[mrgoodbytes]

Originally Posted by L78toLT1

That's not really excessive on these motors. Here's mine at 16k

Are you running a catch can on your car?

[DorkMissile]

The type of fuel is irrelative in the LT1 engine - the valves never see any fuel at all. Just air from the intake.

The build up is oil vapor and moisture that comes from the crankcase into the intake tract thru the PCV system.

From my observation it comes from two major problems - (1) there is excessive amounts of oil vapor in the crankcase and (2) the factory PCV system doesn't have a real good way to caputure the vapor and give it a chance to settle & drain into the crankcase.

The biggest contributor to problem #1 is that the vast majority of people over fill the oil system. The system HOLDS 10 quarts, but nobody measures how much oil comes out when they drain it. If there is a quart of oil in the engine still when you fill it, and you put 10 quarts in it, you are now at 11 quarts.

This in turn creates a ton of oil vapor as the oil level is so high that the crank and rods are now slinging more oil around which creates a ton of vapor, all getting sucked thru your intake and sticking to your intake valves which are hot, so it turns it into the burnt maple syrup you see here.

After rebuilding my engine over the winter to put in forged internals, I can tell you, there is at least a quart of oil in the engine when you drain it. I have worked on several other LT1s and LT4s for friends, and have seen probably 90% of them have some kind of residual oil in the intake when you take it off. i let my engine sit on the stand for two days with the plug out, it was still dripping. There is every bit of a quart trapped in the lifters, pushrods and oil galleys in the block that doesn't drain due to suction.

I have a friend who works at GM at the Prooving Grounds, and they actually thought far enough ahead to put a catch can on these cars stock - it is the black box that sits between the passenger cylinder head and water pump, with the three vertical connectors on it. Two go to valve covers, the third goes over to the intake tube between the throttle body and air cleaner.

When they discovered this catch can setup wasn't scrubbing the oil, they were really far down the road towards production, so they came up with a revision where they added a small little box that helps catch the last little bit of oil. If you follow the hose that comes from the box catch can box thing, that hose goes to this little box which hangs underneath the main air intake tube. This little box will catch that little bit of oil, but only if the oil level is NOT overfilled. If the crank is overfilled, it can't keep up.

When I first got my camaro and started seeing this stuff, I called my buggy at GM and he said "just fill it up until the oil gets to the very tip of the dipstick, like no more up than about 1/8 of an inch and the oil vapor will go away".

However - if you preach this logic around this forum and on the groups on FB, you will get told it is crazy to oil put 8.5 or 9 quarts in.

The goal is to have 10 quarts in the system - not to pour in 10 quarts every oil change.

[mrgoodbytes]

Originally Posted by DorkMissile

The type of fuel is irrelative in the LT1 engine - the valves never see any fuel at all. Just air from the intake.

The build up is oil vapor and moisture that comes from the crankcase into the intake tract thru the PCV system.

From my observation it comes from two major problems - (1) there is excessive amounts of oil vapor in the crankcase and (2) the factory PCV system doesn't have a real good way to caputure the vapor and give it a chance to settle & drain into the crankcase.

The biggest contributor to problem #1 is that the vast majority of people over fill the oil system. The system HOLDS 10 quarts, but nobody measures how much oil comes out when they drain it. If there is a quart of oil in the engine still when you fill it, and you put 10 quarts in it, you are now at 11 quarts.

This in turn creates a ton of oil vapor as the oil level is so high that the crank and rods are now slinging more oil around which creates a ton of vapor, all getting sucked thru your intake and sticking to your intake valves which are hot, so it turns it into the burnt maple syrup you see here.

After rebuilding my engine over the winter to put in forged internals, I can tell you, there is at least a quart of oil in the engine when you drain it. I have worked on several other LT1s and LT4s for friends, and have seen probably 90% of them have some kind of residual oil in the intake when you take it off. i let my engine sit on the stand for two days with the plug out, it was still dripping. There is every bit of a quart trapped in the lifters, pushrods and oil galleys in the block that doesn't drain due to suction.

I have a friend who works at GM at the Prooving Grounds, and they actually thought far enough ahead to put a catch can on these cars stock - it is the black box that sits between the passenger cylinder head and water pump, with the three vertical connectors on it. Two go to valve covers, the third goes over to the intake tube between the throttle body and air cleaner.

When they discovered this catch can setup wasn't scrubbing the oil, they were really far down the road towards production, so they came up with a revision where they added a small little box that helps catch the last little bit of oil. If you follow the hose that comes from the box catch can box thing, that hose goes to this little box which hangs underneath the main air intake tube. This little box will catch that little bit of oil, but only if the oil level is NOT overfilled. If the crank is overfilled, it can't keep up.

When I first got my camaro and started seeing this stuff, I called my buggy at GM and he said "just fill it up until the oil gets to the very tip of the dipstick, like no more up than about 1/8 of an inch and the oil vapor will go away".

However - if you preach this logic around this forum and on the groups on FB, you will get told it is crazy to oil put 8.5 or 9 quarts in.

The goal is to have 10 quarts in the system - not to pour in 10 quarts every oil change.

Wouldn’t it be easier to make a new dipstick then? That part is like $4 for us consumers. So it must be cheap for them, compared to warranty work.

[Ventura 1LE]

So with this factory catch can system is there anyway to drain it..???

Whats the point of catching the vapors and oil if can't drain it.. or be instructed to drain during oil changes..

[Tyestick]

Received my car back today.

Here’s what was done:

[cellsafemode]

The point of the factory system is not to filter out fuel / water (that's intended to remain in gaseous form and sucked into the intake to be burnt and expelled) ... The point is just to keep oil from entering the intake (as much as possible).

if you have an oily intake around the PCV tubes connections then it's not doing it's job.

If you dont, then it is doing it's job (though catch can manufacturers will say that job is incomplete at best because it's not separating those elements from the oil that doesn't stay in gaseous form).

the PCV system though is not soley responsible for carbon buildup on valves. Running rich can be factor - and just being a DI motor without regular intake cleaning additives (like seafoam..etc) will be a factor. A catch can wont be a total solution.

[L78toLT1]

Originally Posted by mrgoodbytes

Are you running a catch can on your car?

I am now. The pic was taken when i had the motor apart, swapping the cam and various other stuff. I added a catch can when i put it back together.

[CTS]

These newer engines use technology that is hard on oil. Active Fuel Management, Dynamic Fuel Management, start stop, variable vavle timings, turbo charging etc. All these new technologies put a lot of stress on the oil. Not all oils are up to the task and that's why GM and other oem's have been pushing for better oil specifications to be developed. Yet there are a lot of oil companies who continue to market "good enough" products and customers who refuse to spend the money continue to buy these "good enough" products for their expensive vehicles/engines. They think frequent oil changes are cheap insurance but in reality, cheap oil is the problem.

Why do you think some oils are cheaper? Where do you think they cut the corners? Did they use cheaper oil base stocks and additive packages? Less highly trained chemical engineers? Did they cut back on quality control? How can they afford to spends millions of $$ on advertising sell to Walmart at extreme low prices and still make money if they claim their oil is best?

[wookwook]

great discussions. I looked at the parts list and they said the exhaust valve was also affected in his case. possibly some other type of defect was going on? one reason I'm considering deploying water injection on my 2T LTG. go fast and go clean.



here is a nod to the legitimacy on WI -



https://jalopnik.com/how-the-absurdl...n-w-1760175847

[6spdhyperblue]

The buildup is mostly from egr reversion from the combustion chamber back into the intake. - per GM genv combustion team

[wookwook]

valve open timing overlap. high back pressures.. Clogged cats maybe?