dieselkiki

Cylinder Head

142 posts in this topic

Congratulations, Dom, for another difficult job well done :thumbup:Bil :sun:

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Well done but please tell us how you timed engine.

Edited by tolsen

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Well done but please tell us you timed engine.

Yes, please tell us how you set up the timing. I might be faced with the kind of job you just went through.

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Around 12h of workmanship times (I didn't have any air tool or lift). I took the time because I'm a perfectionnist.The car was in the garage from saturday morning to tuesday afternoon. (I loose sunday and monday because I didn't got the right pats and the dealer didn't too. They must order it to Toronto). If I got the right parts, the cars was got out the garage sunday in the evening.

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So as promised, here is the timing setting for smart CDI turbodiesel (OM660).

First of all, I want to let you know that neihter me or clubsmartcar.ca can be held responsible for accuracy of this procedure has timing. No rescourse for damages caused by the one who used this procedure. Got it? You are now informed.

Ok, now. The first thing to do when you must doing the timing setting on smart cdi is put your #1 piston in TDC (top dead center) position. To do this, there are tow way to do. The firt (by mercedes-benz) is to align the marks on the crankshaft damper pulley and the front cover (as shown on pictures).

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If your damper pulley are very rusty and the mark are no more visible on it, you can use the second way to do (the one I used). But you need to remove the front cover. Second way is alignment of the crankshaft pulley key with the straight ridge along the cylinder. It's anought precise. ( I remember you that my car is running). :P

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Now you must align the camshaft between "exhaust" and "intake" cycle. Mercedes-Benz procedure is using paint pencil and make a mark on the chain and on the procket to put back the cahin at the same place.

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This way are a good one but... If you put a new chain... "BZZZZZZZRRR" HELL WRONG!!

The other way I found by miself to align the camshaft is this one. On the camshaft sprocket there are 2 flat marks. I just have to align these marks with the cylinder head edge. You can use a flat bar or other flat tool the be sure that the maks are straight align with the head edge.

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Now you can put back your chain, tentioner, etc... Before replacing the cover, it's could be a good thing to take a double check at the marks and turn the crankshaft (clockwise) on 2 full turn to be sure there's no contact between valves and pistons.

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So... thats'the way I did my timing setting. My CDI is running very well. I hope the topic could help some of you. It's so hard to find technical information for OM660 engine. I try to remedy this situation.

Have a good week.

Dominic ;)

Edited by dieselkiki
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Could anyone can explain to me what's wrong with the smart CDI chains?? Why the chain on OM647, OM648 and OM642 are lasting for more than 600000km and the chains are worn out on OM660 before 200000km?? Is that the quality is the same? Could aftermarket chain be more reliable? Nobody have a solution?

Because it's very disappointing to have a diesel can known for its durability and need to replace the timing and oil pump chain before 200000km. It's the fist time I change a timing chain on a car. On my old mercedes 240D, 300D, 300SD and 350SDL, I never touch the engine while I got it. My 240D showed more than 700000km when I sold it and I never touched the engine except for glowplugs. I would like the same for my CDI! So... it's pretty sad.

Pictures of my oil pump chain. It's a chance that I replaced it by the same time as my timing chain. Take a look at this. What's wrong with these chains?? I can't explain.

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Edited by dieselkiki

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I don't think it is the chain, it is the sprockets. Every picture of the sprockets I have seen look wrong to me, the tooth form is too shallow. The chain wants to ride up out of the teeth, the tension is keeping it down. Any slight overload, even momentary, or slackening of tension the chain will ride up the tooth, with unusual load and wear.A properly designed tooth form has exactly parallel-to-the-chain-line force vectors. Tension can be very low indeed, a slow speed chain will run happily with enough slack to actually jump a tooth as long as shafts are horizontal so gravity will tug the slack of chain down.Belts need tension, a chain system should only need lack of slack, and a low-speed chain not even that.

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I still suspect the lower sprocket(s). It seems to wear and then damages the chains...

JWIS makes chain wheels (sprockets) of better materials and hardened teeth

All Flexon wheels - whether in steel, stainless or cast-iron with hardened teeth - are characterized by running precision and long service life.

And better, "Super Long life" chains

Super Longlife

iwis Super Longlife chains (SL series) feature pins with a very high surface hardness. This special design gives the chain outstanding qualities: maximum wear resistance, longer service life, high tensile and fatigue strength, low susceptibility to corrosion and fretting corrosion in the chain links plus enhanced emergency running characteristics to cope with inadequate lubrication.

SOURCE

It would be awesome to source these upgraded parts... unfortunately, smart is not listed in their aftermarket parts catalogue! They are in Munich: http://www.iwis.de/en/about-iwis/iwis-worldwide/contact/

Bil :sun:

And Alex: I believe they make the chain tensioner as well...

