OK, I may have a problem. I just pulled the engine in my 94 Legacy to drop on a rebuilt set of heads I got off of a vendor on Ebay. Heads looked good and supposedly had new seals in them. Now, my engine runs smooth. The original engine suffered a burnt valve at 120K miles. Problem, my engine emits a slight blue white smoke cloud at startup that goes away as it gets warm. I'm putting in what works out to be a quart of oil every 500 miles or less. I've checked for leaks under the engine and haven't found any. When I pulled the engine for the head job, I replaced all of the seals except the rear seal and baffle plate (I'd replaced those previously). I've also got soot in the tailpipe. That was the result of the previous problem with the burnt valve.

 

So... what am I looking at here. The engine runs great and idles smooth. Plenty of power but the exhaust smells kinda funny. Any ideas. Of course, my main question is, will this thing pass a smog test (due in two months).

 

Greg

Have you changed the PCV valve? Also, what oil are u using?

Have you changed the PCV valve? Also, what oil are u using?

 

No, I did not change the PCV valve. Straight 5W-30 oil. Car has plenty of power and gas mileage has gone up as well. If it weren't for the oil problem, it would be perfect. When I pulled the heads, the crosshatch on the cylinders was clearly visible.

 

Greg

No, I did not change the PCV valve. Straight 5W-30 oil. Car has plenty of power and gas mileage has gone up as well. If it weren't for the oil problem, it would be perfect. When I pulled the heads, the crosshatch on the cylinders was clearly visible.

 

Greg

 

OK, now i definitly suggest u change the PCV valve, good thing to try changing.

Why are you running 5w-30? I thought the manual called for 10w-30 or 10w-40? I think you've got oil laying in the cylinder heads....fried rings?

Why are you running 5w-30? I thought the manual called for 10w-30 or 10w-40? I think you've got oil laying in the cylinder heads....fried rings?

 

Really? I thought all subarus run 5w-30

I know you said that you replaced all the seals, but did you replace the valve stem seals too? That involves removing the valve springs to get at them. The smoke at startup suggests oil puddleing on the top of the valve, when you start, it gets sucked in/ burned off, and gives you the puff of blue, but still good comp. I have one bad valve seal, and I burn 1qt per 1k miles. It sucks because I replaced them all, I must have chipped it or something.

I know you said that you replaced all the seals, but did you replace the valve stem seals too? That involves removing the valve springs to get at them. The smoke at startup suggests oil puddleing on the top of the valve, when you start, it gets sucked in/ burned off, and gives you the puff of blue, but still good comp. I have one bad valve seal, and I burn 1qt per 1k miles. It sucks because I replaced them all, I must have chipped it or something.

 

i was gonna mention that..check your plugs for oil sludge build up.i found out that i have a bad valve stem seal also and found out by one plug being completely covered with oil sludge.(i have a pic but gotta find it)

my engine emits a slight blue white smoke cloud at startup that goes away as it gets warm.

 

Typically this is a valve seal issue. There are small "umbrella" seals on the top of each valve to keep oil from running down the valve stem. When one or more of these is damaged, oil can make it's way down the valve stem to the head of the valve. On startup, a small puddle of this oil is burned off resulting in that blue haze. During normal running, the clearances may be sufficient that this leakage does not occur, it may be a small enough flow that you cannot see the cloud, or the cat can take care of it.

 

You may or may not have a emissions issue.

 

While I do not know about the Subie, valve seals can be changed on some engines without removing much beyond the spark plug, valve cover and whatever part of the valve assembly is required to access the seal.

 

Jack

While I do not know about the Subie, valve seals can be changed on some engines without removing much beyond the spark plug, valve cover and whatever part of the valve assembly is required to access the seal.

 

Jack

it would be nice to know just what it takes to replace valve stem seals.

It's easiest to do with the heads off, but you could with the heads on. If you make an adapter so that you can put compressed air in throught the sparkplug hole, you can hold the valves up with the air, Take the valve cover off, take the rocker arm shaft off, and use either the proper tool or a pair of channel lock pliars to push the spring down far enough so that you can get the retainer tapers out. Then use a slip-joint pliar to pull the seal off of the valve guide. Use a deep socket to drive the new seal onto the guide, put the spring and retainers back on, a bit of grease on the retainers helps hold them in place, this part sucks, and reassemble everything. Plan an afternoon, and work on really clean pavement, I gaurantee that you will drop at least 1 of the retainers.

 

The valve seals on these engines are positive type. They press fit onto the guide, and have a garter spring that keeps them tight against the stem, just like the oil seal on the crank.

It's easiest to do with the heads off, but you could with the heads on. If you make an adapter so that you can put compressed air in throught the sparkplug hole, you can hold the valves up with the air, Take the valve cover off, take the rocker arm shaft off, and use either the proper tool or a pair of channel lock pliars to push the spring down far enough so that you can get the retainer tapers out. Then use a slip-joint pliar to pull the seal off of the valve guide. Use a deep socket to drive the new seal onto the guide, put the spring and retainers back on, a bit of grease on the retainers helps hold them in place, this part sucks, and reassemble everything. Plan an afternoon, and work on really clean pavement, I gaurantee that you will drop at least 1 of the retainers.

 

The valve seals on these engines are positive type. They press fit onto the guide, and have a garter spring that keeps them tight against the stem, just like the oil seal on the crank.

 

i'm gonna have to let my mechanic know about this way of replacing..he just said " we'll just put another engine in" after he said that my mind automaticly thought of a 2.5-Hmm?

but i think i'll stick w/2.2

Well, gents. An update. As has been pointed out, my PCV valve was old and I replaced it with an OEM item from the dealer. In about 100 miles of driving, the smoke dissapated and went away. I used to see a cloud come out during hard acceleration, but that has now gone away. The oil level seems to be holding steady now as well. Looks like you gents called it. I have a love/hate relationship with my Legacy. My wife wants me to get rid of it... but it's paid for and I seem to be able to keep the thing going! After the head replacement, it runs as smooth as peanut butter and I'm getting about 400 miles to a tank of gas. Left front wheel bearing needs replaced... but that's another story.

 

Thanks for the help guys!

 

Greg

awesome news, thanks for the update.