Mystery knock

[troy_caleb]

My engine has been making this noise off and on since I bought it almost a year ago and have driven it 9,000 miles since. I thought it was an injector so I bought new BB code injectors and installed them...the old ones were all caked in with carbon. I 've fiddled around with timing a bit and have redone the return lines...however the 4 and 6 injectors seem to leak at the return caps. I've cracked all the lines at the injectors and they all seem to be the same...the engine rmps will drop and the engine will shudder. Sometimes the engine runs smoothly and there's no noise....Getting to the point today i blocked off the CCV by kinking it and the noise stopped and the engine smoothed I don't know if that would point to anything. I've listened around with a screwdriver and stethoscope and can't hear it on the injectors or valve covers all that much...seems louder on the drivers side. The engine has 109000 thousand miles and sat for about 5 years before I bought it. It smokes greyish smoke at start up for a few minutes but i think that is mostly from the return line leaks and old gp's. It has alot of blow by as well. Heres a video. sorry for the long post...
http://www.youtube.com/watch?v=5RbBKbw36sA&feature=youtu.be

 

[troy_caleb]

Really? No comments...I think it might be a lifter on the drivers side for an exhaust valve...just a hunch...butchering a deer right now but I will pull the valved covers later and check it out. Also going to loosen the rockers and pressurize the cylinders to check for cavitation, gasket failure, and valve leaks. Hoping that the block is good...did sit for five years on the kenai peninsula...anyone heard of the cylinders rusting and what that may do....if i can get it running good without pulling the heads then i will...but if i have to then getting a good hard look down into the cylinders and at the pistons won't be a bad idea. Just hoping it's not a main bearing, wrist pin, or cracked piston...has gone 10,000 miles off and on like this...guessing not a bearing....we will see...just don't want to keep pushing it and drop a valve or something...
Any input on the noise from the video would be great...I know there's alot of knowledge on this forum, I was bragging about this online community to my friends and family.

 

[hesutton]

The intermitant nature of the noise and recurrent leaking on certain return caps makes me think an injector or two may be suspect. But, I don't know why pressurizing the crank case make that noise better. Will have to think about that one for a bit.

Speaking of thinking, what made you want to try and pressurize the crank case?

Heath

 

[troy_caleb]

I was testing the coolant system for crankcase gasses because I thought that there was oil in the coolant and figure the it could be a blown head gasket. I read somewhere that blocking the ccv helps with the test...and while doing so I noticed that whenever the ccv was plugged the sound diminished...odd right?
Cracking the injectors seems to have the same result from all of the injectors...the engines just dies down a bit and rattles a little more like you would expect. There is a miss associated with the knock and it seems that you can hear is out the exhaust farily well so I'm hoping it's a lifter or exhaust valve.

 

[troy_caleb]

Also the engine smooths out at about 1200 rpms and the noise dissapears for a few seconds then seems to catch up and you can hear it in the exhaust and feel it slightly at 2000 rpms it's really hard to tell....but i've been listening to the damn things so much i can hear it in my head even when i'm inside watching tv or reading or whatever...damn noise has got me paraiod...

 

[Dieselcrawler]

well, the CCV is the only open hole outa the crankcase. sound and air travel out it. now with it kinked off, sound and air cannot travel out, thus creating presure in the crank. pressure in the crank could do some things, possibly take some play outa a worn wristpin? valve play? got me stumped.



also that blow by isnt that bad. seen alot worse.

 

[troy_caleb]

Yeah, me too...looks like a guessing game at this point until I dig in a little...i'm really hoping for something on the top end...and if not at least no damage to the block....i'm not in a good position to pull the engine and rebuild it....heads would be a nuisance but i would be ok with...if it comes to pulling the engine than I might have to find a running one to drop in while I rebuild this one....crossin my fingers...heard that noise from the video before...its odd how it's deep, hollow, and not always rhythmic....

 

[troy_caleb]

oil on the #8 gp...hopefully just head gasket

 

[hesutton]

I had several bad injectors on my 6.9 crew cab, one was actually stuck open. The "crack each injector line" trick didn't show anything with my truck either. It doesn't work everytime unforntunately.

Let us know what you find out man.

Heath

 

[troy_caleb]

that's good to know, the noise sounded like it could've been an injector...but I pulled the valve cover and gp's and pumped 100 psi into the cylinder after loosening the rockers and a good bit of air was coming out of the intake so I guess I'ts a good time to get some head work, inspect the cylinders, and get head studs? I live on an island in southeast ak and theres no machine shop...so I'm hoping one of the mechanic around hear has a valve grinder...there wouldn't be anyone to deck the heads if they were warped so I'm hoping they aren't. I should get my injectors pop tested while I'm working on it too. Did you listen to the video I posted above heath?

 

[SLC97SR5]

It sounds like incorrect timing to me. What are you running for fuel? Is Alaska on #1 diesel?
Just for fun, try adding a gallon of 2 stroke oil or whatever diesel oil is cheapest up there in your fuel tank and see if the sound changes.
My truck will knock intermittently if I use too much kerosene or D1 and not enough oil to add some btu's and cetane back into it.

 

[troy_caleb]

I've tried advancing and retarding it... definitely sounds better retarded...the knock seems to not be as intense and less frequent. Not sure about the diesel here...and I question the quality of the fuel we get...I add lucas to every fill and diesel kleen when it's cold out.

 

[troy_caleb]

pulled the heads and started a new thread about it, posted photos