Now what? Horrible clanging engine sound

Oonrahnjay · November 17, 2016, 06:41:04 AM

Quote from: Geoff on November 17, 2016, 05:48:07 AMBroken crankshaft?
--Geoff

I hadn't thought of that, but I've seen some crankshafts that break very cleanly so the the break is sort of like a "slip joint" -- they kind of hold together until they're under stress or load and then the broken parts move against each other. Of course, there are other failure modes of broken crankshafts, too. It would be a major failure if that's the problem, but it does sound like a possibility.

luvrbus · November 17, 2016, 06:53:46 AM

There is a hub with a key that drives the fan maybe they forgot or the key sheared I hope the crank didn't break George has had quite a trip,I hoping it is something in the direct drive fan assembly

what's another weekend Farmington NM after 3 months

daddysgirl · November 17, 2016, 07:20:48 AM

I noticed they wrapped your pipes. GREAT stuff for keeping temp in check, but is it possible one of the stainless steel straps is loose, or didn't get cut off and is hitting something?

chessie4905 · November 17, 2016, 07:33:43 AM

Sound continues for a second or two after shutting off engine........ eliminates most conjecture here. Turbo is most likely as they spin after engines are shut down for a few seconds.

Oonrahnjay · November 17, 2016, 07:46:31 AM

Quote from: chessie4905 on November 17, 2016, 07:33:43 AMSound continues for a second or two after shutting off engine........ eliminates most conjecture here. Turbo is most likely as they spin after engines are shut down for a few seconds.

This has been something that I have been thinking about too. But now that you've said this, I realized that I'm not sure if he meant "continues after the engine has been switched off but before engine rotation has completely stopped" or "engine shut down and come to a complete stop and the noise continues after all rotation has ceased". Chessie, I think you're right, it's almost certainly the turbo, with a slight possibility of some other rotating part that's come loose and continues to spin when it should be stopped. But working on the principle "the simplest answer is most likely to be correct", that points towards turbo. But part of chasing problems is eliminating all the little not-likely issues.
It will be interesting to see what's found when an experienced tech gets into it with a well-planned trouble-shooting plan.

Jeff Willard · November 17, 2016, 08:21:50 AM

Well.... considering the fact that he's been stuck in Farmington for 3 freakin' months it's sort of a tip off that "Experienced tech" isn't an option.
I agree that the turbo is most likely, going off the list of symptoms, and since it's real quick to check, it should have already been checked by the tech that came out.
This ordeal just makes you want to go sigh.......
Jeff

luvrbus · November 17, 2016, 08:51:18 AM

You can put your hand on a turbo with the engine running and tell if it is vibrating from a failed part on the compressor or turbine wheel

TomC · November 17, 2016, 08:53:15 AM

It has such a tinny, rattling sound, I still say it is a baffle in the muffler that has come loose and blocks the exhaust causing the black smoke. First remove the intake on the turbo and wiggle the turbine, then can use a piece of wood to keep it from spinning and start the engine to see if it is coming from the turbo. I would say to disconnect the exhaust side from the turbo to bypass the muffler, but then it would be so loud you couldn't hear anything above the exhaust note. Good Luck, TomC

brmax · November 17, 2016, 09:39:57 AM

plus one on somewhat tinny sound, I was there and then started listening to other videos where focus was other places around the motor also, ?.
With these I'm trying to get my thoughts on a coupling with some lite metal adjacent that will continue to spin.
what has me is the mention of a bit of black smoke but not a real feel in power loss, actually a let off at first, understandably but just that part says not much power loss in that moment respectfully.
I am sorry for sure, and my armchair sometimes is out there, goodluck.

Floyd

gumpy · November 17, 2016, 10:25:33 AM

~~I was going to say the dampener behind the crankshaft pulleys has come apart, but on further analysis, I think Geoff is correct. Your crankshaft is broken.~~

After looking at it again, I think that's the camshaft pulley, and I think the pulley assembly has come apart inside. Maybe they forgot to bolt it onto the shaft.

You can see it flopping around in the first video and the pulleys are unbalanced and not turning at appropriate engine speed.

scanzel · November 17, 2016, 11:10:16 AM

Just my two cents but if the crank had broken and was in fact slipping wouldn't it throw the firing order out of order and cause more severe issues or does this not pertain to a two stroke. To me a broken crank would cause more than a clanking sound more like a catastrophic failure to the power train.

luvrbus · November 17, 2016, 11:17:40 AM

Quote from: scanzel on November 17, 2016, 11:10:16 AM
Just my two cents but if the crank had broken and was in fact slipping wouldn't it throw the firing order out of order and cause more severe issues or does this not pertain to a two stroke. To me a broken crank would cause more than a clanking sound more like a catastrophic failure to the power train.

No it could break on the step down past the oil pump and it would still run and have oil pressure

chessie4905 · November 17, 2016, 11:39:25 AM

Why would it still run if engine was turned off. With new cylinders and rings it should stop quick. The other thought is that something was forgotten to be tightened, but still sounds like the turbo, especially in that short of a trip.

gumpy · November 17, 2016, 11:43:47 AM

Watch his first video in slow motion. At 0:04 you can see the pulley wobbling and something behind it is flopping.

I think they just forgot to tighten the bolts on the crank pulley and they fell out. It's now slipping on the shaft.

Geom · November 17, 2016, 12:04:34 PM

Clifford, my friend, you are, without any doubt, truly a bus Yoda!

The two shops talked this morning and decided to disassemble the fan drive and take a look.
They took it apart and didn't seem to find anything.

But after looking at the turbo, it does indeed appear to be that. Or at least the turbo is certainly one of the problems we're seeing. The exhaust side of the turbo was essentially just free-spinning and loose. It doesn't appear that there's any shrapnel and the turbo blades (exhaust side anyway) appear intact. This is from just a cursory exam as they haven't fully disassembled that yet.
I also have no idea if the intake side could've done something to the engine. Here's to hoping for not!

Before shipping it, the engine shop had mentioned "not liking something" about the turbo when they were dynoing it, and said they'd ordered another one.

But that could explain the entire chain of events. Smoke, seeming loss of power, etc. it all happened so quickly and so close to one another, and of course on a hill.
The sound was also very deceptive, because it was definitely coming from the lower left side of the engine.

We've contacted the engine shop to source a new turbo, which will be interesting the week before/of Thanksgiving.

Anyway, that's the update. More to come later...