Another M271 Cam Chain Issue

[Mike_wilts]

Hi from a Newbie!

New to this site and new to Mercedes..

About 2 weeks ago I was seduced by a 2005 C200K and having looked at the condition of the car thought to myself. 'that would make a nice project' having one or two scuffs and requiring a new column switch. Initially the engine was quiet, smooth and i was delighted with the 76K on the odometer.

Then suddenly 2 weeks on having covered in the region of 1k miles it started missing! felt like a coil pack had failed but alas the car was not going to get me home and promptly cut out and left me waiting for a recovery truck. My local garage soon informed me of the problem..

Chain had jumped the intake gear and i was looking at a minimum 2K bill...Really? Now, i'm pretty sure that i am not going to pay for a repair that could exceed the cost of the vehicle.

I proceeded to research the problem and to my horror discovered through the forums that this is a common problem..oh! don't we have 20 20 vision in hind sight!

I don't like to be beaten and having had the vehicle recovered back to my home set about inspecting the engine and proceeded to expose the cam chain and check the condition.

Initally the cam chain was not slack, rockers are where they should be, but suspect that some valve damage may be present but don't know for sure..

The problem clearly appears to be the intake gear. As it has very little of its teeth left!

It was clear as soon as I rotated to TDC that the intake was some number degrees out (significant)

After repositioning the cam shafts back to tdc, my intention was to rotate the crank clockwise to check for any strange noises or resistance (plugs out), however, the toothed wheel simply dosent have enough depth of teeth to prevent the chain slipping. The slip in the photo is one or two teeth..

I found it interesting that the chain when set to tdc and cams set to tdc, they line up, so i suspect there to be little cam chain stretch...

So how far do i go with this? I like the car and will undertake the repairs myself and would be interested if anyone has any views on the following

I have seen on Ebay the following... http://www.ebay.co.uk/itm/NEW-MERCE...966758?hash=item2386b69026:g:tVYAAOSw0j9ZP5Wk

My thought is that the merc gears were never fit fo there purpose and i don't see how any other gear could wear as equally as fast. Quotes for assembled gears vary from 430-920 per pair....

Has anyone on this forum gone this way.

Replace the gears, rotate crank manually to feel any resistance, if clear, re-assemble it and try to start it?

I suspect valve damage but would rotating for the simple hand over the spark plug hole confirm compression and exhaust?

I preloaded the tensioner with oil before re-fitting to in the car and the chain feels suitably tight. I dont want to throw hundreds and hundreds at this car, cant help feel slightly dissapointed with mercedes at this point. I'm sure that it would not be unreasonable to expect these key components to exceed 76K!

Another thought, does anyone have a used E gear which they have replaced, that they could spare (worn) so that I could get rotation via the crank which may have better teeth than the one i have for the purposes of diagnotsis?
I hope my time with the merc isn't over as i feel like the old girl needs a bit of tlc and consider that this problem cured would at least give me a couple of years motoring..that was the intention for buying it...

Thanks for reading and any views would be recieved gratefully.

Mike

 

[Tuercas viejas]

Mike
Greetings
Looking at your photos its pretty clear to me that the sprocket chain wheels are shot.
That means the chain is stretched excessively and very likely the crank sprocket is affected in the same way as well.
All this means that you need a timing chain kit with guide rails & tensioners to effect a reliable repair .
Before you spend lots of money, your first requirement is to verify if the valves haven't clashed with the pistons and bent them.

Sorry but the finger on the plug hole is not precise enough.

Rather you need to introduce an air line with about 7 bar of air pressure to each plug hole with the engine (each cylinder in turn) physically on TDC and check for leaks out of the inlet tract & exhaust pipe.
Any leakage means a valve problem, and that is going to mean head off and overhead rectification on top of the valve train issues you have cited here.
Think smart here !
The costs of the repair can easily exceed the value of the vehicle and a precise diagnosis is essential for you to gauge a course of repair action.
In some cases a good take out engine might be a cheaper/ quicker option for you since you are intending to do a DIY'r on this.
Hopefully not having an MB lawn ornament for months as the neighbors might start delivering garden gnomes into it!
And frankly who wants garden gnomes in their front yards complete with plastic pink flamingos!
All the best
Tuercas viejas

 

[grober]

These guys have been mentioned in the past----http://www.m271.com/

 

[Mike_wilts]

Before you spend lots of money, your first requirement is to verify if the valves haven't clashed with the pistons and bent them.

