need to locate TDC - Ford Forums

lisadan · 06-14-2007, 08:56

Have a 1997 f150 4.6l v8. Have pulled motor from truck as compression test showed zero in cyl #4. Need to find TDC now. Thanks.

thefonz · 06-14-2007, 18:56

Pull #1 spark plug out, have someone turn engine by hand while you hold your finger in plug hole. When you feel compression coming out, look in plug hole and watch piston. When it reaches the top and just starts to go back down, that should be TDC, Check timing marks to get right on.

lisadan · 06-15-2007, 09:02

thanks for the reply, we are pulling our hair out here. Would it make any difference if the timing chain has skipped a tooth or two?

thefonz · 06-18-2007, 15:18

Quote:

Originally Posted by lisadan

thanks for the reply, we are pulling our hair out here. Would it make any difference if the timing chain has skipped a tooth or two?

Would what make a difference?
Zero compression on #4.... no
Timing issue... Absolutely

wwb · 06-19-2007, 14:58

Zero compression on a cylinder (assuming all the others are okay)....

Rings totally shot.... usually indicated by huge blue clouds, fouled plug, and more oil consumption than gasoline consumption.

Busted valve spring or keeper - valve not seating.... pull the valve cover

Busted con rod...... you would have heard it

Blown head gasket.... pull the head

Badly burned valve..... pull the head