Direct Injection = Carbon Buildup?
Evidently from the buildup of oil residue from the PCV system since there is no longer a fuel there to act as a constant solvent. I was completely unaware of this, having owned a335i in the past that ran awesome even as the mileage got high. I based my opinion completely anecdotally and stand corrected.
Evidently from the buildup of oil residue from the PCV system since there is no longer a fuel there to act as a constant solvent. I was completely unaware of this, having owned a335i in the past that ran awesome even as the mileage got high. I based my opinion completely anecdotally and stand corrected.
My LS2 intake would be dripping with oil before I installed the catch-can, although the port injection did keep the intake valves clean. In the 20k miles since I've installed the catch-can, I haven't seen a single drop of oil in the intake manifold...it's bone dry.
But wouldn't a simple properly setup catch-can solve this issue completely even on a direct injected engine?
My LS2 intake would be dripping with oil before I installed the catch-can, although the port injection did keep the intake valves clean. In the 20k miles since I've installed the catch-can, I haven't seen a single drop of oil in the intake manifold...it's bone dry.
My LS2 intake would be dripping with oil before I installed the catch-can, although the port injection did keep the intake valves clean. In the 20k miles since I've installed the catch-can, I haven't seen a single drop of oil in the intake manifold...it's bone dry.
I think BG addressed that pretty well and said the machining problem was on a single batch of parts from an outsourced company. That kind of issue doesn't show up in testing and every manufacturer has to deal with it. A widespread problem like BMW's DI carbon build up is a different kind of animal...
Not when engineers are breaking new ground or aggressively pioneering. In this case, others led the way, exposed the issue, and the engineers following have the opportunity to specifically address it.
If anything, I'd be more worried about problems no one has seen before.
Not when engineers are breaking new ground or aggressively pioneering. In this case, others led the way, exposed the issue, and the engineers following have the opportunity to specifically address it.
If anything, I'd be more worried about problems no one has seen before.
The facts are the admission from GM is that the problem started in 2008 and was fixed by the 2011 model year. IMO, BG's statements are not 100% accurate on the matter.
2. I hope that you are right. Unfortunately, the truth behind all of it is that the auto manufactures are in it to SELL CARS and if the bean counters don't think a certain move makes sense, no matter how much the engineers think its important well... things get put on the shelf until someone can get around to it. Most unfortunate really... but it is what it is.
Evidently from the buildup of oil residue from the PCV system since there is no longer a fuel there to act as a constant solvent. I was completely unaware of this, having owned a 335i in the past that ran awesome even as the mileage got high. I based my opinion completely anecdotally and stand corrected.
That is the part that kills me... the manufacture(s) KNOW this is an issue however they continue to produce a "flawed" product and fix it by maintaining the flaw under warranty. At the end of the day it costs less to maintain the engines under warranty with some solvents and service hours, maybe throw in a few pistons and rings vs redoing an engine and addressing the real problem.
That is the part that kills me... the manufacture(s) KNOW this is an issue however they continue to produce a "flawed" product and fix it by maintaining the flaw under warranty. At the end of the day it costs less to maintain the engines under warranty with some solvents and service hours, maybe throw in a few pistons and rings vs redoing an engine and addressing the real problem.
My brother has a 335 and can't even get their Factory Service Manual. They treat it like some kind of top secret document and the dealers (we were told) are instructed to shred them when they no longer need them.
The 2006+ VW GTI has this exact problem and there are a lot of those cars out there. From what I have read on the VW forums a catch can doesn't solve the problem. Its been said that the deposits are also from the accumulation of oil that slips past the valve guide seals.
Makes sense to me since no valve guide seal is going to seal perfectly, and small amounts slip past whenever the car is running, and probably the most when the intake manifold is seeing high vacuum.
Makes sense to me since no valve guide seal is going to seal perfectly, and small amounts slip past whenever the car is running, and probably the most when the intake manifold is seeing high vacuum.
Makes sense to me since no valve guide seal is going to seal perfectly, and small amounts slip past whenever the car is running, and probably the most when the intake manifold is seeing high vacuum.
Either way, I personally believe that a healthy engine (one that does not have oil seep from these random seals) with a catch-can will be pretty much sludge free. Yes other issues can come up and cause such buildup, but then again these issues can happen on any engine even port injected ones like the gen 3/4 LS engines. The port fuel injection only really help keep the intake valve clean...anywhere else is open to sludge buildup in these cases where seals are busted for oil to seep in.
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On The Tree
Joined: Jan 2004
Posts: 179
Likes: 3
From: Warsaw , Ohio
Used to see deposits like this all the time back in the 60's-70's even into the 80's , seemed to go away with Port Injection. But the detergents in Gasoline probably had more to do with it. Back then anytime You did a valve job You had to bust off the carbon and coke with a chipping hammer and clean the rest of it off with a wire wheel. Sometimes it was so bad , you'd wonder how it even ran at all. I'm sure some of the other Oldtimers on here remember this.
Used to see deposits like this all the time back in the 60's-70's even into the 80's , seemed to go away with Port Injection. But the detergents in Gasoline probably had more to do with it. Back then anytime You did a valve job You had to bust off the carbon and coke with a chipping hammer and clean the rest of it off with a wire wheel. Sometimes it was so bad , you'd wonder how it even ran at all. I'm sure some of the other Oldtimers on here remember this.
