DI intake fouling
12-13-2013, 06:04 PM
#1
DI intake fouling
Sorry in advance for the long post/question but I hope someone in here can share some information. I now have a 06, C6 Coupe and would like to move to a C7 in the near future. There is a concern I have about the DI engine which although it would not be a deal breaker, I would like to know if and how GM has addressed it. My awareness of this started in 2010 when my wife and I got a new CTS with the 3.6 DI engine.
At that time I started visiting various Cadillac and 3.6 DI related forums and learned the following. In a DI engine since the gasoline is injected directly into the cylinder, the back side of the intake valves are not subjected to any cleaning by the fuel, so that any oil mist which comes thru the PCV system can collect in the intake runners and on the valves. The oil then cooks on the valves and soon builds up as a carbon deposit which in time restricts and disrupts the air flow around the valve. There are borescope pictures showing severe fouling in these engines with relatively low miles.
Just out of curiosity I removed the intake manifold cover on my engine and was surprised at how much oil had accumulated in the manifold and how wet with oil the intake runners were. This was at about 10K miles. I cleaned it as best as practical, installed a catch can and will check it again later. I understand some are cleaning their intake systems with various chemical treatments while others with more severe fouling have resorted to an engine teardown for a complete cleaning.
So you now know my concern. I have evidence with my own car that this is an issue at least with the 3.6 DI engine, and have heard of it being the same case with other brands, domestic and foreign. Does anyone know if GM is addressing this situation with it's new V8 DI engines, one of which the C7 uses?
Please share any info available.
At that time I started visiting various Cadillac and 3.6 DI related forums and learned the following. In a DI engine since the gasoline is injected directly into the cylinder, the back side of the intake valves are not subjected to any cleaning by the fuel, so that any oil mist which comes thru the PCV system can collect in the intake runners and on the valves. The oil then cooks on the valves and soon builds up as a carbon deposit which in time restricts and disrupts the air flow around the valve. There are borescope pictures showing severe fouling in these engines with relatively low miles.
Just out of curiosity I removed the intake manifold cover on my engine and was surprised at how much oil had accumulated in the manifold and how wet with oil the intake runners were. This was at about 10K miles. I cleaned it as best as practical, installed a catch can and will check it again later. I understand some are cleaning their intake systems with various chemical treatments while others with more severe fouling have resorted to an engine teardown for a complete cleaning.
So you now know my concern. I have evidence with my own car that this is an issue at least with the 3.6 DI engine, and have heard of it being the same case with other brands, domestic and foreign. Does anyone know if GM is addressing this situation with it's new V8 DI engines, one of which the C7 uses?
Please share any info available.
12-13-2013, 06:08 PM
#2
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Member Since: Nov 2013
Location: Astoria NY
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I'm fairly concerned about this. While you can't stop the fouling, you can certainly reduce it with a good catch can. Obviously, the catch can doesn't affect the fouling that occurs from DI, however, it can greatly reduce that which happens from oil entering the intake.
12-13-2013, 06:11 PM
#3
Team Owner
According to info released so far it is a non issue with this Gen V engine.
Here's a prior discussion with some info from the BASH and other places:
http://forums.corvetteforum.com/c7-t...n-fouling.html
Here's a prior discussion with some info from the BASH and other places:
http://forums.corvetteforum.com/c7-t...n-fouling.html