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DIY: SOHC Timing Belt Change w/ Pics!

279K views 221 replies 97 participants last post by  FryphaX 
#1 · (Edited)
So, it's never be too late to buy a GC chassis Subaru and if your mileage is going high and it's time to replace those timing belts! Subaru recommends timing belt to be changed every 75k miles and changing idler gear/pullies and tensioner won't be a bad idea either. I did this on my 2001 2.5rs MT and it was fairly easy task.

There are a few timing belt DIY around but I'm adding some photos in there so it can clarify some mechanically-challenged owners.

Tools
- 1/2 and 3/8 ratcheting wrenches
- 10mm, 12mm, 14mm, 17mm, and 22mm sockets
- Breaker bar + extension
- small c-clamp
- Nose plier
- PB Blaster or WD-40
- Gloves and goggles for safety

Unplug Spark Plug wires
- Remove the 4 spark plug wires toward the top. Just pull them firmly gripping the end and they will pop out. This is crucial for bumping the crank bolt loose.


Removing the radiator fans
- Start by going under the car and unplug the radiator fan connectors. There's 1 per fan. Simply lift up little tab and pull it to remove.



- Now that the fans are disconnected, remove the coolant reservoir by removing the 2 10mm bolts (red) and simply lift it up.
- Remove the 2 10mm bolts securing the fan (orange) and lift up to remove the driver side fan.


- Remove the 2 10mm bolts on the passenger side fan and lift up to take it out.


Removing the Alternator belt
- Start by loosening (do NOT remove) the 12mm bolts (red) on the alternator and on the tensioner. Loosen them enough to be able to spin them by hand.
- Loosen the 12mm Tensioner bolt (orange). As you loosen this bolt, you can push down the alternator, giving the belt enough slack to remove.


Remove the A/C belt
- Start by loosening the idle pulley 12mm (red)
- Loosen the 12mm tensioner bolt (orange) so it relieves the tension on the belt.
- Finally, remove the 2 12mm bolts (blue).


- Remove the tensioner assembly.


- Remove the a/c belt.

Remove the Crank pulley
- This part is quite easy. Just place a 22mm socket on your trusty 1/2" ratcher or a breaker bar, find a long enough pipe or extension (mine was a floor jack handle) and rest it on DRIVER'S SIDE ground.


- Sit in the car, then crank your engine. It should come off on the first try. If not, try it again.
- Once it's loose, remove the crank bolt and remove the crank pulley.

*EDIT*
This is just one of many way to remove the crank bolt. I personally had no problem using this method since I don't have any air tools or impact wrenches. Due to popular demand, here's the link to another way to remove the bolt

http://www.rs25.com/forums/f105/t113885-better-way-remove-your-crank-pulley.html

Remove the Timing belt covers
- This 2 piece plastic timing belt cover is held on by 13 10mm bolts (3 on driver's side, 10 on passenger's side). They can all be reached from the engine bay and remove the driver's side first.


- Continue to the Passenger side and remove the cover.


Remove the idler gear and pulley
- Remove the lower left idler pulley by removing the 14mm bolt first to gain some slacks.


- Then, remove the idler gear by removing the 14mm bolt on the center.


Remove the tensioner
- Remove the tensioner by removing the 14mm bolt.
- If you're planning on reusing the tensioner, you must compress the tensioner's hydraulic thingi. You can use a c clamp, or a table vise. Just remember to compress it slowly or it may damage the hydraulics. Compress the tensioner enough so you can insert a small nail, pin, or 2mm allen wrench to hold the tension.


- Once the tensioner is out, remove the old belt.

Line up the Cam positions
- On SOHC engines, the aligning the timing mark is quite easy. All you need to do is to line up 3 markings. Period.


- First, line up the crank cam. There's a difference between a timing mark yellow) and the arrow (red). Line up the marking as shown.


- Next, line up the driver's side cam. Use 17mm socket wrench to turn the cam and align the marking. *This can be tricky because when the timing mark get closely align, you'll be fighting compression so you'll have to use some force turning the gear. Don't use brute force! or it'll pass the timing mark and you'll have to turn it again.


- Finally, line up the passenger side's cam. This one is easy. Just like the driver's side, use 17mm socket wrench to turn and align it to the proper marking.


Install the new timing belt
- I use the OEM Mitsuboshi timing belt and it came with TDC (top dead center) marking and other 2 timing mark. In most cases, the new timing belts will have markings already printed.
- On the FSM, teeth counts were supposed to be 44/40.5 tooth between the cams, but mine were 44/47 tooth. Just go by the markings on the belt and you'll be fine.
- Start by reinstalling the Tensioner assembly first. Install the 14mm bolt and tighten it to 39±4 N·m (4.0±0.4kg-m, 28.9±2.9ft-lb).

- Line up the Crank first.


- Next, the driver's side.


- Finally the passenger side


- Let the belt sit as shown.


- Since the driver's cam is quite unstable, I used a small c clamp to hold its belt location so I don't lose my alignment. Don't clamp it too hard or you'll damage your new belt!


- Install the gear idler pulley and tighten it to 39±4 N·m (4.0±0.4 kg-m, 28.9±2.9 ft-lb).


- Install the smooth idler pulley and tighten it to 39±4 N·m (4.0±0.4 kg-m, 28.9±2.9 ft-lb).


- MAKE SURE the belt is still aligned to the timing belt before proceeding to the next step or you may have to start all over again!


- Now for the final step. Grab a nose plier and remove that grenade pin. Once the pin is removed, the hydraulic will kick in and tighten the belt.


