2003 yukon 5.3l flex fuel lifter noise and code misfire PO300 235,000 miles

[Summajet]

Motor has 235,000 miles, 5.3l flex fuel
I have noticed I have loud lifter noise coming from the passenger side of yukon.
i am not sure if it has a LS motor. I thought I had read a Ls motor requires removing the heads?
I am looking for suggestions for diagnosing?

Would a failing/collapsed lifter cause code PO300 (random/multiple cylinder misfire detected)????
Here is what I was thinking to check,

1. compression check each of the 8 cylinders. What should compression for a un-modified 5.3l flex fuel?

2. remove valve covers on each side and check for broken valve springs, loose rocker arms, collapsed lifters, and bent push rods.

3. If there is a collapsed lifter or bent push rods is this the process for removal and repair,

Remove valve covers
Remove the intake and leave the injectors on the intake?
Remove the valley pan
remove rocker arms
use push rod tool and tap out the push rod
remove lifters (2 per cylinder and 16 total)
purchase a intake gasket-felpro?
valley pan gasket-felpro?
brand preferred for lifters, and push rods?

When installing the push rods, lifters and rockers arms are there any special tools needed to remove or install the parts mentioned above?

Was going to use ac delco parts and do repair. I really appreciate any advice anyone can offer to help me make the repair and save money

 

[Summajet]

From what I read online last night I will need to remove the LS heads to access the lifters.

 

[Kraig]

You will need to remove the heads if you need to change lifters, it do the diagnostics you described first—remove the valve covers and check for play in any other rockets, crank it over and see that all rockers are moving, etc.
What are your oil change intervals, how long since last oil change, what oil and filter, and did this noise start suddenly after the last oil change or some other event? Also, make sure you aren’t actually experiencing an exhaust leak at the manifold/head, which can sound like a lifter ticking.

 

[Kraig]

Oh, and the only ‘special’ tool you’ll need is to remove the fuel line.
And you don’t need to remove the valley pan to change the lifters, but you might want to and change the knock sensors while you’re in there. AC Delco parts made it this far—don’t cheap out on parts store knock sensors or you’ll be doing it again. Change the knock sensor harness at the same time it’s cheap insurance.

 

[Summajet]

If I understand correctly, to replace the lifters I only need to remove the two heads. There are no bolts on the valley pan that are bolted into the heads? I also will check with the stethoscope sounds for a exhaust leak at the manifold.
Oil was changed two months ago. Truck driven about 600 miles a month.
I think I used 10w30 oil and definitely used an Ac Delco oil filter.

Between compression and removing valve covers should help to diagnose it quickly.
When doing the compression check I would,
1. remove all 8 spark plugs
2. compression check each cylinder on driver side
3. compression check each cylinder side on passenger side.
4. compare compression readings and should not differ more than 10% per each cylinder reading?

When installing heads does this sound right,

1. check heads for square and no warping.
2. new heads bolts
3. new head gaskets any particular brand?
4. any procedure or tips in making sure the heads sit correctly on the block?
read something mentions an angle at 90 degrees?
5. Should I worry that the needle bearings could have failed or fallen out in the lower block?
Thanks,

 

[Kraig]

The valley cover bolts directly to the block, no connection to the heads.
The heads have locating dowels to properly align.
The head torque sequence has you torque to a certain number of foot pounds, then you use a torque angle gauge to get to the final torque, but some daring individuals like myself might eyeball it.

 

[Schemmer]

I’m about to replace my lifters and I have the exact same engine. Since you have the flex fuel engine, I’d recommend getting all of the AC Delco flex fuel gaskets if you ever run E85. I got all of my gaskets from rockauto.com. I’d also recommend ARP head bolts. Since the head bolts are torque to yield, they stretch. So don’t reuse your old ones. If you’re using AC Delco head bolts, you’ll need a torque wrench and a degree tool bc you tighten to a certain torque then another set degrees of a turn. The most important thing when doing this is that there is a torque sequence. You’ll need to look up the specs on all of that bc I don’t have it handy but I’ll find something and pm it to you.

 

[Summajet]

How long before you start your lifter replacement? Might by chance you take pictures to help me and others on the forum.
Had read that you torque heads in 4 steps and angles also.
Also when replacing lifter do the valve seals, and new lifter trays.

 

[mattt]

Check your oil first. Does it not look normal? If not, you may have water in it from a cracked head or compromised head gasket. One day last year out of the blue my 04 5.3 flex fuel engine started with lifter clanking. I tracked it down to water in the oil causing all the issues. Drained oil, changed twice, and fixed the leaky head. No more lifter clacking and I did not replace them. YMMV....

