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DISCLAIMER: This DIY guide has been put together using knowledge from various third party sources, and demonstrated on one vehicle. It is not endorsed or property of this forum or myself in any way/shape/form. This is simply more information for those who are curious about the cleaning process. Neither this forum nor myself are liable for any damages that are incurred as a result of using this guide. The end user (you) assume all risks to you/your car/your environment by using this guide. E.g. you take the risk of breaking your car/voiding your warranty by using this guide.
I also do not endorse any of the products used in this DIY, purely one man’s tools and opinions.
Now let’s get to it. I want to give thanks to the following as this would not have been possible without the information they provided:
Theta's excellent DIY guides in the stickies section.
RX for their videos showing their intake valve cleaning
coSPEED2 and other vendors for bringing this issue to light
user Wormwood for his advice/expertise as he had completed this before me
various other users and threads detailing the BMW “walnut shell cleaning”
The C7 Z51 is the second GDI (Gas direct injection) engine I have had. I previously had a VW that I completed a similar cleaning before. Knowing that, I immediately installed Elite Engineering’s clean oil separator and catch can upon picking up my car at the dealer last year. I also immediately drained all the oil and completed a new oil change and performed a cleaning of intake air tracts at that time. My C7 is a weekend car, and only very few miles and is not tracked. I used a boroscope a few months ago and confirmed that my intake valves were pretty clean and did not need a cleaning right now.
My friend bought his C7 Z51 shortly after I did. His was used and came with 6k miles. At the time he bought it, it did not have a catch can or oil separator installed, and records showed that it received the first oil change at around 1200 miles. He installed the same catch can and air separator shortly after buying the vehicle. He was worried about valve coking issue after reading several threads, and proceeded to our local Chevy dealer to inquire about induction cleaning service. When he talked to the service advisor, they looked at him if he had grown two heads. One of the techs said that they could spray a cleaner into the intake and clean it that way, but that he would be charged $400. My buddy at this point approached me for help.
There are differing opinions on how much this affects performance/efficiency and what type of cleaning is warranted, I am not hear to argue those issues. There are those who have just sprayed/poured cleaner into their manifold and then crank the engine. This type of cleaning causes me nightmares as I can see countless chunks/sludge and deposits making their way past the intake valves and into the chambers. I put together this DIY for those who wanted to know more about the process of cleaning the valves. This was done on my buddy’s 14 Z51, but I can see the same thing being applied to the wet sump engine as well.
Last edited by A471133; 10-08-2015 at 01:38 PM.
Reason: Update
Now onto cleaning. Please read in entirety before starting.
-disconnect negative battery terminal in back. Make sure windows are lowered first. Wait 10 mins or step on the brake after disconnecting to dissipate any residual charge
-remove fuel rail covers/intake manifold covers per Theta’s DIY guides. When you encounter the center manifold cover, you may notice the wire bundles on either side are zip tied in. To keep the zip ties in place, you need to carefully squeeze the retaining tabs on the underside of the cover. I chose to clip them off and will replace them with new ones.
-remove air intake tubing and catch can if you have them. Air intake to filter case takes a Torx screw. Disconnect the electrical/vacuum connections to the intake manifold per Theta’s guide.
-IMPORTANT: before removing the intake manifold, take time to vacuum and blow the areas surrounding the intake manifold to eliminate as much sand/dust that has gathered there. I chose to first use the shop vac micro attachment with the brush and then used compressed air at 100psi to blow any residual dust/sand out.
-use 10mm socket to loosen the 10 bolts holding down the intake manifold. These have retainers that keep them in the manifold itself. As you loosen them, use rubber bands or pieces of tape to hold these screws in the “up” position so they don’t drop down and hamper the process of removing the intake manifold.
-Ensure all connectors to manifold/throttle body are disconnected per Theta’s guide. As Theta noted, there is a tube held onto the rear driver’s side of the intake manifold by a compression collar. There is very little slack to get a hand and remove this. I ended up shifting the manifold very slightly forward to obtain a couple inches of wiggle room to access this. You may also want to disconnect the last 1 or two of the harness bundle connectors on each side to allow more room as well. You should be able to see the red compression collar at this point. I used a vinyl panel removal tool to pop the collar and tubing out. See picture above.
