Timing marks are off

[nthach]

I'm in the process of replacing the timing belt on a 1991 Lexus LS400, and I noticed the timing marks are way off - When the timing marks on the cams are lined up, the crank is off by a good 90 degrees - when I first lined up the crank to 0, the cam marks were off by 10-20 degrees, and I rotated the crank to double check and they are off now. Now, the 1UZ-FE for this generation of LS400 is a free-wheeling design, and my instinct is to leave the cams lined up, pull the crank pulley and when it's time to install the new belt, rotate the crank to align with the timing marks on the oil pump, while using the harmonic balancer to reference my work. Does this sound doable or do I also need to find TDC on the #1 cylinder?

Here are some pictures -

http://s961.photobucket.com/user/nfthach/library/

 

[Quest]

when doing t-belt change or timing verifications, always start by using crankshaft side of the timing mark as a reference.

You then follow through with the rest of the camshafts (sprocket markings) and the rest of the proper procedures.

Q.

 

[86cutlass307]

I would first reference your tech data for the first reference on TDC. If they want you to bring the crank into position first, start there. You can always roll the cams into position. I haven't done a Toyota timing belt in ages...been with Honda for 13 straight years now. My Tacoma is chains; belts stretch and the tensioner takes up slack but that seems to be quite a bit. Does the engine run well? Have good power and no CEL's in the past? Anyway, keep us informed on what you find. Pray to the Toyota gods to show you the light

 

[BigD1]

Top dead center on #1 compression stroke. Then line cams up verifying that #1 intake and exhaust are closed.

Never done a dual over head cam, but I have done single over head cams, and this worked the last time a friend of mine had his Nissan all out whack, and the truck would not hit a lick.

You might want to look at a manual to see if there is a specific procedure to align the cams.

 

[Drew99GT]

Are you at TDC compression stroke? Sounds like you're at TDC exhaust. Verify 100% that the number 1 cylinder is at TDC compression stroke. Pull the distributor cap off and make sure the rotor is pointing at the number 1 cylinder.

 

[kschachn]

Help me out here, don't you line up the crankshaft timing belt pulley with a mark on the oil pump housing? Not the harmonic balancer. Sorry if I'm not getting it, I've changed lots of timing belts in Toyota engines but not this one.

 

[CT8]

How many rotations did you do to get the timing mark off.

 

[kschachn]

We need more information. If the belt is installed properly (not off a tooth) then when the crankshaft is rotated two revolutions the timing marks on the camshaft sprockets will align with the marks on the cover (or wherever they are supposed to align). It is physically impossible for them not do to so unless a cam is broken, which I doubt.

The marks on the belt will NOT align with anything after rotating. Once you use the marks on the belt to get it installed you ignore them and only look at the crank pulley, camshaft pulleys, and the respective timing marks.

Be careful you are looking at the correct mark on the oil pump housing AND on the camshaft pulley. There can be other dimples or marks which are not the correct ones.

 

[eljefino]

Originally Posted By: kschachn
Help me out here, don't you line up the crankshaft timing belt pulley with a mark on the oil pump housing? Not the harmonic balancer. Sorry if I'm not getting it, I've changed lots of timing belts in Toyota engines but not this one.


Don't you pull the harmonic balancer pulley and then verify with the inner one, with teeth, that actually interface the belt? I think your balancer is shot.
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As for the oil pump sprocket, if it's part of the distributor or spark trigger system it needs lining up. Otherwise, maybe not. Look for a pair of marks.

 

[nthach]

So I did the TDC trick and when the crank was at TDC as indicated by the crank pulley marks and timing gear as well as a piece of 1/4" bar stock, the cams were off by a few teeth. I was able to move the cams back in time. Looks like we're back in business.

 

[The_Eric]

Originally Posted By: kschachn
Help me out here, don't you line up the crankshaft timing belt pulley with a mark on the oil pump housing? Not the harmonic balancer. Sorry if I'm not getting it, I've changed lots of timing belts in Toyota engines but not this one.



This guy has it. Pull the damper and verify.

 

[nthach]

Originally Posted By: kschachn
Help me out here, don't you line up the crankshaft timing belt pulley with a mark on the oil pump housing? Not the harmonic balancer. Sorry if I'm not getting it, I've changed lots of timing belts in Toyota engines but not this one.


So here's what happened last night - I was able to get the crank bolt off, after breaking $27 worth of bar stock and bolts and a 600ft-lb Mac impact wrench failed to budge the bolt. I used the starter bump trick which I was hesitant on doing. Once I rotated the crank to TDC per the harmonic balancer marks, I pulled the balancer and I found the marks on the crank sprocket and oil pump. Those agreed. The right cam was off by 4 teeth and the left cam was off by 5-6 teeth. I used a thin steel bar to verify TDC via the #1 cylinder. I was able to retime the engine but it did jump out of time when I pulled the cam sprockets. I was able to move both cams without feeling a hard stop or hearing a clank - although the sudden release of valve spring tension was a little unnerving!

I was able to install the new OEM-spec timing belt and I rotated the crank 2 times and the marks on both the cams and the crank did agree with each other.

I was about to wrap it up but I lost the crank bolt - off to Toyota to order a new one!