OM606.910 cam timing enigma
 

I don’t mind admitting this one has me completely stumped.

Brief history, low mileage car/engine with fully reconditioned head which I fitted sometime in April 16, since then the engine has never been 100% at tick-over with a slight wobble but not a miss.

At the time I had concerns when setting up the cam timing due to not being able to get exact TDC reported here, this I put down to chain stretch (as per thread) as I tried both tooth positions either side of TDC settling for the one shown.

Pic of final set-up showing 5 degrees or so ATDC

http://i225.photobucket.com/albums/d...psvsn5luff.jpg

http://www.peachparts.com/shopforum/diesel-discussion/300145-e300d-timing-chain-stretch-2.html

After the rebuild compression figures looked like this with probably wet bores from assembly (please see follow-up post, as these figures may have been achieved using 14 BTDC configuration).

Cylinder bar

1 26
2 25
3 22
4 27
5 25
6 27

Since the rebuild I have carried out another compression (about six months ago) test followed by two this week

The figures from six months ago showed a significant drop but not as bad as the first set this week below, cylinder 3 and 4 have actually failed as per MB spec hence the decision to pull head.

Figures this week, timing still set as above

Cylinder bar

1 21
2 19
3 16
4 16
5 19
6 19


The compression tests this week showed a huge amount of oily carbon build up not only on the injector faces but also caking the heat shields across all six, oil was also seeping heavily out of breather pipes indicating blow by, smell of burnt oil was strong too.

As the compression test this week revealed a fail on cylinders 3 and 4, I immediately thought the timing is out clipping some of the inlet and exhaust valves, perhaps some worse than others due to variations on compression results, this was the only thing that seemed to make sense given the oily build up. So, out comes the parts list for a replacement head, parts ordered including dial gauge to make sure TDC is correct and the pointer hasn’t been moved during a water pump overhaul, however after reading another thread where the chap zip tied cam sprockets (same as my approach) but had an almost identical issue (loss of compression but resolved by moving cam timing),

Post 2

http://www.peachparts.com/shopforum/diesel-discussion/208998-606-head-removal.html

I thought give it a try, after all nothing to lose lose as swapping out head anyway, results are below.

Cylinder bar

1. 24
2. 27
3. 24
4. 22
5. 28
6. 22


Well there's a surprise similar to that experienced by the poster above, cylinders 3 and 4 are now well into spec but the problem is crank marker reads roughly 14 degrees BTC

https://s5.postimg.org/tqsjxr5tj/IMG_3484.jpg

So in summary, I have two settings, one ATDC and one BTDC both of which give different compression readings on different cylinders, returning duds to almost new pressure. Is there anything in-between, another adjustment perhaps, would moving the chain on crank sprocket as opposed to cam sprocket make any difference (clutching at straws here) ?

Not sure whether to pull head or not, over to you guys

Thinking back, the first set of comp figures may have been done with the timing set at 14 BTDC, then on checking I may have moved it to the ATDC believing this was nearer TDC.

Can't be 100% sure but makes sense looking at like for like comp tests.

sp:

As to the difference in pressure, when the cams are advanced the inlet valves close earlier, hence there are more degrees of compression stroke after valve closing, resulting in increased pressure.

One tooth on the crank is a lot; example: if the crank gear has 18 teeth, one tooth = 360/18 = 20 degrees. One tooth on the cams would be 1/2 that amount; 10 degrees.

Cheers Frank, on the first setting ADTC the engine is clearly consuming oil and lots of it, so i imagine the timing is leaving valves open when cylinders are under partial compression driving oil from rocker area directly into valve inlets.

Engine was running very bad when purchased due to carbon amongst other things, cam sprockets were zip tied on head removal with chain kept tight on pull side to avoid any jump of injector pump sprocket.

head returned from shop, replaced but may have changed to ATDC as mentioned above given how far out the other setting is.

I'd start by re-establishing TDC (if that is in doubt) to make sure your crank pointer is accurate. Remove the injector from #1, rig a clear tube of some sort (sticks up about six inches past the top of the valve cover) to make a good seal in the hole the injector screws into, and fill up that cylinder with oil about half way up the tube. Rotate engine, watching the oil level rise and fall with the piston. Find TDC by marking on the crankshaft balancer where the oil stops rising and then again where it starts failing, and TDC is exactly in the middle. Repeat this several times to make sure you get the same TDC each time, and then move the pointer so that you KNOW where TDC is.

