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Cleaning My Intake Valves (Semi DIY)


Tempe, Arizona
VW GTI MkV Fahrenhei
50,000 miles has come and gone. My idle has been odd and I get a lot of cold start misfires. More and more threads have been popping up about intake valve deposits and what to do about them. Unfortunately, no chemical will solve the problem and manual cleaning is the only way to get rid of them...for a short period until they return :mad:

Here is my experience of cleaning my intake valves. Big thanks to guilford32 for letting me use his heated garage when it was 40 and raining outside and staying up all damn night :thumbsup:

Parts required:
Intake Manifold Gasket -- 06F 129 717D
Injector Seal Kit** (read note below) -- 06D 998 907
Part MNXZ10 - 10 mm 12 Point Driver -- go here and scroll down:

Removing the intake manifold
This part is relatively straight forward. STaSIS has a very good document on how to remove it. You can get the document here.

**If an injector comes out with the manifold, you will need to reseal it. Follow the directions on the document, but you will need an injector seal kit and replace the teflon seal and blue o ring.

Cleaning your valves

This is what I was looking at before I began:

Looks like fun don't it, hehe

There are 4 metal "trays" as I call them in the hole for each cylinder. They should slide right out. Place them on a clean shop towel on the side and come back to them later. Keep them ordered so you know which one goes to which cylinder. Personally I dont think it matters, but it is better to be safe than sorry.

Here is what you all wanted to see: valve deposits. First some history about my car and what was done.

- Currently at 50,5xx miles.
- Water/methanol for 25k miles.
- Seafoam at 30,xxx miles.
- Car is driving hard-ish. I dont beat it, but I have my fun.

With all that said, this is what I found:










Cylinder 1 was the best and cylinder 4 was the worst as you can see. The valves were progressively worse as you went from #1 to #4.

Cleaning the valves

PUT TAPE OVER YOUR INJECTORS NOW!! If you do not, you risk clogging an injector with all the shit that comes out of the valves. Use painters tape as it leaves no residue. Cover the o ring and back of the injector in tape.

You will need to rotate the crank to close the cylinders. I ended up getting 3 closed and 1 was a tiny bit open. If you get a similar case, just clean the ones you can and tape up the one that is open. Once the others are finished, rotate the crank again. Having a friend look down the holes helps A LOT. To rotate the crank, there is a 19mm bolt on the crank pulley.

I had a set of picks I bought at harbor friend for a few dollars. I picked up some carb cleaner at Autozone for a few dollars. I carefully sprayed some carb cleaner on the valves. I was careful not to get that stuff on anything else. It is highly corrosive. My rubber gloves were being eaten by that stuff, no joke.

I let the carb cleaner soak for a few minutes and then went to work. It took about 20 minutes per valve. If you use picks, be very careful not to scratch anything. Do not scrape with the point, use the side of the hook. I used shop towels to get the liquid out. If you put too much carb cleaner in there, poke around at the carbon and get it off and let it sit for a while. The extra liquid will evaporate enough and turn everything into a paste which can be pulled out with the picks. Repeat the process for each valve.

This is about as good as you can get:


All other valves looked similar after being cleaned.

Once all the valves are cleaned, we need to clean the intake trays. Grab one at a time from where you placed them earlier. I used the side of a hook pick to scrape off the carbon, then sprayed it with carb cleaner and wiped off all remaining carbon.

Currently scraping off carbon

Before and after

Now that everything has been cleaned, I wanted to take a look at my throttle body to asses if it needed cleaning. I thought, "surely if the valves are this dirty, the throttle body would be similarly dirty" Boy was I wrong, partly.

Unfortunately, no dealer in the area had a throttle body gasket. This limited me to not being able to actually remove the throttle body from the intake manifold/fuel rail assembly (pictured below).

Intake manifold/fuel rail assembly

The side pointing away from the valves is SPOTLESS :happyanim:

Unfortunately, I will never know how the other side was. The butterfly valve didnt want to move and I didnt want to force it in fear of breaking it. Throttle bodies arent what we call cheap.

