N62 misfire

[andrewwynn]

I've been informed people for years to replace your chain tensioner regularly else this sort of thing will happen.

[murmansken]

Originally Posted by andrewwynn

I've been informed people for years to replace your chain tensioner regularly else this sort of thing will happen.

Chains tensioners and guides was done about 30000 km ago according to the papers and reciept that followed with the car, what happen with the tensioner that can cause this sort of damage? I work as a mechanic and I can´t se how its possible that the tensioner can stretch the chain without breaking. it must be a couple och centimeters longer now than before.

Now I have to replace both timing chains guides one solenoid etc...

[andrewwynn]

Originally Posted by murmansken

Chains tensioners and guides was done about 30000 km ago according to the papers and reciept that followed with the car, what happen with the tensioner that can cause this sort of damage? I work as a mechanic and I can´t se how its possible that the tensioner can stretch the chain without breaking. it must be a couple och centimeters longer now than before.



Now I have to replace both timing chains guides one solenoid etc...

Tensioner will stop providing tension. At this point the chain gets loose and "whips" think of a bull whip but made out of steel and pushed by unlimited force of the momentum of a V8 engine!

Pretty bad to fail so quick: was the tensioner OEM? I've seen non OEM I sent right back because the design didn't even LOOK similar no way it would function the same. After that one example and helping rebuild several engines that had internal destruction I would never use a non OEM tensioner.

I'm not familiar with the geometry of the N62 but did the chain "derail" and jump off track of the guides to get onto the solenoid?

There is no chance the chain from N62 is 2cm longer than new. The apparent extra length comes from guides getting chewed though usually. In rare occasion that will be followed by the chain actually coming off a toothed sprocket. At this point usually very quickly chews through the chain covers, a jam and breaks the chain and some bent valves.

Oh: loss of oil pressure due to low on or pump failure will cause loss of chain tension also.

[murmansken]

Originally Posted by andrewwynn

Tensioner will stop providing tension. At this point the chain gets loose and "whips" think of a bull whip but made out of steel and pushed by unlimited force of the momentum of a V8 engine!

Pretty bad to fail so quick: was the tensioner OEM? I've seen non OEM I sent right back because the design didn't even LOOK similar no way it would function the same. After that one example and helping rebuild several engines that had internal destruction I would never use a non OEM tensioner.

I'm not familiar with the geometry of the N62 but did the chain "derail" and jump off track of the guides to get onto the solenoid?

There is no chance the chain from N62 is 2cm longer than new. The apparent extra length comes from guides getting chewed though usually. In rare occasion that will be followed by the chain actually coming off a toothed sprocket. At this point usually very quickly chews through the chain covers, a jam and breaks the chain and some bent valves.

Oh: loss of oil pressure due to low on or pump failure will cause loss of chain tension also.

I havent looked at it yet but my guess is poor quality on the chain, have seen some with failed chains earlier but not on a bmw. Im going to remove the valve cover and timing cover and inspect what could have gone wrong here.

On the m62 the chain can get longer if it chew up the guides, but on the n62 I dont know.

It has not "derailed" because it ran just fine except from chains rattling and out of spec on the timing (kinda obvious) and a bit rough idle, I checked vanos solenoid to start with because they could get clogged and found that issue with chain chewing threw the solenoid.

Getting my hands on the car this weekend to inspect what has happened. Hopefully something easy but I think I have to replace chains, guides, tensioner etc...