CHEVY SILVERADO MISFIRE INTERMITTENT COMPRESSION

In today's video we take a look at a 2013 Chevrolet Silverado 1500 with a V8 5.3l engine. The customers complaint is that there is a misfire on cylinder number 8. The repair shop replaced spark plugs, wires and even swapped ignition coils and injectors, but the misfire continued on cylinder number 8. Convinced that the engine had a mechanical problem they asked me to take a look. What I found was something very interesting. Cylinder number 8 at times had good compression and at times had low compression. Could it be a bad lifter, camshaft, valve spring or a valve seat?
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Disclaimer:
Due to factors beyond the control of Advanced Level Auto, I cannot guarantee against improper use or unauthorized modifications of this information. Advanced Level Auto assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Use this information at your own risk. Advanced Level Auto recommends safe practices when working on vehicles and or with tools seen or implied in this video. Due to factors beyond the control of Advanced Level Auto, no information contained in this video shall create any expressed or implied warranty or guarantee of any particular result. Any injury, damage, or loss that may result from improper use of these tools, equipment, or from the information contained in this video is the sole responsibility of the user and not Advanced Level Auto.

[jamespatterson]

I do appreciate the fact that you get strait to the issue at hand and not just talk for half the video about things that don't pertain to it. Thank you.

[fixitjerry]

GM mechanic here, see this every day, I got my money on lifters and possible cam damage. Do them every day! Great video

[ThunderbirdRocket]

Your coaching is particularly good due to the fact that you are coaching us AND zooming in video to demonstrate how to tap into the circuitry . Thanks !

[jameshappl]

Excellent diagnosis, I like the way you systematically break down each test that you are going to do

[edwinlomonaco]

This is where an in cylinder pressure test would help. The waveform could likely reveal where the issue is without removing the cylinder head.

[davidnanze]

You never disappoint Great job as usual. As a shade tree mechanic i have to take my truck in for issues like this. without the scan tools i dont have a chance.

[ronniegarland]

I learn so much from your videos have a solid 40 + year mechanic background but suffer from lack of experience at times on new technology..you explain straight forward without excess information that boggles this old noggin
I watch your content and have a better understanding of the big picture and more confidence to, at times stumble, through diagnostic testing and eventually have that light bulb moment and, GOT IT !!! Thanks and keep up the good work 👍👍👍

[john]

Great video! The only thing i would have added to the diagnosis would be to put a borescope in the cylinder to look at the valves, then bumped the key to pressurize the fuel rail and see if the injector was leaking by ... Thanks for sharing.

[TStockton]

Very informative. Your explanations make sense. You explain in way where you are in-between someone who knows nothing about cars to experts. You find that middle ground very well.

[JimmyMakingitwork]

Just had the same issue on a 6.0 Chevy truck. It had very bad intake vacuum leaks on cylinder 4 and 6 causing misfire and lean codes. But repairing it only lead to no more lean codes, but the misfire codes returned.
Intermittent compression loss on cylinder 4 which reduced at higher engine speeds. Sometimes the valves stick in the guides, lifters and cams also fail, but this engine was very clean. Customer also declined further inspection. Hate not knowing the exact cause, but that's our world. :)

[advancedleveldiagnostics]

Excellent video, Thanks! This is where a transducer in cylinder is really helpful. I would gladly pay for a premium channel with you, you give really clear explanations!

[trishexploring]

Thank you so much for putting this video out!! I've been having issues with my truck for awhile now and you just gave me information I haven't been able to get out of any mechanic I've taken my truck to. They just trying to suck what little money I have and NOT fix the problem. They also tell me crap that I've known was BS! THANK YOU THANK YOU THANK YOU!!

[gman]

great video on diagnosing this issue i totally agree with it . I would be 100% positive that it is a valve seating issue, with a small bore camera you would be able to see inside the cylinder without having to take it apart. just a tip . Good job.

[curtismorrison]

Your videos are always extremely informative. Thank you for sharing your experience and skill.

[mikechiodetti]

I was thinking like you with the valve sealing problem. One more thing would be a weak valve spring or a sticking valve. GM had problems with valve guide problems in the past. I have seen a valve seat problem. It took many miles for the problem to occur, but at idle the engine would lope turning on the MIL light and yes, gauge compression and cylinder leak down was good compared to other cylinders. This was before scope testing. The engine was a 1997 Dodge 360 (5.9L) V8. Contacting Chrysler for information, they claimed it was a "metallurgy problem."
The fix. Replace the cylinder heads. The reman heads had the latest and greatest in valve seats. Engine ran great after that.

[andrewvillanueva]

You are very skilled mechanic bro and you explain the problem well.

[KRTube]

The 5.3L is known for AFM lifter issues but #8 is not an AFM lifter. However, they can stick and jam up internally which will cause a lifter tick. If they are not hearing a lifter tick, I doubt that's the issue. I'd be looking at a bent or sticking valve or a broken valve spring on #8.

They might be able to detect a sticking valve by running or even just cranking the engine with the valve cover removed.

[chi-towntrucker]

This was very helpful, very interesting how that scan tool found the problem

[chrismechanic]

some diag guys dont know this, some cars will shut off the fuel injector in a multiple missfire situation, bmw is one of them, i have seen guys call a bad injector because the ecu is not triggering the injector to stop cat damage and bore wash/engine damage, id say it is a typical valve not sealing issue.
good call eric.

[almamadrigal]

Ty for explaining this problem issue and that's wats going on with my truck now. It didn't pass smog took it to a mechanic he said it was the #8 misses fire sometimes but it the time I just don't have that $For the extra work which consist of opening the motor and taking a look. Smh.