Hi all. I have a very strange problem and I am wondering if anyone else has experienced it.

A few weeks ago I was driving on the HWY in VERY cold weather (-35 C). I had the cruise set at 120km/hr. Then I made a last minute call to stop for gas so I pulled off the HWY abruptly. When I disengaged the clutch the revs dropped down to idle from about 3500 rpm. OK all is normal this is where it gets strange. Almost, immediately, the heater blew cold air and the coolant bottle overflowed. The car still ran great and the coolant temp never moved. I figured that the sudden drop in flow through the heater core had caused the thermostat to pop open and the cold coolant from the rad had "gelled" ( kinda frozen ) the coolant. It happens sometimes on really cold days. Anyway I let the car sit for about 30 min fired it up and all was well, heat from the heater and everything.

I reasoned that my coolant must be getting old even though it tests good to -45 C. So I did a coolant system flush.

Sorry, this is such a long post ... but here is where my problem starts.

Now, sometimes when I drive on the HWY (-5 C) and let off the gas suddenly, the heater core blows cold air, and sometimes the temp gauge starts to raise up off the mid point almost to the hatch marks near H. If I pull over shut it off and let it cool down for a 5 minutes then start it up all is fine ... heat, temp and all. When the heater blows cold air the heater core hose leaving the heater core is actually cold.

This is the part I really get confused by. As far as I understand the subie cooling system the heater core is independent of the thermostat. The water pump should always be circulating coolant through the heater core no mater what the Tstat does. I know this to be true when the engine first starts up the heater core hoses are hot first, then the Tstat opens and the upper rad hose gets hot.

I dont understand what the hell is going on ... here are my best guesses.

1) water pump shot ... does not provide enough flow at low rpm

2) Tstat is shot ...

3) some how air gets in the system ...

4) head gasket blown ... ( head warped etc. ) god help me !

I would really appreciate some trouble shooting help.

\\'

 

Well ... it was the head gasket.

When I got home on Friday I checked the coolant again and there was a bit of oil in there. ( very bad )

So I pulled the plugs to see if one or both of the gaskets was gone. Turns out it was the driver side. The plugs where white from the coolant.

Then I did a comp check. 180 on the good side ... still 170 or so on the blow gasket ( with the rad cap off ). But the car was cold. I imagine it olny becomes an issue when the car warms up.

Turns out this is a common problem. But every thing seems fine until the block goes through a big temp swing ... hwy load to stop. Aluminum has a pretty big coeffiecient of expansion. So the gasket holds until the heads and block move a little.

I was going to to the work my self but I dont have the time and I need the car. So its in the shop.

Anyone have an idea of what reasonable shop time is (6 - 8 hrs) ?

Should I have the good gasket replaced as well ?

I am soooo choked I bought the sube because it was supposed to be bulletproof ....

 

YUP have to pull the motor. I decided to let the shop have a crack at it in hopes that they fixs some of the other **** that is still wrong with the car no charge.

I am regretting that decision so far. The car has 103,000 km ( 64,000 miles ) on it and already I have had to change.

1) starter
2) camshaft seals
3) crank seals F/R ( R twice, F 3 times)
4) PCV cover ( twice )
5) head gasket

so far the only thing I am going to get stuck paying for is the head gasket but at 2 large, I am pissed.

This will be my first and last sube !

 

sorry..., but i'd have to agree it's a headgasket. i just had to get a whole new shortblock after almost a year of denial. forget tests.. just get your engine torn down and get it over with. it's not worth the mental anguish of trying to find another fix.