Edited by bilgladstone

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Bil: As we can read on my camshaft sprocket, this is already Iwis who make the OM660 timing chain and sprocket. :(Alex: Sprocket damage are caused by worn chain. Worn chain have an hand play between links. When the link start to climb on a tooth because the space between 2 links are larger than the space between 2 tooth... it's at this moment that sprocket worn begin. If chain could resist, sprocket will last too! I'm almost certain.

Edited by dieselkiki

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What we need is a volunteer (not me!) whose car has well over 200,000 km on it and no known problems with noise to tear down the engine and see if there is any wear on the chain or the sprockets. I would theoretically love to do it on my 240,000 km car, but I don't have the money or the time.Once the engine is making unusual noises, it's probably too late to figure out what the root cause of the problem is.If Alex is correct, all cdis should be showing the same phenomenon as they get up to 200K km but I am pretty sure it's not universal....I would lean instead towards suspecting some duff batches of parts with faulty metallurgy - mainly, the chains. That the tenioners on Dom's car were fine is truly vexing to earlier theories about failure modes.

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Bil: As we can read on my camshaft sprocket, this is already Iwis who make the OM660 timing chain and sprocket. :(

Yes, this is true. What I mean to say, is that IWIS also make higher-grade, superior quality versions of their chains and their sprockets. maybe Mercedes chose lesser/standard grade and it is possible to find the same specs but higher quality for replacement?Bil :sun:

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The failure sequence could also have to do with sticking valves? If a valve train "hiccup" causes momentary or intermittent chain tension/slack, this might begin a knock-on fatigue leading to later failure in a link or tooth :dunno:Again, a replacement SL chain and/or stainless, hardened-tooth wheels might resist wear/fatigue from whatever transient cause...Bil :senile:

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I am willing to chase IWIS on this. Just need part numbers involved:Cam chain = Cam sprocket, upper = Cam sprocket, lower = Oil pump chain = Oil pump sprocket = With this info and if I may use Dom's photos of tooth and chain damage, I will send an enquiry and see what the Mfgr has to say, both about these failures and also about possible higher-quality substitutes.Bil :sun:

Edited by bilgladstone

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What we need is a volunteer (not me!) whose car has well over 200,000 km on it and no known problems with noise to tear down the engine and see if there is any wear on the chain or the sprockets. I would theoretically love to do it on my 240,000 km car, but I don't have the money or the time.Once the engine is making unusual noises, it's probably too late to figure out what the root cause of the problem is.If Alex is correct, all cdis should be showing the same phenomenon as they get up to 200K km but I am pretty sure it's not universal....I would lean instead towards suspecting some duff batches of parts with faulty metallurgy - mainly, the chains. That the tenioners on Dom's car were fine is truly vexing to earlier theories about failure modes.

I'll do it soon, intend to open out engine and inspect the chain drives. Mine has only clocked just above 176,000 km but I think it is better to do the inspection now than suffer expensive repairs in the future. Then do periodic inspections perhaps every 25,000 km unless I renew both chains now. We will need more owners participating in the chain drive inspection scheme.

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I am willing to chase IWIS on this. Just need part numbers involved:

Cam chain = 660-997-00-94

Cam sprocket, upper = 660-052-01-01

Cam sprocket, lower =

Oil pump chain =

Oil pump sprocket = A660-181-00-12

With this info and if I may use Dom's photos of tooth and chain damage, I will send an enquiry and see what the Mfgr has to say, both about these failures and also about possible higher-quality substitutes.

Bil :sun:

Sorry for the other part numbers Bil, they are in the bottom of my garbage can. <_< Of course, you can use my pictures to send an enquiry to Iwis. ;)

Tolsen: Doing inspection of chain every 25000km??? What kind of car need it?? A car with a diesel mercedes-benz engine?? Seriously? I can't believe it! It's absurd. The rationale of a timing chain is "be better than a belt". At this time, I'm starting to seriously doubt.

Edited by dieselkiki

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Bil, if you send pictures to Iwis, dont forget this one too.

Thank you Domenic - wow! that one is HORRIBLE!The message is sent, we will see what happens now....B :sun: Edited by bilgladstone

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The chain damage should be visible through the oil filler hole, assuming that the rollers rotate freely on the chain as they do on most. Might be a good idea to have a close look through the hole!

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The chain damage should be visible through the oil filler hole, assuming that the rollers rotate freely on the chain as they do on most. Might be a good idea to have a close look through the hole!

I do that every oil change. You can't see the oil pump drive, though. Perhaps an endoscope may be able to be threaded down and have a peek.Even with a new chain and sprockets the cam chain comes close to touching the return length, if we can get a measurement of the gap and estimate a minimum distance acceptable wear that could be checked from above. A go/no go ball on a stiff wire tool would be easy to fabricate.

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I have thought for some time that a micro-light endoscope might be very helpful! Not to mention a cool toy!

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