jcalhoun

Changing the timing belt on my 2005 RX330. I have watched lots of videos and read lots of DIY articles and forums. Most of my questions have been answered but I still have a question related to top dead center.

Do you get to TDC simply by lining up the timing marks on all 3 of the timing gears or is there something else that you also have to do in addition to lining up the marks?

I understand TDC is critical but I am confused about how TDC is actually achieved. I am thinking all I need to do is align all the timing marks on the gears and on the belt. Am I missing something or is it that simple? I definitely don't want to jack something up by not having TDC correct.

FYI, I have the old belt removed and am ready to install the new belt.

Thanks in advance. I am new to the forum and it has been very helpful so far.

kiwi

When in doubt, pull number one spark plug and gently insert a long skinny screw driver, if its at the top, then you are good to go (along with the marks lined up.

on another note, hopefully you bought an OEM belt with marks on the belt to align with the pulleys, makes life much easier.

jcalhoun

So do I have it right that lining up all the timing marks should bring it to top dead center without having to take any other steps?

HtownBlue

TDC is achieved by turning the CRANKSHAFT to proper alignment with respect to the timing marks. If I recall correctly, the crankshaft has a white Dot or line that lines up with a white line or arrow that is located on the block itself. When this is achieved the #1 piston is at TDC. The two cam shaft pulleys up top each have a white mark that should align with a mark as well, and the belt has 3 separate lines that should align very closely with the aforementioned marks.

The simple answer to your question, is that when the crank shaft marking is aligned with the mark on the engine block, the #1 cylinder is TDC.

jcalhoun

Thanks for the replies, they were helpful.

smassey321

Keep in mind that the crank rotates at 2x compared to the cam. TDC in regards to timing belt is when the piston 1 is all the way up and all valves are closed.