NEED HELP Intake manifold sludgy, plus smell of fuel when removing?

02FailBlazer

02FailBlazer

Member
Aug 8, 2025
112
U.S.
Pulled my intake manifold today and there's some oil sludge. Doesn't appear to be anything but oil thankfully. Just wanted a second opinion on how bad this is before writing this off as a simple PCV issue. As you can see in the third pic, the center gasket was barely doing anything and it's flatter than a pancake. I've got gaskets so it's getting a fresh set. The manifold itself is only sludgy around the "ports", it gets fairly clean in the upper portion and where the throttle body mounts.

RE the PCV, am I correct in that I can blow air into the hole in the side of the motor to help "purge" the PCV of debris? See photo 4, the hole I reference is circled in red.

Finally, while unbolting the intake, I got the occasional tiny drip of fuel near where the fuel pressure regulator is and every once in a while caught a faint whiff of fuel which quickly dissipated. There is no ongoing smell of fuel. The drips I noticed seem to come from around the intake manifold bolts rather than from the fuel pressure regulator or anywhere else, but I'm not 100% on that. Thoughts?

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The Short Answer to the Question of Engine Oil Consumption and the actual reason(s) for this Phenomena are: Engine Combustion Chamber-Gas-Gummed Up Top Two Compression Rings (Trapped) Resulting in Partially Burned Excess Combustion Blow-By.

The Excess Blow-By Pressurization inside of the Lower Engine Crankcase destroys Engine Oil Lubricity by mixing Un-Burned Raw Fuel with the Engine Oil. Then under such pressure, it works its way upwards and escapes through the Small Rubber Hose leaving the top of the Sealed Valve Cover Nipple, carrying away Residual Cast Off Engine Oil from the Hectic Rotating Camshafts and Valve Train moving it up, out and into the Air Box Plenum.

From there, the NA Vacuum occurring inside of the attached Throttle Body pulls on that Black "Carbon Mung" Oil Laced Air Mass and from thence, it gets sucked down inside of All Six Intake Manifold Runners and then drawn in past the Intake Valves and down inside of All Six Cylinders to be re-burned and plague the CAT Converter with Excess Hydro-Carbons that can "Poison The CAT.." .

THIS --> is WHY all of that Carbon Black Oil surrounds and collects near the Intake Ports of Your Engine Head and THIS --> IS a Treatable Condition by Non-Invasive Non-Mechanical Intervention using a "Top Engine De-Carbonization Procedure".

HOWEVER.... ACDelco NO LONGER SELLS THIS PRODUCT!

So review THIS Link FIRST and seek out a Replacement Product from this Best OF Solvents for De-Carboninzing Engine Combustion Chambers:

carsolutionpro.com

Best Top Engine Cleaner: 8 Products Expert Tested & Ranked

I spent six weeks testing 8 top-shelf cleaners on GDI and port engines. I measured carbon reduction rates to find the definitive best top engine cleaner.
carsolutionpro.com carsolutionpro.com

These Threads provide all of the reasons WHY this procedure is required:

ZD3SF

Thread 'Carbon cleaning the 4.2L LL8. Experiment'

I have recently performed carbon cleaning on the pistons and valves using a method recommended by @MRRSM and I figured to document the experience for those who would like to pursue this in the future. The method involves pouring AcDelco Top engine cleaner in the spark plug holes. This is NOT a guide, nor do I pretend that the performed method is the flawless.

Required tools/materials:
  1. 10 mm socket, 13mm socket ,5/8' spark plug socket, ratchet, and suitable extensions.
  2. AcDelco Top Engine cleaner (PN: 10-3015 ), 2 x 32 oZ cans
  3. Shop towels
  4. Optional: seafoam, new spark...
  • Like

C

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

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?

C

Thread 'Oil change coming up....time to do the Top Engine Clean......a question or two please.'

I've seen most of the links to the T.E.C. procedure but just want to clarify a few things....How much of the AC Delco TEC needs to go into each cylinder? I've seen quantities from 10 oz of the liquid in each cylinder to a few squirts of the foaming cleaner? And now that I mention it....Should I go with the Liquid? Or the foaming spray?

Also, I know I have to drain the oil and replace the filter after the soak, but do I need to do another short oil change after that? Or can I just do a regular oil change and run it for the 4000 mile interval? Thanks all for any info.

P.S. Envoy...

C

Thread 'I'm going to use the A.C. Delco T.E.C. Liquid or Aerosol?'

Hi all. I've decided to do the top end soak with A.C. Delco product. They make it in an aerosol also. Any suggestions on which might be better? After doing some add'l research...It appears the aerosol is made to use while the engine is running by spraying it through the intake.

It looks like I'll stay with the liquid and soak the cylinders as mentioned in previous threads.

PS... While you have the IM Off... Consider Replacing the Valve Cover and IM Gaskets with a New Gasket Set as this Motor uses only 89 Inch Lbs of "Snugging" force... as it expects to meet up against PLUMP Gaskets and NOT have Old, Flattened Out ones in place in order to "float and seal" with Minimal Torque applied to the 10 Trapped Fasteners on the IM and the same goes for the myriad ones surrounding the Valve Cover. The IM and Valve Cover are never, ever actually meant to be in direct physical contact with the Aluminum Engine Head
 
Last edited:
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mrrsm said:
The Short Answer to the Question of Engine Oil Consumption and the actual reason(s) for this Phenomena are: Engine Combustion Chamber-Gas-Gummed Up Top Two Compression Rings (Trapped) Resulting in Partially Burned Combustion Blow-By.

