Top Dead Center

bmg97 · 08-14-2007, 03:03 PM

Hi, I have a 2000 XJ. How to I make sure the engine is at top dead center.

severous01 · 08-14-2007, 03:56 PM

pull #1 plug and stick your finger in there...move engine slightly with a big wrench or socket. when it stops moving upward, you're there.

also, you can use a starter but keep your finger out. use a piece of paper and ball it up...shove it in the hole and when the piston comes up on compression it will blow it out. just tap the starter to move the crank, dont hold it. this may take several times and you can test with a pen.

Blue XJ · 08-15-2007, 07:42 AM

Quote:

Originally Posted by severous01

pull #1 plug and stick your finger in there...move engine slightly with a big wrench or socket. when it stops moving upward, you're there.

x2

If you can get the right angle on it with a flash light you can see the piston moving too, obviously you'd need someone else turning the block. You have to make sure its on the compression stroke too, so when you have your finger in there, make sure there is air blowing out when the piston is coming to the top, if its not, your not on the compression stroke and have to wait until the motor goes around again.

Also, when I replaced my harmonic balancer, the timing marks on it lined up perfectly, so I am able to look at that to get it to TDC. However, my stock balancer did not line up that way, so it may not work for you.

JEEPINWI · 08-15-2007, 08:32 AM

There is a notch in the harmonic balancer that will line up with the zero timing mark to the right of the balancer when looking at it from the front. Why do you need to find TDC anyways?

bmg97 · 08-15-2007, 09:18 AM

Well I replaced the Cam Position Sensor in my truck because the other one was ticking. If it is not lined up right the truck will run like shi!. So I thought I had it perfect and now I have been driving with the check engine light on for about a month. I can really feel the loss of performace. I tried to search the Cam Position Sensor but there are really no articles on this. I saw the marks on the balancer. I will have to try and line it up again. Anyone ever have this happen?

08-14-2007, 03:56 PM	#2
severous01 Registered User Join Date: Jan 2006 Location: Hamilton, NJ Posts: 2,118 Profile Gallery Classifieds My Jeeps	pull #1 plug and stick your finger in there...move engine slightly with a big wrench or socket. when it stops moving upward, you're there. also, you can use a starter but keep your finger out. use a piece of paper and ball it up...shove it in the hole and when the piston comes up on compression it will blow it out. just tap the starter to move the crank, dont hold it. this may take several times and you can test with a pen. __________________ 1994 jeep cherokee, xj, 3" rough country springs / bilstein 5100's, 31" tires with trimmed fenders, aussie locked front diff, herculined ext, hella FF75 driving lights on factory fog location [COLOR="Lime"]soon to be[/COLOR] 4.11 gear and and a ford 8.8 LSD rear and herc'd interior

08-15-2007, 08:32 AM	#4
JEEPINWI Registered User Join Date: Jan 2003 Location: Eau Claire, WI Posts: 621 Profile Gallery Classifieds My Jeeps	There is a notch in the harmonic balancer that will line up with the zero timing mark to the right of the balancer when looking at it from the front. Why do you need to find TDC anyways? __________________ Brian- 99 XJ Cherokee, 2 door, 4.6L Stroker, 5 speed, 4x4, 8.25" rear, 3.07 gears

08-15-2007, 09:18 AM	#5
bmg97 Registered User Join Date: May 2005 Posts: 232 Profile Gallery Classifieds My Jeeps	Well I replaced the Cam Position Sensor in my truck because the other one was ticking. If it is not lined up right the truck will run like shi!. So I thought I had it perfect and now I have been driving with the check engine light on for about a month. I can really feel the loss of performace. I tried to search the Cam Position Sensor but there are really no articles on this. I saw the marks on the balancer. I will have to try and line it up again. Anyone ever have this happen? __________________ Brian [COLOR=Navy]2000 XJ[/COLOR]