OM616.912 Camshaft Timing Question - PeachParts Mercedes-Benz Forum

240D.Bill · #1 10-19-2016, 10:32 PM

I checked my camshaft timing using a dial gauge on #1 intake. I don't know of another way so I'm doing it by the book. My camshaft code is 02 so at 2mm of lift I read @ 15° after TDC(spec being new chain 11.5°/used chain 13.5°). How on earth anyone can see resolution within 0.5° is inconceivable to me on these counterbalances. I'm a perfectionist to a fault so I want to achieve the specs but...

How do I know if the timing indicator isn't off by a couple degrees? Does someone know if they are adjustable or prone to installation error/wrong part from previous owners?

I'm in the ballpark I suppose. A 3-4° woodruff key will get me to 'new chain' spec. It just seems like there is little tolerance for error with a lot of factors which could be throwing me off. Maybe I'm just overthinking this...

Stretch · #2 10-20-2016, 04:35 AM

Quote:

Originally Posted by 240D.Bill

I checked my camshaft timing using a dial gauge on #1 intake. I don't know of another way so I'm doing it by the book. My camshaft code is 02 so at 2mm of lift I read @ 15° after TDC(spec being new chain 11.5°/used chain 13.5°). How on earth anyone can see resolution within 0.5° is inconceivable to me on these counterbalances. I'm a perfectionist to a fault so I want to achieve the specs but...

How do I know if the timing indicator isn't off by a couple degrees? Does someone know if they are adjustable or prone to installation error/wrong part from previous owners?

I'm in the ballpark I suppose. A 3-4° woodruff key will get me to 'new chain' spec. It just seems like there is little tolerance for error with a lot of factors which could be throwing me off. Maybe I'm just overthinking this...

I have checked several Mercedes engines and the position of the TDC pointers to make sure everything is OK. I've found that the pointers are pretty much bang on - may be a slight hair's breadth out - but they are good in the context of what they are meant to be used.

The "2mm lift" test is worth completing a few times to make sure you are getting consistent readings.

Make sure your head is in the right position too! If you don't look straight down at the pointer then you might be able to get a variation in your reading.

If you really want to check the pointer try and find TDC. I've used a version of the method in chapter 03-345 (dropping the valve on the piston crown) to find TDC before - make sure the piston is near the top of the cylinder though...

...as the offset keys - well I think they don't do what they are meant to do. I've played about with measurements and think that they adjust for slightly smaller values =>

OM617 (non turbo) cam profile specs, piston height specs etc

I might be wrong - see what you think. The acid test is to fit one of the keys and see if it does indeed make the difference it is meant to do - I've not done that. I opted to change the chain for a new one because the age of it was unknown.

Diesel911 · #3 10-20-2016, 11:43 AM

Quote:

Originally Posted by 240D.Bill

I checked my camshaft timing using a dial gauge on #1 intake. I don't know of another way so I'm doing it by the book. My camshaft code is 02 so at 2mm of lift I read @ 15° after TDC(spec being new chain 11.5°/used chain 13.5°). How on earth anyone can see resolution within 0.5° is inconceivable to me on these counterbalances. I'm a perfectionist to a fault so I want to achieve the specs but...

How do I know if the timing indicator isn't off by a couple degrees? Does someone know if they are adjustable or prone to installation error/wrong part from previous owners?

I'm in the ballpark I suppose. A 3-4° woodruff key will get me to 'new chain' spec. It just seems like there is little tolerance for error with a lot of factors which could be throwing me off. Maybe I'm just overthinking this...

I think the 4 degree offset key is the smallest increment available. In theory that would return the camshaft timing back to 11 degrees ATDC.
I don't believe these engines need absolute precision.

leathermang · #4 10-20-2016, 12:37 PM

After any change in the chain be sure to reset your IP timing. The FSM method of using one drip per second is good because it is a bottom line measurement... wear on parts may be cumulative... or may counteract each other... the one drip deals with the reality of the moment for the setting...

