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Author Topic: engine knock review.  (Read 6871 times)

sanchez

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engine knock review.
« on: January 10, 2008, 03:31:39 PM »
hi, After listen opinions about my engiene sound, I took tis footage with the microphone covered with a finger (to ear only the hammer noise, is confirmed, this engine is knocking too loud. Today or tomorrow I'll remove the cover to inspect the crankshaft bearings and rod bush and bearing. The results will be posted, for now apreciate the sound in the video.http://youtube.com/watch?v=zeBlxjL5dT8

ronmar

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Re: engine knock review.
« Reply #1 on: January 10, 2008, 03:48:16 PM »
DOn't forget to check your flywheels and gib keys.  IF you can listen to it from several different sides, bot up high and down low, you should be able to determine the general location.

Good luck
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sanchez

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Re: engine knock review.
« Reply #2 on: January 10, 2008, 06:34:20 PM »
jens, that sound some mystical, but any  the way, I will have the chickens near while I work in the engine...... ;D ;D ;D

biobill

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Re: engine knock review.
« Reply #3 on: January 10, 2008, 08:35:08 PM »
Sanchez,
  I had a noise in one of my engines that I would have sworn was a rod knock. Turned out to be the idler gear slapping up against the side of the crankcase. You could see it walking back and forth as the engine was rotated by hand.
  Just something else to look out for.   Bill
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BruceM

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Re: engine knock review.
« Reply #4 on: January 10, 2008, 09:33:42 PM »
I"d like to pass on a tip from Hotater that I found useful- make sure you inspect the UPPER crank bearing surface.  This is where problems show- not on the bottom bearing half.


rocketboy

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Re: engine knock review.
« Reply #5 on: January 11, 2008, 02:33:51 AM »
Double check the timing and then the piston/head clearance.

good luck.

Bob
Sadly, artificial intelligence will never be a match for natural stupidiy.

xyzer

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Re: engine knock review.
« Reply #6 on: January 11, 2008, 02:53:52 AM »
Double check the timing and then the piston/head clearance.

Wouldn't you feel if the piston meets the head as you crank the engine over ?

Jens
Jens,
I believe Bob was refering to http://listerengine.com/smf/index.php?topic=2310.0
Basicly the compression ratio. If you pull the head be sure to check it.
Dave
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oliver90owner

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Re: engine knock review.
« Reply #7 on: January 11, 2008, 07:08:59 AM »
Another possibility for knocks is given as a sticking valve (being closed by the piston), usually the exhaust valve.

Also a carbon build-up can knock loudly.  You would not feel it so much cold and slow, but there would be just zero clearance when hot.  Once took the head of a small petrol generator to find about 20% of piston area covered neatly with carbon build-up.  Old engines (cars) were recommended to decoke every 4000 miles back in the 30s/40/s for that very reason.  Poor fuel was one factor.

RAB

sanchez

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Re: engine knock review.
« Reply #8 on: January 11, 2008, 02:30:20 PM »
thanks guys,

I will check the engine the next week, this weekend is the birthday party of mu daugther. but answering, the engine rotate by hand smoothtly and you do not feel any contact or friction. I don't know now if  the engine have a real problem, let me explain, with the engine started and under load, I cut the fuel rack off, the sound disapear, them, quickly I release the rack and the engine revolutions raise (breaking the inertia) with a heavy injection steram, black smoke and all the other...., during the engine recovering, the sounds increase proportianally to the overinjection, when the engine stabilize, the sound is regular. I think that the knock is normal in the DI engines, what all you think?

biobill

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Re: engine knock review.
« Reply #9 on: January 11, 2008, 05:18:24 PM »
Sanchez,
   My DI is definitely "knockier" than my IDI        Bill
Off grid since 1990
6/1 Metro DI living in basement, cogen
6/1 Metro IDI running barn & biodiesel processer
VW 1.6 diesels all over the place
Isuzu Boxtruck, Ford Backhoe, all running on biodiesel
Needs diesel lawnmower & chainsaw

sanchez

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Re: engine knock review.
« Reply #10 on: January 11, 2008, 08:55:58 PM »
great to ear so, but a rod inspection is easy, better I'll do to be sure.

rocketboy

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Re: engine knock review.
« Reply #11 on: January 12, 2008, 03:46:32 AM »
Your knocking sound sounds very much like a problem we had with an engine that was improperly timed. Timing is my first choice for your troubleshooting. Good luck.

Bob
Sadly, artificial intelligence will never be a match for natural stupidiy.

diesel guy

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Re: engine knock review.
« Reply #12 on: January 12, 2008, 04:01:57 AM »
rocketboy,

It sounds too advanced to me also.

Diesel Guy

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Re: engine knock review.
« Reply #13 on: January 12, 2008, 04:49:18 AM »
jens,

Injection timing, remember the other post when I mentioned, if the fuel is injected early it would produce rapid acceleration ATDC, on your belt slipping post? The crack you are hearing is the extreme pressures in the combustion chamber, this reduces engine life many folds.

Diesel Guy