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Old 06-06-2001, 01:54 PM   #1
Homicidal Maniac
Member#: 1612
Join Date: Jun 2000
Location: Austin, TX
2008 STI

Post How To: Setting Valve Lash on SOHC EJ25

A couple people have asked me for this, so I figured it might be something lots of people would be interested in. Listed below are the steps to set the valve lash on the SOHC EJ25 commonly found in the MY99, MY00, and MY01 2.5RS's. MY98's are totally different, so please don't attempt to set the lash without further instruction.

There are two ways to set the valve lash, one of which takes 2 hours and the other takes about 3 hours.
When I first did my cams, I figured that you had to have the timing belt cover off in order to see everything going on with the timing belt (read: timing marks). It helps, but its not necessary. To get the timing belt cover off, you have to remove both radiator fans (two screws in at the top and one fan plug on the bottom of each). With those out, you have to remove the crank pully by removing any accessory belts, putting your car in 5th gear, standing on the brakes, and having somebody run a long breaker bar. Once the pully is out, you can proceed to remove the 10-15 screws holding the timing belt covers on. From here you can remove your spark plugs and then rotate your motor clockwise with the crankshaft pully bolt.

You need line up all the lines on the timing belt gears/pullies to the 12 o'clock position. There should be a timing mark on the gear in the middle and one on each camshaft pully. Now you can remove your valve covers (5 bolts). If the motor has been sitting for a little while, there won't be much oil coming out. With all the lines in 12 o'clock position, your motor should be in top dead center (TDC). This is where all of your cylinders are at rest, but most importantly, cylinder 1 (front passenger side i think, though it says on your coil pack on the intake manifold) )is at the top of the compression stroke. This is where you need each cylinder to be when you set the valve lash.

You will need a feeler gauge with .007" and .009". If you don't have one, you can easily pick one up at any autoparts store for a couple bucks. You need to set the valve lash to .007" on the intake side and to .009" on the exhaust side. To do this, you push the feeler gauge in between the valve tappet and the top of the valve. If it is too loose, then you loosen up the 10mm nut on the end of your rocker arm, and with the use of a screwdriver, you can screw the valve tappet down until it is pushing on the feeler gauge. Make sure you still has enough room to move the gauge back and forth, but tight enough that there is not slop if you wiggle the rocker up and down. Now while holding the screwdriver in the slot on the valve tappet (to hold the tappet in place), keeping the feeler gauge under the valve tappet stil, you then screw the 10mm nut back down, securing the valve tappet in place. Recheck the lash with your feeler gauge. If it is still tight, but moderately movable, then you can move on to the next valve; if not, try again. The intake side will be done from the top of the car, and the exhaust side was done with one person below and one person above the car. Once you have done both the intake and the exhaust side of cylinder #1, you need to rotate the motor slowly clockwise until cylinder #2 (front drivers side) is at the top of the compression stroke. To check this, you just put your hand over the spark plug tube and as the cylinder is coming up, you will feel air pushing on your hand; it will also be giving a hissing sound as air is being pushed around. If you take a flashlight and a mirror and use those to look down into the sparkplug hole, you should be able to see the piston. Once it has stopped moving (top) then you are there. If you wiggle the crankshaft bolt back and forth, you can see where the piston is sitting. Now you repeat the vavle lash procedure for both intake and exhaust side for cylinder #2. Then you cycle the motor over to cyclinder #3 (back passenger side), set the lash, then cycle to cylinder #4 (back drivers side), and set lash.

You are now done with setting the valve lash and you can begin reassembly of the car by putting the valve covers back on, the timing belt cover, the crankshaft pully (torqued back down to 130ft/lbs if its the stock pully), radiator fans, and plugs and wires. Reset your ECU.

The shorter procedure simply bypasses the removal of the timing belt cover. You still have to remove plugs, valve covers, and radiator fans however. Since the crankshaft pully is keyed, it will only go on one way. While rotating the motor around with the spark plugs removed, you should be able to see a little knick or line on the backside of the crankshaft pully. If you watch for the compression on cyl. #1 while rotating the knick up to the top, you should be able to find TDC with the timing belt cover still installed. It should take 720 degrees to rotate the motor through one entire revolution. Once TDC is found, you can follow the steps listed above to set the valve lash.

Any questions or comments? Feedback is definitely appreciated. Please correct me if I have neglected a step or wrote down a step incorrectly.

I'll try and put it up on my webpage later...

-Jon www.susogi.net/stimpy
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Old 06-06-2001, 02:55 PM   #2
Cobb Tuning
Member#: 4803
Join Date: Mar 2001
Location: Austin, TX

Great write-up Stimpy.

Here is how we find the position of each cylinder to set lash, which is just slightly different than what Stimpy has written.

Setting valve lash on 2.5L SOHC.
1) Remove the radiator overflow bottle.
2) Remove the driver's side section of the timing belt cover (just 3 bolts) to expose the driver's side camshaft sprocket.
3) Remove valve covers and necessary components (we typically pull air filters/boxes and the windshield washer bottle to get better access.)
4) With a 22mm socket and long breaker bar, rotate engine until the ARROW on the driver's side camshaft sprocket is at 12 o'clock (UP). Set the valve lash on the #1 cylinder when camshaft sprocket is in this position.
5) Rotate engine through two revolutions and set ARROW on the camshaft sprocket at 6 o'clock (DOWN). Set the valve lash on the #2 cylinder.
6) Rotate engine again 2 revolutions and set the arrow on the camshaft sprocket at 3 o'clock (RIGHT) (standing in front of engine bay). Set the valve lash on the #3 cylinder.
7) Rotate engine again 2 revolutions and set the arrow on the camshaft sprocket at 9 o'clock (LEFT). Set the valve lash on the #4 cylinder.
8) Put everything back together and test drive.

This might be more exact if for some reason you can't tell the exact position of each cylinder. Plus, it makes it easier than pulling all the timing covers off. We rotate the engine 2 rotations to give the cam a full turn (it turns 1/2 speed of the crank) and recheck the lash on the cylinder we just set before going to the next. It's not a requirement, but it's a good QA step.

Other than that, the lash adjustments Jon (Stimpy) wrote were dead on. Make sure you keep the feeler gauge on the same "plane" as the top of the valve. If you have it in at an angle, you might set the valve lash too high and it'll be noisy. Take your time, and you'll get it right. It is definitely something you begin to get a feel for after you've done it a few (hundred ) times.

Cobb Tuning www.cobbtuning.com
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Old 06-06-2001, 03:28 PM   #3

Member#: 922
Join Date: Feb 2000
Chapter/Region: MWSOC
Location: Schaumburg, IL
16 WRX (white)
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When in the valvetrain's life should this be done? Sounds pretty simple.
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Old 06-06-2001, 03:58 PM   #4
Homicidal Maniac
Member#: 1612
Join Date: Jun 2000
Location: Austin, TX
2008 STI


Trey, thanks for posting that. I am glad somebody knows of a trick or two so we don't have to resort to guessing when the hissing stops I never even thought to check the angle on the camshaft gear.

I have set the valves twice on my car, but I installed the cams first. First time was detailed by the instructions, the second time it was simply because I could hear my valves ticking. Thats basically how I was told to determine if valve lash needed to be set: simply listen to see if you engine is ticking from the valve train area. In my case, the engine was ticking very loudly.

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