Clacking sound from engine
Thread Starter
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
Clacking sound from engine
I'm afraid I'm going to be tearing into this engine again after only about 20K on a rebuild done by the guy who has the best reputation in this town. The clacking seemed to be a lifter at first, so I changed the oil and put a can of goop in. That quieted the sound almost completly, for an hour or two of run time. Now it's back, though not as loud.
It's hard to isolate exactly where its coming from, but pulling the injector plug on #8 shuts it up. The spark plug is tight, there is no indication of a leak at the header on that cylinder, and the injector itself sounds the same as the others using a stethoscope. Also oil temperture and pressure seem nominal, but the fact that pulling the injector plug quiets it has me worried its a bearing in the #8 rod.
I'm not sure where to look next at this point, short of tearing down the engine. I took an oil sample when I changed it, but Blackstone will take a couple of weeks to get me a report that will hopefully tell me if a teardown is necessary or not. Any ideas on other things to check?
TIA
It's hard to isolate exactly where its coming from, but pulling the injector plug on #8 shuts it up. The spark plug is tight, there is no indication of a leak at the header on that cylinder, and the injector itself sounds the same as the others using a stethoscope. Also oil temperture and pressure seem nominal, but the fact that pulling the injector plug quiets it has me worried its a bearing in the #8 rod.
I'm not sure where to look next at this point, short of tearing down the engine. I took an oil sample when I changed it, but Blackstone will take a couple of weeks to get me a report that will hopefully tell me if a teardown is necessary or not. Any ideas on other things to check?
TIA
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
It is tough to guess from a verbal description of a noise, but based on what I've read in your post, I'd start by readjusting the valves. It is cheap, and if it is the problem, it beats totally disassembling the engine only to find no problems.
RACE ON!!!
RACE ON!!!
Thread Starter
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
I should have mentioned that I already tried to readjust the valves. The first time I did it, the noise was gone when I was done, but it came back after the engine cooled again (I did the adjustmet with it running). Then I added the goop and changed the oil, which made it go away again - for a while.
Anyway, pulling the injector plug wouldn't quiet a bad lifter or loose rocker, would it??
Anyway, pulling the injector plug wouldn't quiet a bad lifter or loose rocker, would it??
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
Pulling the injector plug stops the noise. So, it is either the injector or combustion in the chamber causing the noise, right? Unplug the spark plug but do plug in the fuel injector. It the noise continues then it is the injector, right?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Originally Posted by scranage
I still don't see why you are pointing towards a valve lash misadjustment when the noise goes away when the cylinder isn't firing (from a disconnected injector)
RACE ON!!!
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Thread Starter
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
I'm asking a question. Doesn't the removal of the combustion combined with the dissapearance of the noise eliminate a problem in the valve train. Period. I wasn't trying to insult anyone.
Last edited by scranage; Nov 20, 2007 at 08:41 PM.