Next, with the engine at #1 TDC, look on the front right of the camshaft gear assembly. There is a hole on the driver's side camshaft gear which is supposed to line up with a hole in the support behind it at TDC. You should be able to stick one of the valve cover bolts through. There are also two index marks (dots) on the camshaft gears that should be lined up at the same time.

OM606 Camshaft Timing Marks
 

Here is a screen shot of the FSM procedure AR05.20-P-6010HA, that shows what I'm talking about above. "A" is the index hole, through which you should be able to insert a bolt from the valve cover with engine at #1 TDC, and "B" are the index marks on the gears to make sure the two camshafts are timed together.

Don't worry about the timing chain moving on the injection pump timing sprocket, one of the pins through the timing cover prevents this, it is so close to the sprocket that it traps the chain to prevent exactly that.


Carbon: Caused by incomplete combustion. Have you fixed that?

Max, that is probably one of the best solutions I have seen posted, very ingenious using oil to get past pre-chamber - brilliant!

Cams already locked with appropriate sized drill, thanks for the pdf though.

https://s5.postimg.org/waxdjc853/IMG_3478.jpg

It's more oil than carbon, very soft and lots of it. I could smell burnt oil as soon as rocker cover removed.

The current setting of 4 degrees or so ATDC appears to be incorrect given oil burn and low compression, this changes quite dramatically as above, although not sure the BTDC is right also.

Sorry, just re-read your last post on carbon.

Once the car was returned home after purchase, went straight into my garage for strip down due how bad it was running.

Everything topside is new or reconditioned including the head, EGR sorted too.

Let me see where we are at on TDC and go from there, having a known benchmark will give me a bit of reassurance as currently bewildered lol

Max, in case your following my exploits, current thread here.

http://www.peachparts.com/shopforum/diesel-discussion/386034-re-etching-timing-marks-2.html#post3710622

I read a little of that, I think the marks on the crank balancer are good.

What happened to this car??? It would seem that either the crank pointer is moved, or the crank balancer is off. Can you question the PO?

I can't claim credit, just passing on an old trick. Dan Stokes has another good idea - remove pan and measure movement from below. That has it's own challenges though, when the engine is still in car.


Do the round timing marks on the two cam gears line up when that drill bit is in place?

Max, this is a very good question and one that I have asked myself many times whilst carrying out work.

I read a post by Moth some years back on the 124 picture thread (think it was MB org web site) where he posted pictures of his beautiful S124 in DB189 - Smaragdschwarz. It's a really unusual colour probably best described as blue/black with an undertone of Emerald green, I think at the time he also mentioned how rare it was especially in UK diesels - imagine my surprise to read one of the free ads with an S124 300TD advertised which had more than a passing similarity to the colour, above, I rang the owner thinking this couldn't possibly be the colour but sure enough the owner came back after lifting the hood and said, "the three numbers are 189, letters DB"

After getting back off the floor due to the sheer coincidence if nothing else, asked if he would take an offer subject to a few checks, (yes the picture were all taken in the rain from about 20 feet away, - :P).

The cars mileage checked out at around 123k or thereabouts, it was also being sold from an affluent part of the world so I took a chance, offer accepted !

A week later we tentatively pulled up at the address in my partners jeep only to be very disappointed, it had been used as a work horse and not maintained properly since the last owner.

The chap was probably looking out of the window sensing my disappointment popped out to say hello. There was a moment when the hand reached for the 'R' position in the Jeep to make good our escape, but that's not me, a deal is a deal.

He informs me there's no fuel in the car making it 50/50 if we will make it to the service station, we did though on five cylinders.

Eventually we get the car home for a proper inspection, two front tyers were bald and should never have been on the road, engine has two stuck glow plugs along with a manifold half blocked in soot carbon.

Here's the puzzling part, the overall body is in good shape, very good shape with only cosmetic rust on a few bits, structurally around suspension mounts, jacking points it's all good prompting me to restore the car as a daily driver.

What I do not understand and cannot get my head around is how from the time of his ownership, in miles around 40k so many parts ended up worn to the absolute point of failure, especially as prior to this it had MB service history up to 80k ish.