Im assuming these were engines with carbs right? The intake tract was seeing fuel however you had carbon build. Perhaps todays fuels do a better job at cleaning engine parts however removing the fuel before the valve will take all those advantages away.
Another interesting thing that I ran into was talks about the OIL itself being used and it having more or less of a viscosity "thingy" which results in more or less carbon buildup. I have to find the source to be certain however what is notable to mention is that the new LT1, at least not in the corvette will NOT run traditional mobil 1 syn oil. I wonder if the new oil has better properties that aid in not generating carbon buildup?
This is a really great point. If there's no solvents running over the valves, they could easily collect crud that gets to them. I wonder if GM will have special procedures/tools to do top end cleaning for this engine? (All the methods I'm familiar with involve hooking up to the fuel rails or dumping chemicals in the fuel tank.)
On The Tree
Joined: Jan 2004
Posts: 179
Likes: 3
From: Warsaw , Ohio
I think that most of the problem was the Fuel itself , it would leave gummy deposits in the fuel bowls and passages of Carburetors, PCV systems sucking up oil , EGR ,and Some of the problem was from oil that would run down the intake guides , compounded by the lack of detergents in fuel = carboned up Intake ports along with deposits cooked on the back of the Intake Valve.
In 84 - 86 I worked for Oldsmobile and We cleaned cloged Injectors on the Port Fuel 3.0 & 3.8 frequently. The problem seemed to go away all by itself part way thru the 86 model year. We found out it wasn't magic just the oil companys adding a better detergent package.
As far as this problem happening to the new LT1 I aint gonna worry about it . Big Guns and His team sound like they REALLY know what They are doing , besides it aint the 70's,or 80's, when the Customer did the durability testing.
In 84 - 86 I worked for Oldsmobile and We cleaned cloged Injectors on the Port Fuel 3.0 & 3.8 frequently. The problem seemed to go away all by itself part way thru the 86 model year. We found out it wasn't magic just the oil companys adding a better detergent package.
As far as this problem happening to the new LT1 I aint gonna worry about it . Big Guns and His team sound like they REALLY know what They are doing , besides it aint the 70's,or 80's, when the Customer did the durability testing.
If the system is routed elsewhere, then the only source of oil that can get on the valves would be K&N air filters. (Initially, this comment started out as a lol, but after thinking more - it could be a small issue. I'll bet an oiled air filter is not a tested condition for GM engineering.)
Just had a thought... If the PCV system is hooked up to a vacuum pump, the gasses can be dumped anywhere. No need to route them through the intake.
If the system is routed elsewhere, then the only source of oil that can get on the valves would be K&N air filters. (Initially, this comment started out as a lol, but after thinking more - it could be a small issue. I'll bet an oiled air filter is not a tested condition for GM engineering.)
If the system is routed elsewhere, then the only source of oil that can get on the valves would be K&N air filters. (Initially, this comment started out as a lol, but after thinking more - it could be a small issue. I'll bet an oiled air filter is not a tested condition for GM engineering.)
Take a look:
http://www.gminsidenews.com/forums/g...dium/GenV1.jpg
The line going back into the TB (traditionally on the passenger side on the LSx pcv setups) is now on the driverside and comes DIRECTLY from the valley cover. I don't think I see a check valve there but who knows.
Also, both valvecovers have fittings for lines on the front of each however I haven't seen any pics with those hooked up to see if they go to a pump or even how they are routed.
So what does this mean? I have no idea!!! But it's definitely different. I thought I saw once a pulley on the lower left of the accessory system that could very well be a belt-driven vacuum pump but again, I really don't know and haven't found that pic again.
What I do know is that we all have a lot of questions... hopefully they'll get answered soon enough.
The unveiling in detroit this january would probably be our best bet. Funny thing is that the wife and I have been toying with the idea of going up there for the unveiling but its one hell of a drive and on a weekday.
I guess I can wait for pics.
I guess I can wait for pics.
Found it!!! It was right there in the home page of tech.
Looks like they both route forward, perhaps to the intake coming from the passenger side. The c6 z06 stock intake had a filter of some sorts adhered to the inside of the stock air bridge that supposively help catch some of the oil from entering the manifold. I wonder if that was revised and these are plumbed infront of that? And hopefully they used a better adhesive so we dont have to fish them out of the manifold.
Or they could be going somewhere else entirely.
If those new valvecovers do the trick then hardly any oil should see its way back into the manifold and down the intake ports. Hmmm.. the more I lookduminto it the more im liking the new engine. Those pics of low mileage Audis remind me of the early 2000s Chrysler 2.7 V6 engines that had oil drain back issues from the top of the engine. These things were seizing left and right with 20-30k miles on them, and Chrysler was voiding warranties unless you could prove you had changed the oil in under 3000 miles every interval to avoid a recall of epic proportions.
http://forums.subdriven.com/showthre...?3730193/page1
http://forums.subdriven.com/showthre...?3730193/page1
^ That diagram is interesting with the two lines disappearing behind that cod piece. I would have thought they'd come together closer to the block.