, I pressure checked, and burped correctly. Also I even popped off the spark plugs, while doing a pressure check to see if any seepage could be seen. NOTHING. COmpression check showed 160psi in each cylinder.
So it brings me to this morning. I checked the fluid before going to class, and it was at the regular full mark. I go to class (1/2 mile) and find out its canceled, hop back in the car and make it a 1/4 mile before the temp creeps up to the highest mark. So I turned the heat on, its toasty hot (especially since its 85 degrees outside) and it doesnt make a difference. I get home, and pop the radiator cap thinking it had cooled off.....
there went all my coolant. So here I sit, wondering what the heck is going on?
Ive pressure checked the colling system, no problems. Compression checked the engine, great psi. Replaced the hoses, t-stat, and flushed the coolant. It has only overheated twice, but sometimes the temp gauge will go from half way, to three quarters for a minute, and then back down.
I have read at least 2 hours of all the posts in here, and other forums, and I hate to say it, but I think it is a head gasket..... without any symptoms besides over heating. No white exhaust, no leaks on the ground, no low compression, no bubbles in the overflow, no gunky looking coolant.
I really would hate to have to do a HG with finals in a few weeks, and I have to get home haha.
Any help would be appreciated

[hitzkrieg]

Is the thermostat you're using a genuine Subaru part? It's very common for aftermarket thermostats to cause overheating and the coolant overflow to fill up and overflow. There's a bleeder valve for filling the coolant on the passenger side of the radiator to eliminate air pockets. Also, do you know the history of the timing belt/water pump replacement? Might be worth looking into

[allwheeldriver]

The thermostat isnt the genuine subaru part, but it does have the jiggle screw. I just dont understand why it happens every once in a blue moon. I mean if it were happening constantly that would be more definitive. Ill check on the water pump/timing belt asap. The car runs flawless, gets great gas mileage, and has no power loss. I am in love with subarus because of this car, it has taken me EVERYWHERE I have asked it to go, with no problems. I mean EVERYWHERE. I also just picked up a 91 ss, with a few light mods, I am contemplating building it.

[hitzkrieg]

My old roomie had a 93 n/a legacy sedan, and had the timing belt and water pump replaced by an independent mechanic. The mechanic decided to use a parts store thermostat that had the 'jiggle screw' but a shallower thermostat element. After my roomie picked up the car, it drove fine for a couple of days then overheated when going up a hill, coolant flowing out of the overflow. After it did that, I felt the lower radiator hose and it was stone cold. Refilled and bled the cooling system, thinking it was an air pocket. It did it again, I replaced the thermostat with one from the Subaru dealer and it's been fine since. If you get it to overheat again, check to see if the lower radiator hose is hot or cold, that'll tell you for sure.

[H4_Deucer]

Imports and Subaru's in particular are touchy on using parts store stuff, thermostats being one of them. T-stats work off of wax melting at a predetermined temp and allowing the spring to open the t-stat, if a aftermarket place uses inferior products to build their stuff, that will give you the inconsistency in the overheating problems. If you do like stated above and feel the hose and it is still cold, the t-stat is bad, if not, an easy way to check headgaskets is start the car with the radiator cap off and if it blows coolant into the air, your headgaskets are shot.

[allwheeldriver]

I got the car to overheat again, tonight. This time, I had the radio off, and the temp gauge was rising slowly to the highest point. Suddenly I heard a very loud "click" and the temp gauge went back to normal in about 5 seconds. The car was fine the rest of the night. I popped the hood after getting home, and checked the fluids, added some antifreeze as I had taken the cap off earlier in the day and some shot out all over my new shirt.... grr
as I was pouring the antifreeze in (with the burp screw open) I heard the thermostat having only what I could describe as a seizure. It was clicking so fst for a few seconds. Then nothing, for a few seconds as I stopped pouring, and then the same clicking as I poured. eventually it stopped, and I filled the radiator up, and that is where im at.
It sound like the thermostat is working, but not when it is supposed to. I have only had it in for a few weeks, and this is the only time it has given me a problem. Where is the best place to get a Subaru t-stat? I dont have any dealerships locally.

[allwheeldriver]

For your viewing pleasure. My new (to me) 91 SS. 250k, tmic, wrx turbo back exhaust, wrx hood, kn filter, and short throw shifter.
I personally dont like the hood scoop, but Im stuck with it for the time being.....
What do you guys think this is worth? Runs flawless, but has pretty high miles, and isnt that "good looking" as the PO said.



