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6.9 cam timing marks

Started by ramiro, 29 September 2023, 08:08 AM

ramiro

Hello,
I am still fighting with my 6.9 that is overheating and also has no real power above 4000 rpm and top speed is also only ~ 200 - 210 GPS and the idle is always a litte lumpy so my idea that maybe everything is connectet somehow.
I checked the ignition and also the fuel system and both are completly fine , so today i decided to remove the cam covers and check the timings.

All 3 timing marks ar perfectly aligned , so i decided to check the timings by checking when the intake valve on the 1 first Cylinder opens , and i found after measuring 4 times the same thing that i opens 5 Degress after TDC instead of 14 like it should be.

I measured the other side and hit is around 20 so it is retarted , actually if i would change the other 1 toth both cam shafts should match.

Has anybody checked their timing marks on a 6.9 if they are correct ?
I spoke with an engine builder and he told me that he had mercedes engines where the mark was of by half a teth.
Thank You
Ramiro


daantjie

Maybe post pics of your timing marks.  It's been a while since I looked at this stuff but as I recall the driver side (LHD) cam must line up with damper mark at 0.

There are offset keys available to finesse the timing. Do a search I'm pretty sure some members have run into this issue.
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

Some cam mark pix HERE with a lot more details on cam timing.  Might be helpful....  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

rumb

Are you following procedure 05-215 in the 100.985 engine manual to check valve opening? It mentions valve lift of 2mm when checking.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

ramiro

#4
Yes i followed 05-215 exactly also changed to lifter to manual adjustable ones.
My marks are exatcly centered , i would even say that in the other thread on mark is 0.1 mm off that my isn't.
I retarted the passenger side cam 1 tooth but now it seems to be at ~ 28 after tdc also far away from spec(14 at 2 mm intake valve lift) i don't know why it is not at around 20 because 5 + 18(1 tooth) should be 23 not nearly 30.

One more thing when i got the car the same cam that is now out off adjustment was 1 tooth off the timing mark and i corrected(but only checked the mark not the actual timing) it suspecting that i found an issue but now it seems that it was maybe more correct.

EDIT:
I rotated the engine 1 more around with the chain tensioner in place and now it is around 25 also when on the mark it shows 15 Degress off same like when i got the car , this setup actually makes much more sense it would mean that my chain is stretched around 6 - 8 degress one the driver side and around 10 -12 on the other , but i still don't understand why the mark is not matching ?

rumb

Im a bit confused by some of your statements.

"All 3 timing marks are perfectly aligned"
and
"my chain is stretched around 6 - 8 degrees on the driver side and around 10 -12 on the other"


With 10-12 stretch (that is the spec limit) it seems to be time for a new chain. It's normal for each side to be different on an older engine.  Even MB expects ~4 degrees stretch after 20K.If 
you use keys at some point it wouldnt hurt to add a degree or 2 initially.

BTW on my 300se a new chain I could definitely feel better power.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

ramiro

#6
Ok to make it clear :
All timing Marks aligned :
Driver side (left) intake valve opens(2mm) ~ 20 after TDC
Passenger side(right) intake valve opens(2mm) ~ 5 after TDC

Passenger side one toth retarded and timing mark for that cam aligns at 15 degress after tdc on the crankshaft:

Driver side (left) intake valve opens(2mm) ~ 20 after TDC
Passenger side(right) intake valve opens(2mm) ~23 after TDC

So i am really confused if mercedes machined the groove for the camshaft gear wrong on 1 cam

ramiro

To be sure i confirmed the measurments again today (0.1 mm vavle could already make a degree difference) and got the same like yesterday 23 right side and 20 left side.
So should i correct it using the special wedges or use a new chain normally i would think that the chain is somehow worn to the gears and it would be better leave it in ?

Attached some pictures from the results.
I set the dial at exatctly at 3 mm on when the valve was closed , so you can see it went exactly 2 mm.

rumb

So if spec is 14 and you are now at 20 and 23, that means you are off by 9. 10 is the limit, so I would pull a new chain in. Assuming your guides are fine the gears should be also, though look close at the cam gears at least. Those are easy enough to replace if needed.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

ramiro

Just wanted to give a feedback , i put the chain in and enjoyed the car for 3 weeks now , the car drives much much better has really got power above 4000 now and the idle is sometimes smooth never got that before

Different fight was the CIS 2 months ago i suddenly had huge trouble with the CIS doing whatever it wants sometimes rich sometimes lean changed the fuel distributor and did not change much , put injector cleaner in the tank and it got much better with the previous distributor that i bench tested before, but still not perfect , so today i decided to change the 2 year old MANN fuel filter and it turns it had dissintergrated inside and put all the dirt into the system , never had that before.

The new chain ended up with 10 (as spec for a new chain) on the passenger side , and 16(should be 12 for a new chain) on the driver side.

daantjie

Pretty sad that once great manufacturers are now also producing garbage.  Just look at how bad Bosch has gotten over the years :o
Daniel
1977 450 SEL 6.9 - Astralsilber

ptashek

I exclusively use Mann, and their secondary brand filters in all my cars since I had cars. Many, many moons at this point.

Haven't had a single issue. Ever. There's always a chance of something slipping through QC in a batch. I wouldn't discard the entire brand as garbage based on a single case.

And they absolutely deserve credit for still making fresh filters for 40+ year old cars too :)
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ramiro

Crazy what a difference the cam timing makes , before the car refused to go faster then 220 on the speedometer now on a semi flat autobahn it goes to 240.
Also attached a picture of the broken filter , and it defintive was loose before i opened it, because i could hear it moving around inside when i was shacking the filter.

ptashek

Looks like that filter was due for replacement years ago.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ramiro

Years ago that Filter was not even made , i bought that filter in Dezember 2020 and drove 20000 KM with it , or is the interval 1 year and 10000 km ?
The metal cap that was glued on was already off before it took the filter apart for me it looks like the glue failed.