06 Denali 5.3L: Misfire #6 Collapsed DOD Lifter

[brianvander]

2006 Envoy Denali, 5.3L, 126K mi, 4WD. I am not a gear head, so bear with me...

OK so 10days ago, driving on the freeway (4 miles) then coming onto a off ramp when I slowed to a idle stop, I then noticed a serious/severe engine vibration and then noticed that my engine light was flashing, no "ding-dong" signal though. I limped home an additional 4 miles and shut down the motor and left it as is the remainder of the day.

On Monday AM before work, I started the truck, same heavy vibration, so not to risk anything I shut it down and did not drive the truck that day. Once home, hooked up the ODB reader and I had a P0306 code: Cyl #6 misfire. At 8pm I ran to Autozone picked up a plug a replacement plug, put in in, (which is not easy) and restarted. No change.

On Tuesday AM, I choose to drive (limp) it into a local shop, 4 miles, but after 1/2 mile, my Oil Pressure dropped to 0, so I took it back home, called a flatbed and had it towed to the shop.

After a 1day diagnosis, the shop told me they wanted to perform a "hot" oil flush first, thinking it may have excess sludge built up over the years and they may contribute to the low oil pressure, they did so and pressure came back up but the truck was low at least a quart. After the flush, the shop then noticed blue smoke from the exhaust, (Ive never seen blue smoke, nor have I ever smelled burning oil from the truck). They measured the compression on the cylinder #6 reported it at 15-20psi (they told me normal was 110-120psi, I dont know). From this they diagnosed it as most likely failed piston rings and advised to replace the motor as it was more time consuming to fix the piston and rings vs swapping the motor, they estimated $3-5,000.

Not quite agreeing with their conclusion, I contact a GMC dealer and spoke with them. They advised that they have had 6 to 7 5.3L in their shop over the last few months with very similar symptoms and each time it has need a broken Rocker or Rocker spring. I choose to re-towed it to the GMC dealer for a 2nd opinion.

After 1day of diagnosis, they pulled the valve covers and found the following:
1- Oil in the Intake Manifold, via the PCV valve. They think that this may be there because of the oil flush but they are not positive. They also think that this is the cause of the blue smoke reported by the other shop.
2- #6 Cylinder DOD Lifter is collapsed and is not responding.
3- the Valve Springs & Rockers look good.

Based on this, they believe the DOD lifter failed which caused the valve to remain open thus causing the the low compression and the misfire. They are recommending to replace all 8 DOD valve lifters (on both sides). Which apparently requires:
1- Removal of both heads
2- Installation of new Lifter Oil Manifolds (2) - I dont know if this includes the oil solenoids or not
3- Installation of new DOD lifters (8)
4- Possible Replacement of new CAM Shaft (left side only)
5- Replacement DOD Valve Springs & Rockers
6- Replacement Valve Covers
7- Misc stuff, bolts, washers, seals, etc...

They also suggested that a replacement motor may be the easier fix.

The tech said over the years he has only seen a small handfull of failed DOD lifters. So it sounds like a very unusual failure. They are estimating $1800-1900 in parts and $1500-1800 in labor costs. A new replacement motor from GM is $7200 installed, I don't have an est for a re-manufactured motor.

Here's my Questions:
Has anyone had this issue, does all of this sound correct?

Is it needed/recommended to replace the DOD lifters on both sides? It makes sense to replace the DOD lifters on the on left side but why both sides?

Thanks for any advise and opinions.

Brian

 

[Mooseman]

It would make sense to me to replace all the lifters. If one failed, the others can't be too far behind. Don't know about how common this failure is, I have read about it. That and ring wear causing excessive oil consumption. That's another reason some have the dod disabled through a tune, which I will be doing on my 9-7x.

 

[C-ya]

Welcome, and sorry for the bad news.

Yes, DOD lifter failures are one of the major failures that can happen. The other major failure is the rings sticking, causing excessive oil consumption. The ONLY way to fix a bad lifter is to pull the intake manifold, head(s - it is best to do them all at once), and do the repair. If it was me and they are going that far, ask them to rebuild with a DOD elimination kit, which would also require a program update to the ECM. (Not sure a dealer would do that, but a private shop might.) There have been posts here and I'm sure elsewhere about that kit.

 

[C-ya]

Moose, I was just reading about the LH6 (DOD) engine and the Rainer wasn't slated for DOD. Did the Saab get it for some reason? The reason was about the muffler valve and not enough room in the short wheelbase vehicle.

