hey there so when the timing chain and gears were removed from 1997 land rover discovery.......

BOTH gear marks were at 12 o'clock ......for refit the overhaul manual states

Timing gears - refit
1. Clean gear locations on camshaft and
crankshaft, fit Woodruff key to crankshaft.
2. Temporarily fit crankshaft gear and if
necessary, turn crankshaft to bring timing mark
on gear to the twelve o’clock position, remove
gear.
3. Temporarily fit camshaft gear.
4. Turn camshaft until mark on camshaft sprocket
is at the six o’clock position, remove gear
without moving camshaft.

is this right??

also please explain....why if this is correct ....

thanks can't get my head around it....

 

In addition to my other response; If you keep turning the crank the gears should line up. Cam gear is 40t, crank 20t. For every turn of the crank the cam turns 180 degrees.

 

They have to be in this position to ensure proper timing or phasing of the engine. That is, the proper lobe on the cam actuating the proper valve in the firing order.

I would be curious to see where your timing mark on the harmonic balancer was with the #1 piston at TDC.

I would re-asemble it per the manual...both timing marks aligned, one on top of the other.

 

ok so from reading other sources and understanding what yall are saying ....the camshaft turn at half the speed of crank so therefore if I .....replace timing set up and turn to next instance of TDC the marks should be lined up at 6oclock on the cam 12oclock on the crank..... I am goin to do it this way rather than turn them independantly....the manual acts like doing it independantly is fine but since I cant figure out why I will just turn them together.....

hh65flyer...my camshaft gear was at 12oclock at removal my crank gear at 12oclock also.....so 1turn of the crank should bring the cam gear mark back to 6 oclock....as desired......ohhh....the physics of two sized gears ...

thanks

 

Turning them together or independently doesn't matter. As long as piston 1 is at TDC, crank at 12, the cam can be at 6 OR 12. Think about how a 4-stroke works for a while and it'll make sense

 

I have a simple question. After she completes the assembly with the timing chain in place, can't it be rotated by hand slowly just to see that everything is properly aligned or is that not feasible?

I ask because i have never had to tear into any engine internally myself.
Have done the grunt work tearing one out and replacing it many years ago, but had friend who got us another friend professional garage one weekend.

I know the details are critical and can make a first timer doubt things or feel lost or uncertain. I would want to know if there were such a simple check.

Also any tips for that first time you do spin it over with it complete. Like tom brought up about disconnecting fuel pump at the underhood inertia switch so you could spin it with the starter to avoid a dry start after oil changes. Sounds like you may want to do that prior to first real run.