Quick question on Timing Chain timing....... - PeachParts Mercedes-Benz Forum

deerefanatic · #1 02-11-2007, 10:53 PM

Well all,

My dad and I changed my timing chain Wednesday, when we did it, we ended up skipping a tooth on the cam sprocket... GRRRR......

I didn't realize it a first, I thought I had done everything right, but then upon closer inspection I saw that the pointer at the harmonic balancer was pointing at "18" and not "02". Turns out, that is the exact amount one will be off if they skip a single cam sprocket tooth.......... Not a problem, with the chain tensioner off, I was able to work the chain one link at a time around the sprocket and get it back in time..... (Now reads dead on "0" when the cam tower marks are lined up.)

I decided to check the IP timing while I was at it. It *appears* by just using the "welling-up" method to be about 20 degrees BTDC....... Not optimum I know, but that totally rules out having skipped a tooth on the crankshaft sprocket or IP drive sprocket, right?

Just wanna make sure..........

RAYMOND485 · #2 02-12-2007, 01:26 AM

1984 300d 142,000
Check The Cam Exaust Lope No 1 Is Pointing To The Left Drivers Side Of The Car Horizontally The Intake Will Be Pointing Toward To The Left 30 Deg To Make Sure The Piston Is At The Top If Not You Are180 Deg Off Slip The Chain One Tooth At Time On The Cam Gear When The Spring Out The Front Side Top Engine TENSIONER

deerefanatic · #3 02-12-2007, 11:49 AM

I've got the camshaft corrected, used that method.

I was just wondering about the IP. I was told by a member of another forum that due to the way the block is designed, it's basically impossible to skip the chain on the IP sprocket unless you drop the chain entirely down the chain galley.

Looks like I'm good to go!

Thanks!

GRIESL · #4 02-12-2007, 12:14 PM

Quote:

Originally Posted by deerefanatic

I've got the camshaft corrected, used that method.

I was just wondering about the IP. I was told by a member of another forum that due to the way the block is designed, it's basically impossible to skip the chain on the IP sprocket unless you drop the chain entirely down the chain galley.

Looks like I'm good to go!

Thanks!

I have same problem, so I'm curious to hear responses. I was told prior to head r&r that you could drop the chain in the case and not come off the crank, but nobody mentioned coming off IP. I PM'ed a dude who's been inside a 603 and he said if you saw the sprocket assembly, then you'd know there is no way to skip a tooth. He didn't know about the 617.

GRIESL · #5 02-13-2007, 02:05 PM

What would happen if when lining up cam timing marks the bottom crank was pointing to the Zero on the balancer, but the crank was in fact on Bottom Dead Center instead of TDC?

vstech · #6 02-13-2007, 02:37 PM

???

??? not sure what you are asking?

GRIESL · #7 02-13-2007, 02:49 PM

Quote:

Originally Posted by vstech

???

??? not sure what you are asking?

Well, here's the situation. Doing head replacement on a 617 turbo. Chain has skipped teeth on the cam during reassembly. Then chain felt like it was sticking down the case, so I tied the chain to a bungee overhead and spun it to kind of free it. Clearly not a good idea. So, I got bottom crank on zero and lined up the cam timing marks. Thought I'd be good to go. But the car is running real rough--way off timing has got to be the problem. So, I'm trying to rule out the timing chain having skipped a tooth on the IP as well. If the bottom turns twice for each turn of the cam, then isn't it possible that I'm off between those two gears? But it seems the only way I could be off is by 180deg., and that seems like the valves would definitely be hitting pistons, right? I turned the engine by hand before starting to ensure no contact between piston and valve. Any help is greatly appreciated.

vstech · #8 02-13-2007, 02:59 PM

ahh, well many things are possible, you could be 180° out IP / cam timing, you could have the timing off a tooth or so, if you did not remove the IP, it is unlikely to be out of time with the crank, but the cam could be out of time with the IP/crank.
John

GRIESL · #9 02-13-2007, 03:01 PM

Quote:

Originally Posted by vstech

ahh, well many things are possible, you could be 180° out IP / cam timing, you could have the timing off a tooth or so, if you did not remove the IP, it is unlikely to be out of time with the crank, but the cam could be out of time with the IP/crank.
John

Would 180 off on the cam jam valves into pistons?

vstech · #10 02-13-2007, 03:07 PM

no, I don't believe so. crank will be in same position either way, but 180° out, you will have valves open when the fuel is injected... kinda hard to run.
John

GRIESL · #11 02-13-2007, 03:10 PM

Quote:

Originally Posted by vstech

no, I don't believe so. crank will be in same position either way, but 180° out, you will have valves open when the fuel is injected... kinda hard to run.
John

So cylinders could still build compression on a compression guage with cam off 180?

vstech · #12 02-13-2007, 03:14 PM

yes, I believe so, just fuel will not be close to correct time.
John

vstech · #13 02-13-2007, 03:15 PM

don't get me wrong, the thing can still run this way, it will just be REAL rough, and very hard to start. also it could easily be prone to Run away conditions too.
John

GRIESL · #14 02-13-2007, 03:21 PM

Quote:

Originally Posted by vstech

don't get me wrong, the thing can still run this way, it will just be REAL rough, and very hard to start. also it could easily be prone to Run away conditions too.
John

You are shedding lots of light on this. Tell me more about the runaway conditions. Would that explain car not turning off with key?

vstech · #15 02-13-2007, 03:31 PM

probably not, runaway means there is a unregulated amount of fuel being injested by the motor resulting in over revving of the engine and destruction of the motor, in your case, the car not shutting off, is probably due to vacuum and the fuel shutoff.
but if the cam is indeed 180° out from the IP, then the pump could be throwing a lot of fuel in there that is not getting combusted until the third or so pass at the compression. this could cause a small runaway, and be very dangerous.
if you do have it 180° out, it's kind of hard to fix, so be sure before you proceed. only way I could think of fixing it short of pulling the head back off, would be re indexing the IP. or removing the cam itself. get the instructions here with a search for ip timing or replacement, and cam marks or something... I have never done this on this type of motor, so I am useless here.
but I would think with the Valve Cover off, you should be able to verify cam to crank timing, then verify IP timing with a drip tube or something.
John