Hi guys!
What will be the results of bad valve adjustment on a WRX02 (north american model) in all conditions (idle, acceleration, cruise)?
Cheers, Frank

 

Please explain what you mean!

Bad valve adjustment: Do you mean an incorrectly fitted cambelt? Incorrectly fitted cams? Or do you have the Variable Valve Timing System?

Or do you mean a completely different valve all together?

Steve

 

if the gap is too large yo ucan get excessive cam lobe wear, if it's too tight the valves will not sit on the seats and you will get poor performance and possible fatigued valves.

0.010" is pretty common, but you can go to 0.008" on the inlet due to reduced temps compared to exhaust valve (will expand less)

Paul

 

could do any number of things when hot, not a lot when cold.

if you're worried the best thing you can do is get it checked.

I think you're waiting for someone to say it will be fine, well it might be, or it might get damaged very badly.

Why *exactly* should you have to worry?

Paul

 

Well, to do a short story, I made an engine swap with all electronics componants. I took an engine and ECU with wires from a WRX02 and I installed it an a GC8 normaly aspirated (2.5RS MY01 north american) body. The thing is that the engine is coming from a smached car and the engine as been damaged (bent valve). I realy don't know if the engine rebuilt as been done properly. The engine is hunting at idle and runs lean when normal acceleration. At WOT, the engine runs rich (that is normal). I had a doubt about my instalation of the elctronics components, but after 7 hours monitoring all sensors with a Subaru technician (500$CDN), no trouble as been detected. He think that the valve adjustment has not been done properly. That's the reason why I want to get a second verdict!!! I don't want to spend money for nothing!!
Cheers

 

I would do a compression test first, if there is a valve not seating it will show up. I would then check the cam timing first, specifically has the belt been fitted correctly?

If the engine doen't run properly from stone cold, it's unlikely to be a valve clearance problem.

Sounds like a vacuum leak, check all the hoses on the inlet pipe.

Paul

 

Timing belt and vacuum hoses as been checked and tested. I get an appointment at Subaru tomorow. Engine is running bad from cold to warm condition... seems to be a bad valve adjustment!
Thanks a lot everybody!
Cheers, Frank

 

Compression test has been done this morning:
cyl.1 = 150PSI
cyl.2 = 125PSI
cyl.3 = 150PSI
cyl.4 = 150PSI

Valve adjustments are within specs. Two choices occurs:
1- Leaking valve
2- Piston rings

The engine is 17000km old. I ran with the stock boost since I installed it in my car (7500km old when installed), so probably, it's not the piston rings or a piston failure. I suspect a leaking valve...Is there a test that I can do to know if a valve leaks?
Cheers

 

Pavlo & Eprom,
You were right! I double check the cam position... crank shaft was one tooth out. I fixed it and no more trouble!
Thanks a lot, you made me save a lot of $$$$
Cheers Frank

 

Steve,
I mean by valve adjustment, gap between the cam and the valve. All that I know is that each valve on a WRX02 as a kind of shim with a specific dimension installed between the valve and the cam. What will happen if the gap is barely out of spec?
Cheers

[Edited by fmessier - 6/8/2003 1:39:47 PM]

 

Thanks Pavlo,
But what are the effects when the engine is running at idle, normal acceleration, wide open throttle and cruise? I mean will the engine runs lean, hunting at idle...!!
Cheers

[Edited by fmessier - 6/8/2003 10:30:47 PM]

 

The only other way is to investigate is a leak down test, this will require you removing some components from the engine to hear if the leak is on the exhaust side or inlet side. Inlet side you could listen through the throttle body, exhaust side may be more difficult. May have to remove the headers, if its blowing past the piston may be able to hear this through the oil filler . My bet will be on cam timing have you double checked this? you only have to be one tooth out.

[Edited by Eprom - 6/12/2003 11:31:01 AM]