DESPERATLY needing moderator's and expert's advice. - PeachParts Mercedes-Benz Forum

newr · #1 02-09-2005, 02:40 AM

I posted this question in another thread on the 2nd page Free 1991 420SEL and nobody seemed to give me a solid answer so I am turning to you experts for help. PLEASE HELP!!!

I am in the process of installing the rebuilt heads on the 420SEL and running into this problem.

The manual instructs to turn cylinder 1 to TDC which I did (1st picture). The woodruff key on camshaft should point up (2nd picture). I am confusing as to exactly which direction UP it should be? Should it be up perpendicular to the ground (3rd picture) or up perpendicular to the head (4th picture). Is there any referenced mark on the first camshaft bearing or anywhere for the woodruff key to line up to? Is the process the same for both camshaft?

Thanks.

gmaltz · #2 02-09-2005, 03:54 AM

Newr - Calm down, take a deep breath, no need to panic. Think. The crank is at TDC on #1 , right? The cam gear can only go on one way because of the woodruf key. Up means not down. Perpendicular to the head or ground does not matter because with the chain on, the cam gear has to line up with the timing mark on the head. As long as that timing mark is set on both cams, with the chain on, your ok.

Now look at the position of the cam lobes for the #1 cylinder. The exhaust lobe will open next when the piston fires down and then returns up to push out the spent gases and then close when the piston is on the down again.

The intake lobe just opened and closed to let in the fuel mixture right before TDC, so its lobe sequence is behind the exhaust lobe.

When you have the chain on, you can check by slowly rotating the engine from the crank (spark plugs removed) while looking at cam for #1, right on the engine stand

Think simple, like a four stroke lawn mower engine for the #1, the rest of the cylinders will follow, like sheep.

Hope this helps.

126nut · #3 02-09-2005, 08:57 AM

Like Gmaltz says and like I told ya in your other thread. You need to get the cam gears on and look for the marks.

Now please, STOP WORRYING ABOUT THE WOODRUFF KEY!!

newr · #4 02-10-2005, 11:40 AM

Ok I am calm down and not worrying about he woodruff key anymore

.

The manual got me confused (yeah, blame it on the manual

. I think I have figured it out. It turns out that the timing mark on the cam is the same position as the woodruff key. There is also timing mark on the camshaft first bearing/tower. Right now, the cylinder #1 is at TDC and both camshaft timing marks line up with the bearing/tower marks so it should be good to go. I will turn the engine over by hand a few times and see if everything is in sync.

Thanks for the HELP!!. and I will keep you posted in my orgiginal thread.