He gave me a new turn signal, I just havent put it on yet. As well as a speedo cable, as it broke last week





And here is the 93 n/a I am having the issue with.

[mrmcq]

I might suggest a flush just to see what comes out of the coolant passages. I thought I had a blown headgasket but once I pulled the heads, the gaskets looked good, I found sand and shit in the block... WTF right??? that was probably the cause for overheating... also, i hear the thermo is a good thing to check as well...

[Legacy777]

As I think you have found out, you've got an issue with the t-stat. You can pick one up from a local dealer or you can order one from one of the online Subaru dealers: www.subarugenuineparts.com www.subaruparts.com www.1stsubaru.com

It should be around $20.

The other thing to note is that the Subaru thermostat is deeper and sits further inside of the water pump housing. Additionally, if you boil both a subaru & aftermarket t-stat you will see different rates of opening/closing with temperature changes. Subaru t-stats tend to be more stable with temperature swings. They also tend to not open as far either.

I went through the aftermarket t-stat issue/discovery back around 1995, and I've seen it many times since then.

[allwheeldriver]

Sweet! Thanks for the info, I really hope that it will fix the problem, I love the wagon, but it would just become a parts car until I had the time to do the HG.
Ive been reading tons of build threads on the SS, and I think I will start one when I get out of school in a few weeks. That way I have a garage and all my tools to work on it. Plus, Ill have some income Ive caught the Subaru bug haha and its not going to be cheap

[allwheeldriver]

picking up a 04 WRX wiring harness, ecu, heads, intake manifold, struts,springs, calipers, master cylinder, steering rack, and possibly a few others. The seats are in good shape, and I was thinking about the dash, but that seems like too big of a project at the moment. I want to start off slow. what all would I need to do the ABS conversion? also are the calipers a bolt on, or if fabrication needed?
I plan on finding a ej257/255 block and putting the 205 heads on it, then doing a full obdll conversion using the harness, and ecu. Then eventually trying the dash swap. Get rid of that ugly hood scoop, and throw a ss wing on it, do some body work and paint it. Im liking a charcoal, or metallic grey, with gunmetal wheels.
What do you guys think? I plan to have it done by January of 2012. Since I get home from school in a few weeks, Ill have about 6 months to do it. Thats why Im collecting parts now, and doing my research

[Legacy777]

Not sure I understand your question regarding the ABS conversion. The SS already has ABS and will function fine with any brakes you stick on there. The WRX calipers will bolt on.

There are quite a few wiring and sensor differences between the WRX & SS. The only way I would suggest doing a conversion is to do a complete wiring harness swap where possible. You will likely still have to merge some parts of the harness together, and will possibly need to add components to the SS to make things work. For example you would need the fuel pump setup from the WRX since it has a fuel temp sensor. ABS system will be different, and that's just to name a few.

I don't want to discourage you, but I also want to make sure you have all the information so you know what you're getting yourself into.

If I were to do this, I would probably excise the engine harness/wiring and any additional sensors necessary for the WRX ECU to function correctly and merge it into the SS harness. To do this and do it correctly will require knowledge of wiring and the ability to properly read and understand wiring diagrams and verifying that the wiring matches what's in the diagrams.

[allwheeldriver]

No, I understand what you are saying, I plan on taking my time with it, as I want to learn as much as I can. The only reason I am picking it up, is because for $500 the guy will sell me all the above and then some. So unless Im mistaken its a killer deal. I can generally find my way around a wiring diagram without too many problems. But that is what I love about this forum, someone has done it before

It might be a while before the obII conversion, but Im just collecting parts as I go so when it comes time, I can have a nice little stock pike

[allwheeldriver]

I switched out for a subaru thermostat which was $23, and the gasket was $3
Flushed the system again, and then made the 900 mile trip back home for the 4th.
NO PROBLEMS WHATSOEVER
I believe that the t-stat was to blame, and in comparison the Subaru t-stat had an element almost twice the size of the parts store.

[allwheeldriver]

The one I am holding is the "OEM Replacement" and the bottom is the Subaru Part

[Legacy777]

Yup, they are quite different.

Glad to hear you got the issue resolved.