Jump to content
Ultimate Subaru Message Board

Recommended Posts

Here's the skinny. The engine in my son's 98 Legacy continues to overheat after we did a short block rebuild. I have done all that I can think of to do as to figuring out what is causing it.

The car warms up at idle-2000rpm just fine and cycles the fan and thermostat normally. But when I take the car out on the road, after several minutes, the gauge starts to climb and the upper hose gets swollen and really hot, while the lower hose stays very cool with no pressure on it. After turning off the car, you can hear coolant boiling in the engine and radiator, and it forces coolant out of the neck. into the overflow. Once it all cools down, it works like normal again until I drive it. Oh, and it starts running like crap once the temps go up. I've done several tests including looking for signs of a blown head gasket.

So. now I'm looking for some help, before I roll it out in the field and set fire to it. No, seriously, I'm thinking of burning it to the ground, and cutting my losses.

Here is what I have done:

Flushed the radiator and had good flow.

Replaced the new thermostat , with another and tested it before it went in.

Jacked the car up, and burped the air out of the system, which it did have a good burp after it was up to temp and I revved it a few time up to 3-4k rpm

Compression test. (Result: 190-200PSI)

Leak down test. (Result: Pass)

Coolant system pressure test with warm engine: (Results: System held pressure and had no sign of coolant in the cylinders)

 

The only thing I haven't done is replace the water pump, which was replaced just before he bought the car. I haven't changed it, because I'm thinking with the pressure in the upper part of the system, tells me the pump is working.

Here's a couple pics/video I managed to take

43967410920_5d56cec0af_b.jpg

45059976114_b8c321cc91_b.jpg

44871661195_dcf6152cf0_b.jpg

  Edit: The gold/brown stuff on the plugs, is anti seize, not oil

 

Edited by 98GT

Share this post


Link to post
Share on other sites

Murray, I believe.

My boy bought a water pump today, but I'm still not convinced its the pump. I did spin it by hand when the belt was off, and It felt firm. Easy to turn, but no free spin.  Are these made like a boat water pump out of rubber, or are they metal fins like the older domestic pumps?

Share this post


Link to post
Share on other sites

You need a factory Subaru thermostat. They are made by Tama so if you find a supplier that sells those they will also work. ALL OTHERS WILL NOT WORK. That is almost certainly your problem. 

Your water pump is fine. The impeller is cast iron. 

GD

Edited by GeneralDisorder
  • Like 3

Share this post


Link to post
Share on other sites

I'll call the dealer tomorrow and order one, and cross my fingers that it fixes the problem.

I'm not a long time Subaru owner, but I just don't get why these cars are so OEM dependent. And why, if things like the thermostats are so sub-par, the aftermarket isn't forced to pick up their game to make better parts.

Edited by 98GT

Share this post


Link to post
Share on other sites

Mostly it comes down to Subaru being a very small company and the aftermarket parts market doesn't care. They don't sell a lot of Subaru parts because all us professionals know better than to buy them, and that just makes the already small market even smaller and harder for them to get into. Gates and Stant have both tried selling rebranded TAMA thermostats and I guess it wasn't profitable because I don't see them available anymore. 

GD

Share this post


Link to post
Share on other sites

If you have time and the weather is suitable for you, remove the thermostat and see if the car functions normal otherwise. And someone can drive it if it's necessary.

I have experienced the same thing with my ej22 in my 86. These cooling systems are very sensitive to air bubbles and i found that using a vaccum filler provides the best results, but I have also found that the filling on an incline is effective. Occasionally squeezing the lower and upper hose so you can hear the jiggle valve will help remove any remaining air bubbles. 

Who puts the thermostat on the bottom like that? I understand the ej is very sensitive about spark plugs as well, ngk only bla bla bla 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×