00 6.5 Popping Noise In Breather Box

[52TMOD]

Truck Had Cracked Heads Replaced Both Heads And Installed New Lifters And Pushrods And Rockerarms And New Injectors-when First Started It Runs Well With No Noise Once It Warms Up A Little It Will Start Making A Popping Noise Thru The Breather Box Starts Out To Be A Light Noise And Gets Louder But If Throttle Upped The Noise Will Go Away For A Moment But Will Return Quickley..thanks
Vehcile Is 2000 Gmc 2500 Std Trans 2wd

[Mark Rinker]

Sounds like you have an intake valve that is remaining open during cylinder compression or power stroke.

[john8662]

Hmm..

You replaced pretty much all the valve train except the camshaft in this scenario.

New Lifters
New Pushrods
New Rocker/arms
New Heads

Where were the heads from?

What was the cause of removing the heads, the cracks you found were likely the cracks between the valves that are o-so common, but not normally the cause of leaks or poor running. Was the popping sound present before?

J

[ToddMeister]

Sounds like you have an intake valve that is remaining open during cylinder compression or power stroke.

Or....

You have an exhaust valve that is not opening during the exhaust stroke. Left over exhaust gases are popping into the intake when the intake valve opens.

[52TMOD]

The Cylinder Heads Were Cracked And Was Loosing Coolant-the Noise Was Present Before-when Disassemble Found 2 Lifters That Had Come Apart Believed That To Be The Reason For The Popping..i Wouldn't Think It Would Be A Cam Problem Because It Is Not Popping Until It Warms Up And Then It Will Start Popping But If You Accelerated It Up A Couple Of Good Times It Will Quit Popping For Few Moments..thanks

[john8662]

What is the oil pressure you're reading?

Might consider connecting a mechanical pressure gauge to the engine to verify good oil pressure. It's possible your oil pressure it too low hot for the lifters.

The two lifters that came apart, did the retainer clip slip allowing the socket the pushrod sits on to slide sideways?

J

[52TMOD]

yes that is what happened to the lifters..oil pressure with mechanical gauge read between 60-80 ibs of oil pressure....should be plenty????thanks

[john8662]

Have you removed the accessory belt off the engine to verify that it's not an accessory making the noise nearby?

Might try getting the engine up to the operating temp where it makes the noise consistantly, then kill it, remove the belt then restart, just for grins of course.

Vacuum pumps when they fail make a huffing noise in that area of the engine.

An audio clip might be helpfull in diagnosing this.

If the lifters came apart in the way I'm describing, then they probably didn't cause cam damage, usually just bend pushrods. If the roller on the bottom of the lifter was in good shape and the lifter didn't twist in the guide, then the cam could be sound.

Hmm..

[52TMOD]

You Can Pull The Breather Box Apart And It Will Be Blowing Cool Air In Everytime It Makes The Noise..thanks

[john8662]

Just thought I'd throw that one out there.

Might consider running the engine w/o the valve covers. Remove the intake, then remove the injection lines, then remove the valve covers, then install the lines again and start it w/o covers and see if you notice anything odd, like a valve stem not moving.

You may consider not starting it as well and just rotating the engine over by hand and listening to the engine, and watching the valvetrain as you move it several revolutions.

Check when you have the valve covers off, that you didn't accidentially miss a lifter with a pushrod, with the pushrod sitting right beside the lifter where it should be. It happens, accidents do happen (whistling loudly now).

J

[bcbigfoot]

Does the engine start running rough or missing when the noise occurs?

[52TMOD]

No The Engine Dosen't Run Bad Or Miss When The Noise Comes-once Engine Is Reved Up It Will Go Away For A Moment..thanks

[52TMOD]

Here's What We've Done-beleive That We May Have Gotten Bad Fuel-purchased Some Lucas Upper Cylinder Lubricant And Installed Drove The Vehcile For 2days Now And No Noise As Of Yet-did Make Noise For The First 30-40 Minutes After Installed By Not Since..thanks For The Help

[john8662]

Really?

I would really have liked to hear the noise while you were troubleshooting it.

I sure hope that's all that it was!

Keep us updated!

[52TMOD]

Day 3 And Still No Noise...keeping Fingers Crossed..thanks