OK, so I assume this is the problem. When driving my 1999 SUS the needle for the heat is in the mid range, then will jerk up and down and then proceed to rise to the hot level. When I got back to work after lunch, I happened to turn back around and saw my engine was smoking. I opened the hood and smelled burning coolant. So I am assuming that my thermostat needs replaced from what i have asked other people.

 

here is my question.

 

#1 Anyone got instructions on replacing a thermostat?

#2 Do I need to drain the system of coolant before I replace the thermostat?

You may need a new thermostat, but you may have other issues as well.

 

I'd start with the thermostat and go from there.

 

It's located on the underside of the engine, and you do need to drain the coolant in order to get at it.

Use only a Genuine Subaru Thermostat. These engines are odd in a few ways and the low mounted thermostat is one of them. There are numerous threads here on the job and most importantly the refill procedure. The engine will not forgive you if it's run dry, so you want to ensure the engine block itself contains coolant. One easy first step is after you're back together, take the top hose off the radiator and pour new coolant down the hose into the engine. That will fill both sides and really reduce the likelihood of a dry start. after the engine is full to the top of the hose more or less, connect it and then fill the radiator. It will still need a top off, but this technique works pretty well.

You may need a new thermostat, but you may have other issues as well.

 

I'd start with the thermostat and go from there.

 

It's located on the underside of the engine, and you do need to drain the coolant in order to get at it.

What Legacy777 is alluding to is that the "burnt coolant" is one of the symptoms of head gasket failure on these cars. Combustion products are pushed into the coolant. The coolant is pushed into the overflow bottle. If bad enough, the coolant overflow bottle overfills and splatters coolant in the engine bay.

 

Look for bubbles coming up thru the coolant in the overflow bottle. Look for an oily scum in there as well (by-product of the combustion gases passing thru the coolant).

 

Good luck.

 

Commuter

 

PS - The thermostat is not symmetrical on these engines. Stick to the OEM unit and make sure the notch is aligned in the housing properly.