Article here - http://www.superchevy.com/how-to/engines-drivetrain/0405sc-gmdod/

 

[brianvander]

C-Ya, thanks for the info, but would it be necessary to replace BOTH the left & right side. The failed DOD is on the left side and yes it only makes sense to replace all the lifter while the head is opened. But should if be necessary to then open up the right side and replace those lifers also?

Thanks
BV

 

[C-ya]

If it was mine, I would pull the other head and replace all the DOD lifters. Well, if it was me, I'd rebuild with the DOD elimination kit. I had my DOD turned off earlier this year and don't regret it one bit. If I have a lifter fail now, I'll rebuild with the elimination kit. If a body, for some unknown reason, wants to keep DOD, then yes, I would recommend replacing all DOD lifters at once. 3/4 of the work (and labor cost/time) is already done considering what you have to do to get one head off. Might as well pull a few more bolts and replace the lifters on the other side. This is a V configured engine, with only one cam shaft. A failed lifter shouldn't hurt the cam as it designed to operate in a collapsed (well, non-pressurized) state. Also, the valve(s), springs, and rocker(s) should not need to be replaced unless they were stuck or bent or something like that. Again, this engine was designed to run with collapsed lifters and closed valves. By the lifter failing, what happened was that valve couldn't operate as needed so the engine was not operating correctly - running rough. Depending on whether it the intake or exhaust valve would determine how bad it was running. If it was the exhaust valve, I would imagine it would run terribly!!

 

[C-ya]

Since you said you aren't a gear head, here is a quick, down-and-dirty video of a small block V8 engine. Liberties were taken in the "assembly", but it shows the major components. Our engine, at the end (or beginning?) of the day is a small block Chevy (SBC), after all.

https://www.youtube.com/watch?v=aATDsYVVcRM

This is pretty good - disassembly of a SBC. https://www.youtube.com/watch?v=LZO1fWVxN4c

Again, our engines are more modern, but the guts are essentially the same.

 

[Mooseman]

Moose, I was just reading about the LH6 (DOD) engine and the Rainer wasn't slated for DOD. Did the Saab get it for some reason? The reason was about the muffler valve and not enough room in the short wheelbase vehicle.

Article here - http://www.superchevy.com/how-to/engines-drivetrain/0405sc-gmdod/

I dunno. Maybe they didn't mention it because it's a Saab? Or it didn't exist yet prior to 2005. But it does have it.

http://www.edmunds.com/saab/9-7x/2006/?style=100621219#specs-pod-anchor

What's New for 2006
For 2006, the Saab 9-7X's V8 receives Displacement on Demand technology. Saab says that this feature enables fuel economy gains of up to 5 percent by reducing the number of cylinders engaged in the V8's combustion process.

When I drove it home, it kept kicking on and off. Felt weird to me and didn't care for it too much. Was worse than TCC unlocking.

 

[C-ya]

OK, makes sense. That article is an old one. But it's weird how the DOD engages/disengages on different vehicles. Mine was seamless - I could never tell which mode it was in unless I was going slowly by a building/wall/parked cars with a window down and it was on (4 cyl mode). I could hear a different sound. If I put it in 3rd, the tone changed since it was back in 8 cyl mode. I could never feel it, tho.

 

[88Ironduke_1]

I'm very glad my 5.3 is not equipped with DOD. AS for the low compression I can't say how the garage dives right into trashed rings before tear down. Unless they accomplished a leak down test on the cylinder and then verify it leaking past the compression ring a bad cylinder is not troubleshooting. Pull both heads, inspect the cylinder bore for #6 and then make a choice for rebuild or new motor. The time required to pull both heads is a 3-4 hours for a decent mechanic. Heck they may even have a small bore scope.... Its an LS so broken exhaust manifold bolts are expected. The surprise would be all the bolts coming out in one piece. Change all the lifters, inspect/replace any broken stuff and put it back together. Getting rid of the DOD system is a viable option and if it were mine I would be going that route.

Good luck
88Ironduke

 

[brianvander]

thanks for the responses, I appreciate it. I dont think i will have them remove the DOD system (I dont think the dealer would do that anyway). They will tear down the heads and inspect the CAM and cylindar walls for any damage before rebuilding.
BV

 

[brianvander]

OK, so after further teardown, the dealer is now also saying that there is excessive "pitting" on the lifter roller and camshaft and they are advising to also replace the camshaft. I dont know how to iclude a photo in this post, but the photo does show what I can only describe as 'hammering looking marks" on the roller.

 

[Mooseman]

For pics, if you click on more reply options, then you can attach files. Just can't be too big though. Or just use a photo sharing site, like photobucket and put the link to it here.

