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

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

OP
OP
S

Summajet

Full Access Member
Joined
Feb 7, 2019
Posts
176
Reaction score
68
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?
 
OP
OP
S

Summajet

Full Access Member
Joined
Feb 7, 2019
Posts
176
Reaction score
68
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.
 
OP
OP
S

Summajet

Full Access Member
Joined
Feb 7, 2019
Posts
176
Reaction score
68
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?

20190714_184928.jpg 20190714_184951.jpg 20190714_184957.jpg 20190714_185513.jpg
 
Last edited:

Forum statistics

Threads
133,035
Posts
1,878,782
Members
97,998
Latest member
Jeremytahoe

Latest posts

Top