Dan Stokes · #5 10-20-2016, 03:24 PM

Hey Bill -
I have briefly owned a 616 (I stole the trans and sold the engine to a friend with the body going to PnP) but I've been messing with my 617 for a while now (same engine, just 1 more cylinder). Perfection is NOT required with these tough ol' engines - close enough is good enough and they're not too fussy about minor timing issues and things of that sort. Remember that taxi drivers all across the third world keep these suckers running acceptably with a tire iron and aluminum cans. Sorry, but these guys won't run much different if you strive for perfection!

I have one of the fastest 617's in North America (223 RWHP, 129.6xxx mph, real data from a dyno and a race track) and I honestly don't know exactly what my cam timing is! I TRIED to resolve this but it was kicking my butt and race weekend was coming up so I threw it back together and it ran just fine.

So don' worry, be happy.......

Dan

jay_bob · #6 10-21-2016, 11:55 AM

Agreed. These are some of the toughest engines on the planet in a consumer motor vehicle. Get the timing in the ballpark and enjoy driving your car!

240D.Bill · #7 10-23-2016, 04:27 AM

Thanks Dan. LOL Fast... not often heard in reference to these but I'd love to see your track runs. I hear ya on the details of the devil thing. This is my second 240 which I'm pampering for no apparent reason. My first would probably still be going but I let my ex-wife use it. Worse yet, I let the car go before her.

240D.Bill · #8 10-23-2016, 04:38 AM

Theres a vendor selling 2, 3, 4, and 5° offsets for the OM616.

240D.Bill · #9 10-23-2016, 04:43 AM

Quote:

Originally Posted by leathermang

After any change in the chain be sure to reset your IP timing. The FSM method of using one drip per second is good because it is a bottom line measurement... wear on parts may be cumulative... or may counteract each other... the one drip deals with the reality of the moment for the setting...

ThTs something I've never done so I'll have to set down and figure out what I need sometime. Sounds fun. Thanks for the advice. I meant to pose that question as well but was hell bent over a few degrees to the left or right.

Dan Stokes · #10 10-23-2016, 09:25 AM

Quote:

Originally Posted by 240D.Bill

Thanks Dan. LOL Fast... not often heard in reference to these but I'd love to see your track runs. I hear ya on the details of the devil thing. This is my second 240 which I'm pampering for no apparent reason. My first would probably still be going but I let my ex-wife use it. Worse yet, I let the car go before her.

There's some video posted here - something like "Mutt Goes Down The Track" or something. Search for "Mutt".

Dan

240D.Bill · #11 10-24-2016, 01:32 AM

Quote:

Originally Posted by Stretch

I have checked several Mercedes engines and the position of the TDC pointers to make sure everything is OK. I've found that the pointers are pretty much bang on - may be a slight hair's breadth out - but they are good in the context of what they are meant to be used.

THATS REASSURING. THANKS

The "2mm lift" test is worth completing a few times to make sure you are getting consistent readings.

DID THAT FOR SURE.

Make sure your head is in the right position too! If you don't look straight down at the pointer then you might be able to get a variation in your reading.

ROGER THAT.

If you really want to check the pointer try and find TDC. I've used a version of the method in chapter 03-345 (dropping the valve on the piston crown) to find TDC before - make sure the piston is near the top of the cylinder though...

NAH! I'M GOOD

...as the offset keys - well I think they don't do what they are meant to do. I've played about with measurements and think that they adjust for slightly smaller values =>

I MAY TINKER WITH IT SOME MORE BUT FOR NOW IM JUST HAPPY ITS RUNNING. THROTTLE RESPONSE IS SLUGGISH... NEED TO RESEARCH THAT ONE.

OM617 (non turbo) cam profile specs, piston height specs etc

I might be wrong - see what you think. The acid test is to fit one of the keys and see if it does indeed make the difference it is meant to do - I've not done that. I opted to change the chain for a new one because the age of it was unknown.

I'LL GET A KEY BUT I'M ONLY GOING TO USE IT IF STRONGLY SUGGESTED FOR OTHER SYMPTOMS I ENCOUNTER.

Settiing up dial gauge was 95% of the procedure. The tip of the wasn't long enough to reach the valve/spring keeper. I used a metal shim and a few neodymium-magnets to secure it to the top of keeper(like a diving board) to measure from the same plane and get the probe perpendicular... and if someone reads this reply out of context... I'll probably need a new username.