3rd Gen Timing Marks for Timing Belt Replacement

[FTW1996]

I have a 1996 4Runner that needs a timing belt replacement. I've never done one, but after pouring through all the great information on this site and other 4Runner sites I decided I could probably handle it. So, last January I started replacing my timing belt. When I put the new belt on (with all the marks on the belt lining up correctly with the pulleys) I saw that the timing mark on the crank shaft pulley lined up at about the 5 degree mark on the engine even though the cam shaft pulleys are both properly lined up with their marks. It looked to me like moving the belt by one tooth would move the pulley more than the 5 degrees need to make it line up with 0, so I was stumped. It was at that point that I decided to procrastinate, and here I am, 9 months later with the new timing belt still in the same position that I left it it January.

The thing is, I vaguely remember (imagine?) that the crank pulley mark was lined up somewhere near the 5 degree mark before I took the old belt off, but it's been so long that I could easily be remembering it wrong. Further adding to my confusion is something I saw in my Haynes repair manual. It says that the ignition timing should be 8 to 12 degrees before top dead center. So, is it possible that my timing mark alignment as shown in the pictures below is correct at 5 degrees? Or, if the timing mark on the crank shaft pulley absolutely must line up at 0 degrees, what do I do to make it line up?

Thanks in advance for any advise offered.

 

[98OzarksRunner]

The timing marks on the belt should line up with the marks on the top pulleys. The crankshaft should be at 0, lined up with the marks as shown in the service manual. Here are the instructions from the service manual.

 

[TheDurk]

Yeah, you're out. It needs to be at zero degrees when the cams are on their marks. That is for VALVE timing.

The other spec is for IGNITION timing, and you read that with a stroboscopic timing light hooked to the No. 1 spark wire. (The exact spec is: Ignition timing w/ Terminals TE1 and E1 connected to DLC1 is 8 - 12° BTDC @ idle). This means with the strobe you will see the pulley mark move forward and back rapidly and continuously while the engine is running. NOTHING to do with valve timing). It varies continuously between these numbers, as opposed to being simply set to some single number in between the 8° and the 12°. Google valve timing and ignition timing to learn the difference--it's important.

But there are two possibilities, and you need to be sure which it is. One is that the pulley is misaligned on the crank by five degrees but the sprocket is correct. This happens when the crank pulley bolt is not tightened to the 213 ft-lb spec and the pulley starts to shift, shearing the Woodruff key. The pulley only engages a mere 1/4" or so of the key, so it can do this easily IF the bolt is loose. Almost all of the key is under the timing sprocket behind the pulley.

The second case is that the belt is off by a tooth on the cam pulleys. (If it was off on the tiny cam sprocket, it would be way more than five degrees.) The only way to tell, is to remove the pulley and inspect the woodruff key and the timing marks on the sprocket and on the block, as described in attachment posted above. If all is well with the woodruff key, you will need to reinstall the timing belt. This will require using a special tool to compress the tensioner, or removing it and compressing it in a vise. There are lots of DIY's on this.

The important thing to understand is that, if the pulley is slipping because the crank bolt is coming loose, bad things will happen, possibly very soon, which can ruin your harmonic damper, or worse, the nose of your crank, effectively killing your engine, as a whole new engine is cheaper than swapping a crank. It is probably not this, because it has been stable since January, but I sure would want to know for certain if it were mine. And it doesn't sound like you were certain it was that way in January.

 

[stir_fry_boy]

Haynes manuals suck. Use an FSM for guidance.

 

[jeremyc74]

Or, if the timing mark on the crank shaft pulley absolutely must line up at 0 degrees, what do I do to make it line up?

.

Unfortunately you're going to have to tear back into it enough to get to the tensioner and compress it. You can probably do this without removing the crank pulley though, so at least there's that. If you don't already have one it's worth it in this case to buy the tensioner compression tool (about $25) so you don't have to remove the tensioner to compress it in a vice.

Those white stripes on the belt should be lined up with the timing marks on the cams, and the crank pulley should be at 0 Degrees. Those lines are there to help you get the teeth right while the belt isn't fully tensioned. Looks to me like you're a tooth off.