Oil on intake valves - 2008 GTS DFI 4.8 V8
03-07-2017, 07:43 PM
#1
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Oil on intake valves - 2008 GTS DFI 4.8 V8
My intake manifold is off. I am replacing the coolant temperature sensor.
There is oil all over the intake and inside various vacuum lines.
There is also oil caked all over the intake valves.
Should I try and clean the stuff on the valves? Any advice?
It is really hard to reach in there...
I know that some it is to be expected on DFI engines, but it sure looks like a lot:-(
My cayenne only has 100000km.
There is oil all over the intake and inside various vacuum lines.
There is also oil caked all over the intake valves.
Should I try and clean the stuff on the valves? Any advice?
It is really hard to reach in there...
I know that some it is to be expected on DFI engines, but it sure looks like a lot:-(
My cayenne only has 100000km.
03-07-2017, 07:53 PM
#2
Three Wheelin'
Direct injection sucks for carbon buildup...Manufacturers need to figure this out but it usually doesn't screw stuff up until after warranty so my guess is nobody will do anything about it...
03-08-2017, 02:00 AM
#3
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CaptGSR - I'd suggest they need cleaning. It's not a simple 5 minute job.
What is sometimes done, in the absence of walnut shell blasting (old BMW way also adopted by some other euro mfgs) - for the DIY guy - is making certain the cylinder valves are both closed - then soaking the area in some solvent (probably something like Techron would help - or some spray product meant to remove carbon from piston crowns when an engine is opened up..) then gently scraping the valves and area with a strong plastic scraper and vacuuming out the remains.
Ugly job. Your vehicle will run better after that's done. You may want to check that the oil separator is intact and working. It does look a bit wet in your photos which could be oil not being separated out and returned to the crankcase.
03-08-2017, 01:54 PM
#4
Some shops have equipment specifically designed to remove "upstream" deposits like these, safely. Unfortunately, I can't recall the name of the equipment and a quick Google search only seems to turn up DIY "solutions"... though some of the DIY solutions (water, CRC Intake Cleaner, or Sea Foam) where before and after pics are posted look convincing, it's hard to know if the photos are real or not. They run the fully assembled engine to remove the deposits. I would never EVER put any kind of chemical in the intake runner with the cylinder head still mounted on the block. Any amount of leakage (could be drops, a drip, a dribble, or no leakage at all) past a valve will go right onto a piston. You can only do this when a valve is fully closed and that can be tricky to determine when looking through the intake runner in the head. If you decide a valve is closed and it's not quite closed, you could flood a cylinder with whatever you use as your "cleaner". That makes the DIY procedure where you suck the cleaner (water, CRC Intake Cleaner, or Sea Foam are mentioned most often) into the throttle body. Speaking of throttle body... those can get sticky around the butterfly causing a sticky feel to the accelerator pedal (assuming you still have a cable from the pedal to the intake system) because varnish seems to collect around that area once you have fairly high miles (circa 100,000 or more). So cleaning the inside of the throttle body can make cable-operated throttles feel better also (especially in the transition from idle to anything above idle).
There appears to be a patent addressing the issue of carbon in DFI engines ("they all do that")... it requires vehicles with valve control systems that can intentionally prevent a valve from fully closing on a compression stroke so some fuel mixture is pushed back into the intake passage (behind the valve), and that immediately gets sucked back into the cylinder on the next intake stroke. This system kicks in during periods of "cruising" with small steady throttle opening, cleaning the backs of valves and intake runners while driving with nothing more than the gas from your tank. Sounds like it cold be effective, but who knows if anybody is actually USING that means of keeping the valves cleaner.
There appears to be a patent addressing the issue of carbon in DFI engines ("they all do that")... it requires vehicles with valve control systems that can intentionally prevent a valve from fully closing on a compression stroke so some fuel mixture is pushed back into the intake passage (behind the valve), and that immediately gets sucked back into the cylinder on the next intake stroke. This system kicks in during periods of "cruising" with small steady throttle opening, cleaning the backs of valves and intake runners while driving with nothing more than the gas from your tank. Sounds like it cold be effective, but who knows if anybody is actually USING that means of keeping the valves cleaner.
03-08-2017, 10:39 PM
#6
I just finished using the CRC GDI cleaner on my wife's Q7 with 80K miles and it made an incredible difference. It starts faster and idles and accelerates so much smoother. I plan on using this on the 957 this weekend weather permitting.
03-09-2017, 12:03 PM
#7
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I asked the local dealer today. They pretty much told me to live with it...
How do you introduce the cleaner into the intake? Vacuum system, via what looks like a Brake booster line? (small line that comes out of the front side of the intake manifold, bottom right when facing the car)
How do you introduce the cleaner into the intake? Vacuum system, via what looks like a Brake booster line? (small line that comes out of the front side of the intake manifold, bottom right when facing the car)
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03-09-2017, 12:58 PM
#8
You spray the cleaner into the intake after the MAF. I plan on loosening the clamp right in front of the throttle body since there are 2 air intakes that go into one. Hopefully I can fit the straw in between the 2 fittings as I did on the Q7. There are a lot of YouTube videos on the application and instructions on CRC's website. I may try a can and a half since this is a 4.8L and a can will also do cars less than 2 liters.
03-09-2017, 06:19 PM
#10
I am interested in this as well but for a 955 CTT.
From my prior Audi experience, Seafoam was the go to. I am hesitant to try it on the CTT given how sensitive these P!Gs seem to be.
From my prior Audi experience, Seafoam was the go to. I am hesitant to try it on the CTT given how sensitive these P!Gs seem to be.
03-10-2017, 11:24 AM
#12
I did this last night. I wrapped a plastic bag around the intake and throttle body to keep a seal as not to confuse the engine by bypassing the MAFs. I also wanted to point the straw into the throttle body instead of relying on the airflow to draw it in and have the CRC spray run down in the intake to the air filters since they run downhill. My observations so far after a couple of drives. The idle is smoother, acceleration appears to be more responsive, it seems to coast better (not sure why this would change things or if it just my imagination), when I stomped on it on the freeway this morning, it felt like it pushed me back in my seat which I have not felt before. These are all just my feelings with no real way to verify. Could just be a placebo affect but I really don't think it is. I filled up my tank last night after I did an Italian tuneup to try to clear the rest of the carbon out per the instructions. I will report back to let you know my MPG observations as this is really the only measurable result I can do now. I typically calculate 14.5 mpgs. Looking back, I guess I could have done some runs up to 70mph while taking a video to time it and compare.
03-11-2017, 09:04 AM
#14
They say one can no matter what size and you spray in short bursts. You run the car at 2000 RPMs. I put a piece of wood between the front of the seat bottom and the accelerator and adjusted the seat until it was reving at 2000.
Details including before and after claims here: http://crcindustries.com/gdi/#howtouse
Details including before and after claims here: http://crcindustries.com/gdi/#howtouse
03-11-2017, 10:51 AM
#15
The V8 Porschephile
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