Pagz

Hello Guys,

Not too much info on this topic with M112/113, hoping one of the MB techs or someone with hands on experience can help me out here.

I have a donor 113.984(CLK55) with 150kkms and looks to have been run on full synthetics at 18 - 20kkm changes.

WIS says the used chain timing calls for 25 ATDC @ 2mm lift on the intake valve both sides of the V.

When I test this I am using my dial gauge onto the centre of the top of the rocker directly above the lifter, I'm doing this to remove lash from the lifter...Is this acceptable?

The readings I get are 31 ATDC both sides, which I would have thought if chain stretch was apparent there would have been noticeable difference in values between the two sides. (when I go direct onto the valve its about 35 ATDC)

Now what is interesting, when you install the cam locking plates you install the right hand first, then when installing the left hand you need to turn the cam sprocket anticlockwise some ~2-3 degrees to allow the locking plate to bolt down.(yes never turn anticlockwise)

Now assuming there is no chain stretch due to the fact the values are equal both sides, Is it more than likely the play is coming from guide rail and/or idler pully?.

Your thoughts?

cm60k

Very good input Paul,

Honestly, i don't have an idea, there are an Excellent professionals here got a value info., "Shardul/Blackbenzz/MarcusF",,

ZAYED,,

Pagz

Thanks Zayed,

Also ,
-When only right hand cam lock in position crank angle reads ~48 Degree's.
-When only left hand cam lock in position crank angle reads 40 Degree's.

so when both cam locks are in place chain between the cams is slack and crank angle is 40 degree's.

I assume this is coarse measurement and maybe cam locks are not very accurate,however I would imagine the right side should be much closer to 40 degree's?.

Maybe wear is happening in upper guide rails? and also the left hand rail(causing the 31 ADTC @ 2mm)

Ausmbtech

I would suggest just replacing the chain and tensioner while you've got the engine out, it's pretty easy to do and then you wont worry about it. The guides don't seem to give any trouble on M112/M113's so I wouldn't do them unless the timing case off for some reason as you need it off to replace them.

The easy way to change it is to attach the old chain to the new chain and feed it through.

Pagz

Ausmbtech,
I guess I just want to prove there is a problem before making the next move. It feels like there is something not right about how I have checked the timing. WIS gives you values for timing but I cannot find a procedure to use them with.

Unfortunately I don't have the right tools to draw a chain through and crush the link. the engine is in long block form , if need be I could remove the timing case and redo the sealant...I have the MB corking gun and sealant for this.
The valve seals are weeping just slightly so would like to do these(C43 engine was dry) ,I will need to modify my standard valve spring compressor to work from above and pressurise the cylinders...or take the heads off.

Pagz

One thing I cant seem to get my head around is the chain distance from left hand sprocket to crank is nearly half the distance of the right side, so if there was chain wear would you expect the values to differ between left and right banks by near 1:2 of the stretched value?.( I must be missing something out here surely with 150kkms there will be some stretch?... though I have seen people say they have zero stretch at 80km miles which isn't too far of what this has done)

cm60k

Paul,

Shardul suggest to check the timing with the crank pulley set to 40 degrees....

ZAYED,,

Pagz

Zayed,

Yes sure,I mentioned that with locking plates in the left hand sprocket is exactly 40 degree's but the right side locks in around 47-48 degree's. so when locking plates are both in the crank is exactly on 40 degree's but of course the left side makes it this way because its closest to the crank....with both locking plates in there is slack in the chain between the two cam sprockets. that's why I think there is wear somewhere or is this normal?

The more accurate way to measure is at 2mm valve lift, for the intake valve on an M113.984 WIS says 25 ATDC with used chain, I assume this means this is the maximum value above a new chain? I get 31 ATDC on both right and left banks which is theoretically 6 crank degree's stretch..., I am not confident I am correct.

Ausmbtech

The distance from the crank to the cam (or cam to crank) is half the distance from cam to cam, so the difference cam to cam will be twice are large.
This pic should help you see the length. Why I have this pic is a topic for another thread coming soon.....
Sounds like the chain is stretched, the cam locks are usually no more than a 1-2degrees out.

Pagz

Thanks for the pic!( mbworld needs to host pics locally and I need to figure out how to convert the images from WIS!)

Walk me through the stretch theory.. I have checked intake valve lift at 31 ATDC - both sides are equal. If the chain was stretched wouldn't the CA value be different between the cam sprockets due to the difference in chain length?

Lets make assumptions, say a new chain is 22 ATDC and I have tested my used chain as 31 ATDC on the right sprocket,so that's 9 degree's stretch, that would mean I should get 25 degree's on the left sprocket no?? (3 parts stretched equally is 3 degree's each left sprocket has one part the right has two parts chain)

I will re measure the cam locks to see how far they are out, are you saying 1-2 degree at the cam or crank?

Thanks for your help.

Ausmbtech

The cams aren't particularly aggressive on any MB engine, The cam lift method can be a little hard to use.

