Carbon'd up valves

[MyFirstZ]

Good'ol BMW

This is coming out of a BMW 335xi, intake valves. The 335xi is the twin turbo 6cyl. this engine has tons of fuel issues and turbo issues. One of the cars I warn people about owning outside of warranty.

This car is getting a head for other reasons but I need to swap everything over and decided to show you guys some carbon build up that you will probably never see like this.

Car has 98k miles and has always been on time for schedules maintainence.
Exhaust valves are spotless.

I will soak these vavles in a combo of fuel system cleaners over night then take a soft wire brush to them before I lap them for the new head.

BTW this repair is about 12-14k $ out of pocket for a customer. This customer is getting lucky and its being goodwilled

one of the two from cylinder 6 intake valve
This is after a few hours sitting in my concentrate and a light cleaning for those that aren't sure what they shoud look like

Rushed the process, but all clean now


a few other from bank 2 (cylinder 4 5 6)


A combo of carbon scrapped off from the 12 valves before soaking in some fuel rail cleaner and fuel system concoction that I make to clean valves.


Newly added






Good for flow right ?

[Anti_Rice_Guy]

Good lord, what was the reasoning behind the excess carbon buildup?

[WildBillyT]

Holy crap. Did corporate say anything about it?

[MyFirstZ]

Haven't seen anything officially released yet but they definetly know about it. We have fixes for it without pulling the heads. But this one I can clean since its getting a new head anyway.

[The_Bishop]

Probably a good PM for something problematic like this is MMO in the tank at every fillup. Better still would be the factory owning up to a crap design that lets oil down the guides. Poor valve seal design is my guess.

Also: Good inexpensive cleaner for something like that? Knock off the big stuff and soak overnight in Pine Sol. You can also wire wheel that stuff off without hurting anything.

Edit -Forget the MMO, just remembered that this is a direct injection setup. MMO won't help. Still say it's a guide seal issue made worse due to the fact that you don't have fuel washing down the back of the valve.

[Stevoone]

Do BMW engines use direct injection? GM was/is having similar issues and from what I've heard it is caused by the Direct Injection setup. A normal fuel injection service that runs chemicals through the rail and injectors will not clean the the valves on a direct inject engine because the fuel gets sprayed straight into the cylinder and not past the valves.

[Mark B]

Doesnt going WOT from time to time keep this from happening? I utilize this method on all of my cars. lol

[MyFirstZ]

Yeah these motors are direct injection so anything introduced into the fuel will bypass the valves. I don't know if it is valve seals or just oil consumption through the turbos (excess crank case)

[The_Bishop]

From a little research, it seems to be a combination of factors. You have oil getting down the guides, which in small amounts is unavoidable/necessary for lubrication of the guides. You also have oil in the crankcase vent vapors.

These aren't cheap cars, and having to shell out a couple hundred bucks every 20k-30k miles to clean it up would piss me right off.

[Jersey Mike]

How do you always end up doing carbon cleanings on heads?


That's night & day, man!

[MyFirstZ]

Alot of oil in the crankcase vapors and when the oil seperator is in the valve cover and very difficult to know when it fails.

To top it off the previous dealer he went to said his consumption was normal. But it was due to excess crank case pressure from the seperator failing. So its getting a new valve cover to aid that along with new valve seals. The car will be a top whens its done.

Never seen one motor with so many and such costly problems

HA couple hundred ! Most of it would be covered under warranty to remove the intake and blast em

But its probably closer to a grand minimum to blast em customer pay.

[The_Bishop]

A grand? That would result the car being placed back in the dealer showroom via the front windows. What a POS.

[maroman88]

mother of godddd

[MyFirstZ]

labor @ 150$/hr adds up very quickly

[DaSkinnyGuy]

Son, that right there is job security.

[Blacdout96]

Mini coopers with the d.I engines are having the exact same problem.

[MyFirstZ]

probably identical components and system

[sweetbmxrider]

Not bad....

[198esp1]

toyota had the same issue on 88-92 tercels, they would carbon up a little worse than the one valve you pictured. That recall paid for my first house

[Grifter]

Geeeeeez. Cadillac isn't any better...

[The_Bishop]

What? Isn't that the special canted valve performance option?

[V]

was that the early cadillac 3.6 with bad timing chain?

[Stevoone]

I pulled bent valves like that out of a NorthStar with 12k miles. I also had a 3.6 with a shattered valve, blew a hole straight through the piston. I wanted to tear it apart to get a better look but GM wanted it back untouched.

Only valves I've seen loaded with carbon have been on the DI engines. IMO the gasoline flow on a normal engine helps keep the valves clean. I also think it has something to do with the VVT exhaust scavenging in place of a conventional egr system

[DaSkinnyGuy]

Is any of the fuel problems because of the ethanol used in our gasoline?

[Z28 Heritage]

Originally Posted by Stevoone

I pulled bent valves like that out of a NorthStar with 12k miles. I also had a 3.6 with a shattered valve, blew a hole straight through the piston. I wanted to tear it apart to get a better look but GM wanted it back untouched.

Only valves I've seen loaded with carbon have been on the DI engines. IMO the gasoline flow on a normal engine helps keep the valves clean. I also think it has something to do with the VVT exhaust scavenging in place of a conventional egr system

Good old Northstar hating haha its a great motor but with piss poor problems.