Piston slap or lifter

Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Hello everyone. I know this was probably already answered but I'm losing sleep over this. I bought a 2003 trailblazer ltz and it was neglected a bit. About 4 months ago after sitting overnight upon start-up there is a strong ticking almost knocking sound. I'm running full synthetic with an stp extended performance filter. After about 10 minutes of driving it completely disappears. Driving it cold the noise does follow engine speed. Don't know if I should try a flush or try another filter or what but this is our family's only car. Is there a way to test for piston slap? In dire need of help, please.
 

NJTB

Member
Aug 27, 2012
612
Flemington, NJ
Start with the easy stuff. Try running something to de carbon the engine (Chevron Tech, Lucas) first. May help your problem.
Alot of these Trailblazers have piston slap on cold start up.
 

TollKeeper

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Member
Dec 3, 2011
8,045
Brighton, CO
My 5.3, everyday with temps below 40*, I get piston slap, and it does sound like a knock. Been doing it for nearly 100k miles now.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Sounds like a lifter is sticking. I'd try a flush with an oil change replacing one quart of oil with tranny fluid for its cleaning ability. It's an old hotrodder trick. I don't think these engines are prone to piston slap.
 

Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Sounds good, thanks guys.Will try the gas additive and do the oil. How about the timing chain? I had my front diff go out so, I figured if it was time it might save me some money if they went a little further since the diff needs to be swapped out pulled the pan and did the chain? I sure hope these things help the motor. No sense in spending the cash for the diff if the motor is on the way out. It's got 143,231 on it now so, we'll see what happens. Does anyone know a certain oil filter for these engines? I'm using a stp extended performance but, willing to try something better.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
The timing chains on these usually last the life of the vehicle. I had a tensioner fail on me but I think it was caused by poor maintenance of the previous owner of this particular engine. I am one of the few on this forum that has done it. I do remember another member that had the chain guide shoes fail. These are rare occurrences. Replacing the chain and hardware is not a trivial job and should only be done if necessary.
How to replace I6 timing chain and tensioner

Oil filters is basically anything but Fram (except for the Fram Ultra Synthetic, which is excellent). Opinions vary but any quality filter will do. STP Extended is quite a nice filter and from reviews I've seen on YT, it's well built. In fact, I think it's better than the Mobil 1.

BTW, some have replaced the front diff without having to remove the oil pan.
How to remove front differential
 
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TollKeeper

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Member
Dec 3, 2011
8,045
Brighton, CO
I wonder if the differential removal described will work on the 5.3?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Maybe ORTB has some info on that.
 

Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Thank you. I wish I could do this myself but, can't because of where I live. I used to work at the dealership and have everything I need but management would probably frown on me doing it in the parking lot. I'll post back about what I find with the motor. Thanks again for all the quick replies, love this site.
 

Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Reporting back. I tried the fuel additives and did yet another oil change running 6 qts of supertech high mileage synthetic, 1 qt of mmo and a mobil1 filter to no avail! Was going to check the manifold but will have to snap off the bolts holding the heat shield on or possibly the vvt sensor? Will these things cause the noise when cold? The vvt had oil inside the electrical connection so I cleaned it out and no change. Haven't pulled it out to look at the screen yet. Would the vvt cause it, manifold or something else when cold? Fires right up and runs good otherwise. What do you think?
Also, no change with belt removed from vehicle and no engine light.
 

Mike534x

Member
Apr 9, 2012
894
The VVT is just a solenoid, it wouldn't cause any noise at least from what I've seen. If it was bad there would be idle issues and code or too if I remember correctly.
 
Dec 5, 2011
574
Central Pennsylvania
Reporting back. I tried the fuel additives and did yet another oil change running 6 qts of supertech high mileage synthetic, 1 qt of mmo and a mobil1 filter to no avail! Was going to check the manifold but will have to snap off the bolts holding the heat shield on or possibly the vvt sensor? Will these things cause the noise when cold? The vvt had oil inside the electrical connection so I cleaned it out and no change. Haven't pulled it out to look at the screen yet. Would the vvt cause it, manifold or something else when cold? Fires right up and runs good otherwise. What do you think?
Also, no change with belt removed from vehicle and no engine light.

Closely inspect your exhaust manifold and the bolts that hold it on. I've had a tick/knock from day one. It's gotten more pronounced and improves when the engine heats up. I just recently checked the exhaust manifold and found at least 2 broken bolts and clear signs of exhaust leaking around 2 ports. Until then, I was concerned it was a stuck lifter or stuck injector. Now I'm convinced it's neither of those and will be doing my manifold first chance I get.
 

Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
I also forgot to mention that this annoying noise barely does it at idle or reving engine in park. As soon as I put it in gear and drive from a cold start it is loud! But, still goes away in about 15 mins of driving. Also, when I punch it on the highway hitting about 4500-5500 rpm it REEKS! Smells awful like a burning chemical smell or something. Could this problem be carbon? If it was a rod knock, would it go away when the engine gets hot?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I don't know about the smell but I wonder if the noise could be the flexplate? @Capote has lots of experience with them.

A rod or mains knock would not change. If anything, it would get louder as the engine gets hot and oil thins.

For the smell, years ago, they used to say that when the cat was bad, you'd get a rotten egg smell. Can you describe the smell?
 

Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
I don't know about the smell but I wonder if the noise could be the flexplate? @Capote has lots of experience with them.

A rod or mains knock would not change. If anything, it would get louder as the engine gets hot and oil thins.

For the smell, years ago, they used to say that when the cat was bad, you'd get a rotten egg smell. Can you describe the smell?
It is kinda like a burning rubber/chemical smell inside the cab but only after I really get on it. I will also try to post the sound it makes. I'm going to check the manifold and then take off the valve cover and check the valvetrain. I noticed the port hole cover in the bellhousing. Is that an access point for the flexplate can I check it from there?
 

mrrsm

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Oct 22, 2015
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The odors you describe indicate a large Exhaust Leak ...and if the vapors are able to enter the Cabin...you and your family members run the risk of being exposed to Dangerous Levels of CO (Carbon Monoxide). The GM LL8 Engine sports an exhaust system that is in the shape of a "Dog's Hind Leg" that puts an incredible twisting stress upon the Exhaust Manifold Fasteners. Acting like a LONG LEVER that starts just aft of the Catalytic Converter... as the Engine gyrates left and right during periods of acceleration and deceleration... the weight of everything attached from the Exhaust Manifold on down moves up and down ...working against the EM Bolts ...often bending them to the point of snapping them off... and leaving the Bolt Heads stuck in place... concealing this problem. A Loose Exhaust Manifold can also mimic the sounds of serious Engine Knocks.

If this turns out to be the case and you need to replace the Exhaust Manifold... it is likely that only the Dorman version will be available which will include a New Heat Shield with Fasteners and an MLS Stainless Steel Gasket. You should be aware though that due to the added thickness of (5) MM in the Bolt Hole Flanges... the GM Stock 8MM X 1.25MM X 30MM Flange Bolts will be TOO SHORT... and so the use of the 8MM X 1.25MM X 35MM Bolts will be required to hold the Exhaust Manifold securely to the passenger side of the Engine Head.

It does not take very much (CO) to become dangerous inside of a Closed Cabin... so the sooner this repair can be done...the better. Please note that if the noises you hear subsides after (15) Minutes...this gives more credence to the idea that the Heating up of the Exhaust Manifold over that time frame might make it expand enough to close that Leak Gap and explain the change in the sound. You would still be able to smell the escaping exhaust though as the added level of 4,000 Plus RPM would force out more exhaust around a leaking Exhaust Manifold Flange,

This is Dorman's Offer for this R&R of the EM:

https://www.amazon.com/dp/B0049E7XVM/?tag=gmtnation-20

DORMAN2003TBEM.jpg

Here are the Dorman Fasteners:

https://www.amazon.com/dp/B00K5A9MZY/?tag=gmtnation-20

DORMAN8MMX125MM.jpg

You WILL need this Tool for the O2 Sensor R&R

https://www.amazon.com/dp/B01C4OB3XC/?tag=gmtnation-20

ARESO2SENSORTOOL.jpg

Put a very small amount of O2 Sensor Approved Anti-Sieze on the O2 Sensor Threads...about two thread lines from the bottom of the sensor to avoid contaminating the Cubic Zirconium Internal Sensor.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I'd ditch the TTY manifold bolts, OEM or Dorman, and get a set of 12.8 grade bolts from a fastener supply house. I did that when I swapped the engine and manifold and that came out in one piece 7 years later.
 