Rather you need to introduce an air line with about 7 bar of air pressure to each plug hole with the engine

Hi Tuercas

I am concerned about the valves, i would be extrememly lucky to have avoided some sort of valve damage! I like the idea of an air line, do you know of an adapter that will make attaching an air line to the plug hole? i guess at 7 bar i would need to ensure that the air line dosen't blow out. In any case i will need to replace these gears in order to do the tdc valve test on each cylinder?

i'm very aware that just the cost of the parts might prohibit the repair and maybe easier to purchase another coupe where the gears have been done. Think i'm going to be really reluctant to purchase an engine where this inherent problem would still exist on the replacement unit and still leave me have to purchase the spares.

so how best to approach this? buy a couple of gears just to find out if i have any leaks..or just carry on stripping down and refurb the head?

Not fancying it much as a garden ornament! but it's much prettier than a knome!!

 

[markjay]

In a worst case scenario, the bent valves may have also damaged the piston(s). If this proves to be the case, then the cost of repair will definitely be prohibitive.

So I think that in parallel you should also look at the cost of second hand M271 engine with the 200 tune level - lots of Mercs had it from around ~2003 to ~2008, so breakers will have plenty of low-mileage ones to choose from. You could then decide if you also want to change the timing gear pre-emptively... or just rely on the mileage 'left' in the second-hand engine.

But unless you can confirm with certainty that there's no valve damage, I would not invest in renewing the timing gear.

 

[Mike_wilts]

But unless you can confirm with certainty that there's no valve damage, I would not invest in renewing the timing gear.

I have to agree! whilst sat here pondering my direction i thinking that if i remove the camshafts (again) am i correct in thinking that all of the valves will default to a closed position making an air line test reasonably accurate?

 

[markjay]

Also... while this issue is no doubt a weakness of the single-chain M271 engine, it is worth noting that this is a 4-cyl petrol engine and was generally fitted to entry-level models that tend to depriciate quickly, meaning that cars fitted with these engines got into the bracket where they are bought by people on a budget who maintain them on a budget after about 8-10 years or so... and if owners do not use 229.3/229.5 oil and/or habitualy exceed the time/mileage between services, then I think the engine if far more likely to suffer timing gear failure compared to a well-maintained engine from new.

 

[Tuercas viejas]

I have to agree! whilst sat here pondering my direction i thinking that if i remove the camshafts (again) am i correct in thinking that all of the valves will default to a closed position making an air line test reasonably accurate?

Yes removing the cams will seat the valves --all of them!
By introducing an air pressure remember the engine will kick back or forward depending upon the position of the crank & piston when the jner the air is inechted b

Hi Tuercas

I am concerned about the valves, i would be extrememly lucky to have avoided some sort of valve damage! I like the idea of an air line, do you know of an adapter that will make attaching an air line to the plug hole? i guess at 7 bar i would need to ensure that the air line dosen't blow out. In any case i will need to replace these gears in order to do the tdc valve test on each cylinder?

i'm very aware that just the cost of the parts might prohibit the repair and maybe easier to purchase another coupe where the gears have been done. Think i'm going to be really reluctant to purchase an engine where this inherent problem would still exist on the replacement unit and still leave me have to purchase the spares.

so how best to approach this? buy a couple of gears just to find out if i have any leaks..or just carry on stripping down and refurb the head?

Not fancying it much as a garden ornament! but it's much prettier than a knome!!

