help please

J

johnroake

Guest
im just home now from work, and on the way home i glanced at the temp and it was hovering around the H mark, i slowed down a bit to make sure i wasnt seeing things, and i wasnt, but then it dropped down to the norm, but every so often it was rise up to bout 3/4's or so, then drop back down again. the gauges i had put in reads norm the whole time after heating up to the proper temp. any ideas what could be wrong. is the rad or someting worse??
 
Hi,

I had exactly the same with mine Impreza 98 classic wagon. Now here are some options I found out:
- Too much water in the cooling system, check if you can see water drained over the overflow (supposed to be the little tank righthand side behind the head lamp)
It has a yellow cap (snap on cap) on it. Never refill the cooling system through it. I did it and had too much water in mine. Sounds strange, but after driving a while the temp goes up to almost max and then it starts pushing water through the overflow. Have you recently re-filled the cooling water?

- Head gasket, if the head gasket is gone, you might see similar issue. An other member had the same issue last year. out of nowhere his scooby started overheating. It turned out as the head gasket. Same sympthoms... Temp goes up and water was pushed throughout the overflow. In this case you might see white smeer on the inside of your oil cap. Usually a sign of a broken head gasket is water in the oil. If your oil looks grey / milky that's the headgasket defo.

Btw.: What Subaru do you drive? I guess a classic shape 2l turbo? Maybe 98-99?

Anyway, this sounds so familiar. If it is option 1 (overfill) just leave it as it is and do not put too much water in it. The marks on the white bottle righthand side are not too good to check the level. Was on mine totally useless. I just ignored the prob for a day because I couldn't stop every 10 km to refill and out of a sudden it leveled out it self and since then my temp is ok. No further issue. JUST MAKE SURE, YOU ARE NOT DRIVING HER WHEN TEMP IS TOO FAR UP. BETTER MAKE A BREAK AND LET HER COOL DOWN BEFORE GOING AHEAD. DON'T OPEN THE WATER TANK WHEN SHE IS BOILING. WAIT 5-10 MINUTES AND THEN GO AHEAD. NEXT DAY WHEN SHE IS COLD, CHECK WATER LEVEL AND TOP UP IF NECESSARY.

If you haven't refilled, check the level. If you need to refill, make sure you refill only through the main water tank (metal tank centre left - orange cap?) Be carfully if the engine is hot!!! You might open a little vulcano :whistle: Best to wait until the car is cooled down before opening the tank.
The metal tank should be almost full to the top. I guess 1 cm to the top is fine.
If you refill through the white bottle righthand side, you might enclose air into the system and thats bad as well.

Let me know how you're going on.

Akki :thumbsup:
 
thank you for such a solid answer, it is a 1996 jap wrx, ill check out those things, and ill let you know what happens
 
Oh and John....

I almost forgot... The radiator cap on the metal tank could also be a problem. This cap has a pressure valve included. If the spring is losing tension, it will open too early and the cooling system is losing pressure which also will cause overheating. Just to go safe, replace that cap if your problem continue.

The cap cost about 29.- jojos with Subaru as original part. You will get an STi high pressure cap from Ebay. The standard pressure is about 0.8 bar and the STi one should have about 1.3 bar. This means your engine can build up more pressure and so the boiling point is a bit higher.

If your radiator is pretty old, you might not want to try it because I am not sure how it will handle the higher pressure.

Anyway... I have my old radiator cap still here. It is the standard one which I have replaced after I bought the high pressure one.
I also got a new radiator because my old one just broke in Mondello :angry1: last year.

So if you wanna try the other cap, let me know.

Akki
 
just had a look under the bonnet, there is no gunk in the oil cap, i took off the rad cap and it was very low, so i topped that up, and when i put the cap back on i noticed there was a crack in the cap on the outer part, could this be the problem.
 
I would need to see where the crack is, but if the crack let pressure pass by, then this will be a problem.
Anyway you should get a new cap then.

Just wondering, how a metal cap can crack :dontknow:

Akki
 
the best i can explain it is, you have the radiator cap and in the middle of that is a button with push written on it, the part with push on it is the bit that is cracked. not the actual cap
 
If you have any issues with the cap, replace it. If it happens again, check (with the engine hot, but switched off) for any cold spots in the rad, usually around the middle. If there is any, replace the rad. If not the thermostat is the next suspect, as long as you have no leaks of coarse.

There is no such thing as too much coolant in the system. If you over-fill the plastic resivoir, the first time the system gets hot, any excess is expelled onto the ground, with no after effects.

John
 
Well Johnny... I made a different experience. Maybe there was something else with mine, but if I had too much coolant in the system, the temp needle went up to the red area and water was pushed out the overflow (onto the ground). When I reved the engine above 3000 rpms the temp went down a bit.

I also thought that this might be the thermostat, but I have replaced it and I still had the issue. I also had a new Rad, which was completely warm. At the inlet point at the top it was very warm and further down to the outlet the temperature dropped (as supposed to). Water was circulating and the heating was working fine as well. I also heard the theory that I might have air enclosed in the cooling system, but I have drained the system 3x and made sure to refill the tank properly. After the surplus water was drained, the temperature never went above half way up again.

Head gasket was fine, no oil in water or vise versa.

Maybe you have an explanation for that, but I don't. Even Subaru wasn't able to explain that and a mechanic said (I quote) :"Probably too much water in the system opening the overflow valve because of too much pressure. After pressure was released the pressure in the system wasn't high enough and water starts boiling." Sounds a bit stupid to me, but the facts seemed to be right. :dontknow:

Maybe anyone else had a similar experience?

Akki
 
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