Capote

Supporting Donor
Member
Jul 14, 2014
24,227
Atlanta, GA
It is kinda like a burning rubber/chemical smell inside the cab but only after I really get on it. I will also try to post the sound it makes. I'm going to check the manifold and then take off the valve cover and check the valvetrain. I noticed the port hole cover in the bellhousing. Is that an access point for the flexplate can I check it from there?
You'll check it from the bottom where the rubber plug goes. Rotate it with a long screwdriver and look carefully for any cracks or bolts walking out. I certainly didn't have any odors, was just noise. But that could be something else really. Would be hard to diagnose with a video, as when I took a video when it happened to me it sounded like a spun bearing. I got EXTREMELY lucky when my flexplate cracked. The hub section spun free, but when it happened it lodged itself together. I couldn't even hit out the hub with a hammer when it was taken out. You'd think it was welded back in place. So it kept functioning, but rotated off-axis a tad and ate up some of the rear of the crank. If you discover a crack, you'd want to deal with this asap and not drive it. Doubt you'll be as lucky as me if it gets worse. You'll probably have yours explode completely doing a ton of crazy damage.

Here's a link to what it looked like after I took it out...it's nuts!
https://gmtnation.com/forums/thread...-bottom-end-troubleshooting.15534/post-515350
 
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mrrsm

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...and if you hear a distinct "Bell Ringing" sound at any time ....but most pronounced at idle.... with the engine off and everything "Stone Cold" take a Small Dead Blow Hammer ...and locate the center bottom of the Stainless Steel "Can" at the underside of the CAT... Lightly Tap that area with the DBH... and listen carefully for anything that sounds like rattling 'Pocket Change inside of a Shaken Tin Pot".

If that rebounding sound is detected.... it means that the Brittle Ceramic Honeycomb center of the CAT has fractured into pieces that will Tinkle like Glassware when agitated by a Dropped Quarter. A New Replacement CAT is unfortunately the only solution. If Cracked... the Flex-Plate can also make this Rhythmic Pinging noise... so determining which one is the actual cause of the sound problem could prevent you from performing some unnecessary repairs.

Following @Mooseman's suggestion ... I found that these have a Much Larger surface area under the Flange area under the larger Bolt head at M8 X 1.25 X 35 MM precisely... they will hold the EM in place...with a lot less loss of metal from Rust because the Bolt Shanks are not completely Threaded like the Dorman versions... making them stronger besides. If you Google the Part Number... the Fastener Supply House I got these from should come up.

The one cautionary suggestion I would make about PT (Partial Thread) Fasteners though, is that you should 'Mike' the Average Thickness of the Exhaust Manifold Flanges at the Holes... and if necessary... install some comparably Wide M8 Stainless Steel Washers to compensate for the need to keep these Bolts from bottoming out inside of the Engine Head and NOT being snug enough to hold the EM to the face of the Exhaust Ports. Using S/S washers if needed will allow a margin of tightness and safety ... and thus prevent the undersides of the Bolt Head Flanges from wearing against any tendecy to move over Cast Iron EM flanges and gradually loosen them up over time:

METRICEXHAUSTMANIFOLD1.jpgMETRICEXHAUSTMANIFOLD2.jpg
 
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Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Thank you for all the advice. Will have to wait till I have the green to purchase a new manifold. The pics of that flex plate was crazy! I did notice once in a while the starter makes a slight short grinding noise when engaging the plate during start. Would flex plate noise go away when the engine warms up though? I wouldnt think so but still will take a peek. This weekend I'll check all that was mentioned above. Will post back with my finds. Thanks again, love this site, extremely helpful.
 
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Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
I posted that audio of the noise from a cold take off. Let me know what you think. Keep in mind that is completely gone after 15min of driving.
 
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mrrsm

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You're Quite Welcome, Brother... And that "Grinding" noise you've experienced is symptomatic of having a Fractured Out, Broken CenterArea (inner Crank Locale) of the Flex-Plate between the edge of the Crank to Flex-Plate Bolts at that Flange ...and the damaged portion of the Larger, Outer area of the Flex-Plate.

This problem presents itself as a Hesitation... First Slipping ...and then Catching... over and over until it the Outer Flex-Plate Portion finally manages to grab good enough and hold onto the Fractured Flange adjacent the Crankshaft Bolts as the pieces temporarily knit together well enough to turn the Motor over and start the Engine.

With so much damage to the center area closest to the Crank Flange... the only thing that manages to keep the Fire Ring with the Outer Gear Teeth from completely slipping free of the Starter Motor Gear... are the Three Bolts Holding the Flex-Plate to Torque Converter, situated 120 Degrees apart.

If you can pull that Shiny Circular Metal View Port Cover on the limb of the Bell Housing of the 4L60E Transmission and pipe a 7MM to 9MM USB Mini-Cam Lens in there and look around... you might be able to get better confirmation of the Cracks in the Flex-Plate being present... if they are even there... prior to performing the difficult R&R necessary to perform this repair.

