A.C. Delco Foaming Top End Cleaner....

c good

Active Member
Original poster
Dec 8, 2011
386
Good Evening All,
I've read about this procedure here on the forum. I'm wondering if it would be OK to do, regardless of if I have carbon build up or oil consumption.

I have noticed a small amount of oil accumulated in the intake plenum. I do have a little piston "slap" that goes away upon heating up to operating temp. I tend to use about a quart of oil in 3000-4000 miles. Engine currently at 190 k miles.

Any drawbacks to doing the top end cleaning process? Or best to leave things alone?
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
21,859
Ottawa, ON
@MRRSM can confirm since he is ACDelco's Top Engine Cleaner SME here, I don't think it would harm anything. If anything, it might help free up the rings and reduce blowby.
 

NJTB

Platinum Donor
Aug 27, 2012
543
Flemington, NJ
GM Top Engine Cleaner works very well, follow the directions on the can. It wont hurt anything.
Also, check for blockage on the hose under the resonator, and the orifice on one that goes into the block. (PCV system)
 
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MRRSM

Lifetime VIP Donor
Oct 22, 2015
5,729
Tampa Bay Area
A brief "How To" when using ACDelco TEC in the GM LL8 Engine from another Member that had positive results as the outcome:

 

chris68369

Registered Member
Nov 18, 2018
12
Michigan
For some reason I thought that the 4.2 engines aren't suppose to have piston slap. I know I have cold carbon knock when it's cold on first startup but goes away after a few minutes of driving. I've gotten used to hearing it and only happens on first startup but I'll give this a shot just to see how it does.
 

MRRSM

Lifetime VIP Donor
Oct 22, 2015
5,729
Tampa Bay Area
All In-Line 4, 5 & 6 Cylinder Four Cycle (4-Stroke) Engines develop "Piston Slap" to some degree over time due to the need to have their Piston Wrist Pins-to-Connecting Rods slightly off-set in order to allow them to roll though Top Dead Center and keep their "Power Strokes" driving the Crankshaft Journals enough to rotate around only in a Clockwise Direction.

The other factor contributing to this problem involves the shorter designs of modern engine piston skirts versus those of their 'longer cousins' from earlier engine designs. Longer Piston Skirts were better at resisting the rocking action. However, they were naturally added unnecessary weight to fight against the motion of the Rotating Mass, making them less responsive to power demands while also being less fuel efficient.

As the Pistons in the 4.2L In-Line Six Cylinder Engines reach TDC... they bobble slightly, rocking suddenly from one side of the cylinder to the other, in line with the direction of rotation. This tendency can cause additional Piston Ring-to-Cylinder-Wall wear and adds to the actions that can oval out the upper cylinder walls.

Whenever engines are cold... the Pistons along with their Low Tension Compression Rings contract enough to provide the added space to allow this rocking-slapping action to become more excessive. As the engine heats up, the Pistons and Rings expand and tend to lessen the "Piston Slap" effects up to a point.

These images illustrate the wear conditions of the Cylinder Walls in a GM 4.2L LL8 Engine after 160,000 Miles and from exposure to the Dusty Air Environment of Arizona. Note the presence of an extra deep worn in oval where the Piston Head makes abrupt contact during the repetitive "Piston Slap" events as it digs into the Upper Cylinder Wall:

42574059335_bc8327e7d4_c.jpg43430665072_869ff6c28e_c.jpg

The other artifact that can extend the lives of Modern Four Cycle Engines is having Low Tension Compression Rings. These Rings can coax motors like the LL8 to last perhaps as long as 300,000 Miles or more if very well treated and serviced on schedule.

The "Old Chevy 265, 283, 327 and 350 CID" blocks would often require rebuilding right around 100,000 Miles or so because their Cast Iron Compression Rings were as "Thick as Re-Bar" and chewed quickly into Cylinder Walls... wearing out Motors rapidly and often leaving Rings or Ridges of Metal Deposited along the Upper Engine Block openings requiring "Ridge Cutters" just to remove the Pistons during rebuilding.

The down side of using these 'Low Tension Rings' is their tendency to STICK TIGHTLY inside their Lands & Grooves of the Pistons after being exposed to WAY TOO MUCH CARBON and un-burned Combustion By-Products that will literally Glue or Lacquer them right into the sides of the Pistons and thus, invites Excessive Gas Blow-By and increased "Piston Slap".