-remove the intake manifold. IMMEDIATELY use painter tape to seal all port openings to prevent dust/sand from entering. You can also tape off the ends of the vacuum/electrical connectors to keep them clean.
-again, use the shop vac w/ brush attachment to vacuum any sand/dust from the areas around the ports, and use compressed air to clean again. Make sure ports are taped off before you vacuum/blow air
-attach the strap wrench to the harmonic balancer. You will be turning the crank CLOCKWISE if you are standing in from of the car looking at the front of the engine. DO NOT TURN IT THE OTHER DIRECTION!!! If you wish to verify the crank direction, you can start the car before taking the stuff apart and verify the crank rotation direction.
Now to clean each port, I used the following procedure. I started from the frontmost driver’s side port, worked back, then switched to passenger’s side front and worked back as well.
-uncover only the port you are going to clean. This is where my iPhone was handy. I opened the camera app and switch to video and turned the flash on. When you sit the phone over the port, it gives you a great view of the port itself and also covers the port. After you obtained a good view of the valve, rotate the crank until you can clearly see the valve open and then close and seal. I did this each time to verify how much deposits were there and also to ensure port sealing.
-as you can see, there is alot of crud and carbon deposits. My buddy does not track the car, and the car has around 13k miles right now (7K w/ catch can and clean oil separatory).
- with the valve closed and sealed, spray the Top engine cleaner. Two or three long sprays is enough to coat the walls and the valve areas. You do not need to put an excessive amount in, just enough so that it covers the walls and valve. I let it sit for 15mins to do most of the work for me. As the white foam cleans, it will turn brown and then into a black oily mixture.
-now it’s time to break out the pistol cleaning kit. The aluminum bar will have a handle. The handle has a small window that shows a retaining pin. Remove the pin and the handle slides off. Keep the pin/handle if you wish to use them later to clean guns. Secure the rod in the drill. Attach the brass brush to the end
-Position yourself over the port. I used a stool and then one hand on the windshield to steady myself. Avoid placing weight on the engine components as there are plastic connectors and fuel injection components all over the place.
-insert the brush and dip it into the cleaner that has settled, now probably a black color. The cleaner should have settled and covered the entire back of the valve. Using just the bristles and light pressure, brush the surfaces of the walls and valve. You do not need excessive pressure.
-change the brass brush to the “mop” attachment from the gun kit. Again dip it in the cleaner in the port, and scrub all the surfaces again. The size of the mops/brass brush should allow the back of the valve stem to be cleaned without bending the brushes.
-use the micro tube attachment from the shop vac. Suck out all the dirty fluid.
-spray additional 1-2 spray of cleaner to lightly coat inside of port and valve again.
-take the oval loop attachment from the gun kit and fold 2-3 pieces of the lint free cloths and thread the end of the cloths through the loop. There should be enough pressure to hold the cloths secure. As you run the drill in the forward direction, it will wrap the cloths around further preventing detachment in the port
-with this attachment on the drill, dip the cloths in the solution in the port and again sweep the surfaces of the port. The solution should be much cleaner this time, and you should see the walls of the port clean up as well.
-again, use the shop vac to suction out the fluid
-now, insert a corner of a clean rag into the port. Use a screwdriver to gently advance the rag into the port until the inside walls of the port and the back of the valve is contacted by the rag. This will absorb any residual cleaning fluid and pick up any deposits that are left over. Remove the rag.
-use compressed air at 100psi and blow into the port. I used approx. 3 gallons of compressed air (about 45secs worth).
-at this point, the port should be clean. See picture above. Any residual oil/light brown spots can be picked up by an additional run with the rag stuffing.
-seal the clean port with tape again, and move onto the next port. Some may want to do multiple ports at a time due to multiple valves being closed, but I just worked on one at a time. This way, I could verify how many deposits there were by opening the valve, and then ensure complete valve sealing by closing it.