I had to do just that back in 2015 during a 4L60E R&R ...and take my word for it... it is a Very Big, Laborious, PITA Solo Job that took too long of a time frame to complete and required no small amount of strength and an impossible abundance of patience while doing so. It matters NOT that your intent is to JUST R&R the Flex-Plate... The 4L60E Transmission will be in the way... and it MUST also be R&Rd to perform this repair..

If you happened to notice that when at Idle.. Your LL8 Engine "Shakes like "A Chihuahua Sh*tting a Peach Pit" and the SUV Body, Steering Wheel and Seating likewise shake and shudder... then it follows on that your Motor Mounts will likely need replacement as well. Believe it or not... Having Bad Motor Mounts WILL induce Cracks in the Flex-Plate over time... and so cause a repeat this very failure of the New Flex-Plate much sooner than later if the Motor Mounts are not soon replaced.
 
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mrrsm

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THAT is a Great Video for Image Quality and Sound.... But what we need to listen to and observe is the actual START of your vehicle with the Camera-Microphone placed underneath the Vehicle and aimed up towards the interface between the back of the Engine Block and the Transmission Bell Housing.
 
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Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
The grind noise hasn't happened in 3 days so it's hard to tell when it will do it. That is the original noise that has been going on for about 4 months now. I will check the flexplate tomorrow if i can. The phone placement under the hood was between the coolant and windshield washer reservoir. It does not make the noise in park even if I rev the engine. Seems like only under a load. Does it sound like it could be anything else? Sorry to press this issue but, I need to make a big decision cause I'm already gonna sink another 3,000 into it just for front diff and suspension.
 

mrrsm

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The problem is trying to isolate Engine Noise while it is running... from the very temporary sounds created from the moment that the Starter Solenoid fires the Small Gear into engagement with the Fire Ring Gear...and it oscillates because the Ring Gear is Broken at its Center at the Crankshaft and thus ..it tries to get "Out of Round" as it spins the OUTER Flex Plate. Meanwhile... the Center of the Flex-Plate-Crankshaft is doing NOTHING... as the the outer portion passes over it and struggles to lock it up... like "Sharks Teeth" trying to bite into the Broken Flange of the Flex-Plate and begin to turn over the Motor.

Sometimes ...those 'pieces' will wedge themselves tight enough for a while and NOT make the same Grinding Noises... a Very Deceptive and Sneaky way to conceal the problem. If it "Locks Up" you will NOT hear any problems of this weird noise... because the Engine RPM and Torque will manage to power-fuse them together when under acceleration.

But just know ....that when this problem finally gets bad enough to break loose again and give way... You'll hear the Starter turning rapidly ....but with no "Shark's Teeth" left at the Center sufficient to Grab and Hold the Crankshaft... soon enough ...you'll notice that the Engine will NOT Turn over and Start.

Please be aware... that the OTHER phenomena is that if this "Loss of Teeth" Securing the Flex-Plate -->to the Torque Converter--> to the Crankshaft occurs WHILE YOU ARE DRIVING ALONG... then you'll notice that the Engine suddenly Races under accelerating RPM as you step on the Gas Pedal ...but the Vehicle does not respond in kind and will soon STOP MOVING WITHOUT DRIVELINE POWER... a feeling akin to having the Transmission virtually... Disappear from under the Vehicle. And.... as soon as you coast along to the nearest curb... that will be as far as you can drive ...without the help of a Tow Truck. There is no telling when this problem can rear its Ugly Head.

There is no reason to rush to perform any other Videography this late on what must be a Very Frigid Night for you, Mike. But I will say, Congratulations to You for taking the time to do this. I suspect that many other Members will very much want to View, to Listen and to Comment about your First Video for other clues they might see and explain any other possible problems they might discover.

When the 4.2L Engine in the Trailblazer-Envoys is Idling... with some variation to your own circumstances ... a Confirmed Cracked Flex-Plate will sound pretty like much like this one does ...and please notice that the VOP (Video Original Original Poster) has removed that aforementioned "Round View Plate" allowing even more of the "crackling and tapping" noises to be heard:

 
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Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Ok. Yup, it's frigid here for sure. During the course of the next few days after checking those things mentioned earlier off the list I will report back what I find if anything. Thanks again.
 
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Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
While i was checking for a cracked manifold before the winter hits i found this. Would this cause a ticking sound when cold? Both rear bolt heads are gone!1010191529.jpg
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Yup. Missing bolts and cracked manifold are classic exhaust tick sources.
 
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Stuntmanmike77

Original poster
Member
May 6, 2018
137
Sanford, ME
Ok, thank you. Just wanted to make sure before i got into this. I'm thinkin they snapped the bolt heads off trying to replace it. I'll make sure to get new bolts too.
 

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