Proper Treatments using the ACDelco Top Engine Cleaner can dissolve these built-up Carbon Bonds, loosening them and returning the ability to flex and expand while better sealing the Two Top Compression Rings. This action can serve to increase compression, improve power, reduce fuel and engine oil consumption and reduce Gas Gum Deposits and Carbon Blow-By Products from 'Polluting and Diluting' the Engine Oil and collecting "Black Carbon Mung" all over down inside of the lower Crankcase.

Excessive Gas Blow-By can also seriously reduce the lubricity and protection of Motor Oil and along with Dirty Air Filtration, it invites excessive engine wear over time. Changing one's Motor Oil in this LL8 Engine every 3,000 Miles should be done for these and other reasons using Mobil1 FULL Synthetic and either Mobil1 or K&N Oil Filters.
 
Last edited:

chris68369

Registered Member
Nov 18, 2018
12
Michigan
Thank you very much for this needed explanation! I'm sure others who read this will feel the same way. I am at the 212000 mile mark but I'm going to try this and see how well it works out in my favor. For me it's for maybe 3-5 mins and once she's warmed up you don't hear it anymore. But it never hurts to try something new
 
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MRRSM

Lifetime VIP Donor
Oct 22, 2015
5,729
Tampa Bay Area
NP... By the way... Take a close look at the tops of the Piston Head shown in those images...

THAT is the result of soaking each Cylinder in AC Delco TEC (Top Engine Cleaner). They required NO scrubbing and NO other aggressive attentions in order to clean them right down to Bare Metal with just the swipe of some Scott Blue Shop Towels. So these results should encourage others to appreciate the beauty of this Chemistry by Direct Contact.
 
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c good

Active Member
Original poster
Dec 8, 2011
386
All Four Cycle Engines develop "Piston Slap" to some degree over time due to the need to have the Piston Wrist Pins to Connecting Rods slightly off-set to allow them to roll though Top Dead Center and keep their "Power Strokes" heading only in a Clockwise Direction.

The other factor contributing to this problem involves the shorter designs of modern engine piston skirts versus those of their 'longer cousins' from earlier engine designs. Longer Piston Skirts were better at resisting the rocking action. However, they were naturally added unnecessary weight to fight against the motion of the Rotating Mass, making them less responsive to power demands while also being less fuel efficient.

As the Pistons in the 4.2L In-Line Six Cylinder Engines reach TDC... they bobble slightly, rocking suddenly from one side of the cylinder to the other, in line with the direction of rotation. This tendency can cause additional Piston Ring-to-Cylinder-Wall wear and adds to the actions that can oval out the upper cylinder walls.

Whenever engines are cold... the Pistons along with their Low Tension Compression Rings contract enough to provide the added space to allow this rocking-slapping action to become more excessive. As the engine heats up, the Pistons and Rings expand and tend to lessen the "Piston Slap" effects up to a point.

These images illustrate the wear conditions of the Cylinder Walls in a GM 4.2L LL8 Engine after 160,000 Miles and from exposure to the Dusty Air Environment of Arizona. Note the presence of an extra deep worn in oval where the Piston Head makes abrupt contact during the repetitive "Piston Slap" events as it digs into the Upper Cylinder Wall:

View attachment 102223View attachment 102224

The other artifact that can extend the lives of Modern Four Cycle Engines is having Low Tension Compression Rings. These Rings can coax motors like the LL8 to last perhaps as long as 300,000 Miles or more if very well treated and serviced on schedule.

The "Old Chevy 265, 283, 327 and 350 CID" blocks would often require rebuilding right around 100,000 Miles or so because their Cast Iron Compression Rings were as "Thick as Re-Bar" and chewed quickly into Cylinder Walls... wearing out Motors rapidly and often leaving Rings or Ridges of Metal Deposited along the Upper Engine Block openings requiring "Ridge Cutters" just to remove the Pistons during rebuilding.

The down side of using these 'Low Tension Rings' is their tendency to STICK TIGHTLY inside their Lands & Grooves of the Pistons after being exposed to WAY TOO MUCH CARBON and un-burned Combustion By-Products that will literally Glue or Lacquer them right into the sides of the Pistons and thus, invites Excessive Gas Blow-By and increased "Piston Slap".

