Video: Diesel engine knocking noise

[billyonemate]

Hi All,

Am trying to work out the source of the heavy knocking noise on this Jeep Diesel engine (see video link below). The oil cooler failed and it did overheat as there was contamination of the coolant with oil. Oil cooler now replaced and coolant flushed. Now coolant is good with no contamination, but there is this metallic knocking noise, any thoughts what it might be?

http://youtu.be/Ux9mR-hmguU

thanks

 

[RossABQ]

Billy, what market offers Jeeps with that engine? Who makes the engine?

 

[MikeHalloran]

One hint from bitter experience:

If you can't account for every last gram of piston ring material, you need to expose and brush clean every bit of the engine interior including the oil galleries.

That includes specifically pieces smaller than a grain of sand that can go through the oil pump screen. On the first cold start, they will flow through the oil filter bypass valve, and take out a rod journal.



Mike Halloran
Pembroke Pines, FL, USA

 

[Jiujitsu10]

Well, this happened a while ago, but it is quite interesting.

When analyzing power cylinder failures it is always best to analyze the cylinder with the least amount of damage, for it will tell you how the scuff started. It can start on the ring, or on the skirt or on the pin, all different kinds of issues.

The image from the piston is quite consistent with overheating, because we can see that the scuff occured almost all the way to the face tranversal to the pin, and since we all know pistons are oval, it makes sense that the scuff on a overheated piston will start there and progress from there.

It is difficult to analyze now with just one screwed up cylinder because the scuff progressed pretty badly on that one, and it takes away evidence of the cause.

But it makes sense that this piston (It must be the one farthest from the coolant inlet) will scuff first. And then you corrected the issue with the coolant and it was ok. Also, all the post failure cranking to hear the noise, will do more damage to a scuffed piston, thus making it harder to evaluate.

Power cylinder failures are always very good exercises for the mind.. I've worked through several of those, and I can say, the engine always surprises us with new screwed up ways to scuff and break down.