Help Me Diagnose a Problem?!?

[Blkdawdg]

I came upon another Cummins "speedbump" tonight and I need your expert opinions on where to begin. I had just gotten into town and met up with some friends, (I was driving it pretty hard on the way in... EGT's @ 1300 but only for a second and held steady at about 1000) so I stop and turn off the truck. I immediately look up at the EGT gauge and see that it's @ about 395, so I started the truck back up to cool the EGT's down since I was stupid and forgot to look before I turned it off. The time between shutdown and restart was probably about 3-5 seconds. Well as soon as the truck started, it was making a horrible clanking sound like someone beating on the side of the block with a hammer. (I may know that answer but I'm afraid to admit it).



Why would restarting the truck make it start this noise? It wasn't doing it before I shut it down. I've started checking the rods and made it to #5 before I got tired and decided that I will start on it in the morning. Nothing looks out of place from what I can see on the top side under the valve cover.



Thanks for the help and keep your fingers crossed for me.

 

[Todd T]

interesting, maybe it had boiled off the oil from the bearing surfaces of the turbo. or the oil drained off the top end of the engine due to it being so hot. causing the valvetrain to be noisy for a few seconds until it got fresh oil again.

 

[Blkdawdg]

It's still doing it

I ran the truck for 5-10 minutes @ idle and it was still doing it. It should have had enough time to get cooler oil to the top of the engine, right?

 

[Blkdawdg]

Update

So I pulled all of the pushrods today and they were all fine. After I readjusted the valve lash, I cranked the truck and unfortunately the "knock" was still there. So decided to draint the oil to see if there were any metal flakes in the oil, but there wasn't. You guys have any idea of what I need to do next?

 

[hawkerpilot]

At idle, crack open each injector line one at a time and listen to see if noise changes or goes away. Repeat process for each cylinder. this will tell you if you have a bottom end problem .

 

[Briar Hopper]

If you crack open those injector lines, don't overtorque them when re-tightening ! A 3/8" drive torque wrench, and 19mm crow's foot will work to get them to 28ft. lbs.

 

[Blkdawdg]

No ChangeS

I cracked the injector lines and there was no change or disapperance of the noise. Does that mean that I have a "head" problem?

 

[Gary - K7GLD]

There's NO WAY that immediately re-starting the engine could so quickly create a lubrication problem! That engine should run for several minutes at idle before oil starvation could start problems...



Look at how long the engine runs with minimal oil flow at startup after sitting for several DAYS without failure...



PLUS, the fact that cracking the injector lines didn't change the knock in the slightest, pretty well eliminates a single-cylinder problem as far as lubrication starvation is concerned. I would suspect something else, like a AC pump, power steering or harmonic balancer... OR even an exhaust system hitting something in close proximity to the engine...



Be interesting to hear what you find - keep us posted!



And good luck...

 

[hawkerpilot]

no change is good . bottom end is solid . You may have valve sticking or a belt driven componet bad. TRY Removing serpentien belt. for a few. This will set a code or a light or both do to lack of charging not a big deal . Worth a try , belt removal is vary ez .

 

[WeirCummin]

Eric, Didn't just change the clutch? You may want to start thinking about something in the bellhousing. Just a thought.

 

[Blkdawdg]

What could it be in the bellhousing that would cause a noise like that to start? I immediately thought of that but I couldn't think of anything that would make a knocking noise.

 

[Gary - K7GLD]

Loose flywheel bolts will get yer attention in a hurry...

 

[abledog]

loose clip on the throw out bearing might lead to a rattle?



Another possible cause for an engine nock is a loose nut behind the stearing wheel

 

[Blkdawdg]

NEW ENGINE!

Well I finally broke down and took my truck to the dealership. Found out that the thrust washer came off of the crank I now have to put a new engine in my truck! I think with this new engine, I'm going to put 3-5K miles on it before I add any performance parts. On my "last" engine, I added the parts with 170 miles on the odometer, and I seemed to have had a lot more problems then others with the same mods. I'm not saying that this is the reason for my probs, I'm just mentioning my new experiment.