-This worked for me until the rearmost port on the passenger’s side. There is not enough room between it and the overhanging windshield cowl to allow the drill and attachment in. Also, it is so angulated that the only way to see inside is with the iPhone. For this port only, I doubled the dwell time and used each attachment/rod twice as I was using my fingers to spin the brushed by hand instead of a drill.
-Each port took me about 20mins once I got the hang of it. During the times that you are letting the initial sprays of cleaner dwell and clean, you can clean the air intake and intake manifold itself. I took this time to wash out the entire inside of intake tubing with intake cleaner, clean the MAF sensor with MAF safe cleaner, and clean throttle body as well.
-to clean the inside of the intake manifold, cut multiple strips of cloths (4.5in by 1 in) and make a hole towards one end of the strip. Attach the multiple strips onto the gun cleaning rod and sandwich them with a plastic attachment. Using this and the drill, insert this into the intake manifold ports and clean the inside. I used dry strips at first to see if there was oil in there, and then used a can of intake cleaner to spray inside the intake manifold and then used my attachment to spin it clean and dry. There was some fresh oil in the manifold, as well as a thin coat of old oil along the entire intake tube, throttle body, and inside the intake manifold.
-after everything is clean, and just before I was ready to install the intake manifold, I vacuumed again. I did this by untaping the ports sequentially from back to front and inserting the shop vac tube inside each one. DO NOT use compressed air at this point, as some valves are open and you can blow stuff into them.
-immediately install the intake manifold, taking care to install the driver’s rearward vacuum tube and reconnecting all connections. Keeping the manifold bolts taped/rubber banded up will help with the installation. Reconnect all the connectors, and torque per Theta’s guide in the specified pattern and the two passes with specified torques. BE AWARE that the torque is in INCH POUNDs, not foot pounds.
-reinstall air intake and covers, and also catch can/air separator if you have one.
-reconnect negative battery terminal. Ensure all tape/tools/equipment is removed from engine bay (I almost left the strap wrench on)
-Start the car, first start may be a little rough, my idle smoothed out within 3 seconds.
First gather your tools. I pondered whether or not to use the “walnut shell” cleaning method, and in the end decided not to as it would require more equipment that many people don’t have and would have to buy and the possibility of making a huge mess since there is not a premade “adapter” for shop vacs to fit into the LTI ports. Below are my suggested tools. I tried to keep the list down to what most people already have or can run out and get without breaking the bank.
-Not pictured: air compressor w/ blower attachment, standard socket/wrench/ratchets (1/4 and 3/8) adapters, set of standard Torx bits, screwdrivers, cordless power driver/drill
-shop vac with wet/dry capabilities (for sucking up cleaning solution, make sure to collect this and dispose of properly as it is toxic)
-Shop vac Micro cleaning kit (Walmart #1165124 $12.97)
-Bucket and lots of rags/towels
-painters tape (wide 3in)
-strap wrench (Lowes/HD-around $10-make sure to get a long one, I had to improvise to increase the length of the one I bought to wrap around the harmonic balancer)
-inch pounds torque wrench
-Pistol cleaning kit – Walmart – this is made for multiple calibers, it was about $10, had multiple brass brushes/mops/lint free cloths/aluminum rod. There are kits with cleaning solutions, you do not need the solution
-dry erase marker for making things
-fender covers to protect while leaning
-headlight (super helpful)
-stool (unless you are a giant and can successfully lean and peer into each port)
-phone with camera/LED (very helpful, I used my iphone 6)
-new engine oil filter and engine oil for a fresh change after completing the cleaning.
Now the cleaning solution. There are multiple products you can use. CRC makes a new cleaner, there is of course seafoam and other third party fluids, the BG stuff that is rare around my area and hard to find, and finally what I ended up using: GM Top engine cleaner. Here’s my experience with each and why I settled on GM’s product:
-CRC Fuel injection/intake valve cleaner: smells like a lot of ether, initially has some “foaming” action, but then quickly turns into waterly fluid and runs off
-Seafoam: you have to pour in, no foaming action
-BG products: again, pour in, no foaming, and hard to find in San Antonio. The specialized “induction cleaning” kit requires special equipment and kit and can get expensive.