Mileage is held electronically here in the UK, prior to this I have paper with the exception of one of the earlier years, however it was under different ownership at the time.

The car has spent several years in my garage, plus my impression of PO he wasn't mechanically minded, maybe he thought cars don't need maintenance!

So, basically I am not surprised with this timing mystery and in a way, a little relieved as finally getting to the bottom of why the engine has never run properly despite reconditioned head, new nozzles, glow plugs, DV's and other ancillaries.

That was a good shout though, overcoming something which at first glance looks insurmountable using a liquid.

yup, the two dimples are in horizontal pitch next to each other, two dimples on the cams match up with cam cap housing marks too.

https://s5.postimg.org/rk6ossu2f/cam_cap_marks.jpg

Check that the engine has the injection pump on the right stroke. These cars can run much better than the old 123s with the injection pump on the wrong stroke. You mention a lot of carbon and that makes me suspicious.

Basically with cams in proper position. The tang in the injection pump should be about center when you move the crank to the right degrees for start of injection. The smallest distance as possible turned with the crank to get there. We had a member purchase a car and drive a long way home.

His engine not running right was exactly this. You may have also gotten he injection pump on the wrong stroke when you had the head off. You did make sure both the harmonic balancer marks and the cam marks where lined up when you pulled the head? If not there is a fifty fifty chance of it being wrong right there.

It does happen. Just by neglecting to check the cam marks are lined up when the bottom harmonic balancers are. Or else the injection pump was not on the right stroke when you purchased the car. You then duplicated it when you did the head job.

Anyways you have to stop playing around with the timing marks until you verify the injection pump is on the right stroke.

It only takes a few minutes to check and is absolutly required in your case.

Update
 

Cheers Barry, and agree, will re-check.

Current situation after my calculated experiment detailed here:

http://www.peachparts.com/shopforum/diesel-discussion/386034-re-etching-timing-marks-2.html#post3710622

Engine is running a lot better with the appx 14 degree advanced settings, more responsive with more power, its also lost the 'wobble' on tick over with a much smoother idle. Starting is also more or less on first click of key, this I compare to my 210 with 962.


Its slightly noisier than before with one injector nailing although this has improved with each short journey, it could be there is a large carbon build up from before which might need shifting for complete smoothness. I also need to refit the plastic cover which may make a difference to the engine tone.

Apart from the nailing above, it now sounds like a 606 which is a refreshing having driven it on the other setting for so long.

The oil is probably pretty contaminated, so will change this out tomorrow, refit rocker cover. top up with new coolant and go from there.

I need to explore the crank vibration damper and exactly how that may have moved, as a general observation it looks like one solid lump of iron so not immediately obvious.

Just thinking this through, assuming the pump hasn't slipped on the chain it should now be at TDC, i.e 14 degrees ATDC with current set-up?

Out of interest, anyone know what the + sign followed by 0.5 means, is it + or - with 0.5 being the tolerance?

http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/605_606/07.1-8410.pdf

Sure enough, there's the tang at TDC now -

The engine is running beautifully now except for one thing, a mechanical noise, it's not nailing more of a cam type or valve issue. My thought's are given the level of carbon on heat shield/injector faces, the pre-chamber is probably choked, would this cause pre-detonation, i.e 'pinking' ?

I say this as the engine is very quiet for first five minutes, new oil today too. It never made this noise before but there again was hardly firing properly with such low compression.

The new exhaust doesn't help really, very tinny compared to what was removed (MB).

But lost as to what to do next really, kind of solved one problem but now have another, lesser problem although saved huge amount of work not pulling the head.

https://s5.postimg.org/yawctpvzr/IMG_3490.jpg

Going to re-fit the water injection kit to see if it will dislodge any possible pre-chamber/cylinder carbon build up.

300psi pump - spray patter on full flow.

https://s5.postimg.org/a8opqbu47/Spray_pattern.jpg

Nozzle location, facing crossover pipe tapped into butterfly flap which has been removed - needs 2,200 revs to keep mist air borne.

https://s5.postimg.org/jryejshmf/IMG_3071.jpg

Pretty certain this is the correct position for valve/pump timing given the performance, currently waiting for 9 liter water tank for loading area, pump will be slung underneath housed in sandwich box (without the sandwiches) :)

Anyone have an idea how the crank has slipped around by 14 degrees, this whole thing has me completely stumped?