The Excess Blow-By Pressurization inside of the Lower Engine Crankcase works its way upwards and escapes through the Small Rubber Hose leaving the top of the Valve Cover, carrying away Residual Cast Off Engine Oil from the Valve Train up and into the Air Box Plenum

Then the NA Vacuum occurring inside of the attached Throttle Body pulls on that Black "Carbon Mung" Oil and from thence, it gets sucked down inside All Six Intake Manifold Runners and drawn in past the Intake Valves and down inside of All Six Cylinders to be re-burned and plague the CAT Converter with Excess Hydro-Carbons that can "Poison The CAT.." . THIS i--> is WHY all of that Carbon Black Oil surrounds and collects near the Intake Ports of Your Engine Head.

This IS a Treatable Condition by Non-Invasive Non-Mechanical Intervention using a "Top Engine De-Carbonization Procedure".

HOWEVER.... ACDelco NO LONGER SELLS THIS PRODUCT!

So review THIS Link FIRST and seek out a replacement product from this Best OF Solvents for De-Carboninzing Engine Combustion Chambers:

carsolutionpro.com

Best Top Engine Cleaner: 8 Products Expert Tested & Ranked

I spent six weeks testing 8 top-shelf cleaners on GDI and port engines. I measured carbon reduction rates to find the definitive best top engine cleaner.
carsolutionpro.com carsolutionpro.com

These Threads provide all of the reasons WHY this procedure is required:

ZD3SF

Thread 'Carbon cleaning the 4.2L LL8. Experiment'

I have recently performed carbon cleaning on the pistons and valves using a method recommended by @MRRSM and I figured to document the experience for those who would like to pursue this in the future. The method involves pouring AcDelco Top engine cleaner in the spark plug holes. This is NOT a guide, nor do I pretend that the performed method is the flawless.

Required tools/materials:
  1. 10 mm socket, 13mm socket ,5/8' spark plug socket, ratchet, and suitable extensions.
  2. AcDelco Top Engine cleaner (PN: 10-3015 ), 2 x 32 oZ cans
  3. Shop towels
  4. Optional: seafoam, new spark...
  • Like

C

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

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?

C

Thread 'Oil change coming up....time to do the Top Engine Clean......a question or two please.'

I've seen most of the links to the T.E.C. procedure but just want to clarify a few things....How much of the AC Delco TEC needs to go into each cylinder? I've seen quantities from 10 oz of the liquid in each cylinder to a few squirts of the foaming cleaner? And now that I mention it....Should I go with the Liquid? Or the foaming spray?

Also, I know I have to drain the oil and replace the filter after the soak, but do I need to do another short oil change after that? Or can I just do a regular oil change and run it for the 4000 mile interval? Thanks all for any info.

P.S. Envoy...

C

Thread 'I'm going to use the A.C. Delco T.E.C. Liquid or Aerosol?'

Hi all. I've decided to do the top end soak with A.C. Delco product. They make it in an aerosol also. Any suggestions on which might be better? After doing some add'l research...It appears the aerosol is made to use while the engine is running by spraying it through the intake.

It looks like I'll stay with the liquid and soak the cylinders as mentioned in previous threads.
Click to expand...

Interesting. Sounds like the same stuck piston ring issue from the infamous 2AZ-FE "oil burner" engine found in so many Toyotas, of which I happen to be an owner, so I'm familiar with the issue.

Berryman's B12 is favored by Toyota owners for unsticking piston rings, but I'm wondering if I can get away with just running Valvoline Restore and Protect oil. They're anecdotes, but lots of people seem to have success with it unsticking piston rings.
 
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Sweet! Best Of Luck with using the Best Treatments Available! These Treatments are a much more direct means of getting the Valve Seats, Piston Rings and Piston Tops fairly well cleaned and with a bonus of renewed Compression and Fuel Economy much sooner than later.
 
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I use Valvoline R&P but don't think that what it is designed for will help completely with this sludge problem, in the pics. I saw the intake sludge on a 1996 2.4 Tacoma and I cleaned as best I could but did not know of this particular problem and the Berryman 2611 capability to help clean this. That Tacoma is no longer owned and I no longer work on it. But, my girl owns a 78k miles 2002 TB with the 4.2 and I want to stay ahead of the likely oncoming problem. I looked thru the link supplied by @mrrsm and believe that the Berryman 2611, is the way to go.

@mrrsm, do you have any links to videos of the application/usage process?
 
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I did find this link at you tube on how to use the Berryman 2611 product.

 
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The sludging is caused by the PCV system from the hose at the bottom of the resonator, which is why we have to regularly clean the throttle body. It's by design. So much so that they programmed the PCM to compensate for the dirty throttle body by adjusting the idle over time. That's why disconnecting the battery screws that up and we get idling issues.
 
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Mooseman said:
The sludging is caused by the PCV system from the hose at the bottom of the resonator, which is why we have to regularly clean the throttle body. It's by design. So much so that they programmed the PCM to compensate for the dirty throttle body by adjusting the idle over time. That's why disconnecting the battery screws that up and we get idling issues.
Click to expand...
Yea, am aware. It is one of my best maintenance sells. Cleaning the throttle body, when I do it, means throttle body removal, new seal and cleaning both sides.
 

 
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Went and bought the Berryman 2611 kit and will post results here as well as pics or video.
 
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Here it is in August and I have still not gotten the ok to do this cleaning, from Linda. She says it runs great and does not want to mess with it, yet.
 
If you haven't gotten the OK better not try to sneak it in--they can tell :-)
 
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We have been putting 75 miles a day, for last 7 days, on it with no problems at all and lots of power and very smooth idle.
 
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