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How To Get The Timing Back


dashan
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1996 LS400.

I am replacing the timing belt. I place the crank pulley 50 degree pass TDC.

I turn the left cam by accident when the belt is off. How can I get the left cam timing back?

Thanks

Just rotate the cam back in the opposite direction from where you first rotated it until you get back to the timing marks. Do not force it if you hear a metallic sound (like hitting valve(s)).

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1996 LS400.

I am replacing the timing belt. I place the crank pulley 50 degree pass TDC.

I turn the left cam by accident when the belt is off. How can I get the left cam timing back?

Thanks

Oh my God. If you do this wrong, you are going to be soooo sorry!

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Oh my God. If you do this wrong, you are going to be soooo sorry!

What's up with the 'DEATH_AWAITS_YOU' and your doomsday predictions. Death awaits all of us. It's what you do with your life until then that matters. Life is a journey not a destination.

If you are trying to come across as a nut job with that handle you've done so.

To OP: After you get belt on just check cam markers line up with lines on TB and same goes for the sprocket on the Crankshaft. If all the lines line up you are fine.

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Oh my God. If you do this wrong, you are going to be soooo sorry!

What's up with the 'DEATH_AWAITS_YOU' and your doomsday predictions. Death awaits all of us. It's what you do with your life until then that matters. Life is a journey not a destination.

If you are trying to come across as a nut job with that handle you've done so.

To OP: After you get belt on just check cam markers line up with lines on TB and same goes for the sprocket on the Crankshaft. If all the lines line up you are fine.

Hi, I am with you on both statements,..... he is some kind of a nut (need to remove him)

Dashan follow Landars post.. you will be fine.

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I turned the cam clockwise by accident. Per Landar's method I tried to pushed it back but could not go all the back to original position.

I think the easiest way for me is to realign all of the three marks of the belt to the marks at engine, respectively. The Crank is currently at TDC+50 degree.

My goal is: Crank at 0, and the cam marks on the timing belt align with marks on the engine.

I don't know I should turn each pulley clockwise or counterclock wise.

Could anyone have experiences please give me a writeup of the procedure (as detail as possible).

or is there a shop manual on how to do that?

Thanks

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I turned the cam clockwise by accident. Per Landar's method I tried to pushed it back but could not go all the back to original position.

I think the easiest way for me is to realign all of the three marks of the belt to the marks at engine, respectively. The Crank is currently at TDC+50 degree.

My goal is: Crank at 0, and the cam marks on the timing belt align with marks on the engine.

I don't know I should turn each pulley clockwise or counterclock wise.

Could anyone have experiences please give me a writeup of the procedure (as detail as possible).

or is there a shop manual on how to do that?

Thanks

If you rotated it CW by "x" degrees, you should be able to rotate it CCW by "x" degrees and get it back close to where it needs to be. The crank is at TDC+50 to give you the most clearance between valve and pistons. IOW, its a bit of wiggle room while putting on the new belt and to keep from damaging the valves if(more likely when) the cam snap-rolls due to spring pressure. How far, in degrees, do you estimate that you accidentally rotated the cam? You do realize that the cam will snap-roll? You may only be fighting the spring pressure to return it to original position, which is fine.

Take a look at this thread. Should be close -> http://us.lexusownersclub.com/forums/index.php?showtopic=61372&st=0&p=394040&hl=how_to&fromsearch=1entry394040

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I turned the cam clockwise by accident. Per Landar's method I tried to pushed it back but could not go all the back to original position.

I think the easiest way for me is to realign all of the three marks of the belt to the marks at engine, respectively. The Crank is currently at TDC+50 degree.

My goal is: Crank at 0, and the cam marks on the timing belt align with marks on the engine.

I don't know I should turn each pulley clockwise or counterclock wise.

Could anyone have experiences please give me a writeup of the procedure (as detail as possible).

or is there a shop manual on how to do that?

Thanks

If you rotated it CW by "x" degrees, you should be able to rotate it CCW by "x" degrees and get it back close to where it needs to be. The crank is at TDC+50 to give you the most clearance between valve and pistons. IOW, its a bit of wiggle room while putting on the new belt and to keep from damaging the valves if(more likely when) the cam snap-rolls due to spring pressure. How far, in degrees, do you estimate that you accidentally rotated the cam? You do realize that the cam will snap-roll? You may only be fighting the spring pressure to return it to original position, which is fine.

Take a look at this thread. Should be close -> http://us.lexusownersclub.com/forums/index.php?showtopic=61372&st=0&p=394040&hl=how_to&fromsearch=1entry394040

I put the crankshaft back, and confirmed that the Crank pulley was indeed at TDC+50 position.

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with the belt off, I think you can turn the CAMshaft pulleys clockwise with out any damage. I dont think you can turn it the other way, more than a fraction without damage. line the three up and put the belt on.

I got this info from others...... none of mine ever moved... so try to get confirmation..

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with the belt off, I think you can turn the CAMshaft pulleys clockwise with out any damage. I dont think you can turn it the other way, more than a fraction without damage. line the three up and put the belt on.

I got this info from others...... none of mine ever moved... so try to get confirmation..

Lexus should have manual to deal with this situation.

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The cam belt was the only job I let my local independant do so never experienced this problem but most engines have locking tools/pins fitted to prevent the cams from moving once the belt tension is off.Is it different with these engines?

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The cam belt was the only job I let my local independant do so never experienced this problem but most engines have locking tools/pins fitted to prevent the cams from moving once the belt tension is off.Is it different with these engines?

Yes, the cam(s) can snap-roll when you take the belt off or try to maneuver them when you put the new belt on. They only roll maybe 10-15 degrees so you can put them right back with a socket on the cam bolt. You will, however, be fighting the spring tension. But you can go "backwards" to get the cam to the original position. I would not think you should try to rotate the cam in any one direction a complete revolution. That would surely make the valves on that bank contact the pistons. The very reason for setting the crankshaft at TDC+50 is to allow for a little extra clearance between valves/pistons on the VVT engines. No cam locks required.

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If you rotated it CW by "x" degrees, you should be able to rotate it CCW by "x" degrees and get it back close to where it needs to be.

With this piece of information in mind and other suggestions from forum members, I DID put the belt back and each timing mark matched with their partner.

Thanks

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