Intake Valve Carbon Deposits

S

switz

Member
:
2008 Mazda5 GT 5-spd manual
Hi everyone.

I'm a current Mazda 5 owner and am hoping to upgrade to a SUV at some point in the future. I have been researching the pros and cons of direct injection (DI) system (the new SkyActive engines are all direct injection) and am discovering, to my horror, that in DI engines from Audi to BMW, and to even Ford, the intake valves are getting huge amounts of carbon deposits that needs to be physically removed every 40-100,000km at quite an expense to the owner!!!!! That is fine if you only keep your vehicle a short amount of time, but I keep mine for quite a while (my '08 5 currently has 429,000km with absolutely no engine problems yet, knock on wood!!!) and I am not interested in having the intake manifold removed every 40k to get the intake valves cleaned. It appears to be a DI problem. With no fuel spray on the backs of the intake valves to clean off any PCV vapors or oil leaking down the valve stem, deposits will form, no matter what you do. I've read that installing a a PVC canister to collect vapors (which will likely void the warranty) only slows down, but does not eliminate, the inevitable carbon build-up on the backs of the intake valves.

I'm sure Mazda is aware of this DI problem. My question is, does anyone here know what has Mazda done to eliminate this problem? I'm not interested in purchasing a vehicle with a DI engine knowing this is a problem.
 
Don't know if anybody has a fix but I would venture to say in a handful of years they'll all have it.
As far as warranty it all depends on the dealer and what fails. I have a catch can on my F150 and depending on the weather and how I drive the amount of crud caught varies but it's never a lot. Am I worries about voiding the warranty with it? No because the on part that changes costs about $30 to reverse and they won't be able to tell it was ever there. And since the warranty is shorter than the amount of time it takes for most to have the problem I'll be doing the work on it anyway.
Here is a pic of the stuff after 18k miles. Wish I could tell you what all four layers were, I do know one is gas and one oil.
02364f79-19f9-47bd-92fd-2fc4a687c8d3_zpskfd00yld.jpg
 
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Scott, you quote that "... in a handfull of years they'll all have it" .... well frick. Hopefully someone figures it out, or I'll be buying up old multi-point fuel injected vehicles until they're all gone off the planet before I get a direct-injection gasser.

Hmmm ... diesels are direct injected, have they had this problem all along as well? OMG :( I thought we were building better engines, not worse ones!
 
The real issue is oil filling up your intercooler ( look at 2011 f150s drill mod) where they drill the ic and oil drips out.

An oil catch can is 100ish and some 3/8 tubes are ~5 $

And it will save you tons of headache​ down the road.

I will install one in my 17 cx-9 gt in the coming week and i will post pix
 
Scott91370 said:
Wish I could tell you what all four layers were, I do know one is gas and one oil.
02364f79-19f9-47bd-92fd-2fc4a687c8d3_zpskfd00yld.jpg
Click to expand...

I would say that there only looks to be 3 layers, and that the water and fuel boundary zone is creating that middle "fluffy" between them, with the engine oil on the top. However from here it is a bit hard to truly ID without swirling a sniffing myself.

Have you ever thought about trying a Blackstone labs Oil Analysis? http://www.blackstone-labs.com/
 
switz said:
Hi everyone.

I'm a current Mazda 5 owner and am hoping to upgrade to a SUV at some point in the future. I have been researching the pros and cons of direct injection (DI) system (the new SkyActive engines are all direct injection) and am discovering, to my horror, that in DI engines from Audi to BMW, and to even Ford, the intake valves are getting huge amounts of carbon deposits that needs to be physically removed every 40-100,000km at quite an expense to the owner!!!!! That is fine if you only keep your vehicle a short amount of time, but I keep mine for quite a while (my '08 5 currently has 429,000km with absolutely no engine problems yet, knock on wood!!!) and I am not interested in having the intake manifold removed every 40k to get the intake valves cleaned. It appears to be a DI problem. With no fuel spray on the backs of the intake valves to clean off any PCV vapors or oil leaking down the valve stem, deposits will form, no matter what you do. I've read that installing a a PVC canister to collect vapors (which will likely void the warranty) only slows down, but does not eliminate, the inevitable carbon build-up on the backs of the intake valves.

I'm sure Mazda is aware of this DI problem. My question is, does anyone here know what has Mazda done to eliminate this problem? I'm not interested in purchasing a vehicle with a DI engine knowing this is a problem.
Click to expand...

I am currently driving a stock 2009 Mazdaspeed3 that is also turbo and Direct injected. For what it's worth, there is no issue with engine or valves at 283k miles and counting... (455,444.35 kilometers according to google)
 
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The carbon on the backs of the intake valves is design dependent. Not all DI engines had the problem. Try this...what's an older Mazda design with DI? Ask the dealership service writer their experience with this carbon build up and getting it cleaned. I think there will be no problem, certainly on the newest engines, and likely not on all older engines. I was speaking with a Kia service guy, and he said that they never did this, never had the need. I think you'll find the same thing with Mazda.
 
mazdadude said:
I would say that there only looks to be 3 layers, and that the water and fuel boundary zone is creating that middle "fluffy" between them, with the engine oil on the top. However from here it is a bit hard to truly ID without swirling a sniffing myself.

Have you ever thought about trying a Blackstone labs Oil Analysis? http://www.blackstone-labs.com/
Click to expand...
Yeah, I wasn't sure if the fluffy stuff was a boundry or an extra layer.

I haven't done an analysis, yet. I'm still one of those that change every 3500-4000 miles and I measure how much comes out. So far at my 18,500 mile change I'm still getting out close to the 5.5qts that goes in and I'm not seeing any other fluids - as much as can be seen by eye.
 
DI doesn't spray into the intake tract so none of the fuel (seafoam) hits the valves so it wouldn't help. You could spray so,e through the intake so it would though.
Also some engines are starting to co e with dual DI and regular injection so this could be the solution to deposits.
 
Ali 556 said:
The real issue is oil filling up your intercooler ( look at 2011 f150s drill mod) where they drill the ic and oil drips out.

An oil catch can is 100ish and some 3/8 tubes are ~5 $

And it will save you tons of headache​ down the road.

I will install one in my 17 cx-9 gt in the coming week and i will post pix
Click to expand...

Did you ever get it installed ? Looking to do the same, where did you get the catch can?
I'm looking to do the same
Thanks
 
Yep, got it on the 9 for a while now, got ny CC from amazon, just surch mishmoto catch can you will find it with the 50mic filter for ~119$

Small amount of oil was found in the CC, granted i only drove the car for ~300 miles since installation.
 
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