L94 Knocking

[jrobie79]

2011 Escalade with RPM dependent knocking (video attached) - 293k, no codes, oil pressure around 30 at idle. Pulled valve covers, all the rockers move, so I don't think its a collapsed lifter, pushrods are straight, looking for next step to diagnose/repair.

I'm not familiar with pushrod engines, I've only ever torn down BMW DOHC engines, so looking for advice so I'm not wasting my time doing anything unnecessary

https://flic.kr/p/2o6zodG

 

[B-train]

It definitely sounds like a lifter to me. Does it actually run OK? If so, maybe try some ATF in the oil and see if that frees up a sticky lifter. 1 quart should work added in.

But, honestly if it were mine, I wouldn't run it anymore. You may have a wiped out cam too by this point. Either way you have a big job ahead of you.

Others who've lived through this will chime in as well.

 

[jrobie79]

You may have a wiped out cam too by this point. Either way you have a big job ahead of you.

It runs fine, it felt like it was a little sluggish when I was in stop and go traffic, buy that could just be cause I was in stop and go traffic. When cruising I didn't notice anything negative. I'm about to pull the cam to inspect it. Just really can't afford the downtime of a full rebuild ‍

 

[Doubeleive]

sounds like noisy lifter to me, my 03 did it for 10+ years off and on it has almost 300k on it and still runs fine
it did it consistently for 5 years or so at startup but would quiet up after a couple minutes then come back if left idling for a period of time
then one day I did a oil change and it stopped completely for a couple years then it went back to same old routine
you could try some snake oil treatment and see if it goes away before digging into it.

 

[B-train]

It runs fine, it felt like it was a little sluggish when I was in stop and go traffic, buy that could just be cause I was in stop and go traffic. When cruising I didn't notice anything negative. I'm about to pull the cam to inspect it. Just really can't afford the

It runs fine, it felt like it was a little sluggish when I was in stop and go traffic, buy that could just be cause I was in stop and go traffic. When cruising I didn't notice anything negative. I'm about to pull the cam to inspect it. Just really can't afford the downtime of a full rebuild ‍

I'd maybe do what @Doubeleive stated as a first try. Pulling the cam is no small job. Have you already torn down the top of the motor?

 

[Doubeleive]

ya at 293k if it needs a teardown then may as well do a whole rebuild in which case may as well just drive it. I wouldn't waste my money otherwise

 

[jrobie79]

Only the valve covers

 

[swathdiver]

I had an exhaust leak that sounded like that. Swore it was a lifter but I was wrong!

 

[jrobie79]

I had an exhaust leak that sounds like that, swore it was a lifter but I was wrong!

I changed both gaskets and installed ARP studs (I plan to install headers after this nonsense, so I figured I'd use the hardware now)

 

[jrobie79]

Figured it out. Partially collapsed intake lifter on cylinder 6. Not enough to throw a code, but definitely knocking