Broken manifold bolts, oil leak - and preventative fixes 2011 6.2 DOD Delete

[Enoob]

I have the lovely broken rear exhaust manifold bolts to fix. I have the brackets that I could do a temp fix with, but thinking that I want to do it the right way and remove the heads to get the broken ones out. Partly due to seeing oil around the valve covers and I am not sure where it is coming from. I have read that there are issues in the valley cover area and wondering if it is there, valve cover gaskets or something else. My plan would be to remove the heads, get the bolts out, have a shop check the head for level, new gaskets on everything removed, etc.

I am thinking to do all of this at once since I will be in there, so I am wondering what else I should look at/consider doing while I have it tore down this far. I've done the oil pressure unit fairly recently. I've read that there are some issues with lifters in some of these, but not sure this is that year. It's a 2011 Yukon with around 170k. Attached are a few pics of the oil that I am seeing. I live in a cold climate so it will still be a short bit before I tear into this. Thanks for any suggestions.

 

[Foggy]

Definitely do the valve covers and the VLOM cover. Looks like both are leaking.
IF you pull the heads *which I wouldn't think you have to* for the exhaust threads....
I'd do the lifters.. You'll need 8 regular and 8 AFM lifters.. Then program the AFM/DOD OFF !
If you already have the DOD/AFM turned off in the PCM, I wouldn't worry about the lifters as
long as you know they are working correctly now

 

[Enoob]

Thanks Foggy - I bought the truck with maybe 85k miles. I do not know if the AFM was previously turned off (and assuming I have AFM). How do I find that out? I've read that there might be more to turning AFM off, like non-AFM camshaft etc. Is that an issue with this engine? I am not certain that I'd pull the heads, but not sure how I will get the broken studs out that well if I do not. I can do a lot of things, but not sure I want to attempt drilling them. Is there any disadvantage to pulling the heads? I am fairly mechanically inclined. Was thinking new gasket there would not hurt either, but maybe they don't tend to have as many issues as the other gaskets?

 

[Foggy]

2011 6.2 Yes, you do have DOD/AFM that shuts off 4 cylinder at a time.
When you are in light cruising mode (usually over 40 mph) your DIC should read out
either 8 cyl or 4 cyl mode - I think its in the Instant MPG readout -
With the heads off, you are quite a ways to cam and lifter replacement.. So that's up to you.
You'd have to remove all the front stuff on engine= timing, balancer, water pump etc and
you fans, radiator, condenser to remove the camshaft, timing chain etc

It's a pretty big job so it's up to you... Or you could just put in new AFM lifters Call it good !

 

[swathdiver]

I have the lovely broken rear exhaust manifold bolts to fix. I have the brackets that I could do a temp fix with, but thinking that I want to do it the right way and remove the heads to get the broken ones out. Partly due to seeing oil around the valve covers and I am not sure where it is coming from. I have read that there are issues in the valley cover area and wondering if it is there, valve cover gaskets or something else. My plan would be to remove the heads, get the bolts out, have a shop check the head for level, new gaskets on everything removed, etc.

I am thinking to do all of this at once since I will be in there, so I am wondering what else I should look at/consider doing while I have it tore down this far. I've done the oil pressure unit fairly recently. I've read that there are some issues with lifters in some of these, but not sure this is that year. It's a 2011 Yukon with around 170k. Attached are a few pics of the oil that I am seeing. I live in a cold climate so it will still be a short bit before I tear into this. Thanks for any suggestions.

Your engine is an L94 and those have AFM. If you are going to pull the heads, replace the lifter trays with GM OE only.

If you are going to retain AFM, and decide to put in new lifters, it is SOP to also replace the VLOM.

If you desire to delete it, put in all new regular lifters with new lifter trays and the camshaft from the L9H.

Disable AFM in the tune, block off the AFM towers in the lifter galley. This can be done with rivets, new o-rings, etc.

 

[Enoob]

I plan to keep this Yukon for a while, so thinking it might be best to really be thorough since I am tearing into things. I've watched some videos on doing the delete and my biggest concern would be the cam and getting timing right. One vid shows doing it without dropping the oil pan. Is the pan hard to drop? Thinking I'd rather have a better view on the timing marks, etc, and seems tricky if you don't drop it. Since I am at about 180k, should I consider putting on a new oil pump and or timing components as well?

 

[Enoob]

I have reviewed a few of the threads on Deleting and have decided to delete DOD but retain VVT (assuming I have VVT). I'll be pulling the oil pan and will replace the "o" ring at a minimum. I will be replacing the oil pump and wonder if I should go with a high volume due to the mileage/age? I figured on replacing the timing components and see mention of replacing the tensioner with a damper, but not seeing which/where to get that part. Is it recommended to have the heads checked over, checked for level, check valve seats, etc.? I was thinking so just to have things fresh. If they would need to mill them at all, what do I need to consider regarding push rod length, etc., or ask the shop to do regarding the heads? I know I may have a better idea of what I am dealing with once I tear down, but I am shooting to have ready what I can to reduce downtime. I am checking with TSP (awaiting reply) to see exactly what they recommend for parts and see that suggest replacing springs. Another forum suggested OEM rockers? Good to do while in there?

 

[Enoob]

Well, I just got a misfire code on cylinder 1. No better time than to tear down. The rocker on cylinder 1 was loose (not sure how to attach video clip). Got to the lifters and found that the loose rocker appears to have a lifter with a collapsed (stuck) spring (see photo). Is this the issue that is mentioned frequently for failing on these AFM systems? The rods appear to be straight still. Anything else to look for? It only ran a short time after the misfire.

So the heads are now off and going to the shop for a check and clean up. I was reading in other posts where some do a 3 angle valve job. Should I consider any such thing for the shop to do or consider new springs and clips? If I do any of these things, will it throw off the push rod length...not real interested in getting that detailed, but will if needed.