Oil/Dirt in intake and runners

**corvet786c** · 07-16-2009, 07:16 AM

I noticed that when we took off the LS1 heads that the runners were very dirty with thick grime. You can see the diffrence where injectors squirt fuel. What causes this how can I prevent it?

**shady milkman** · 07-16-2009, 07:20 AM

Originally Posted by corvet786c

I noticed that when we took off the LS1 heads that the runners were very dirty with thick grime. You can see the diffrence where injectors squirt fuel. What causes this how can I prevent it?

getting oil pushed back into the intake...its a common thing with the lsx platform ...switch to a ls6 valley cover and get a catch can..then your intake manifold will get clean and so will your runners. ..als obe worth it to sea foam your car.

**JoshieDoom** · 07-16-2009, 07:20 AM

Install an Oil Catch Can.

**JoshieDoom** · 07-16-2009, 07:21 AM

Originally Posted by shady milkman

getting oil pushed back into the intake...its a common thing with the lsx platform ...switch to a ls6 valley cover and get a catch can..then your intake manifold will get clean and so will your runners. ..als obe worth it to sea foam your car.

Dammit.

**99RTA** · 07-16-2009, 11:51 AM

It happens in ALL engines. All you are seeing is the normal carbon build up from the combustion process that happens in the intake. I know you are going to say combustion happens in the cylinders how could it get back into the intake. If you could look inside the intake as the engine was running you would be shocked at what goes on in there. Flash over from the valves opening causes combustion gases and oil to get burnt in the intake.

Try running Techron every 3k miles in the gas, it will help clean. You could run something like Lucas fuel system treatment in the gas all the time. This will keep it clean.

**Firebirdjones** · 07-16-2009, 12:06 PM

Originally Posted by 99RTA

It happens in ALL engines. All you are seeing is the normal carbon build up from the combustion process that happens in the intake. I know you are going to say combustion happens in the cylinders how could it get back into the intake. If you could look inside the intake as the engine was running you would be shocked at what goes on in there. Flash over from the valves opening causes combustion gases and oil to get burnt in the intake.

What you are speaking of is called "reversion". That is usually more prevelant with larger camshafts that have more overlap.

**99RTA** · 07-16-2009, 07:27 PM

No it happens in ALL internal combustion engines.......i don't care what the cam specs are.

**dklowrider** · 07-17-2009, 03:04 AM

Originally Posted by 99RTA

No it happens in ALL internal combustion engines.......i don't care what the cam specs are.

i think he said "usually more prevelant", not :no it doesnt.

**shady milkman** · 07-17-2009, 04:15 AM

Originally Posted by Firebirdjones

What you are speaking of is called "reversion". That is usually more prevelant with larger camshafts that have more overlap.

Originally Posted by 99RTA

No it happens in ALL internal combustion engines.......i don't care what the cam specs are.

Originally Posted by dklowrider

i think he said "usually more prevelant", not :no it doesnt.

and we have a winner dklowrider come on down you are the next contestant on the price is right!

**dklowrider** · 07-17-2009, 04:20 AM

Originally Posted by shady milkman

and we have a winner dklowrider come on down you are the next contestant on the price is right!

no, bright lights make me nervous.

**99RTA** · 07-17-2009, 05:09 AM

Its just something that all engines do.....some combustion takes place in the intake. Then as the engine gets older and the valves leak a little more it gets worse. Think about this if a intake valve leaks just 1% those combustion gases are going into the intake manifold where they are going to start burning on the way to to next intake valve that is open. Then also add thie fact that ALL engine also heat soak the intake causing carbon depoists in the intake and on the injectors.< that is a huge reason why injectors get blocked....they block from the heat soak carboning the exit holes in the injectors.

Lesson for today is over...tune in next time for fun with Dick

**Firebirdjones** · 07-17-2009, 07:17 AM

Originally Posted by dklowrider

i think he said "usually more prevelant", not :no it doesnt.

Thank you sir,,,you are correct

**Firebirdjones** · 07-17-2009, 07:45 AM

To explain a little more, Reversion is exhaust gasses that are getting up through the intake valve during the combustion process,(aka: carbon),,this is completely different than oil in the intake that the original poster is talking about.

The reversion process isn't so much of a problem in cars with stock camshafts. Most lobe seperation angles are spread out as far as 117 degrees to build low speed cylinder pressure by closing that intake valve sooner. Keep the exhaust gasses in the cylinder rather than escaping up through the intake track. If you have a valve seat leaking then you have other issues that need to be addressed.
I've taken 150,000 mile stock motors apart and see more oil issues with worn valve guides coating the intake and exhaust valves than I've seen with reversion.

Granted it does happen even with stock camshafts, it's not enough to even worry about. The biggest issue with these 4th gens is the PCV system that actually sucks the oil into and through the intake system. That's what needs to be addressed and can be stopped.
There is nothing you can do about reversion. And more people are sticking larger camshafts in these cars every day, which makes reversion more prevelant. Those are the ones to keep an eye on. Although it's just a necessary evil we live with. You want to make more high rpm power with a high overlap camshaft, you get reversion.

**corvet786c** · 07-17-2009, 08:32 AM

I just got new afr heads put on so I know it is no valve leak. I just want to clean intake and dont want that garbage on the new heads. U know what I mean. I just ordered a catch can hope this helps with oil in intake.

**dklowrider** · 07-17-2009, 12:47 PM

Originally Posted by corvet786c

I just got new afr heads put on so I know it is no valve leak. I just want to clean intake and dont want that garbage on the new heads. U know what I mean. I just ordered a catch can hope this helps with oil in intake.

im new to these cars and learning things almost daily, that is next on my list. at113k its a little late to worry about the oil deposits, but at least i wont be mixing the oil into the intake stream, should run better but i dont know if its a seat of the pants improvement though. the can from the ws6 store is a pretty good price, i dont know yet if it works or is just a can without a screen or something to promote the oil and condensation dropping out of the air.

**Firebirdjones** · 07-17-2009, 01:34 PM

Originally Posted by corvet786c

I just got new afr heads put on so I know it is no valve leak. I just want to clean intake and dont want that garbage on the new heads. U know what I mean. I just ordered a catch can hope this helps with oil in intake.

Yes,,,reversion that 99RTA mentioned would allow combustion or carbon to come up through the intake valve. I think he got that confused with the oiling problem through the PCV that it appears you are experiencing.
To be sure you can pull the throttle body and stick your hand in the intake just behind the throttle body and feel around,,,if it's oily residue then it's the PCV. You can also pull the PCV apart and check for oil inside the hose, PCV etc... In some cases such as mine, it would back flow (somehow) and puddle up in front of the throttle body in the bottom of the smooth bellow.

The catch can will stop it from entering the intake system.