Basically with the crank at 40ATDC the cam locks should fit and at most only a small amount of rocking on the crank pulley to make them fit. If the cam locks don't fit in easily turn the crank shaft *1* rotation only and retry. The will change the loading on the cam from the valve springs and will make a slight change on the way the timing chain is loaded. If it still doesn't fit then the chain is stretched.

Standing in front of the engine the LH cam is usually the one that the cam lock wont fit if the chain is stretched.

If there is a lot of stretch I'd suggest change the cam gears too, they are relatively cheap.

blackbenzz

How many people have seen a stretched chain on a m113? They are pretty heavy duty. The cam lock tools fall in when I set crank to 40. I would replace cam gear bolts

cm60k

Bro,

Is those bolts in somehow could loosen-up, or if someone touches them....??

ZAYED

blackbenzz

They can stretch and end up shearing the key in the cam gear. If not properly torqued I guess they could loosen. I doubt this has anything to do with the op though

Pagz

That's exactly why I want to check it properly before install, because everybody only replaces them when they get funny noises...no one seems to preform checks up until then, I'd rather do it now than when its in the car and I'd rather not do it at all if I dont have too because it's expensive.(the chain alone is $520nzd)

Does the ECU flag the differences between Cam the Crank sensor angle as they change over time? Is it possible to view this in SDS?

Ausmbtech

I've only seen 1 M112/113 chain stretch and heard about 1 other. Both had very very poor service histories. The may start to pop up a little more often as they are getting older though.

There is a online Benz dealer in the US I use, timing chain $173USD, tensioner $104USD, cam gears $92USD each. There are cheaper OEM ones available, this is just to give you an idea.

Pagz

Ausmbtech,
Thanks,Thats alot cheaper than through the dealer here, Which site are you using?

Cheers.

Sulaco

My chain is rattling like crazy. I hope it's just the tensioner. But, 267,000 miles...

Pagz

Sulaco,
I'd get that checked asap!. also check your oil pump chain tensioner looks like those go slack too and hit the timing case.

Guys,
How do you check the camshaft number? Do you have to remove the sprocket to see it?...WIS says it's on the sprocket flange but it ain't there as far as I can see.

I ask because I checked the exhaust valve timing last night, the value should have been 35 BBDT but instead I got 25 BBDT, 10 degree stretch!? but hold on shouldnt it also be 6 degree off like the intake was...ironically the 31 on intake and 25 on exhaust lines up with specs for the M113 5.0L's.

Does anyone know why part my numbers like the timing case, flexi plate, water pump etc do not show up in EPC?.. they only show up as used parts when I google them.

Pagz

Ok checked the cams with sprocket off there are no numbers on the flange what so ever.

cm60k

Paul, Is your Engine #: 983 or 984...??

All parts should appears to the EPC, even if not put complete Engine #, if you forward your Vin #,

we could see why some parts not shows-up....!!

ZAYED,,

Pagz

Hello Zayed,

its 984, WDB2083742F158434, all parts show up in EPC, its just that the parts I actually have dont. I checked with my local dealer and they do not show up there either, we assume because they were superseded shortly after manufacture.

Actuals:

Front timing cover - R112 015 10 02 10
Water pump - A112 201 03 01
Flexi plate A112 032 02 47

I was really hoping to check the camshaft code numbers so I could confirm my timing values, it seems this is harder than it looks.


Regards,
Paul

cm60k

Paul,

All these #s you mentioned are an oldy factory #s,

the new #s after 2004 is:

1) Front timing cover, if you mean (Timing case), it should be "112 010 06 33"

2) Water pump, should to come with "112 200 14 02"

3) Flexi plate, if you mean (Flywheel). it comes with "628 030 00 12"

ZAYED,,

Pagz

Thanks Zayed,

I have an interesting suggestion for you to consider... Maybe my cams are worn? Check EPC...there is a note saying stock of early cams should no longer be used , here is my reasoning:

1. Intake timing values are 6 degree over, exhaust is 10 degree over, these values would be same if chain was stretched?.

2. Intake values for both left and right heads are 6 degree's, these would be different if chain stretched.

3. when locking the left hand cam, crank position is exactly 40 degree, indicating no stretch.

But my cam timing does not line up with WIS, this is why I think cams are worn. it also does not help there are no numbers on the cams.

Regards,

NewMLGuy

Pags,

Your readings are off most likely due to the lifters not being pumped up, unless they are not hydraulic. Then valve lash adjustment could be throwing you off (i. e. worn valves and seats, etc. )

You should be taking your readings at the valve and not the lifter. The rocker arm has a ratio that will affect lift and duration, plus valve lash. (i. e. chevy V8's rockers were 1.5 ratio. ) So if lift at cam lobe is 2mm - it would be 2mmx1.5ratio at valve.

If you are rebuilding the engine, a new chain and guides and tensioner are a must. But at the end of the day, 150km is not enough to cause worn cams, lobes etc. But the chain may have some minor stretch in it.