GMs top engine cleaner: $18 at local GM/Buick dealer. Sprays as aerosol foam, foam expands initially and hold great to side walls of chamber, as it cleans it turns from white-brown-black oily fluid that settles. One bottle was enough for me to clean all 8 ports, if you have more crud caked on you may want to get another.
Last edited by A471133; 10-08-2015 at 02:54 PM.
Reason: Update
Now onto cleaning. Please read in entirety before starting.
-disconnect negative battery terminal in back. Make sure windows are lowered first. Wait 10 mins or step on the brake after disconnecting to dissipate any residual charge
-remove fuel rail covers/intake manifold covers per Theta’s DIY guides. When you encounter the center manifold cover, you may notice the wire bundles on either side are zip tied in. To keep the zip ties in place, you need to carefully squeeze the retaining tabs on the underside of the cover. I chose to clip them off and will replace them with new ones.
-remove air intake tubing and catch can if you have them. Air intake to filter case takes a Torx screw. Disconnect the electrical/vacuum connections to the intake manifold per Theta’s guide.
-IMPORTANT: before removing the intake manifold, take time to vacuum and blow the areas surrounding the intake manifold to eliminate as much sand/dust that has gathered there. I chose to first use the shop vac micro attachment with the brush and then used compressed air at 100psi to blow any residual dust/sand out.
-use 10mm socket to loosen the 10 bolts holding down the intake manifold. These have retainers that keep them in the manifold itself. As you loosen them, use rubber bands or pieces of tape to hold these screws in the “up” position so they don’t drop down and hamper the process of removing the intake manifold.
-Ensure all connectors to manifold/throttle body are disconnected per Theta’s guide. As Theta noted, there is a tube held onto the rear driver’s side of the intake manifold by a compression collar. There is very little slack to get a hand and remove this. I ended up shifting the manifold very slightly forward to obtain a couple inches of wiggle room to access this. You may also want to disconnect the last 1 or two of the harness bundle connectors on each side to allow more room as well. You should be able to see the red compression collar at this point. I used a vinyl panel removal tool to pop the collar and tubing out. See picture above.
-remove the intake manifold. IMMEDIATELY use painter tape to seal all port openings to prevent dust/sand from entering. You can also tape off the ends of the vacuum/electrical connectors to keep them clean.
-again, use the shop vac w/ brush attachment to vacuum any sand/dust from the areas around the ports, and use compressed air to clean again. Make sure ports are taped off before you vacuum/blow air
-attach the strap wrench to the harmonic balancer. You will be turning the crank CLOCKWISE if you are standing in from of the car looking at the front of the engine. DO NOT TURN IT THE OTHER DIRECTION!!! If you wish to verify the crank direction, you can start the car before taking the stuff apart and verify the crank rotation direction.
Now to clean each port, I used the following procedure. I started from the frontmost driver’s side port, worked back, then switched to passenger’s side front and worked back as well.
-uncover only the port you are going to clean. This is where my iPhone was handy. I opened the camera app and switch to video and turned the flash on. When you sit the phone over the port, it gives you a great view of the port itself and also covers the port. After you obtained a good view of the valve, rotate the crank until you can clearly see the valve open and then close and seal. I did this each time to verify how much deposits were there and also to ensure port sealing.
-as you can see, there is alot of crud and carbon deposits. My buddy does not track the car, and the car has around 13k miles right now (7K w/ catch can and clean oil separatory).
- with the valve closed and sealed, spray the Top engine cleaner. Two or three long sprays is enough to coat the walls and the valve areas. You do not need to put an excessive amount in, just enough so that it covers the walls and valve. I let it sit for 15mins to do most of the work for me. As the white foam cleans, it will turn brown and then into a black oily mixture.