- Now, use the 17mm socket wrench to turn the gears around. You'll be fighting the compression so you'll have to use some force turning the belt around. Since the crank cam 24 teeth gear opposed to driver/passenger 48 teeth gear, the marking should align every 2 revolutions. Keep turning the belt around to see consistence in timing alignment.


- When everything looks good, pat yourself in the back for a good job and reinstall everything in reverse order. Fire up the car and you're set for another 75k miles!

Disclaimer
I am not responsible if you mess up your car by reading this DIY. I'm posting this DIY for references and some insights on this tedious install. If unsure about installing, please consult a professional Subaru mechanic.
 
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#9 ·
Eek, I wouldn't chance it much longer. From what I understand, the belt itself isn't the issue so much as the idlers / tensioners' bearings going south. Get it done asap, it's every bit as easy as the OP's DIY makes it out to be. Just take your time and double-check your work.
 
#8 ·
The only advice I can offer is this:

-When turning the engine over by hand, it is easier to have the plugs removed. So if you are doing multiple repair items together, it is nice to keep that in mind.

-The drivers side cam pulley (metal one) will want to rotate to the right if the timing mark is right of vertical. Be aware of this, and make sure the crank timing mark is set first!

-If you are having trouble getting the belt on you can try this: Install all idler pulley's and remove the passenger side cam pulley (make sure the timing mark is vertical prior to removing the pulley). Install the belt using the timing marks on everything minus the passenger timing pulley. Carefully put the passenger pulley into the timing belt and place it on the cam. If done properly, it will line up and catch the key-way pin on the cam. Tighten the bolt for the pulley and double check all of your timing marks.
 
#11 ·
if you dont like the starter bump method as a lot of people including myself dont. there is another way. it only works with manual trans though. just put in it 4th and yank the ebrake that will hold the engine. assuming you have a good condition clutch. i have done this method countless times on different cars.
 
#26 ·
Great Post DIY pedpro, I do have a question for those who did their timing belt. When You put everything on and your start turning the engine by hand, are you supposed to feel resistance? Is the resistance major? Is the part where your fighting compression has resistance when turning it by hand? Reason why Im asking is that I'll be tackling this soon and I read this guys thread and got me alittle hesistant on doing it myself?


Here's this guys thread:
Changed timing belt, now no start - NASIOC
 
#27 ·
turning it by hand by meaning, using your 17mm wrench and turning it using your hand.. not with any pneumatic tools or some sort...

having resistance meaning that you just have to give some strength to turn it since you ARE turning the cranks that has pistons attached.
 
#29 · (Edited)
Sorry guys, got one more question regarding the timing belt. So when I go to line up the crank and the cams with the markings on the block, do I rotate it clockwise or counter clockwise for all three? From my research, the drivers side cam(you facing the engine) will be stubborn and move by itself. IIRC from my readings, it would turn to the left?
 
#32 · (Edited)
Thanks Pedpro!!! So finally, my friend and I did my timing belt maintainence service. Swapped out alot of things which included my timing belt, drive belts, waterpump & Gasket, Thermostat & gasket, both driver side and passengers side cam seals, and crank seal. I was lucky though as my friend had the specialty tools to hold both cam in place while cracking the bolt. Replacing the seals was simple.

As much as the timing belt service seemed intimidating, it was straight foward easy/simple. Its just that there was alot of unbolting and bolting of mechanical items like the waterpump, radiator fans, etc.etc. I asked my friends friend who brought the subaru specialty tools whom also is a subaru tech mechanic here at our local subaru dealership told me something that I didnt know. For subaru's when the crank is at Top Dead Center(TDC), it actually is the midpoint where the pistons are positioned midpoint of the chamber. Just thought Id throw it out there. lol. Other than that, i slapped myself thinking that i was scared of doing the timing belt job and was intimidated of bending the valves. As long as the marks are aligned with the marks on the block, you wont have to worry about bending valves. Then my friends friend rotated the crankshaft 2 full rotations to see if everything lined up and everything lined up(I was taking my smoke break during this time lol). So all in all, the job took about 2 hours and 30 minutes.

The reason why I didnt take out my entire radiator was because the subaru mechanic guy said its a hassle to unbolt the tranny cooler and oil cooler line which was located on the very bottom right hand side of the radiator(your looking towards the motor).

One tip for anyone tackling there timing belt job. Do it when the engine is cold!!! We did mines with the motor HOT and having hot coolant spill all over your hands especially unbolting the waterpump was pretty fun(sarcastic) lol. But what the subaru mechanic guy did find that I didnt realize, was that my valve cover gasket needs to be changed cause he found little oil residue on the covers of the spark plugs, one on the passenger side and one on the driver side. Next DIY is valve cover gaskets and spark plug gaskets.

Thanks PedPro for this awesome post!!!!:banana::banana::banana:


I forgot to mention one more thing, we put on all the idler pulleys on, even the toothed one before we slid the bottom portion of the timing belt on. The subaru mechanic told us to do this instead because he seen/done some where he put the entire timing belt on, and then put the last idler pulley on and screw it down, it would get cross threaded, so he reccomended to just put all the idler pulleys on, and then slide the bottom end of the timing belt onto the idler pulleys. Also since mines was a 2004 2.5rs, the lines on the cams were blue, not white. Also when the subaru mechanic guy aligned everything after taking off the tbelt, when he went to put the driver side cam back on after we changed the cam seals, he screwed on the bolt holding the driver side cam with the arrow lining up to the mark on the plastic cover instead of what originally was lined up with the mark was the blue line. Is that alright? The car runs super fine and I dont hear any metals contacting each other like the pistons kissing the valves.
 
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