LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

What's up with the cam timing marks on the VVT-I engines?

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Old 04-14-19, 08:44 PM
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dawson128
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Default What's up with the cam timing marks on the VVT-I engines?

Hello everyone! New member here.

I just picked up a 2000 that was due for it's timing belt. I've done some timing jobs before but not on an engine this advanced, just some older Honda's and Mazda 4-bangers. I was researching and I see that there are two timing marks for the cams, one is a straight line indicating TDC and one is a "T".. what is the T shaped mark used for?

I also read in the factory repair manual that the crank should be rotated 50* ATDC before removing the timing belt. Why is this?

Thanks for any help! I'm trying to learn as much as possible before going into this.
-Dawson
Old 04-14-19, 09:04 PM
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bradland
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The normal marks are for 0 degree (TDC).
When in this position the left cam is very susceptible to spring out of position. Advancing to 50 degrees moves the pulley notches to the "T" marks. The left cam is not under pressure in this position and the belt can be removed safely.
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spuds (04-16-19)
Old 04-15-19, 12:52 PM
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dawson128
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Originally Posted by bradland
The normal marks are for 0 degree (TDC).
When in this position the left cam is very susceptible to spring out of position. Advancing to 50 degrees moves the pulley notches to the "T" marks. The left cam is not under pressure in this position and the belt can be removed safely.
That was my suspicion but I just wanted to be sure. Thank you! Moving the cams to the T seems much more reliable than trying to measure 50 degrees at the crank.
Old 04-16-19, 12:00 AM
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bradland
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The little pin in the plastic timing cover helps to align the crank pulley into the correct position.
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