vito 108d timing chain snapped! Please help.

[Alex Crow]

for the pump timing, remove the blanking plug in the side, might be 17mm. inside the hole you need to lign up a notch which will be apparent if you rotate the pump. if you unbolt the pump drive sprocket beware, i think it is a l/h thread.

 

[Alex Crow]

have you rotated the crank to see that the pistons only go within 10mm of the head? i am sure that this cannot be right at all, the rings will wear the bore below the piston crown so if you are just going by the top of the wear you will be wrong. are there marks from the exhaust valves on the pistons where they have hit? i would definately remove the sump, considering the work you have already done this is no big deal and it will make threading the chain easier. still don't know why your chain snapped though do we!

 

[anthony evs]

for the pump timing, remove the blanking plug in the side, might be 17mm. inside the hole you need to lign up a notch which will be apparent if you rotate the pump. if you unbolt the pump drive sprocket beware, i think it is a l/h thread.

Hi Alex,

Thanks again for your help.

Is this plug in the side of the injection pump, os on the side of the engine housing.

Also, i`m assuming the notch needs to be lined up when at no:1 tdc.

Thanks Alex.

As to the chain breaking, I have to say, having just read the info supplied by Malcolm, i did NOT prime the tensioner. It did rattle loudly just before the break. Having examined the chain, it has twisted badly 4 links from the actual break. I can only assume, that the chain has gone slack after the cam and before the guide, after a period of decelleration, and bunched on the cam sprocket (there is slight damage on two outer teeth on the sprocket), the chain has then twisted, then snapped as the load reapplies to the chain. This is the only deduction i can make, but I will never know, a i cant see any other damage.

Thanks Alex, looking forward to clarifiction on the pump timing.

Cheers, Anthony.

 

[Alex Crow]

it is the very obvious plug on the forward side of the pump. as the chain is off, you may as well rotate the pump to familiarise yourself with the mark. the actual timing may actually be at 20 deg btdc, sorry i can't remember! will look it up tomorrow if i get time.

 

[television]

it is the very obvious plug on the forward side of the pump. as the chain is off, you may as well rotate the pump to familiarise yourself with the mark. the actual timing may actually be at 20 deg btdc, sorry i can't remember! will look it up tomorrow if i get time.

If you do look it up,,its easier under the 202 with the 601 engine

 

[MB Service Centre]

Hi, best thing to do is when valve and crank timing is done, remove the 3 nuts that hold the injection pump in, and pull the pump out< you will find a 17mm headed bolt head on the side of the pump. Remove this and with a light if you look inside the pump and turn the pump at the same time you will eventually see a ridge, This is now firing on no1, you suposed to use a special lock and timing light for this but can be done without< to hold it in that position you can use a wheel stud and screw it in until it jams the shaft and stops it from moving when re fitting the pump.So turn timing until its 15deg after tdc and then refit the pump.
Hope this helps
Rob

 

[Alex Crow]

okey dokey, might just look in auto data timing chains though. an actual book with pages you can flick through! just like the old days.

edit

i was replying to malcolm there mbsc. so it is 15 deg then. i have my own self made tool for this job! a threaded guide bush that fits the pump and a suitable shaft with groove cut in the end, it can be used to achieve a great degree of accuracy with care. have not used it for a couple of years now...

 

[brianbrian]

If you have to take the sprocket of the end of the pump because of damage, yes it is Left hand thread with a washer that bends over the nut to stop it undoing. Hope this helps

 

[MB Service Centre]

Even though you did not prime the tensioner i dont think thats the only fault? the amount of guys i have worked with that never primed them, any case after a few seconds the oil pressure takes up the slack on the chain

 

[Alex Crow]

Even though you did not prime the tensioner i dont think thats the only fault? the amount of guys i have worked with that never primed them, any case after a few seconds the oil pressure takes up the slack on the chain

i quite agree. if it has run for ten seconds it should be fine. i am a suspicious kind of guy and feel that breaking the chain has a part to ply here, sorry anthony! even with the tensioner right back i cannot see the chain bunching. nor can i see the pistons 9mm down from the top of the bore.

 

[Quick Silver]

Before reassembly of new chain it would be a wise move to check the bottom sprocket for wear (teeth should have flat top and pitch between teeth should be even). Bottom sprocket is the one that does all the work and wears the most also that no teeth are chipped or bent .

The 638 Vito with 601 naturally aspirated engine will go forever virtually and is a good engine . Different story with the cdi engine though as Im finding out right now, I definitley wont be buying any more Merc vehicles with cdi engines as unjustly expensive to maintain and lousy reliability in comparison. The 639 Vito is no better. Will buy Jap diesels next time round .The vehicle body normaly fails before the engine on the 108D.

 

[Alex Crow]

quick silver, i couldn't agree more! the naturally aspirated 601 engine is a marel of engineering excellence. shame about newer models.

 

[television]

Before reassembly of new chain it would be a wise move to check the bottom sprocket for wear (teeth should have flat top and pitch between teeth should be even). Bottom sprocket is the one that does all the work and wears the most also that no teeth are chipped or bent .
.

I agree 100% with the teeth on the sprockets,,must be flat on top and not sharp, when sharp it allows the chain to over ride a tooth

 

[anthony evs]

Hi Alex,

Checked the piston travel today, i must be honest, seen a wear goove in the cyl and assumed that was from travel.

I must apologise, the pistons DO travel up flush to the block surface, I cranked the engine around with a socket, turns nice and free, the pistons are travelling ok, alitle slap / wear at the top of the stroke, no damage apparant on the cylinder walls.

I removed all valves out of the head today as a precaution, all are ok, none bent, or any sign of damage on an of them, refitted ready for the head re-assembly.