Sure doesn't sound good. How much is the estimate compared to just replacing it? I would still get DOD disabled through a tune from somewhere else like PCMofNC or Limeswap (which happens to be a whole lot cheaper and just as good). Or they might be able to through a program change with their Tech 2 or newer interface. A tune would be better.

 

[brianvander]

The rebuild is currently at $5300. A new GM motor installed in $7800, they cant get a remanufactured motor through thier channels, but alternate sources have it at $42-4900 for the motor plus around $3000 to install. It looks like the vin M motor is rather difficult to find. I think Ill look into a GoFundMe page...

GMC will not do a DOD modification, they cant for obvious reasons, so for now thats out of the picture.

The block & pistons look great, we can still see the cross-hatching from the final machining, no issues at all. So basically the upper half of the motor will be all new, the only items not replaced are the heads and most of the rockers and arms (they found 2 rockers and arms that have slight damage). But essentially all new inner components on the top half.

The tech working on it is their top guy, and he stated he has only seen a handfull of these lifters fail but never has he seen it affect the cam. Basically the lifter roller failed as well causing the impact damage to the cam.

BV

 

[ddgm]

I may have been out of the loop for a long time, but those prices seem to be very high, especially the $3000 to install an engine.
A 9 year old vehicle would have to be in exceptional shape to justify that expenditure. I do realize that a vehicle without an engine is basically worthless. Best of luck to you on whatever you decide.

 

[Mooseman]

I can understand the labour involved to remove and install an engine in these trucks. Very labour intensive. It is easier to do this work than yanking the engine.

 

[Paul Bell]

Starting in 2005, all these trucks with the 5.3 V8 engine including the Saab received the LH6 engine which has active fuel management, also known as displacement on demand. This includes the special lifters on half the cylinders and the oil manifold which replaces the valley cover.

It sounds like the dealer nailed the problem. As they're replacing the camshaft, and due to the miles, I hope they're also replacing ALL the lifters. Don't go through all this work and re-use them old high mileage ones.

Also make sure the PCV system is in good shape. The PCV systems on these engines SUCK and oil in the intake is never good.

Here's a video (kinda fuzzy) that shows the operation of the system:

https://www.youtube.com/watch?v=OvqQ-EIGkJk&list=PLHwbcZlOq3aZllR0wkRtNXF8tzopFNoj8

 

[mrrsm]

I just linked this thread over to a more contemporary post about the DOD Valve Lifter problem...and as a late arrival to this thread... I just wanted to answer the question raised in this one regarding WHY these DOD Engine Eventually Consume So Much Damned Engine Oil:

If you look at what the GM Engineers had originally intended with the idea of only having (4) of the (8) Cylinders actively working under some driving conditions, it is easy to overlook the unintended consequences of this design. The Engine certainly does save quite a bit on Fuel when the DOD is activated. However... during the time that the Dormant (4) Cylinders are NOT under the usual stress of Ordinary ICPE (Intake, Compression, Power, Exhaust)... the lack of pressure and higher temperature normally present to stress the Rings to seal and the Fuel use subsides.

But... the deliberate and intentional residual Piston to Cylinder Oiling during these operations continues. In the presence of the all that residual heat... the left over residue of Unburned Fuel Vapors and Engine Oil tends to collect in and around the Pistons Rings. Ordinarily... Combustion would do the deed of keeping this from happening... But NOT inside of an Engine equipped with DOD.

Over time, a kind of of Lacquer or Glazing will form that will cause the Piston Rings and Oiling Ring Grooves to fill up with all of that congealed, sticky Black Mung ...and essentially Super-Glue the rings within their groove cavities flush inside and even with the outside of the pistons. They will remain stuck tight and when the (8) Cylinder DOD gets activated after this... the normal "springiness" expected of these lighter tensioning rings will NOT release and return them to their normal sealing capabilities.

The only cure for this otherwise permanent problem ...is a regular treatment using all of the GM Dealership Procedures for Top Engine Cylinder Treatment and Cleaning that is designed to De-carbonize not only the gummed up Valves and Combustion Chamber areas; including the Piston Tops... but much DEEPER as well.

And ...after a long soak of the liquid around the Piston to Cylinder Wall interfaces. that Mung begins to dissolve and melts away all of that collected, congealed Carbon and Goo that allows so much Engine Oil to blow right by the rings when they are so trapped. When this treatment is done right... better compression will return to the four involved DOD Cylinders and the power and performance should like wise show an improvement... and the bizarre loss of so much Engine Oil being exhaled and burned away inside of the CAT ...will cease.