Mike
Hello again & greetings
Suggestion for the air line connector "get", buy (Halfrauds) scrounge, borrow, a cheapo compression tester and use the hose adapter to screw in the plug hole!
Bingo! You now have a cylinder leak down tester which in its professional version is many clams from the Snap On tool truck.
I have one inside my shop roll around 6' x 10' long Snap On double deck tool box. (then kept inside a fine English leather bound brass buggery box! )
I will add from your other post:-

I have to agree! whilst sat here pondering my direction i thinking that if i remove the camshafts (again) am i correct in thinking that all of the valves will default to a closed position making an air line test reasonably accurate?

Yes removing the cams will surely seat the valves --all of them!
By introducing an air pressure remember the engine will kick back or forward depending upon the position of the crank & piston when the the air is injected and you are listening for leaks . Think safety first.
If its manual drive, put it in gear, brake applied .
If auto find something substantial to block the crank. Like socket and knuckle bar on the crank pulley bolt all lashed down so that it won't fly off and go crashing through the kitchen window and scare the bejeezus out of the Missus! (if the thought garden gnomes doesn't that anyway! )
In short keep bits of your anatomy away from things that can turn. Seriously.

Yes buying used take out can be a crap shoot as they say in this side !
So you either have to locate, say a reputable re-cycle yard that has take outs with a warranty, or buy a wrecked unit with a service history.
See if you can find a mechanic that would look the engine over for you (for a few schillings) prior to take out and so that you can hear it running before you buy!
All the best
Tuercas Viejas

 

[Mike_wilts]

Suggestion for the air line connector "get", buy (Halfrauds) scrounge, borrow, a cheapo compression tester and use the hose adapter to screw in the plug hole!

Thanks Tuercas, I have ordered a compression tester from ebay today, cheap! it is just the hose i'm after afterall!

introducing an air pressure remember the engine will kick back or forward depending upon the position of the crank & piston when the jner the air

Duly noted! I can see the danger here, as my cam chain is still on the balancer and will be suitably tied up out of the way there is no way i want this to take on a life of its own! i'm sure this would wreak unbelievable damage to me and the car! So rest assured. I won't do anything dangerous.

I think this approach will determine wether the head comes off or not (i suspect it will) other than the cost of a bit of air line it will cost nothing other than my time to carry on.. I'm pleased this suggestion was made it has slowed down my thought process of buyng anything at this time.

Hoping the pistons are ok...

Thanks for the input guys, I will try and keep you posted as the project progresses...not the tpye of car to buy if your trying budget motoring!

Just a thought on these gears and chain.. when i look into the amount of supppliers, there seems to be loads out there, not really interested in fitting anything from China...but seriously, are these likely to be worse than what mercedes have already fitted. I also consider that the previous owner did not get the oil changed and this has contributed to the failure as the condition of the oil around the gears is far from good..

Mike

 

[markjay]

Have you considered one of these?:

http://www.halfords.com/workshop-to...micro-ca-25-40043-hand-held-inspection-camera

It might not be conclusive (it won't bend upwards to see the valves) but it could help check the piston crowns for signs of valve contact. Assuming the camera's diameter is less than the plug hole's...

(And for the price, it's a nifty tool to have around in general)

 

[markjay]

See also:

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[markjay]

Ha! So you CAN see upwards... with the aid of tiny bolt-on mirror. Very clever.

At any rate the YouTube clip seems to show exactly what you need....

 

[Tuercas viejas]

Thanks Tuercas, I have ordered a compression tester from ebay today, cheap! it is just the hose i'm after afterall!



Duly noted! I can see the danger here, as my cam chain is still on the balancer and will be suitably tied up out of the way there is no way i want this to take on a life of its own! i'm sure this would wreak unbelievable damage to me and the car! So rest assured. I won't do anything dangerous.

I think this approach will determine wether the head comes off or not (i suspect it will) other than the cost of a bit of air line it will cost nothing other than my time to carry on.. I'm pleased this suggestion was made it has slowed down my thought process of buyng anything at this time.

Hoping the pistons are ok...