-now it’s time to break out the pistol cleaning kit. The aluminum bar will have a handle. The handle has a small window that shows a retaining pin. Remove the pin and the handle slides off. Keep the pin/handle if you wish to use them later to clean guns. Secure the rod in the drill. Attach the brass brush to the end
-Position yourself over the port. I used a stool and then one hand on the windshield to steady myself. Avoid placing weight on the engine components as there are plastic connectors and fuel injection components all over the place.
-insert the brush and dip it into the cleaner that has settled, now probably a black color. The cleaner should have settled and covered the entire back of the valve. Using just the bristles and light pressure, brush the surfaces of the walls and valve. You do not need excessive pressure.
-change the brass brush to the “mop” attachment from the gun kit. Again dip it in the cleaner in the port, and scrub all the surfaces again. The size of the mops/brass brush should allow the back of the valve stem to be cleaned without bending the brushes.
-use the micro tube attachment from the shop vac. Suck out all the dirty fluid.
-spray additional 1-2 spray of cleaner to lightly coat inside of port and valve again.
-take the oval loop attachment from the gun kit and fold 2-3 pieces of the lint free cloths and thread the end of the cloths through the loop. There should be enough pressure to hold the cloths secure. As you run the drill in the forward direction, it will wrap the cloths around further preventing detachment in the port
-with this attachment on the drill, dip the cloths in the solution in the port and again sweep the surfaces of the port. The solution should be much cleaner this time, and you should see the walls of the port clean up as well.
-again, use the shop vac to suction out the fluid
-now, insert a corner of a clean rag into the port. Use a screwdriver to gently advance the rag into the port until the inside walls of the port and the back of the valve is contacted by the rag. This will absorb any residual cleaning fluid and pick up any deposits that are left over. Remove the rag.
-use compressed air at 100psi and blow into the port. I used approx. 3 gallons of compressed air (about 45secs worth).
-at this point, the port should be clean. See picture above. Any residual oil/light brown spots can be picked up by an additional run with the rag stuffing.
-seal the clean port with tape again, and move onto the next port. Some may want to do multiple ports at a time due to multiple valves being closed, but I just worked on one at a time. This way, I could verify how many deposits there were by opening the valve, and then ensure complete valve sealing by closing it.
-This worked for me until the rearmost port on the passenger’s side. There is not enough room between it and the overhanging windshield cowl to allow the drill and attachment in. Also, it is so angulated that the only way to see inside is with the iPhone. For this port only, I doubled the dwell time and used each attachment/rod twice as I was using my fingers to spin the brushed by hand instead of a drill.
-Each port took me about 20mins once I got the hang of it. During the times that you are letting the initial sprays of cleaner dwell and clean, you can clean the air intake and intake manifold itself. I took this time to wash out the entire inside of intake tubing with intake cleaner, clean the MAF sensor with MAF safe cleaner, and clean throttle body as well.
-to clean the inside of the intake manifold, cut multiple strips of cloths (4.5in by 1 in) and make a hole towards one end of the strip. Attach the multiple strips onto the gun cleaning rod and sandwich them with a plastic attachment. Using this and the drill, insert this into the intake manifold ports and clean the inside. I used dry strips at first to see if there was oil in there, and then used a can of intake cleaner to spray inside the intake manifold and then used my attachment to spin it clean and dry. There was some fresh oil in the manifold, as well as a thin coat of old oil along the entire intake tube, throttle body, and inside the intake manifold.
-after everything is clean, and just before I was ready to install the intake manifold, I vacuumed again. I did this by untaping the ports sequentially from back to front and inserting the shop vac tube inside each one. DO NOT use compressed air at this point, as some valves are open and you can blow stuff into them.
-immediately install the intake manifold, taking care to install the driver’s rearward vacuum tube and reconnecting all connections. Keeping the manifold bolts taped/rubber banded up will help with the installation. Reconnect all the connectors, and torque per Theta’s guide in the specified pattern and the two passes with specified torques. BE AWARE that the torque is in INCH POUNDs, not foot pounds.
-reinstall air intake and covers, and also catch can/air separator if you have one.
-reconnect negative battery terminal. Ensure all tape/tools/equipment is removed from engine bay (I almost left the strap wrench on)
-Start the car, first start may be a little rough, my idle smoothed out within 3 seconds.