Thinking back to when the cam sprockets were zip tied during head replacement, I seem to remember on re-fitting checking the timing (see post on Jeremy's chain stretch thread) noticing the difference and moving the chain around sprocket to give 4 degrees ATDC being closer then 14 degrees BTDC.

In other words, the original position as removed was 14 degrees BTDC.

Hope that made a bit if sense, waffle city.

Just my opinion. I think a verification of the engines top dead center position is better than not having it. Not that hard to do.

Just remember to rotate and blow the testing fluid out of the cylinder before putting the injector back in.

Because if it is off there is no way to be certain of the valve timing.

Totally agree, this is more of a low risk 'see what happens' before pulling it apart to do the job properly.

Engine-wise however, is improving with each journey, perhaps the carbon is slowly burning away helping smooth things out.

Tank arrived today which is a good fit for rear of wagon loading area, may need some additional tubing though.

Personally i can see no way the markings or pulley damper can move, surely it has a key of some sort to locate when fitting preventing it turning (on crank, not turning full stop otherwise engine wouldn't run)

I may have made a misteak. It sounded to me initially in your post like the tdc mark on the damper was present when the injection pump tang was centered.


If instead the tang was not centered until the 14 degree position was reached all is probably well. Sorry.

Barry, you are correct with the first part of your post, just to confirm. The timing is currently set at 14 degrees BTDC which equals one tooth on the cam sprocket if you take the other 'forward' position (tooth the other way) of 4-5 degrees ATDC.

This means the injection pump tang appears at TDC as opposed to 14 degrees ATDC if that makes sense. That said, I fully appreciate and understand this is not the way to do things properly but..fatigued with so much wrenching on this car over the last 12 months, need a bit of a rest.

Current state of play, not many miles since last post but running well apart from aforementioned 'ting, ting' noise, finally got around to fitting new tank and relocating pump in order to retain spare tyre.

9 liter tank

https://s5.postimg.org/w1r48ua0n/IMG_3564.jpg


Pump housed in rear tyre well

https://s5.postimg.org/spxeta7nb/IMG_3567.jpg

There's 15 liters of de-ionized water ready to be swished through, pure water, no meth - this should equal around 600 - 800 miles depending on frequency of use.

I still think you need to validate that the timing pointer at the crank harmonic balancer is correct (find TDC mechanically), and then make sure you've got the timing chain / camshaft timing all correct.

Yup, very tempted given parts are to hand but there is no escaping...it's running well.. if the tick goes then I will push this down the line for a full engine overhaul including crank damper replacement if needed.

I looked back at my notes/pics when the head was replaced, 99% sure where it is now is where it was when head removed, the compression tests done at the time and now are very similar too (within 1-2 bar).

Speaking to a MB buddy, he theorized the wood ruff key maybe missing from crank hence misalignment.

What's your thoughts on only really having three options, TDC and one tooth either way before valve clipping?

I would imagine that one tooth either way will not cause valve / piston contact, and you can verify by turning the engine over by hand several complete rotations to ensure all pistons go through all four strokes and don't contact a valve.

Of course, it's hard to argue with success, so if you can figure out that noise and solve that without changing the camshaft timing, motor on!

Well that was short and sweet, drove around 50 miles or so with water injection on all fine, nice and responsive except the noise is now twice as loud..I guess the carbon build up may have provided some sort of cushioning which has now been removed.

..oh well, it was worth a shot..

the prechambers maybe damaged or you have a dead lifter in the head, it causes a tapping noise.

My ignorance perhaps. The damper locator on the earlier Mercedes engines uses two dowel pins for locators. Not a keyway. There is now another good reason to check that tdc doing the fluid approach. To verify the marks or show that they are not accurate. It can wait for awhile though as it will take some time to get the carbon buildup reduced.

If it is off you will want to know why. Or at least have a choice to correct it or live with it. I was wondering if perhaps the balancer loosened at one time and the pin holes took a beating but the situation was caught in time before serious damage occurred.