Proper Treatments using the ACDelco Top Engine Cleaner can dissolve these built-up Carbon Bonds, loosening them and returning the ability to flex and expand while better sealing the Two Top Compression Rings. This action can serve to increase compression, improve power, reduce fuel and engine oil consumption and reduce Gas Gum Deposits and Carbon Blow-By Products from 'Polluting and Diluting' the Engine Oil and collecting "Black Carbon Mung" all over down inside of the lower Crankcase.

Excessive Gas Blow-By can also seriously reduce the lubricity and protection of Motor Oil and along with Dirty Air Filtration, it invites excessive engine wear over time. Changing one's Motor Oil in this LL8 Engine every 3,000 Miles should be done for these and other reasons using Mobil1 FULL Synthetic and either Mobil1 or K&N Oil Filters.
What did you end up doing with this engine? Did you bore out the cylinders and go oversize pistons?
 

MRRSM

Lifetime VIP Donor
Oct 22, 2015
5,729
Tampa Bay Area
Nope... Honing out the Cylinders IS an option, I suppose... But I never do anything by halves...

When I opted to Tear this Engine right down to its very Atoms and Rebuild it into a Brand New Condition, I knew very well what I was getting myself into. This involved investing quite heavily in the Tools and the Extensive (spell that EXPENSIVE) parts replacement using only Brand New Components.

Most of us would hazard against buying all of these items without having a Matching Mechanic's Skill Set to actually be able to do all of this work. Take a look at my "Flickr-Bucket" to see most of what I purchased in the way of the required New Parts in preparation for this complete engine overhaul:


In lieu of "Honing Out" the aged Cylinders that started out in life only having a Cylinder Wall Thickness of 1.50mm , I opted instead to just replace them all using the Melling GM OEM Factory LL8 Cylinders. These actions also required the added effort of creating a uniform plateau honing of them all to meet within the Mahle GM OEM Piston and Ring narrow specs for the inside diameter. Ordinarily, only a Machine Shop will do this sort of work.

However, these Engine Cylinder replacement repairs are currently possible utilizing the Melling Cylinder Sleeves Part# CSL331F @ $30.79 per Item available from RockAuto:

MELLINGLL8SLEEVE.jpgMELLINGLL8SLEEVEBOXED.jpgMELLINGLL8SLEEVEWRAPPED.jpg

https://www.rockauto.com/en/catalog...l6,1398719,engine,cylinder+repair+sleeve,5312

The work also requires purchasing THIS complete, EXPENSIVE and unique R&R Kit from K&M Part# EN-45680-400 for the proper Removal, Installation and Head Surface Trimming of the New Melling CSL331F Cylinder Sleeves:

https://www.freedomracing.com/catalogsearch/result/index/q/EN-45680-400/

CYLINDERREPLACEMENTKIT.jpg

THIS Video shows how the first 1/2 of How this Complex Tool Kit works:


In my situation, I wanted to do this work myself and in order to to avoid contaminating the Freshly Bathed Bare Aluminum Engine Block with junk created whenever using the requisite Flex-Hone 95mm 400 Grit Silicon-Carbide Ball Hone, I needed to go one step further.

I wanted to prevent slinging Cutting Oil saturated with Hone Abrasives and Metal Residue all over the insides of the Fresh Engine Block. So I designed and built a Stand-Alone Wooden Jig to 'Hold Fast' the New Cylinders in place well enough to carefully hone them out before installation and using a Bore Dial Indicator to ensure they all sized up correctly with the New Pistons and Rings nested inside with as a prior pre-fit. to using the Kit to install them into the Engine Block:

FLEXHONELL8CYLJIG1.jpgFLEXHONELL8CYLJIG2.jpg

43350756672_b39322b434_c.jpg43350756822_d065b42831_c.jpg43350758192_c7cd7225be_c.jpg43350758402_a89fb682e3_c.jpg

At this point in my explanation, you should be realizing just how much Money, Time and Effort is actually involved in doing this kind of work and conclude that merely "honing out the cylinders" is NOT part of anything trivial you can accomplish with ease once you Tear-Ass into your Engine Block. If you decide to "go into" this Motor... you have to be prepared to "Go ALL the Way..."

Whenever Members from GMTN offer guidance for you to "Find a Good, Low Mileage Swap Engine"... consider carefully heeding their excellent advice. Think long and hard about trying this job on without understanding 'Neo's choices between the Red Pill and the Blue Pill' before you choose to "Tumble Down THIS Rabbit Hole".
 

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