Last edited by A471133; 10-08-2015 at 03:06 PM.
Reason: update
He drove the car for 20-30mins after picking it up. After that, we did a complete engine oil and filter change. There should be minimal cleaning agent/dirty stuff that got past the valves if you took time to close each of them completely, but better safe than sorry. I would wait until you are pretty close to doing an oil change, so you can combine these two services.
Total time: 4.5 hrs with engine oil change
Beers consume: 5
I worked by myself in hot Texas heat. If you have someone helping you, it should not take as long. Please wear gloves, as the GM cleaner stuff smells like crap. Hope this helped someone. If you have any questions, please PM me. If enough people are interested, I can convert this to a PDF.
Last edited by A471133; 10-08-2015 at 03:15 PM.
Reason: update
My buddy took me out to lunch yesterday to return the favor. He swears he feels a better throttle response. Probably just his butt dyno and more likely a combo of placebo and the MAF/throttle body being cleaned for the first time. He is super OCD and just happy that everything is clean lol.
My buddy took me out to lunch yesterday to return the favor. He swears he feels a better throttle response. Probably just his butt dyno and more likely a combo of placebo and the MAF/throttle body being cleaned for the first time. He is super OCD and just happy that everything is clean lol.
One of the first symptoms of the deposits forming is a slight "lag" or hesitation in off idle throttle response. This is due to the velocity of the incoming air flow being the slowest at idle, and any disruption of the port/valve/seat/valve angles from the engineers design will show it'self. As the RPM's rise it is less evident due to the volume of air and the greater velocity. It is not until the deposits build to a greater level that peak power, drivability, and the random misfires begin to occur that can trigger a CEL. Also, the as you can see from your pictures, the deposits on the stem are pulled up into the guide with every cycle the valve makes, and this is wearing them out in short order (see "LS7" valve issues).
Here is a picture of my own C5 at 142,000 miles when I did heads/cam on it:
That is untouched, and I didn't always run top tier fuel. Unreal difference with GDI now. I am trying to get more owners to take their intake manifold off and document the miles at the time and take pictures so all can get an idea on the rate of this coking.
DISCLAIMER: This DIY guide has been put together using knowledge from various third party sources, and demonstrated on one vehicle. It is not endorsed or property of this forum or myself in any way/shape/form. This is simply more information for those who are curious about the cleaning process. Neither this forum nor myself are liable for any damages that are incurred as a result of using this guide. The end user (you) assume all risks to you/your car/your environment by using this guide. E.g. you take the risk of breaking your car/voiding your warranty by using this guide.
I also do not endorse any of the products used in this DIY, purely one man’s tools and opinions.
Now let’s get to it. I want to give thanks to the following as this would not have been possible without the information they provided:
Theta's excellent DIY guides in the stickies section.
RX for their videos showing their intake valve cleaning
coSPEED2 and other vendors for bringing this issue to light
user Wormwood for his advice/expertise as he had completed this before me
various other users and threads detailing the BMW “walnut shell cleaning”
The C7 Z51 is the second GDI (Gas direct injection) engine I have had. I previously had a VW that I completed a similar cleaning before. Knowing that, I immediately installed Elite Engineering’s clean oil separator and catch can upon picking up my car at the dealer last year. I also immediately drained all the oil and completed a new oil change and performed a cleaning of intake air tracts at that time. My C7 is a weekend car, and only very few miles and is not tracked. I used a boroscope a few months ago and confirmed that my intake valves were pretty clean and did not need a cleaning right now.
My friend bought his C7 Z51 shortly after I did. His was used and came with 6k miles. At the time he bought it, it did not have a catch can or oil separator installed, and records showed that it received the first oil change at around 1200 miles. He installed the same catch can and air separator shortly after buying the vehicle. He was worried about valve coking issue after reading several threads, and proceeded to our local Chevy dealer to inquire about induction cleaning service. When he talked to the service advisor, they looked at him if he had grown two heads. One of the techs said that they could spray a cleaner into the intake and clean it that way, but that he would be charged $400. My buddy at this point approached me for help.