Also I ran some experiments with some old Volkswagon diesels years ago and found that with the injection timing advanced the engine still sounded good and power was increased substantially. But the dampers on the two examples did not like it. The rest of the engines seemed to take the situation well. I probably put 10-30 thousand on those engines. They seemed to remain the same as when the experiment started.

That's if your engine also uses the locating pins. . If the marks are on everything is fine. Yet if they are off is another thing. At least to think about.

This is why I am not a fan of advancing the injection timing on the older 123s engines. The damper setup is not the strongest and there are a lot of cases of them coming loose. Even destroying the crankshaft ends in the process.

Who knows what our engines experienced in the past owners hands. I have gotten surprised a few times myself.

The engines past the 123 types needed a better injection timing method as they were just a little more sophisticated. The tang In the injection pump was introduced in the last two years of the 123s and was needed even more as the engines improved. It also made dealing with the timing issues much easier. Sometimes I will use crude methods like watching what the fuel milage is like. If it is what one would expect for the cars type. Make the crude assumption things are not bad in general.

..you have to be kidding..lol

Went out this morning after ordering the remaining gaskets/bits bobs fully expecting to hear that noise, only worse as now cold..but..

Probably best you listen..

First video from cold (ignore oil level light as faulty)

https://youtu.be/80FETpmOtPc

After 5 minute drive (summer here, so reaches temp quickly)

https://youtu.be/3NqbAQl-jmY

A little way through (24 secs) you can hear a bearing noise, aware of this, either w/pump or alternator (possibly).

The down pipes although stainless are a lot less meaty than those removed, this doesn't help but the noise is barely audible.

Started stripping the 962 ready for swap over, only visual differences so far related to the two sensors on 910, 962 has one port plugged.

Checked cam timing, 1 degree of stretch which looks promising - quick question, the 962 has a clutch type alternator, can this be swapped with non clutch type?

Checked EPC but there's a lot of upgrade notes to make sense of.

Just waiting on water pump gasket to swap that out too (assuming same).

962 head removed, any tips for getting rid of metal fragments caused by exploding bit.

It's the top right bolt in this photo which is next to a valve spring, might have to pop the valve out to make sure clear.

I'll check the brand of spline bit, but I know it wasn't cheap - for those reading from Blightly, ended up using their Advance 1/2 drive socket splined bit.

https://s5.postimg.org/txu6nu88n/IMG_3588.jpg

Run a magnet around? Lay the head in a big pan, spray down with WD-40 or brake cleaner, rinse the fragments down into the pan? Last resort, power wash it at the local car wash.

What's the plan for the new head?

I can hear the noise in the video, hard to know what that is without more diagnosis. Are you thinking that is a bad valve or something else wrong in the valve train?

How about sending a used oil sample for lab analysis, that may tell you what metals are too high, which can sometimes pin point the failure mode (bearings or rings).

Cheers Max, magnet picked up most of the frags but worried about inner area and base of spring, ended up removing one of the valves.

Refitting valve, is orientation important (marked head/valve) or do these rotate during use?

Not sure what the issue is with 910 head, it was sent to machine shop a while back (see pre-chamber pics) - need to verify TDC for a clean base line and go from there.

Should be able to pull 910 tomorrow all being well, flipping hot here - has to be 35c ..I know..Arizona..is like melting the sand or something..but it's hot for us Brts :cool:

910 head pulled today, very quick look over reveals one of the inlet valves completely sooty as opposed to the others which are mostly clean.

The odd pattern maybe caused by water injection on the inlet side, certainly the inlets from the 962 with no wi are equally sooty.

I need to check the crank timing next but first need to clear up the (extensive) mess first :)

https://s5.postimg.org/5rxbhxq9j/IMG_3609.jpg

https://s5.postimg.org/shwgax9h3/IMG_3610.jpg

Bit of an update today, started by checking timing visually using number one cylinder of injection stroke, all good within 1-2 degrees but will use a gauge once ready to bolt up again.