Thanks for the input guys, I will try and keep you posted as the project progresses...not the tpye of car to buy if your trying budget motoring!

Just a thought on these gears and chain.. when i look into the amount of supppliers, there seems to be loads out there, not really interested in fitting anything from China...but seriously, are these likely to be worse than what mercedes have already fitted. I also consider that the previous owner did not get the oil changed and this has contributed to the failure as the condition of the oil around the gears is far from good..

Mike

Mike do take into account that a little bird who I worked with at Leyland and and then worked for MB UK told me that much of the Euro spec models had EWIS chains made in China installed in them anyway from new!. Saying you guys over there are lucky, only the real deal EWIS chain was installed for the US market.
Bit of an Oi-Sin sauce or egg on the face problem of that legendary MB reliability.
Yes irregular oil changes and sludge are timing chain killers.
Not just on MB's but L322 BMW /RangeRovers and yes pure BMW's (Bavarian Money Wasters and their awful Vanos systems.
Still I shouldn't complain have just put three kids through university, one a doctor on the proceeds of fixing this stuff.
So life is good on that score..

If you do get the urge to buy a an another MB try to get something with some solid service history and even then get a MB conversant mechanic to look it over for you before you buy . Knowledge is power remember.
Not knowing where you are in the UK. I ought to mention that I do have a younger brother who is a Pro mechanic like me (about 40 years experience ) and has a shop in Gloucestershire. He does a lot of pre-MOT; and pre-purchase inspection for folks like yourself wanting the security of a solid purchase of a used car --or PRE_OWNED as the Yankee versions of Arfur Daly like to call 'em over here .
All the best
Tuercas viejas

 

[NickC1234]

sorry to hijack the thread PM function is broken at the moment Tuercas Viejas could you have a nose at my thread been trying to get your attention !

 

[Mike_wilts]

Update:

Today I carried out a leak down test with my budget tester from ebay.. All the cylinders show the same leakage just outside the green zone (touching the moderate (yellow) section of the guage at about 40%. I can also feel a slight amount of air escaping out of the throttle body. this is the only place i can detect air escaping

so, i expected one or two valves to be damaged amd compression to be varied across the cylinders, not the same % reading from each..so can i safely assume that i have damaged all of the intake valves?

 

[markjay]

I would say that if you are certain that at least one valve is damaged, then it does not matter at this stage how many more valves are damaged.

Take off the cylinder head, and check... it may prove uneconomical to repair, but you'll only know once you can inspect the valves and piston crowns.

The logic behind carrying pressure tests with the cylinder head in-situ was that is you can prove that there's no valve damage, then there's no need to remove the head and you can just replace the timing gear and start-up the engine.

But once valve damage is confirmed, there's not much point in carrying-out any further tests with the cylinder head in place.

Once the head is off, the next step would be to inspect the damage and list the parts required, and then get a cost estimate to see if the repair is economical.

 

[190]

That all cylinders show the same leakage rate seem suspicious to me as an indication of bent valves. Someone experienced with leak down tests on that engine might be able to interpret the results better. There will always be some leakage, it's a case of what's acceptable.

 

[Mike_wilts]

Hi

Just a follow up;

spent Sunday removing the Cylinder head.....

I think I can assume Bent Valves!! These are the worst, however, all eight intake valves are of a similar condition..

Pistons.....

You will see from the image of the cylinder that there is a hose located to the front right of the intake that has a number of splits in it..having trawled through you tube i came across this gent explaining his thoughts on this...

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any views on his thoughts?

I'm assuming that the piistons have been slighty damaged where they have made impact. There is no scoring on any of the barrells. Unlucky with the Head, How many of you would rebuild from here? I beleive the pistons are normally dished to provide valve clearance, would you rebuild??

This is a good view of what happens when the timing change slips a tooth! think i may get away with the exhaust valves but all the inlets are shot..

M

 

[markjay]

The question is if the valve to piston contact can damage the conrods?

 

[markjay]

But otherwise well done for the investigative work (and photos).