Carboned Up Intake Valves

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Carboned Up Intake Valves

Post by Minidave »

A number of people have had this issue, it seems to plague direct injection engines no matter who makes 'em. Corvette is introducing a direct injected engine in next years 'Vette and they went to great lengths to make sure they would not have this problem in their engine by using special scrubbers in the positive crankcase ventilation system. However, those of us with current direct injection engines are not so lucky.

It seems the problem is with the inherent design - in normally injected engines the gasoline is sprayed right at the back of the intake valve, washing any oil vapors off and into the combustion chamber. In direct injected engines the fuel is sprayed right into the combustion chamber itself - after the valves, so you don't get that cleaning effect. Introducing PCV vapors into the intake leaves a nice coating of oil on the valves, the stems and the intake port walls, where it accumulates over time and mileage restricting the port and causing poor running, hesitation, power loss and worsening fuel mileage. 1st gen MINIs do not have this issue because they are not direct injected engines.

I did a little looking into my intake today and sure enough, mine are coked up something fierce. Fortunately my car is still under warranty so Baron is going to take care of it for me (Yay Baron!) The repair is fairly simple, they remove the intake manifold and install a specially made tube into the intake port, making sure the intake valves are closed. A wand goes into this device and blasts the port and valves with crushed walnut shells, a shop vac removes the carbon and shell debris at the same time leaving the valves and ports clean as they were when new. I understand that the results can be felt the first time you start the engine and drive away! This is not a new process, BTW. Audi has been doing this in their engines since the 90's, although I understand their problem was due to poor valve stem seals rather than PCV vapors, and those engines are not direct injected. BMW is having the same problems and in fact the machine and cleaning process was adapted for their engines first.

I have a sand blaster and shop vac, all I would need to do is develope or buy the port adaptor and the walnut shell media and the next time mine get coked up have at them since by the next time I'll need the service I'll be well out of the warranty period. I'm hoping MINI will come up with some sort of separator to keep the oil vapors out of the ports and off the valves, my understanding is the aftermarket devices (catch cans and such) do not really do the trick so if they don't I'm planning on this being an every 30K or 40K process.

I took a video of my ports but as of right now You Tube is not letting me upload it, if they do I'll post the link so you all can see what they look like.

If you have a 40K mile or more direct injected MINI, this is something you should plan for in your maintenance regime. If you're still under warranty, the key symptoms to requiring this service are hesitation, poor running and worsening fuel mileage, just FYI.
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Re: Carboned Up Intake Valves

Post by Zack »

You have me worried now lol. My car is older. I had bought an Alta oil catch can buy decided I didn't need it and sold it as well.
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Re: Carboned Up Intake Valves

Post by Minidave »

Minidave wrote: It seems the problem is with the inherent design - in normally injected engines the gasoline is sprayed right at the back of the intake valve, washing any oil vapors off and into the combustion chamber. In direct injected engines the fuel is sprayed right into the combustion chamber itself - after the valves, so you don't get that cleaning effect. Introducing PCV vapors into the intake leaves a nice coating of oil on the valves, the stems and the intake port walls, where it accumulates over time and mileage restricting the port and causing poor running, hesitation, power loss and worsening fuel mileage. 1st gen MINIs do not have this issue because they are not direct injected engines.
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Re: Carboned Up Intake Valves

Post by Clubby Clutch »

Zach, your car is 1st gen...


Minidave, does this issue only apply to 'S' engines?
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Re: Carboned Up Intake Valves

Post by Minidave »

It applies to ALL direct injected engines, period.......however the S models seem to carbon up faster.

With the possible exception of the new Corvette small block coming next year, where they specifically designed those PCV scrubbers to keep all oil vapor out of the intake. However, I'll bet those scrubbers are a periodic maintenance item too.
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Re: Carboned Up Intake Valves

Post by Zack »

Clubby Clutch wrote:Zach, your car is 1st gen...


Minidave, does this issue only apply to 'S' engines?
Oh ok. I'm good then :)
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Re: Carboned Up Intake Valves

Post by boxer »

Nice write up Dave. I have been reading about this for quite some time. The only thing I would add if this is to be a shop/garage repair in the future is that people should purchase a new intake gasket for reassembly. Look forward to seeing the video. i guess this is one reason to own a rattle trap first generation MINI. :ds:
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Re: Carboned Up Intake Valves

Post by Minidave »

The manifold is plastic on the second gens, and it's sealed to the head by o-rings, you might be able to re-use them as they don;t get damaged on removal - but, it never hurts to play it safe for the cost of a few o-rings.

I think there are trade offs for either car, they both have their negative "features" :)

Here's a link to a You Tube vid on how they do it....

http://www.youtube.com/watch?v=R-HlWELr ... r_embedded
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Re: Carboned Up Intake Valves

Post by Clubby Clutch »

Could you pull the head off then run each valve around a wire wheel and get them squeaky clean and while the head comes off you could use sodium bicarbonate (baking soda) to soda blast the head clead. It could be a PITA but just a thought.

If you have the head off, why not align your spark plugs with the intake valves :lol:
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Re: Carboned Up Intake Valves

Post by Minidave »

I know indexing your plugs is a fave of the drag racing set, but for a street driven car...........nah.......

Pulling the head is a lot of extra work when all that needs to be done is to clean the intake ports and intake valves - not to mention the "fun" of getting the valves timed right again. But yes, you could wire brush the valves clean - were you talkling about removing them from the head or simply wire brushing them in place? Cause doing it in place would be difficult at best, and again removing them from the head is a lot of extra work.