Timing market OT

https://s5.postimg.org/dc4n8l4jb/IMG_3613.jpg

Number one cylinder

https://s5.postimg.org/4idqrhhkn/IMG_3614.jpg

Cross hatching still present but notice extra grey carbon deposit band

https://s5.postimg.org/ru1ugkvuf/IMG_3615.jpg

This extra band can be seen better in this picture

https://s5.postimg.org/jfm7shut3/IMG_3617.jpg

This is the 962 block (W210) with much smaller band

https://s5.postimg.org/99i7n8zsn/IMG_3622.jpg

910 with perhaps half inch below the dark carbon marking

https://s5.postimg.org/sifad9jxz/IMG_3623.jpg

910 valves removed for inspection, using a power drill each one is a slightly off center but this could be the chuck bit

https://s5.postimg.org/vb8hxakaf/IMG_3625.jpg

Glow plugs came out with ease showing no signs of blow-by, one however is corroded

https://s5.postimg.org/r5xlbdmif/IMG_3626.jpg

Replacement alternator fitted, it is big with the larger plastic cowl touching the block cooling hose - will monitor to see how that goes, may need to put an elbow in there.

Question, cylinder 1 on the 910 has the ,marking '10' on older engines this used to signify over sized pistons following re-bore, is this likely or just MB quirk?

https://s5.postimg.org/qqe1tmjp3/IMG_3643.jpg

Inspected the band mentioned earlier, this looks like the steam tackling the carbon build up turning it grey, there's also small parts where it has managed to expose the cylinder underneath.

https://s5.postimg.org/64za1q247/IMG_3629.jpg

Made a small glow plug reamer tool which worked well, unusually the 962 had one stuck plug (2nd from back) which was very sooty -

https://s5.postimg.org/s2vqvih4n/IMG_3646.jpg

It will be interesting to see if the w-i keeps the carbon at bay helping ease future glow plug removal.

Pic request
 

Hi folks, just in the process of sorting out the water pump and housing whilst in bits, quick question -having removed both water pumps from 962 and 910 itemizing respective bolts, I now notice there are only five but seven holes?

Something else bolts on taking up the two free bolt holes but cannot think what, FSM is no help either just listing bolts and torque settings.

Any pics of your own pumps or tips welcome.

Thanks,

https://s5.postimg.org/4cam2020n/IMG_3671.jpg

https://s5.postimg.org/shbbjpmbb/IMG_3672.jpg

All back together today, very pleased with the outcome as the engine note has changed considerably although there is till a very slight ticking noise.

In summary, I reset the timing using a level gauge followed by the injection pump, both were within 2 degrees of spec which is a lot better than before.

Parts changed:

Cylinder head, cam housing, cams and cam caps, cam drive sprocket, chain guides.

Injectors (new)

Glow plugs

Fuel heater, larger bore so needs new piping.

Water pump (the 962 is off concentric which broke housing, temp JB Weld until new one arrives)

Alternator, 115 amp

Belt pulley assembly.

All new gaskets throughout.

As mentioned, there is still a slight ticking noise which is hardly noticeable but may as well sort that too, could it be the vac pump?

Last post to wrap up the thread which had it's ups and downs but has been ultimately worth while.

Engine has settled down now, very quiet and soft if that makes sense, absolute pleasure to drive - added bonus the oil level light now works too, no idea why changing the head would make a difference but it extinguishes as normal.

Other bonus parts, higher capacity alternator and improved fuel heater with large inlet bore, no more air -

Internals, you get the added benefit high temperature kryptonite exhaust valves, this may include the seats also (not checked).

Getting a replacement water pump housing sounds easy right, nope most of the second hand parts corrode around large hose connections - MB only do exchange units with the replacement needing some JB Weld to smooth out milled surface.

The other bonus is my lovely neigbours who helped lower the new head onto block, absolutely amazed the thing works let alone drives after being a pile of bits :P (again)

Congrats, very satisfying when you reach the end of such a huge project.

Cheers Max, must admit to holding my breath when first starting just in case there were subtle differences 962 v 910 - all good though, lots of parts can be interchanged too (except water pump, lol)

One thing I didn't mention when inspecting the 962 head was a huge lump of swarf sitting behind the rear water jacket exit, it my have broke up trying to pull it through the hole - if anyone is doing an engine flush possibly something to look out for.

Water pump differences
 

Didn't have a photo handy yesterday, but wanted to post a pic of the two water pumps for reference - they look very similar and indeed the gaskets fit both, but the 962 to the left is off center causing it to hit the outer casing.

https://s5.postimg.org/6tv6yeks7/IMG_3722.jpg