Well, got my tranny in Sun, and yesterday hopped in the truck to grab some lunch and noticed a WHUMP, WHUMP, WHUMP sound coming from the passenger side of the engine bay. Popped hood, and it sounded like it was coming from the Scotty intake. I put my hand on the housing and you could feel the vibration matching the sound. It sounded similiar to when my #6 exhaust valve was out of adjustment when I first put the engine back together this summer. No white smoke. No loss of boost really. Temps in normal range. I pulled the valve covers and double checked the valve lash. Fired it up and watched the rockers and lifters work. Nothing seemed amiss. I don't think it's a pushrod.

-Could a burnt valve be the culprit? Do i check that w/ a diesel compression gauge, and where can I get one?
-Could it be a weak or cracked valve spring? I had them tested prior to putting the engine back together but that was 6 mo ago. Could the 3GSK and cam together hurt the stocker springs? And would it hurt for nme to run the truck w/ a bad spring until I can get another set?
-Could an injector gone bad cause a sound like that?

Thanks! -Josh

 

S&K should have all the stuff you need for a diesel compression testing at reasonable rates. Our snap-on set up at the shop is not so cheap however. A burnt valve could cause said noise and it could be a result of your springs not being heavy enough. The 3kGSK alone wouldn't have hurt you, but if you installed a high lift cam the combo would tend to kill your springs/valves.

 

Forgot to mention that I cracked all injectors, one at a time, and each cylinder missed when that injector line was cracked. The noise continued throughout the procedure. This would indicate to me that it would not be a faulty injector, and also that there isn't a breech in the headgasket between cylinders. I could be wrong.

Thanks.

 

This is freakin pain in the a$$!!!! I've got a new tranny in and was about to drop in a #100 plate and now I have to baby the truck all the time! Any other suggestions? How do I check for a burnt valve seat or burnt valve? If I have to pull the head again, I'm gonna lose it. Any possibility it might be something other than engine noise? Turbo?

 

bent pushrod maybe?

 

bent pushrod or an exhaust manifold leak?

 

Such a deal
http://www.harborfreight.com/cpi/cta...emnumber=93039

It's just a gauge with some adaptors, how can you go wrong?

 

yup...great deal! Called them up and it's like $60 to overnight it though!!!

Pulled off the air horn and the noise is definitely coming through the intake. I can feel the air blowing back throught the grid heater/intake. Ughhh....next step? Pull head? Any ideas? All the clearances good and springs look good and feel good as far as I can tell.

 

A makeshift but cheaper way to test would be to rig some sort of fitting to pressurize the cylinder with shop air thru the injector hole. I've done gassers by using a rubber tipped blow gun thru the sparkplug hole. Make sure that BOTH valves are closed and then pressurize the cylinder and if you get air blowing back thru the intake, you have a valve or seat problem of some sort.

 

Haha...that's just what we're planning on doing. Picked up a long nozzled rubber tipped blow gun from NAPA today. Just wondering if it'll make enough pressure to simulate the engine actually running. Thanks. -Josh

 

No way that it will produce enough pressure to simulate cylinder pressure but it should be enough to find burned valves or seats or holes in the piston. Small cracks that open up under heat or pressure may still be able to hide.

Let us know what you find.

 

God I'm an idiot... I figured it out. You have an exhaust valve that isn't opening properly. Is what's happening is an exhaust valve isn't opening all the way and so the cylinder isn't being vented completely. Then as soon as the intake valve opens the remaining pressure backs up into your intake. It's called reversion; it's a great thing when building a high rpm gas engine... But one of the worst things you can have on anything turbo charged.

So it narrows it down to a few things:
- Valve lash out of adjustment
- Bent push rod
- Broken rocker arm
- Flattened cam lobe

Now if the cummins were a hydraulic lifter I would have to add low oil/low oil pressure, but as we all know it's a solid mushroom lifter...

 

Good idea, but I checked the valve lash and the rocker assemblies all look and feel good. I would think the push rod would show up in the valve adj. being out of wack, right? So that leaves flattened cam lobe. I didn't change the lifters out when I changed cams, but I was told by the cam designer that I didn't need to because of the design of the lifters/ tappets. Normally that's what would wipe a cam, right? What else would cause the cam lobe to flatten? Man, I hope that's not the case. Thanks. -Josh

 

cluck, u can put a dial indicator on a magnetic base on the rocker arm and roughly check valve lift(possibility of a bad cam lobe) I would run a compression check on all 6 holes, if one shows low, put a squirt of oil in the cylinder and recheck it. If it doesnt come up, you have a bad valve/seat. Just a thought.

 

UPDATE - Well, ordered a compression gauge from NAPA and specified what adapter I needed. Came in to my Dad's shop that day. Wrong adapter Sooo...order the right one. Supposed to come in that day or next, but three days later we call and the local store calls the wharehouse- it's on backorder and everyone forgot to let us know.

So, unable to do a compression test, we ordered the adapter from Snap-on.

Now the FIRST time I pulled the valve covers off and checked valve lash, they were all good. Back together, kept running it. Noise increased so it went in the shop and that's when I stripped it down to take off the head. Since we couldn't do the compression test, we checked the valves again, this time, #6 Exhaust was at .030 instead of .020. Adjusted, smoothed out the noise. Thought hmmm....let's put it back together, run it a day, and see what happens. Well, a couple of days later, noise is back w/ a vengeance. Louder than before and I got it back in the garage as fast as possible. Valve cover back off, I checked lash on #6 Exhaust. WAY off! Could have fit at least three .030 feelers in there. Adjusted it back, started truck up...smooth again.

Sooo...plan is to pull #6 Exhaust pushrod. Maybe broken, or bent bad? Fish around w/ magnet and remove any metal, replace pushrod, back together. I'm thinking now this could be the culprit behind my low mileage and power I've been chasing. Sound right?

Also, contemplating how to remove pushrod. Could pull tower assembly, but I don't have any ARP lube around for retorquing that stud and bolt. AND can I remove just that stud and bolt and retorque just those, or do I have to loosen and retorque the whole head? Thanks guys! -Josh