Lifter, Cam Swap Help

[drastevenson]

I have a 2007.5 GMC Yukon SLT.

Quick Story: did a cam swap and now it won’t crank up. It makes an almost clattering noise and won’t catch. I don’t want to keep trying to crank it on.

Long story:

About a year ago, I started having the lifter tick issue but was able to temporarily fix it by spraying some seafoam down the rocker arms (breaking it up topside) and a motor flush (to hit the bottom end).

That fixed the issue until a couple months ago, driving home, the check engine light came on. Cylinder 8 misfire.



Took it to a local shop, they quoted me ~$2.8k to replace the AFM/DOD lifters. Another shop I talked to told me it would just happen again and I needed to look into AFM/DOD delete. He quoted me a little less than $8k to do it (along with some other necessary upgrades - which I agreed with him on those).



When it comes down to it, I’m cheap, don’t trust anyone and would rather do it myself.



Bought Black Bear Performance Tune for the computer side of the delete. Grabbed an AMS Racing AFM/DOD delete kit with a stage 2 cam and new beehive valve springs. (Hopefully pictures I added show up).



Using the Hanes service manual and YouTube University… I managed to tear the engine down, swap everything out and get it all back together. (Minus a few small mental breakdowns and rage moments). This was over two off days and three days off after work working on it.



Unfortunately when I went to start it, it slowly started to crank and cut off. Started it again and it made this wild clattering sound from what sounds like the cam or crankshaft? (I’ll post a video of it).

Clattering Noise on Start Up

I’m thinking I didn’t properly set the cam position actuator and timing chain in at TDC but I wanted to see if anyone else has ever had this issue.



Since I have to remove quite a bit to get to it, I’d like to check all the troubleshooting boxes while I’m in there.

 

[Foggy]

I can't get to the video, but I don't have instaG...
That cam is going to need some tuning work to even get it to start and stay running.
Did you replace the oil pump, timing chain, anything else besides the cam and lifters??
Did you check your valve lash? It's only "adjustable" by changing length of push rods. And
you are probably going to want hardened pushrods since your spring pressures have changes..
Also did you really check out your rocker arms? They won't last with that cam and springs...
you could be getting noises from the rockers too

 

[drastevenson]

I can't get to the video, but I don't have instaG...
That cam is going to need some tuning work to even get it to start and stay running.
Did you replace the oil pump, timing chain, anything else besides the cam and lifters??
Did you check your valve lash? It's only "adjustable" by changing length of push rods. And
you are probably going to want hardened pushrods since your spring pressures have changes..
Also did you really check out your rocker arms? They won't last with that cam and springs...
you could be getting noises from the rockers too

Based on my research, this cam was as far as I could go without upgrading anything else. Maybe a new oil pump but I wanted to address is after the fact.

I inspected everything and cleaned up the push rods before I put them back in there. Nothing looked concerning or over worn.

My main issue is that it’s not starting and the noise it makes. I figure it should at least be able to crank up .

 

[wjburken]

That sounds horrible.

How sure are you that you’re not 180° out of time? What process did you follow to set your timing chain?

 

[iamdub]

Me when it tried to start:

Sounds like the cam is out of time, meaning your valves are smacking pistons. Don't attempt to crank the engine until you've opened it back up. the damage has probably already been done, but there is a chance it survived if the lifters weren't pumped up for that first start.

 

[wjburken]

Me when it tried to start:

Sounds like the cam is out of time, meaning your valves are smacking pistons. Don't attempt to crank the engine until you've opened it back up. the damage has probably already been done, but there is a chance it survived if the lifters weren't pumped up for that first start.

Right!?!?

good time to get a borescope and put it in a spark plug port to see if there is any damage to the piston head.

 

[iamdub]

Right!?!?

good time to get a borescope and put it in a spark plug port to see if there is any damage to the piston head.

From my recent experience, I'd say the damage would be a bent valve before substantial piston face damage occurred. *cringes*

@drastevenson, I'd remove the rockers and closely inspect the valvetrain from there. If all looks okay, hold the throttle pedal to the floor and crank the engine to see if it acts and sounds normal. It won't start, but you're cranking it to see if it has compression and sounds like it always has when cranking to start. If so, then you've pretty much confirmed a mis-timed cam.

 

[wjburken]

From my recent experience, I'd say the damage would be a bent valve before substantial piston face damage occurred. *cringes*

Agree. I was just thinking it would be a quick thing to check to see if there are any marks on the piston.

 

[iamdub]

Agree. I was just thinking it would be a quick thing to check to see if there are any marks on the piston.

True. One shouldn't use valves to remove carbon from pistons.

I'm still pulling for him that he threaded the needle and it can be fixed with an (albeit time-consumuing) adjustment and the mighty LS will come away unscathed.

 

[Dustin Jackson]

Man that’s sucks. Need to take it back apart and reinspect for damage and start over.

What cam and cam sprocket did you use?