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cdgreen76 05-19-2011 12:33 PM

Tob Dead Center (TDC) and timing issues
I recently replaced my timing chain and sprockets but I think I did not set the TDC correctly. I forgot to put the trans in Neutral when I turned the crankshaft with a socket. Do you think putting it in Neutral makes that big of a difference? I plan to go back in and do it the correct way but what I don't understand is for the engine to be at TDC should just the #1 piston be at TDC for correct timing?

According to the Haynes Repair Manual step 9, After the #1 piston has been at TDC, TDC for any of the remaining cylinders can be located by turning the crankshaft 120 degrees and following the firing order. I don't understand why the book states this info. Should all pistons be at TDC?

If anyone gets this, Please explain it to me so that when I go back in I can complete the job.


2005JGC 05-19-2011 03:38 PM

Re: Tob Dead Center (TDC) and timing issues
I am assuming your dealing with a 4.0 because you said timing chain (singular)... just line the marks up on the sprockets, by hand roll the motor over 2 times and make sure the lines match back up... the gear selection doesnt matter on an automatic as the torque converter wont transfer motion moving as slow as you would roll it over by hand.

cdgreen76 05-19-2011 04:27 PM

Re: Tob Dead Center (TDC) and timing issues
Thanks for the quick response.
Yes, I have a 4.0. I appreciate the info. :eek: And Thank for also confirming that I did the job incorrectly. :(

One other question. I have read that I need to take it to the dealership and have them use the DRB3 tool to program the computer. Is this really necessary?

Thanks again for the assistance. :cool:

Frango100 05-19-2011 07:09 PM

Re: Tob Dead Center (TDC) and timing issues
With "the computer" you probably mean the PCM (Powertrain Control Module)? It all depends on what you did, if it is only for the timing chain change, then there is no need for any programming. If you changed the PCM, then the dealer has to program the VIN into the PCM and if your car has the Sentry key system, then also the secret code has to be programmed.
And regarding your Haynes manual, i think that they only put it as an info regarding the 120║ crankshaft rotation for finding the TDC for each cylinder. You won┤t need it for the timing chain adjustment.

cdgreen76 05-20-2011 07:43 AM

Re: Tob Dead Center (TDC) and timing issues

2005JGC 05-20-2011 02:58 PM

Re: Tob Dead Center (TDC) and timing issues
hehe, seems alldata changes their picture locations around... that is not what I posted... first post edited, picture of timing setup that changed to something else was removed.

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