Video: Diesel engine knocking noise
Video: Diesel engine knocking noise
(OP)
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
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





RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
Do a compression test on all cylinders and see if one is suspect.. If so, a boroscope is a handy tool and easy way to look inside the cylinders and see what might be amiss..
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
I'm guessing there's a piece of a valve or piston banging around in one cylinder.
A compression check will tell you which cylinder, and a borescope will help figure out what's going on, but further cranking or running will do more damage, and you'll have to pull the cylinder head anyway, so I'd just go ahead and open it up.
Mike Halloran
Pembroke Pines, FL, USA
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
I also think you need to have the head off it - reckon you'll find a valve problem.....
Nick
RE: Video: Diesel engine knocking noise
I've heard diesel engines do that because an injector is not properly seated, and I've heard gasoline engines do that because a spark plug was coming unthreaded and was only held in by the ignition coil above it (coil-on-plug engine - a regular engine would have simply sent the spark plug flying).
RE: Video: Diesel engine knocking noise
The clanking seems to me to be a half-engine-speed sound.
Meaning that it is possibly in the valve gear somewhere.
The clanking is so sharp and unmuffled I would guess that it's in the top of the engine somewhere.
Probably just a very wide rocker clearance (like 1/8 of an inch) caused by a dead hydraulic lifter or bent pushrod.
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
An intake valve that doesn't open will make for a soft cylinder since it will pull a vacuum on the intake stroke.
RE: Video: Diesel engine knocking noise
Ivymike - it could be a fuel problem etc. - but it just sounds too mechanical/metallic to me.
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
rmw
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
Regards
Pat
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RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
I hope this is not going to be another of those situations where we never hear from the person who posed the original question.
They must know what is (or was) wrong by now. We all learn something when we all told what was wrong -otherwise -nothing.
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
I am still waiting for a full diagnosis. But I had a guy come round this morning and have a quick look, its common rail and he loosened off the fuel intake on the middle cylindar and reckoned it wasn't that, loosened the second one and it looked like the noise died a little. It started fine cranking over and ticking over ok so he thought the compression was fine. The follower seems to be fav at he mo. He gave me the number of an engine guy who said he would take a look when he is next down my way which should hopefully be this week.
i will keep you posted, the cranking issue is not a problem now at all (that was because i had to disconnect the fuel lines to get the oil cooler off when i was replacing that)
thanks again
RE: Video: Diesel engine knocking noise
If you fail to undo a bolt or two at one end of the head and use a really long breaker bar lifting at the other end, you might remove most of the head.
Regards
Pat
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RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
BigClive seems the most likely "Probably just a very wide rocker clearance (like 1/8 of an inch) caused by a dead hydraulic lifter or bent pushrod"
RE: Video: Diesel engine knocking noise
It does act like a low cylinder when cranking.
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
anyway here's a video of it cranking with the valve cover off, notice it cuts near the end after we take one of the cams off, i'm still confused as to what is causing the noise though - any thoughts ?
http://youtu.be/zF14UVlkJsw
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
http://youtu.be/zF14UVlkJsw
RE: Video: Diesel engine knocking noise
http://www.youtube.com/watch?v=zF14UVlkJsw
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
http://www.youtube.com/watch?v=zF14UVlkJsw&feature=youtu.be
RE: Video: Diesel engine knocking noise
got there in the end!
www.youtube.com/watch?v=zF14UVlkJsw&feature=youtu.be
RE: Video: Diesel engine knocking noise
A twin-cam, four-valve diesel? So much for theories about bent pushrods and damaged lifters etc.
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
youtu.be/4m0dLbrenws
RE: Video: Diesel engine knocking noise
Several others suggested compression checks which at least hinted toward piston.
That twin rail thingy all jammed up with scuffed off piston bits is an oil control ring.
You still need to ensure you rectify the cause for the piston to scuff up like that. It very nearly seized. It is probably a result of overheating, but also possibly poor timing. Basically the piston got to hot and grew to much for the bore.
The bore might also now be out of shape.
Regards
Pat
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RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
I would at least check all the bearings as the load from that damage being caused may have harmed them. Also the metal contamination may have found its way to the galleries and bearings and oil pomp.
Regards
Pat
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RE: Video: Diesel engine knocking noise
RE: Video: Diesel engine knocking noise
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
RE: Video: Diesel engine knocking noise
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.