Another interesting way of cleaning the ports and valves is to blast them with dry ice - it works very much like walnut shells, only it leaves nothing behind besides the carbon that you would simply blast out with compressed air after knocking it loose. I think the walnut shell setup is actually the best, cheapest and easiest way to do this job. Like I said, Audi's been doing them this way since the early to mid 90's.

I'm going to let Baron have at it this time, but the next time it will be out of warranty so it'll be on me, I'm just planning ahead.

I may have accidentally fixed a really annoying buzz/rattle I've had for quite a while. Country Bob gave me a "noise maker eliminator" kit and I finally installed it a couple of days ago, no buzz/rattle since. Wonder if that's all it was? However, I can't tell any difference in the "noise" of the engine FWIW.
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Re: Carboned Up Intake Valves

Post by Counterfit_Mini »

I tried to get Baron to clean the valves before my warranty was up but they said it didn't need it (I'm sure they didn't look either). I'm at 60,000 miles right now and can definitely feel a lack of power and the gas mileage is about 27 mpg.
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Re: Carboned Up Intake Valves

Post by Minidave »

Yes, you have to give them the appropriate complaint for them to get MINI to pay for it, poor mileage, hard starting, hesitation and lack of power are the key words, just FYI.

In my case I offered to send them the video and pics, but they said it wasn't necessary. Once they pull the manifold off they can see for themselves, but there's really no other way to know for sure till you pull the intake off.

I also took the opportunity to replace the air filter, which was definitely due!
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Re: Carboned Up Intake Valves

Post by Counterfit_Mini »

I asked them a couple months ago how much the service costs without warranty an they said about $800. :shock:
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Re: Carboned Up Intake Valves

Post by Minidave »

Yep, $800 is the number I heard too......

My vid is finally up, it's a bit dark, but if you look you can clearly see the valves and how coked up they are, the date on the vid is not right, it had not been set up yet in the recorder.

https://www.youtube.com/watch?v=yXchTCk ... ature=plcp
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Re: Carboned Up Intake Valves

Post by Clubby Clutch »

How hard was it to get the intake manifold off? I am curious to peek at my valves if I get some free time.
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Re: Carboned Up Intake Valves

Post by Minidave »

I didn't take mine off, I merely pushed it back far enough to get the camera wand in so I could vid the valves, however to answer your question it was pretty easy, and on a non-turbo car it should be even easier.

Quick update......my car hasn't thrown a code, and unless it does (and the right one obviously) MINI won't pay to do the repair, so they didn't do it.

I found a part number for the port adaptor and ordered it, so in a couple of weeks I'll have the ability to do my own. I got the last one in the states according to the computer! Score! :mrgreen:
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Re: Carboned Up Intake Valves

Post by GrayGuy »

I have a sand blaster and shop vac, all I would need to do is develope or buy the port adaptor and the walnut shell media and the next time mine get coked up have at them since by the next time I'll need the service I'll be well out of the warranty period.
I have about 10 pounds of walnut shell I'll donate to the cause. I think it's 12/20 which should be very easy for the pick-up to blast. Let me know when it might be needed I'll make sure it's available.
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Re: Carboned Up Intake Valves

Post by Clubby Clutch »

Bare with me for a second...

Would it be possible to use dry ice blasting to clean up the valves. The idea behind it is that only the carbon bits are left behind and no walnut shells?
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Re: Carboned Up Intake Valves

Post by Minidave »

Sure, but you have to vacuum or blow the loosened carbon out somehow, when you do that with the shell blaster the walnut shells come out with the carbon, it's not like you leave them behind.

The difference to me is the cost of the apparatus, I'll have less than $200 invested in mine including a bag of shells, what would it cost to get/use a dry ice blaster, and who the heck would you get it from?

But the theory is the same, and the work required would be about the same.

And I'm not going to get bare with you, tho I will bear with you while we discuss your theory..... :D
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Re: Carboned Up Intake Valves

Post by Minidave »

So I picked up the port adaptor Wed, I tried to buy a small pressure pot blaster from Harbor Freight, but they were out of them so that part will have to wait a bit. I could use my open type sandblaster, but I like the idea of making up a dedicated set up for this job.

In the pics you can see the end that fits into the port, it doesn't need to be sealed as the volume of air from the shop vac will keep it firmly in place, and you need a little air bleed to help move the debris thru the device. Same with the hole where the blast wand will fit in - that's the only part of the tool I haven;t designed yet, I thought I'd wait to see what the blaster comes with first, but I imagine it will just be a piece of brake line bent into a J shape. the key is to be able to move it all around so that it can blast all the nooks and crannies, and hopefully around the back of the valves too.
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Re: Carboned Up Intake Valves

Post by Punk_Mini »

Something that kills two birds with one stone is Methanol injection. It keeps everything very clean all the while adding 20+hp tuned.
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Re: Carboned Up Intake Valves

Post by Minidave »

Does it clean the intake valves on a direct injection engine?

Seems like it would take a lot of methanol to do that, so then you're paying for all that extra juice.....
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Re: Carboned Up Intake Valves

Post by Sspreso »

You don't run pure Methanol in the setup. I run a 40% blend and average using 1.5 gallons of methanol a month. The steam cleaning effect of the water+meth blend helps keep everything nice and tidy.
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Re: Carboned Up Intake Valves

Post by Minidave »

Yes, but where is it introduced, before the turbo?
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Re: Carboned Up Intake Valves

Post by Sspreso »

Standard street setup is after the intercooler in the plastic intake pipe that connects (eventually) to the throttle body. I've read about racing setups that did both before and after turbo.
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