sorry, here is a pretty good written instruction. couldnt find the link, may have been from this forum, do a search for "Timing"
he first repair i made on my yota when i got it was a blown out cam seal. .. i have a decent amount of info on what was easy and hard.
the first thing i would do is degrease your motor. the oil sending unit is next to the oil filter on the block under the alternator.. pretty easly accessed.
another VERY common oil leak is the valve cover gaskets. so check those to be sure they arent leaking as well.
now that you've verified that its not the simple fix of valve covers or oil sending unit it's most likely the cam seal (it will be obvious when you notice oil coming from your timing cover.
first step, pop all the accessory belts loose. then remove the bolts holding your fan shroud and then the four bolts for your fan clutch. now its slightly tricky but push your shroud away from the radiator as far back as possible and then slide the fan blade forward until you can pull it up and off the drive pulley. pull the shroud and fan out simultaneously.
next remove the main acc pulley. usually jus 4 bolts and a light thump will break it free. remove all belts as well
remove all the little 10mm bolts holding the timing cover in place. a air/elect ratchet helps, there are quite a few. pull off covers and set aside.
now you should have a clear view at your cam seal.. yay (now the fun begins)
important!!!!!!!! i cant stress this enough... look at the head behind the cam pulley and find the indent on both sides ( as is behind both cams {one on each side}) now line the dot on the cam pulley up with the dot on the cyl head and the main pulley should be lined up with TDC.. precision is a good thing here! now remember to periodically check these dots during the following steps to insure that those dots stay lined up!
loosen up the timing belt tensioner. i recommend using a impact wrench or ratchet... its a tight squeeze but i got mine in there. just crack it loose, if you loosen it up all the way its a pain to put back in, not to mention the fact that it will ram your impact into the radiator. once cracked loose use a socket to free it up and push it out then re tighten (not all the way, just enough to hold your timing belt loose)
remove the timing belt. to not twist crease or distort the belt in any way that it's not supposed to be, it can ruin the integrity of the belt. also avoid getting any chemicals on the belt, a splash of carb cleaner or acetone with require you to need belt replacement. inspect belt for wear, cracks, abnormalities, and overall thickness. replace if any of these symptoms exist.
note: unless recently done, timing belt replacement is highly advised (since you're this far into the motor already)
so back to business, take a strap wench and hold your cam pulley in place while you remove the pulley bolt with a torque wench.
note: i had to go buy an industrial strength torque wrench to get these bolts loose.. they are so tight i've never encountered anything that tight before. i snapped several sockets and breaker bars before i used the torque wrench. once you get the bolts off both sides check once more time BEFORE removing pulleys that the dots are all lined up. then remove pulleys, exposing cam seals.. finally!
to remove cam seals is a little pain. they WILL get destroyed in the process.. DO NOT REUSE WORN CAM SEALS your work will have been in vain. chances are that is one has blown out the other soon will so replace them both (they are sold as a pair so why not)
use a small pick or flat head with the tip bent to remove the seals. do not damage the raceway or camshaft in the process, a little knick will ruin your new seals almost instantly. a little tip, the camshaft is steel and head is aluminum, steel is way stronger so if you must pry on something, use the steel and dont touch the aluminum. i used a little u shaped pick like dentists use and stabbed it through the rubber and around the metal band in the middle (look at the insides of your new seals and you'll see what i'm talking about) i pulled slow and hard till the band stretched, then the seal popped right out. inspect the oil drain hole behind the seal. blow through it lightly to be sure its clear and free of debris. if not gently unclog it, if it's clogged your new seal will blow out.
by this point if you havent done so already, it's time for a beer lol.. trust me it helps, i need one just thinking about having to do this again...
oh yeah and one more for the road...
ok so now to put your new seals in, grease them up or put some assembly lube on them, cover them pretty good, i never heard anyone say too much lube is a bad thing. slide them over the cam shaft and down to the race way, be sure that they are all even and strait. next tap them into place genitally with a blunt piece of wood or plastic as a punch and a rubber mallet. important!!! go little by little, bit by bit and evenly on all sides, DO NOT SLAM THEM IN, they will become deformed and therefore defective. once you have tapped them flush with the cyl head it's time to start putting things back together.
installation is the same as removal for everything. but when it comes to the timing belt.. remember to keep those timing dots aligned. when you put the timing belt back on.. well this is complicated to explain so let me take mt best stab at it..
*keep all timing marks (dots) lined up and pulley at TDC.
*belt should already be around main drive pulley. now put it around drivers side cam pulley. there should be no slack in belt, pop the belt into the proper groove to where the section between the main pullet and driver cam is tight and you are still holding tension on belt with hand.
*take free hand and wrap fingers around drivers cam pulley to ensure the belt does not pop out of grooves.
* bring belt down and around idler pulley and be sure belt does not pop out of groves on drivers cam or main pulley.
* keeping on e hand on drivers pulley, wrap timing belt around passengers cam pulley and continue to hold tension. now hand on drivers pulley can be removed.
* check one more time that there is no slack in belt anywhere except between main and passengers side cam pulley.
* use right hand to hold tension on belt while left hand loosens tensioner bolt (here's there leaving it semi loose helps!)
* once tensioner is loosened slightly and belt is tight, inspect timing belt. insure that all timing marks are lined up, and main pulley is at TDC....
*** important!!! do not turn over motor.. the tensioner is still loose..
*now once you have checked and double checked that all marks are lined up, push tensioner inward to tighten belt. a decent amount of force is needed, but not too much.
*while pushing in, tighten tensioner very tight. them hit it with the impact to ensure its solid.
now continue re assembly until you are all done.
****important***** drink another beer before starting car, and if it starts and runs fine, drink another one to celebrate a Saturday well spent, if it does not run or runs like a pile of SH!t then drink 2 beers to relieve the stress and go watch some tv for a bit before tearing it back apart to redo