Ordered the new timing chain, should be here thursday. I wont have any time tomorrow to remove the sump as i have a few hospital appointments with my child.

Apart from damage to two outer teeth on the cam sprocket, the cam and pump sprockets are ok. I can check the crank sporcket once the sump is off.

I have found a plug on the injection pump toward the rear of the pump for timing, cannot see anything at the front end, in addition, the pump is near to the radiator, and is going to be difficult to see any markings if the plug is on the side, gonna be hard to see to time it correctly.

I used to have an old 200d R reg 1977, done a rebuild on that and had sone advice on spill timing.
Remove pump from engine block, locate a grove on the pump connecting sleeve, align groove on sleeve with goove on timing sprcket, refit pump.
If i can remember, get the no 1 piston to tdc, and remove the delivery valve out of no 1 pump outlet. Adjust the timing ( adv or retard ) until an out put of approx 1 drip per second flows from the delivery pipe. Did that, engine started no probs. If smoking too much, adv or retard as necassary.

How does that sound, in case i canr se the timing mark on the pump.

Cheers again Alex, Mal and all others who have been kind enough to contribute.

Anthony.

 

[Alex Crow]

you have found the right blanking plug, i am sure you will find it is 17mm. you can use a mirror to see in the hole, and i think you can actually use spill timing on this engine too. you will need to make a pipe that fits the pump nozzles which curves round to face down wards. with the pump primed with diesel this needs to JUST drip diesel at the specified timing - i think!! haynes manuals often have this stuff in btw..

 

[MB Service Centre]

Hi there if you have any problems with timing of the pump, give me your e mail with your address and i will see if i can find my locking pin, and will send it to you, i also have the timing light tool for these pumps with the A and B lights.
Thanks,
Still cant get over you had no damage, but hey thats goodi am pleased for you if its ok
Rob

 

[anthony evs]

Hi Rob,

Thanks for that very kind gesture. I shall have a good go with the info from you all. If i get into real trouble, then i shal take you up on that kind offer.

Thanks very much Rob,

Bst regards, Anthony.

 

[anthony evs]

Update,

Hi Rob and Alexander,

When i got the vito up my friends garage with a lift, could see alot more, and have encountered alot more problems than i thought possible.

Alittle more careful design,then work on this vehicle would be alot easier and far more pleasurable.

First: needed to drop the sump further to examine the crank sprocket and also clen up the sump. However, there is a thermostat pipe that wraps around the engine mount dwown the rear of the engine and under the sump, not allowing the sump to dop low enough to get your hands in to examine and clean, also, the subframe aslo locks the sump in. Awful design, for the sake of a rubber 90 degree elbow on the pipe.

Second: The timing cover removal. Absolute nightmare. There is an ally mount that locks in the o\s drive shaft mounts teh alternator, locates on the front lower corner of the timing cover, and lastly, also locates onto the cylider head. To get this timing cover off and back on is a nightmare due to this ally mount, all for the sake of the little mod that could bolt onto the bottom of the mount and fix into the corner of the timing cover. Crap design.

Third: There`s not enough room around the perriferry of the injection pump sprocket to either slip a link forward or backward to time the pump up with the crank pulley.

Anyhow, enough of my moaning, onto the problem.

After dropping the sump to clean and examine, found a chunk of ally in the sump, this had snapped off the timing cover, its a locating lug that fits snugly undwr the crank sprocket, and as the chain has snapped, aslo snped this off at the same time.

So had to remove the timing cover, also gave me the advantage then to fully examine the area to make sure nothing else was damaged. The area was ok.

Took the cover to a specialist ally welder who done a great job in welding the lug back onto the cover case. ( tried to buy a cover from a salvage yard but wouldnt seperate the cover form the engine.)

Set the crank to TDC, threaded the new timing chain around the crack sprocket, set the pump at spill on n0.1 and threared the chain around the injection pump sprocket, refitted the timing cover. refited the crank pulley to locate the 15 degrees after TDC to time the pump to the crank.

Now had the problem of trying to slip a link on the pump sprocket to retard the pump by the 15 degrees the crank has turned. Hard work.

OK ROB, removed the plug on the pump, got a mirror and light and looked into the hole, could see as the pump was being rotated (hard to describe) like a lug as the pump was on the rock, at the back of the lug was something that looked like a tooth. Is this the tooth / slot that has to be aligned with the crank at 15 degrees after TDC. I hope so, as i have now got this tooth roughly in the inspection window and a tight chain to the crank when at 15 deg after TDC. This position is also on the "rock" of the pump when delivering to no.1 outlet.

If i am wrong with what i have done, could you please explain in a little more detail as to what has to be timed in what position. Thanks very much Rob.

In hindsight, i should have scrapped the engine. Thing is now, i have gone so far, i have to continue to the end with this engine, and if it doenst work i`ll torch the thing (only joking)

Ok, sorry for the long post and moan, but any dditional help from you al would be very much appreciated, nearly there now......

Best regards, Anthony.

 

[Alex Crow]

yes, the 'tooth' you see in the pump is the one, i believe you have been told the timing above^, 15 deg btdc wasn't it??

that hindsight you mention - 'should have scrapped the engine', it could have been foresight if you had taken our advice. i would not have attempted the work you have done without removing the engine, but it sounds like you are well on the way now, so good luck and most importantly, NEVER GIVE UP!!

 

[meanie]

Have been abroad working & have just come across this thread.
Like others here I'm surprised that no valve collided with the pistons. Also the weak tensioner is a worry.
Two things spring to mind;
Is it possible that swarf from the head reface wasn't fully cleaned out of the oil galleries in the head? This would have allowed the tappets to collapse when the valves met the pistons.
or,
Do you have an oil pressure problem? As the tensioner relies on oil pressure, this could account for the failure. You have the sump off so now is the time to check.