There are differing opinions on how much this affects performance/efficiency and what type of cleaning is warranted, I am not hear to argue those issues. There are those who have just sprayed/poured cleaner into their manifold and then crank the engine. This type of cleaning causes me nightmares as I can see countless chunks/sludge and deposits making their way past the intake valves and into the chambers. I put together this DIY for those who wanted to know more about the process of cleaning the valves. This was done on my buddy’s 14 Z51, but I can see the same thing being applied to the wet sump engine as well.
You did an excellent job explaining AND showing how relatively easy this will be for a competent DIYer. The concern here is, after researching the issue on line(not just vette world), that GDI engines could really have problems early on. I now wonder if I should have kept my 12 C6 with 12k miles on it.
I also was able to glean some information from engineering types on this issue(on line blogs) Some have suggested that due to the extra heat that these engines can generate in their lean burn run cycle, if the oil is contaminated to any degree by fuel blow by and or water, that this will effect the vaporization point of the oil in the crankcase. This would lead to oil smoke in the PCV/EGR circuit earlier in the oil life cycle which appears to be the cause of this oil/sludge build up.
I wonder if changing the oil at 50% of the reccomended service interval will help alleviate this potentila REAL PROBLEM. If there are professionals who can address this to the forum, please chime in. Thanks again.
You did an excellent job explaining AND showing how relatively easy this will be for a competent DIYer. The concern here is, after researching the issue on line(not just vette world), that GDI engines could really have problems early on. I now wonder if I should have kept my 12 C6 with 12k miles on it.
I also was able to glean some information from engineering types on this issue(on line blogs) Some have suggested that due to the extra heat that these engines can generate in their lean burn run cycle, if the oil is contaminated to any degree by fuel blow by and or water, that this will effect the vaporization point of the oil in the crankcase. This would lead to oil smoke in the PCV/EGR circuit earlier in the oil life cycle which appears to be the cause of this oil/sludge build up.
I wonder if changing the oil at 50% of the reccomended service interval will help alleviate this potentila REAL PROBLEM. If there are professionals who can address this to the forum, please chime in. Thanks again.
Excellent points. The GDI has so many other advantages, but one thing is never use Dexos or any syn blend due to the heat. only a good full syn for oil. Oil wont make any difference as far as intake valves as long as it is full syn (conventional and blends do coke easier). And sludge is formed by any amount of conventional oil in these now.
Doing the cleaning should be before the installation of a proper GDI designed air/oil separating system like Elite Engineering's E2-X line or ColoradoSpeeds latest that actually stop the ingestion (vs most catchcans only trap a small amount of the total).
The issue is the wear to the valve guides that should be the concern if only cleaning periodically. The deposits begin as soon as the engine is run, and that wear will always be present if it is not stopped at the source. And then we have so many tanks/breathers/etc. that defeat all the other critical functions the PCV system provides. (The PCV system keeps the engine alive by removing all the damaging compounds from the combustion process before they cans settle and accumulate).
The flashing off you refer to the 2 systems made for these also prevents any of that from accumulating as they add a secondary evacuation suction source so at all times the crankcase is evacuated and these are removed while still in suspension.
EXCELLENT post! Mr. Stingray! Your thinking! If you want more on GDI I am a member of SAE (International Society of Automotive Engineers) and we have regular discussion on all of this. Just let me know & I can PM you more.
This method is how I cleaned my C7 valves the first time I did it. The second time I used the crushed walnut method. Good stuff..
Wanted to bump this back up for more to see. Excellent sticky!
Both procedures work well, and for those w/out access to the crushed walnut shell equipment, the OP really did a great job this way. Just make sure the cylinder your working on has the valve closed all the way so no debris can enter the cylinder.
I was going to spray some GM top engine cleaner into the PCV system to help clean up w/out the entire disassembly. Can anyone advise as to which hose you might spray the cleaner through for the best/safest results?
10-08-2015, 12:33 PM
DIY: LTI intake valve cleaning/cleaning deposits
Sticky please.