 

[Summajet]

I will check that. Where was your head leaking at? On drivers side or passengers side and did you remove head to fix the leaking head gasket?

After 6 weeks I finally got to replace my water pump and timing chain on my 00 mercury mountaineer. Bearing/seal failure on water pump. Broke one of the bolts and removed timing cover. Did timing chain as it had too much deflection.. Anyways one done and time to get to diagnosing the yukon.
Asked mechanic at shop and said it is not too hard to do it when removing heads. Important to torque new head bolts in 4 steps. I will look at the oil and water as if head gasket is failing there will be one of the other mixed in.

I am not sure if the previous owners regiment of maintenance. It has 235,000 miles and am sure the timing chain has more than the acceptable chain deflection.

I do not know what date the Water pump was changed. We have owned it since June of 2015 at 199,500 miles.

Once I check compression and change oil I'll proceed from there.

 

[Summajet]

I dropped truck off at shop this past Friday. Machine at shop shows misfire on #2 cylinder. Tech swapped out wires, plug, coil, and injector.
He is a master tech and said the lifters need replacing. Said to only use Gm parts. Shop time is 12 hours labor lifters/heads removed and if cam is worn it is an additional 9 hours labor to remove from timing chain, cam, radiator, and ac condenser. Once heads are removed he said he can look down and see if cam is worn or nicked. Labor is about $1,300 heads/lifters and cam another 9 hours at $2,200 labor.
If I can do the repair I will save the cost of labor. I know it does not have the afm as that started around 2006-2007 model years.

They would let me provide the parts and save cost of markup from the shop. I did a timing chain/water pump on my 00 mercury mountaineer all wheel drive. I encountered the dreaded broken water pump bolt and was able to overcome it and get bolt out. I also was at a local junk yard and someone had removed everything on a 04 5.3 liter except for the heads. I removed the passenger side head and aside from a broken manifold or head bolt seems straight forward? I know I run risk of the cam lobe being scored and it I have to replace it I have a lot more time to remove parts. I have a enclosed garage and once other projects get completed I am feeling confident I can do the repair.
Any thoughts?

 

[Miami-Dade]

bump

 

[Summajet]

I will check that. I took off the valve cover and the noise is coming from the #2 cylinder. I used my stethoscope today noise is coming from the #2 cylinder. Without the heads removed I am going to assume the lifter is collapsed and thus reason for misfire code, and noticeable shake while sitting in the drivers seat. I am also preparing myself just in case the cam is nick or scorred and possibility of replacing that too. With the Valve cover removed it looks straight forward and first making sure it is a TDC and noting the length of the screwdriver inserted into #1 cylinder for easy reference when rotating crankshaft to reinstall the rocker arms.

 

[Summajet]

I got the passenger side head removed and the misfire and ticking noise is the #2 cylinder liter. I have to remove the camshaft and replace it. When removing the head I did not see any dowel rod pins to reattach heads and keep from moving all around in reinstallation.

Besides removing the Fan, Fan shroud, Radiator, water pump, bellhousing, timing cover, timing chain and timing chain sprocket it looks like the cam pulls out the front. I am going to remove the driver side head this coming weekend. Once all the lifters are out and the motor is at #1 cylinder, TDC does the cam slide straight out or do you have to turn camshaft clockwise when removing to pass internal parts.? I saw a youtube video where the person had to turn camshaft to remove it from the front.

What camshaft do you prefer or replace it with, Gm? What is the preferred engine assembly lube for reinstalling the camshaft? Do I need to remove the valley pan cover to inspect the camshaft bearings?

When I removed the scorred lifter I noticed that one was sitting about 3/8" higher than the other 7 lifters. I can sit the lifter on a metal table and move the roller side to side and I can hear almost the same sound as when the motor was running. On the bottom of the roller it is not scorred completely. It almost seems to me the lifter/roller moved up off the cam and turned 90 degrees. Instead of the roller moving the way it was suppose to instead the lifter was dragging/scorring the camshaft. I noticed the Oem lifter tray does not lock the orientation of the lifter in a locked place.

Also my oil pressure was 40 at idle and 55 at 60 mph. Should I be concerned with the metal fragments getting sucked into the oil pump? Should I replace the oil pump and if so do I have to removed the motor to remove oil pickup line in oil pan or is there a work around?

 

[Summajet]

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[Summajet]

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