DI Valve Coking
#1
Le Mans Master
Thread Starter
DI Valve Coking
I don't know if it's a chicken little thing, but I've started to see a lot of references to valve coking and theories that blame the direct injection.
I would imagine that keeping oil out of the air path (catch can) would help, but what about running a full bottle of Techron concentrate every 10th tankful or similar?
I don't believe much in "mechanics in a can", but it's a strong and well-respected detergent package. I wonder if it would prevent coking?
I would imagine that keeping oil out of the air path (catch can) would help, but what about running a full bottle of Techron concentrate every 10th tankful or similar?
I don't believe much in "mechanics in a can", but it's a strong and well-respected detergent package. I wonder if it would prevent coking?
#2
The problem is that the fuel never touches the back side of the intake valve and stem....additives are almost useless. Meth injection, better yet, direct port injection methanol would help with this.
The following users liked this post:
davepl (12-28-2015)
#3
Burning Brakes
I saw this ad in my SCCA magazine. Thought I would give it a try just for grins. Baring a "media" blasting, I know of nothing else that would possibly clean the back of the intake valves that do not make contact with anything other than air, assuming the oil and contaminated vapors from the crankcase have been adequately filtered.
#5
ICE enthusiast
if a catch can is the answer why didn't GM do it??
#6
Le Mans Master
Thread Starter
I saw this ad in my SCCA magazine. Thought I would give it a try just for grins. Baring a "media" blasting, I know of nothing else that would possibly clean the back of the intake valves that do not make contact with anything other than air, assuming the oil and contaminated vapors from the crankcase have been adequately filtered.
#7
Tech Contributor
Member Since: Mar 1999
Location: Northern VA
Posts: 10,057
Received 3,787 Likes
on
1,139 Posts
"Ask Tadge" Producer
Imagine how many people would remember to check their catch can on a regular basis. You can safely assume that percentage is: very small. Now assume the rest of the folks who don't check their catch cans suddenly find oil all over their garage floors on some random day.
Click here for GM's response.
Click here for GM's response.
Last edited by jvp; 12-28-2015 at 07:40 AM. Reason: eye kant spel
The following users liked this post:
Ahmed_otb (12-27-2015)
#8
ICE enthusiast
Imagine how many people would remember to check their catch can on a regular basis. You can safely assume that percentage is: very small. Now assume the rest of the folks who don't check their catch cans suddenly find oil all over their garage floors one some random day.
Click here for GM's response.
Click here for GM's response.
I just have had bad encounters with the catch cans and I don't want to go through it all over again
#9
Team Owner
Member Since: Aug 2005
Location: Riverside County Southern California
Posts: 34,988
Received 501 Likes
on
342 Posts
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17-'18-'19-'20
I saw this ad in my SCCA magazine. Thought I would give it a try just for grins. Baring a "media" blasting, I know of nothing else that would possibly clean the back of the intake valves that do not make contact with anything other than air, assuming the oil and contaminated vapors from the crankcase have been adequately filtered.
It's a fact, gunk will cover the intake valves faster than you think, and I have Seafoam in mind for preventive maintenance..
I can also try this one.
I'm no engineer, but an extra injector in the plenum would be great to run a "cleaning cycle". I'm pretty sure the PhD nerds would know how to design all necessary equipment to make it happen. Something like the wiper's washers.
#10
Team Owner
Member Since: Aug 2005
Location: Riverside County Southern California
Posts: 34,988
Received 501 Likes
on
342 Posts
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17-'18-'19-'20
Well they designed one hell of a baffled valve covers, but that is not enough for the LT4s, and I've seen few videos on LT1s dirty valves.
There is plenty of proof, the supercharger gets soaked in oil without a catch can. I bought the catch can before The Phantom was delivered.
I'm waiting to warm up a little. Here is SoCal we are going thru a snow-less blizzard.
There is plenty of proof, the supercharger gets soaked in oil without a catch can. I bought the catch can before The Phantom was delivered.
I'm waiting to warm up a little. Here is SoCal we are going thru a snow-less blizzard.
Last edited by PLRX; 12-27-2015 at 07:16 PM.
#12
Le Mans Master
Thread Starter
I'm sure they tested well into the 200-300K range on these engines before deciding they would warranty them for 7 years (or whatever the emissions warranty is, which they'd have to cover).
I'll wait a few more thousand miles, pull my cover, and see what I see for oil residue. If there's any I'll likely do the Seafoam thing. More likely take it somewhere to have it done so I don't get arrested doing it in my own neighborhood!
I'll wait a few more thousand miles, pull my cover, and see what I see for oil residue. If there's any I'll likely do the Seafoam thing. More likely take it somewhere to have it done so I don't get arrested doing it in my own neighborhood!
#13
SUBVETTE
All you ever wanted to know about using a catch can on the C7 Z06 and why:
https://www.corvetteforum.com/forums...ver-today.html
https://www.corvetteforum.com/forums...ver-today.html
#14
The Consigliere
Member Since: May 2006
Location: 2023 Z06 & 2010 ZR1
Posts: 22,243
Received 5,423 Likes
on
2,268 Posts
Perhaps one of the more interesting (to me) comments about catch cans on the LT4 lately was Katech saying they don't use them.
https://www.corvetteforum.com/forums...ity-owner.html
https://www.corvetteforum.com/forums...ity-owner.html
The following 4 users liked this post by OnPoint:
#15
Scraping the splitter.
Perhaps one of the more interesting (to me) comments about catch cans on the LT4 lately was Katech saying they don't use them.
https://www.corvetteforum.com/forums...ity-owner.html
https://www.corvetteforum.com/forums...ity-owner.html
I'll take Katech's input on this topic before that from a small vendor who is trying to scare owners into thinking they need one by posting unverified pictures of other makes and/or models with intake valve coking.
S.
#16
Pro
#17
Team Owner
Mine was letting oil draw through the can. Thus oil was coming in the power brake booster line.
#19
I don't know if it's a chicken little thing, but I've started to see a lot of references to valve coking and theories that blame the direct injection.
I would imagine that keeping oil out of the air path (catch can) would help, but what about running a full bottle of Techron concentrate every 10th tankful or similar?
I don't believe much in "mechanics in a can", but it's a strong and well-respected detergent package. I wonder if it would prevent coking?
I would imagine that keeping oil out of the air path (catch can) would help, but what about running a full bottle of Techron concentrate every 10th tankful or similar?
I don't believe much in "mechanics in a can", but it's a strong and well-respected detergent package. I wonder if it would prevent coking?
What I have been waiting on and have yet to have anyone answer is how much "coking" can a full synthetic oil create? AND if the car isn't burning any oil (very little oil between oil changes) how could there be much chance of coking to begin with? The truthful answer to those 2 questions will put your concerns to rest.
#20
Tech Contributor
Member Since: Oct 1999
Location: Charlotte, NC (formerly Endicott, NY)
Posts: 40,076
Received 8,915 Likes
on
5,326 Posts
As Tadge said in the other thread there may be some cosmetic buildup but they firmly believe it will not affect the performance of the car. Just because BMW has a problem doesn't mean GM does. They have installing DI engines in high volume cars for several years now and there hasn't been any howling from Polly Public about a problem. All it took was a few people with the old V6s and V8s in high volume cars to create a misplaced firestorm over Dexcool that is still going on 19 years later.
I believe Cosmetic means what it actually means, Cosmetic, looks bad but isn't, thus can be ignored and not worried about. Same goes for dirt on your license plate.
Bill
I believe Cosmetic means what it actually means, Cosmetic, looks bad but isn't, thus can be ignored and not worried about. Same goes for dirt on your license plate.
Bill