Engine/Transmission (1994 - 1998) Whump,whump, Help!

[cluckmaster]

Well, got my transmission 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

 

[MAleksandrowicz]

Could be the head gasket leaking compression between cylinders. Also a lifter bent/broke and intake valve is working as an exhaust valve by forcing the air past it on the compression stroke.

 

[JAyers]

Mine did that the other day. I was showin a buddy what it would it do. After I got on it in 4th and broke the tires loose i let out of it real quick. I noticed it sounded funny when I let out. It scared the ***** out me, my buddy thought the truck was asposed to sound like that. I pulled over got the flash light out and no external leaks. The overflow bottle looked good. Got back in and it was fine sounded just like normal, ran fine. Id did notice a little white smoke or like a steam out the stack but it was like 10* so I figure it was just condensation. Its running fine, no signs of a blown head gasket. Id also like to know what gives?

 

[cluckmaster]

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.



How would I test for a broken lifter? Thanks.

 

[MAleksandrowicz]

Take the valve covers off and unbolt your rocker pedestals one at a time and take the lifters out and inspect them.

 

[Timebomb]

Take the valve covers off and unbolt your rocker pedestals one at a time and take the lifters out and inspect them.

Last I remember the lifters have to come out with the cam.

 

[cluckmaster]

Yeah, I thought you had to remove the cam to get the lifters as well. ?

 

[cluckmaster]

This is freakin pain in the *****!!!! I've got a new transmission 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?

 

[MAleksandrowicz]

Sorry, I meant the tappets.

 

[JGK]

To check for a faulty/broken lifter (tappet?) couldn't you do a fast valve adjust. Wouldn't a bad lifter/tappet, maybe a bent push rod, or even a valve problem show up as the lash way out of spec? It would be a farily easy check that might lead to some answers.



-Jay

 

[cluckmaster]

To check for a faulty/broken lifter (tappet?) couldn't you do a fast valve adjust. Wouldn't a bad lifter/tappet, maybe a bent push rod, or even a valve problem show up as the lash way out of spec? It would be a farily easy check that might lead to some answers.



-Jay

Valve lash has been checked. All good. Everything LOOKS fine.

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.

 

[JGK]

You can feel air coming back through the intake? So you're running the engine (at idle presumably) with the intake horn off, right?



OK, let's see. valve lash is OK. Air is coming back out intake tract. I think there's just a bit of valve overlap such that a tiny bit of exhaust MAY push its way back out the intake path on the exhaust stroke of each cylinder, but I could be wrong. I mean, it's used to being under pressure being a turbo charged engine normally. Just throwin' out ideas.



But you're getting this odd sound like, what, major air escaping past a valve or something.



I have a compression gauge and an adaptor that fits in the injector hole for 12-valve motors. You're welcome to use it for a compression test for the price of shipping both ways, if you think it will help.



-Jay

 

[cluckmaster]

Yeah, it's pretty loud once the intake horn is removed. Definitely not normal. I think we're gonna pressurize each cylinder at TDC one at a time through the injectors holes and see if the air goes past the valves.





Jay- Really appreciate the offer on the gauge- If I don't get ahold of one locally tomorrow I might take you up on it. My Dad was thinking about getting one anyway for his shop so he might buy one tomorrow.



Started to tear everything off to remove the head this afternoon but I'm gonna wait to pull it off until I do the tests. Headgaskets are too expensive.



Any chance an injector hanging open could make this noise? Thanks. -Josh

 

[JLitton]

This post is scaring me. I started hearing a noise coming from intake about 3 weeks ago that may be this same type of noise. Mine is noticeable, but not real loud. If it weren't my truck I wouldn't even notice it. Actually, my buddy couldn't hear what i was hearing. How loud of a noise are you hearing?

 

[cluckmaster]

This post is scaring me. I started hearing a noise coming from intake about 3 weeks ago that may be this same type of noise. Mine is noticeable, but not real loud. If it weren't my truck I wouldn't even notice it. Actually, my buddy couldn't hear what i was hearing. How loud of a noise are you hearing?

It's not very noticable unless you're kind of listening for it. Actually I didn't notice until I happened to walk on the passenger side of the truck while it was idling. Now I hear it all the time though since I noticed it. It was MUCH louder once I pulled the intake horn off and heard it through the intake/grid heater. I'll post the results of the compression test tomorrow. -Josh

 

[cluckmaster]

Update

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

 

[Mhannink]

check your pushrods i had one that got bent and it sounded like a chopper in there. same exact discription you gave

 

[cluckmaster]

New Twist

Well, I got my new pushrod from Cummins, and pulled the rocker tower off. Pulled out the exhaust pushrod, and it wasn't bent or broken. Pulled the intake pushrod, and after comparison, noticed that the exhaust pushrod had worn from the bottom (end that rides on the lifter) up about a 1/2 " and then formed a ridge where it went back to normal. A magnet pulled a couple tiny chunks of metal out of the top of the lifter. THEN I compared the NEW pushrod from Cummins to the two I had pulled from the engine (which I had ordered last summer from a local parts store/machine shop when I rebuilt the top end). That set was aftermarket but DOES NOT match the new one from Cummins. The Cummins pushrod is a hair longer and the ball on the end that rides on the lifter is smaller in diameter, and the cup on the end that the rocker sits on is bigger. So, we're thinking maybe the shop gave us the wrong pushrods, and the bigger ball end has started to splay the end of the lifter. Make sense at all?

 

[cluckmaster]

WOuld it be really stupid now to put all new Cummins pushrods in, without switching out the lifters? I think the trouble w/ #6 exhaust is due to interference w/ the breather tube vent which occurs bc the pushrod isnt sitting in the lifter as it should and is riding around on top of the lifter. So, all of the other lifters should be ok. We're thinking maybe if the correct pushrod is installed and is riding in the correct place, the lifter will be fine, and if I watch the #6 Ex closely I should be able to catch any problems. I just don't have the time to change the lifters out now as I have to take my girlfriend to interview w/ grad schools in TN and VA late nxt week.

 

[cluckmaster]

If anyone is interested, the part is Sealed Power, and it supposedly IS the right pushrod, but it's d***ed sure not the same as the Cummins part. So, but aftermarket w/ caution. Ordered from Cummins today- $3 per pushrod (would have been $17/rod at dealer). -Josh