technolackey

i have an odd sounding Thumping sound coming from what sounds like a rear cylinder (near firewall) after getting my head gask done.. used Cummins head gasket kit, all New Head bolts (14reg/6med/6long)... and had to replace bunch of push rods....

at idle it sounds like i can hear my diesels heart pumping..... obviously as i rev the noise of it drowns out the thump, but at idle its distinctive....

Need help and Info before i confront the mechanic who has already been paid... HELP!!

patdaly

First thing first, is it running smoothly or does it have a dead miss?

If it runs smooth, look for an exhaust leak at the head on one of the rear cylinders. I have never heard one vent combustion directly to the atmosphere, but I would bet it would be louder that you describe.

RTillery

I would be a little worried. Anytime you have head work done, you have to be cautious of valve to piston contact. If you had several pushrods done, what was the reason? If any were bent, the most common cause is a piston thumping a valve and bending the valve and or the pushrod. Was there a vacuum test performed on the head to determine the integrity of the valve to seat relationship when the head was off?

When the head is off, the piston tops should be checked very critically for any sign of "contact". I suspect the heart beat sound could be a valve leaking.

If the valve to seat seal was ok, was the head checked for straightness? If you lost a head gasket, it is most common to re-surface the head to make sure you get a good seal when the new gasket goes down. More than 9 times out of ten, if there is warpage, it occurs in the head and not the block.

Good luck and let us know what you find.

technolackey

I took it back to the mechanic today and we discovered that it sounds like its coming out of my AFE airbox.... when revved up and dropped to idle sometimes the sound stops for few seconds then comes back again... does the same thing while driving.... just comes and goes.... Did sound test on valve covers and all sound identical....

technolackey

Other then the Wierd Thup thup thup comin outta my airbox the truck Drives FANtastic, more power, no leaks anywhere, but just the wierd sound that comes and goes very randomly after revved anywhere between 1k-3k rpm sometimes it comes back instantly, other times takes up to 10 seconds...

RTillery

If an intake valve is leaking, (slightly bent) it would be leaking back into the intake. As RPMs increase, the intake pulses may overcome the noise backing up, and the cylinder pressures go up dramatically so it could be forcing a slightly bent valve to seal. I'd keep a close eye on it. It does not sound like a normal symptom and a bent valve can lead to a broken valve which can be catastrophic.

It could be checked by pulling the injectors and running a compression check. Would your mechanic be willing to do that?

technolackey

Hes a good Friend so whatever it takes to fix... hes stumped too.... just dont wanna make him rip the head down again if its something simple or normal....
I put the AFE air filter on the week that i bought the truck (at 250k KMs) and just had the head done at 396k KMs.. he was wondering if the pushrods were bent back then and now with new ones if thats a normal sound... I do have the complete HeadShield on the AFE filter as well, so wondering if that is also amplifying the sound as well

rebal

My 90 sounded like that with an AFE but with a BHAF (paper) it sounds normal. same with my 24V

technolackey

http://s725.beta.photobucket.com/use...stall.mp4.html


This is EXACTLY what my truck sounds like... the thump thump thump outta the airfilter.... been checking sites all day... sounds like its a valve issue.... off to the shop she goes

technolackey

Didnt even make it back to the shop today.... Blew a pushrod on the back cylinder on the way back to the shop.....

Tate

What shop are you dealing with?

technolackey

Is a friends shop so dont wanna call him out, hes newer to diesels and trusts his info site more then forums, and from the way the pushrod cup sheared at the weld mark on the rocker end (stayed on top end in valve cover) looks like it was a bad rod from cummins, but hard to tell... but after reading around, #6 exhaust rod is pretty problematic when getting a head redone....he put in new rod and redid the valve adjustment (THANKS TO ALL U MEMBERS) the way it says here on several threads this time..... its now running well.... and while he was workin I removed the silencer ring outta my turbo while i was waitin fer my ride home fer the night...lol

<edit> all u guys say that silencer rings takes 30s, that lil bastard wasnt at "7-8 oclock" it was at 12 and took 20 mins.... lol cant wait to hear it tomorrow morning...