Anyone have knowledge of how to reduce/avoid carbon buildup on the
'direct injection' engines. Just witnessed a decarbonization process on a 25K mile Yukon Denali in our shop. Tech started by taking heads fo to examine valves, then did the process. Is it possible to eliminate since no
fuel passes the valves anymore? Not convinced WOT will help either.
I have seen zero on this issue on this forum.

 

pay close attention to this thread, I'm sure something will come up.....

https://www.corvetteforum.com/forums...-included.html

 

Here are my thoughts:

The research I've done says coking is not a certainty, but rather a possibility. there are variable factors that might influence the likelihood that you have accumulation on your valves. Also, even with a catch can, if you subscribe to the belief that oil is hitting your valves, you will still have oil getting into the intake. A catch can will cut it down, but not eliminate it.

There is lots of controversy about this and many threads.

All that said, I've come across a product from CRC that claims to "wash" the valves. Its specifically made for GDI cars (called CRC GDI IVD Intake Valve Cleaner). I haven't seen much, if any discussion on the forum about these types of products. I first heard about it from my gear head father. Anyway, I'm going to try using that and watch the valves over the next couple of years.

 

Pretty good discussion here:

https://www.corvetteforum.com/forums...n-fouling.html


What Tadge said:

https://www.corvetteforum.com/forums...on-valves.html

 

Anyone watch Motorweek today? Goss' garage explained the coking issue pretty clearly and said adding a catch can solves the problem.

My questions is...does this occur on base, wet sump engines or only the Z51 and Z06 dry sump engines?

 

This issue will occur in any direct injected application. A catch can and air/oil separator significantly decreases oil accumulation on the intake valves but it does not "fix" the problem outright. Regardless, anybody's first "to do" on a direct injected motor should be the catch and separator.

 

Coking as nothing to do with dry or wet sump so base, Z51, Z06 will get some coking.
A "catch can" will help by collecting "some" of the oil mist and other "stuff" that comes from the PCV system, but not all so it will not stop it. However worth the small cost IMO.
But the collected oil and other "stuff" must be emptied periodically from the can. Many don't even check their oil level so can't be expected to empty the can! If not emptied could block the PVC system and hurt the engine.
Then what to do with the collected dirty oil? I put mine in the container that I use when I change oil that I bring to a recycle center. For someone who have the dealer change oil would they bring a 1/2 cup to a recycle center or the dealer for proper disposal?
The new Camaro has a system which apparently drains the collected "junk" back to the pan. Not sure that is as easy with a dry sump.

 

I have seen engines with oil coked valves and engine performance loss is really not noticed. Your engine should go the distance and you will be unaware of the accumulation of crud on the valves. Don't worry, be happy!

 

These get quite lengthy but do cover the subject in depth. I would thank all that contributed. Bottom line is not much can be done to stop the issue, we'll need to wait for a better design. I thinkI'll opt tohave the intake system cleaned on a periodic basis by me dealer. Catch can? I'm still thinking on that.

 

14' Z51 with 9,000 miles. Just had LT's and ported intake done this week, so got to see my valves. Hard to see in this picture, but there is carbon chunks on the stem and the valve face. Send me your e-mail and I will forward you the picture. Zoom in and you won't like what you see. Elite catch can is getting ordered, wish I would have installed day one:

 

A "for what it's worth" observation. I put a catch-can on the day I brought my 2016 base car home- about two months and 1600 miles ago. Yesterday was the first time I checked it. There was perhaps just over a tablespoon of oil in it. It's a mixture mainly of highway, town but also full throttle, give it hell driving when I feel like it. Does not appear to be a "fix" but may help somewhat.

 

Are there any plug and play catch cans? Seems all the ones I've found have really involved installations.

 

Mine is for a stock engine. Unclip the stock hose. Replace it with a provided hose from the crankcase to the can and then a hose from the can to the intake. Bolt the can to an existing ground stud. I've always done quite a bit of my auto work but I would think just about anyone could do it without a problem. If not, find a buddy who's more mechanically inclined. Even if he doesn't have a Corvette, the instructions will make sense to him. The worst part of a catch can is the inflated prices for them.

 

Which one do you have? Also, I have a Z51 with dry sump.

 

Sorry. I should have mentioned that it is not the Z51. Many makers feel that with the Z51 (because of it's tendency to burp oil into the intake) or with more modified engines, two lines are necessary from the can to the intake one of which does involve drilling a hole in the intake hose.

 

You apparently haven't spent any time in the Z06 section.


Pages and pages of discussion. Ignore the few are in complete denial; its a problem that the Europeans have been fighting for years. With no fuel spraying the valves, they are candidates for build-up.


Looks like GM is addressing the problem with the new Camaro, and let's hope the 2017 Corvette will get the fix as well. The fact that GM made this move seems to confirm there is a problem regardless of previous denials.

 

Actually I do but a base engine is just as likely as a z06 engine to have the coking issue, I'm sorry I offended you by posting in this forum.

 

Hmm, been lots of discussion about coking in the LT1 in this general section since I got my Z51 in October 2013! In fact I have commented on most threads!

The debate usually follows about installing a catch can or not. Some argue it's not needed defending that GM says it could affect warranty. Granted if you don't dump the oil in the can periodically (say every few thousand miles) or don't install the dual outlet can properly (it needs a check valve so flow doesn't go from one outlet to the other bypassing the crackcase) it can be a problem.

I had a Z51 BUT only installed one outlet in the same line as the OEM hose from crackcase to intake. It doesn't need a flow restricting check valve as the OEM hose has none.

IMO you only need the 2nd line IF your operating at sustained high speed a lot of time or have a supercharger. I make a good case as to why (I believe) in this PDF: http://netwelding.com/Catch_Can.pdf

I just sold my 2014 Z51, removed the catch can and clean side oil separator from the car and installed the OEM hose. Looks perfect and the new owner will have less oil that ever passed over the hot intake valves and baked!

They will both be installed on my Grand Sport scheduled to be built this week!

 

I installed a catch can and it helps