Along with cleaning the valves, I had some very sexy black billet aluminum bits to install:

Reassembling the intake manifold
Follow the STaSIS document backwards. Be very meticulous and only plug in sensors in the reverse order of the document. This way will guarantee you plug back in all the sensor. Last thing you want is to try turning on the car with no fuel pressure sensor or something hard to get to like that.

Turning the bitch back on
This was scary. Since the entire fuel system, more or less, was depressurized, it needed to be primed again. To do this, simply open the driver door, wait 5 seconds, close the driver door. Do this a few times. Now get in the car, put your key in, turn to accessories, DO NOT START THE CAR, wait a 5 seconds, pull key out. Do this a few times.

Not that the fuel system is primed and ready to go, turn on the car while having your foot partly on the gas. If reassembled everything correctly, the car will start and probably struggle. Dont be alarmed if it takes a few tries to get it started. Just do not hold the key in the on position and let it crank for too long. If it doesnt start within a few seconds, it probably wont. Use your judgement.

Let the car FULLY warm up. Rev the motor a bit, say up to 2000-2500 rpm. You might get some misfires. If you do, just wait them out unless there is an obscene amount of them. I had 40 misfires on cyl 4 when I first revved it. I turned off the car, turned it back on, and no more misfires.

Go and test drive the car. Be very careful and listen for anything that sounds off.

If I know you personally, and you ask me to clean your valves, I will laugh in your face and say short of a few hundred dollars, your valves will remain dirty. This job was a pain in the ass. My back really hurts and I am tired. The job took 10 hours from start to finish.

I am reserving my judgement in regards to the cold start misfires and rough idle for a few more days. It hasnt even been 24 hours yet, so I cant really say if there has been an improvement. At the very least I will have gained a lot of knowledge about this motor and taking it all apart. I will update this once I know.
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Tempe, Arizona
VW GTI MkV Fahrenhei
Longest night of my LIFE!!!!! You can never use my garage again!!!! lol
:bellyroll: Yea dude, I wasnt expecting 10 hours. I dont even remember my drive home. I cant thank you enough for letting me use it though, doing this outside in the cold rain would have SUCKED.


Go Kart Champion
Very nice.
Thanks to you and guilford32 (for letting you use the garage).

Looks like you did some work there. Good news is with the race can installed you wont have to do that again :smile:
I just installed BSH "race" catch can. Everything went fine except one thing.
The plug/nipple that screws on to the PCV plate, does it need to be screwed in ALL the way? I have about 3~4 threads left and it doesn't really go in anymore.


Ready to race!
Miami, FL
Seems like the valves became progressively worse from Cyl 1 thru 4, could it be because Cyl 4 is closest to the OEM PCV return into the manifold.

How long have you had your catch-can?


Go Kart Champion
Columbia, SC
Seems like the valves became progressively worse from Cyl 1 thru 4, could it be because Cyl 4 is closest to the OEM PCV return into the manifold.
This is correct. :thumbsup:

Staulkor, nice write-up man! I've contemplated doing this myself, but just too lazy to take the time. Kudos to you sir. :clap:


Corona, Ca
what else...
sweet write up bro. I've been planning to do this when I get the catch can setup so I can start fresh. It's a good thing I got a friend in parts at the Vdub dealership whenever I need a part just like the gasket for the manifold. Plus I'm fast approaching 50k as well and currently at 46k. It's crazy with all this maintenance at the same time. I'm going to do my DSG flush, then I got the oil change coming up and planning to change out the plugs at 50k as well. Hopefully I wont have to do this again before the car is paid off. sheesh.

2006 GTI
I see that you only cleaned 8 of your valves, is that correct?? becuase i could have sworn we have 4 valves per cylinder.
No, we have a revised version of the 1.8L 8V used in the MKIIs. :rolleyes:

I wonder how much of these deposits that made it past the intake valves were 100% consumed during combustion.


Tempe, Arizona
VW GTI MkV Fahrenhei
unless you want to remove the exhaust manifold and clean the exhaust valves.. :cool:

That and exhaust valves dont get build up. They get so bloody hot they burn everything off. A cool thing about them is the exhaust valves are filled with sodium that liquefies when hot and circulates through the valve stem dissipating the heat into the cylinder head. It is a pretty neat system.