Valve clearance

[Super]

'01 Legacy, 2.5 SOHC, 92,000 km. I about to replace the original plugs, I have to replace some gaskets in the rocker covers as the plug wire boots are oil soaked. I cannot find anything relating to valve clearance specs. Nothing in the owners manual. The hood has been replaced after a collision with a deer and I'm assuming there may have been a specs sticker on the original hood, or not..I would like to check the clearances when the covers are off. I'm hoping I'll find traditional screws/locknuts on the rocker arms of course.....Thanks.

[offroadsubaruguy]

i believe that the 2.5 has hydraulic lifters.... im not sure if you can adjust them... i could be wrong though..

[ferret]

2.5L SOHC Valve Clearance 'Cold' are:

 

Intake 0.20+-0.02 mm Exhaust 0.25+-0.02 mm

[blitz]

To add to ferret's info, the underhood sticker DOES list rocker clearance but specs it as a range rather than a specific figure. to wit:

 

Intake------.10mm-.25mm (cold)

Exhaust-----.15mm-.30mm (cold)

 

You'll have to convert it to inches.

 

I can testify that my '02 2.5 was on-spec at 20k miles, and my used '00 2.2 (essentially the same engine) was on-spec at 80k miles.

 

Barring some event like abnormal valvetrain wear or improper tightening of a locknut, the adjustment seems to stay put.

[Super]

Thanks for the info, I'll have to find a similar car and take a photo of the sticker or stickers....There appears to be two spots cut out in the hood liner....What else am I missing?

[cookie]

And you usually set them when you assemble an engine and the lifter takes up the adjustment. Barring failure or improper assembly these are good until you rebuild.

Somebody correct me if I am wrong about these.

[blitz]

Thanks for the info, I'll have to find a similar car and take a photo of the sticker or stickers....There appears to be two spots cut out in the hood liner....What else am I missing?

Rocker settings are the only specs listed on the one sticker. A diagram of the underhood evaporative emission circuit is on the other.

[blitz]

And you usually set them when you assemble an engine and the lifter takes up the adjustment. Barring failure or improper assembly these are good until you rebuild.

Somebody correct me if I am wrong about these.

Yeah, I think that on an OHC roller cam design, there's very little to wear or to shift around. I'd still run a gauge through at the recommended intervals just to be sure everything's cool.

 

One thing I'm not certain of is whether the clearance is tighter when the engine is cold. I'm assuming so. My last car had a similar layout (SOHC w/roller cam in an aluminum head) and on it the clearance tightened as the engine cooled.

[cookie]

The hydraulic lifter can take up adjustment for the entire anticipated range of wear. You will only have a problem if you go out of spec on a rebuild. Go design another amp with the time you'll save.

By the way did you see my post on the little rectangular resistor that came unsoldered in my Forester clock? I never saw one like that before, are they common now? Why do they seem to overheat and come unsoldered?

[blitz]

The hydraulic lifter can take up adjustment for the entire anticipated range of wear. You will only have a problem if you go out of spec on a rebuild. Go design another amp with the time you'll save.

But the original poster was asking about an '01 which has mechanical lifters. The phase II did away with the hydraulics. I think there was one year for the phase I 2.5 Impreza that had mechanical lifters.

 

By the way did you see my post on the little rectangular resistor that came unsoldered in my Forester clock? I never saw one like that before, are they common now? Why do they seem to overheat and come unsoldered?

I have seen posts on that issue, was that you? I think I read that a larger wattage (1/2 watt) resistor should be substituted in?

[cookie]

Man I'm getting confused here. I thought Forester and Impreza got the phase 2 in 99 and everyone else got it in 2000. If he has a phase 1 he has mechanical lifters and should check the clearance. It does not move much but a worn valve can recede into the seat and cut clearance and burn.

If you are correct and a larger resistor is necessary I may not have fixed my clock for long. Of course it did work for six years with the original solder so I guess I'll see what happens.

[blitz]

Man I'm getting confused here. I thought Forester and Impreza got the phase 2 in 99 and everyone else got it in 2000. If he has a phase 1 he has mechanical lifters and should check the clearance. It does not move much but a worn valve can recede into the seat and cut clearance and burn.

You've got it reversed.

 

Phase I DOHC = Hydraulic.

Phase II SOHC = Mechanical.

 

What, ...too much Jim Beam?

 

If you are correct and a larger resistor is necessary I may not have fixed my clock for long. Of course it did work for six years with the original solder so I guess I'll see what happens.

Yeah, there's really two reasons why a resistor will unsolder itself. Either it'll come loose from heat or from vibration/flexation.

[tomson1355]

There are no hydraulic lifters in the Phase I DOHC 2.5. The lifters, if you can call them lifters, are solid. At least in the two engines I've been inside. Don't know what they did with the Phase II.

[blitz]

There are no hydraulic lifters in the Phase I DOHC 2.5. The lifters, if you can call them lifters, are solid. At least in the two engines I've been inside. Don't know what they did with the Phase II.

Mmm... let's see, I think I'm getting it ironed out.

 

QUOTE FROM NABISCO FORUM:

 

"Actually most of the DOHC heads produced by Subaru use Shim-bucket style of valve adjustment. This is the same method used by almost all Japanese motorcycle engines and early VW Rabbits and Volvos. It is the most diffilcult system to adjust as you will have to buy a shim kit and special tools to depress the valve while you remove the shim. The SOHC Phase II engines use conventional screw-type roller rockers and is the easiest to adjust."

 

OK, HERE"S THE HYDRAULIC PART:

 

"Subaru did produce a quad-cam 2.5 for one year with hydraulic lifters in 1996 or 97. I spoke to Don Heck (Subaru Master Tech at Irvine Subaru) and he stated that Subaru tried hydraulic lifters in the 2.5 DOHC but for some reason did not continue production."

 

"Shim-bucket valve arrangements are quite compact and have less mass than rocker arm styles and so lend themselves quite nicely to high performance situations. Low mass means higher RPM but at the sacrifice of friction. Thus the reason for the roller rockers on the Phase II engine. Lower max RPM but less friction equals same power and better fuel economy."

 

OK, I was a little bit wrong.

[cookie]

by going down to the dealer when I have some time and looking at the setup. If I need to be checking these I want to put it on my maintence schedule. I had been told they were hydraulic lifters.

I just pulled all the wheels and inspected and lubed the brakes, removed the battery, filled it, and cleaned the connections, as well as a complete inspection. I'm going to put a couple of thousand miles on it on a trip next Saturday and want my best bet of no problems.

Since my head gaskets were replaced less than 20,000 miles ago it should be fine.

[jamal]

I wonder if the 2.5 has any correlation with the 2.2. In 97, the 2.2 went to solid lifters (along with slightly different pistons). I'd bet the 96 2.5 had hydraulic lifters, but they went to solid in 97.

 

E: According to an endwrench article I'm reading, only the "first versions" of the DOHC 2.5 had the solid lifters with shims, although it doesn't say which.