Timing Belt Replacement

Timing Belt Pic 1
This is a picture of the most common Subaru engine, the 2.5 liter 4 cylinder. This engine can be found in all 2000-2010 Subaru Outbacks, Legacys, Impreszas, and Foresters, and later on some models. If your car is a turbo or an H6 a lot of these principals will be the same but the costs are higher.

This particular engine came from a 2006 Impreza & has some updates, but nothing that will concern us for this posting.
 
The suggested interval for Subarus timing belt replacement is every 105,000 miles. People call us and ask "How much does it cost to do this job?"
IF... we JUST replace the timing belt by itself, it's just under $400.00.
BUT.... notice all those pulleys that belt goes around? 
They have all been spinning at the same RPM as the engine, for the same 105,000 miles. Those pulleys should be replaced at the same time.
Timing Belt Pic 2 Timing Belt Pic 3 Timing Belt Pic 4 Timing Belt Pic 5
This is a picture of the upper Idler pulley on the passenger side of the engine. Notice the Black outer seal face & it's distance in relation to the face of the pulley itself. This tells us it is a 2 row bearing pulley, one row of bearings towards the front & another towards the rear. This pulley is located on the passenger lower side of the engine. Notice the red (sometimes green if it's been replaced before) face of the pulley & it's distance to the face of it's pulley. This indicates it's a single row bearing. We see these single row bearing pulleys fail a lot. More is better, right? In this case it's definitely true. Why wouldn't you upgrade to a double row bearing, especially if the cost is just a few dollars more per pulley? This shows another single row red faced bearing pulley. This one, along with the others are  called "Idler" pulleys as they guide the belt & don't "drive" anything during the rotation of  the belt. The solid looking pulley is the water pump pulley. This means that if you didn't replace it at the same time as the belt & you might have to tear everything back apart (or pay someone) to replace it if it were to start leaking. This is the timing belt tensioner pulley assembly. Its job is to take up the slack & keep the belt tensioned as the belt stretches over time. Subaru has made enough updates to this part that we don't trust it to outlast any of the others. It too would be replaced during one of our "proper" t/belt jobs.
 
Timing Belt Pic 1
OK, Back to the full frontal view. Note the larger pulleys at the outer edge of the engine. These are the camshaft pulleys. Their job is to open & close the intake & exhaust valves to let in the air / fuel mixture in & the exhaust gases out in precise timing with the center pulley that drives them. Behind each of these are oil seals that we would replace at the same time as the other pulleys, water pump, & timing belt. This assures that you wont have to spend the money to replace any one item 6 months or even a year down the road. If you spend the $1000.00+ to do this job right, you will get another 105,000 miles out of your next timing belt trouble free.
 
NOTE; If your timing belt does fail, major engine damage will send this repair close  to $3,000.00. The math is pretty simple, you get what you pay for.