So, as the title suggests, I’m trying to find out how you guys are cleaning your intake valves of buildup? I recently helped my brother with his ‘17 Tahoe. He bought an aerosol can of some sort of cleaner designed for this issue. He took the boot off the front of the TB, and while I held the RPMs at about 2k, he sprayed the entire can in, according to the directions on the can. That’s the second time he’s done this clean, as the truck has about 80k miles on it. So, this past weekend, he did the exact same thing to his sons (my nephew) Denali, and it blew a headgasket in this process apparently. The Denali is under warranty and is going on Monday morning for repair. What are you guys doing about this issue…or is it even an issue? I haven’t been inside a high mileage LT DI engine yet to see for myself if in fact it IS an issue.

​​​​​​……EDIT…………
So…it turns out it wasn’t a headgasket after all. There’s more to the story here (isn’t there always!). The Tahoe (Denali) was taken in to the dealership a couple weeks prior to this cleaning, for an oil change. After the oil change, my nephew says the engine had a very noticeable tick to it, so he called the dealership and reported it, and it was documented. Well…the warranty was just about to expire at this time. Good on him for reporting it and getting it documented, because it turns out, the thing lost (was in the process of losing it) a lifter that hurt the camshaft, and he got a new engine out of the deal. The valve clean was just a routine deal that happened to take place coincidentally during this timeframe and was totally unrelated the failure. My brother was beside himself here, because the Tahoe (Denali) developed a misfire on #3 immediately after the cleaning he did for his son (my nephew), so he thought he hurt the engine. It was all just a weird timing deal.
The dealership recommends a valve leaning be done regularly, and the tech told them that they would do this cleaning in the same manner, if using that product.

 

Sounds like he may have been using some form of a "Top end cleaner". GM makes this as do several other companies, and IIRC, it's a 2 stage process. The first is to spray it into the intake with the engine off (but fully warm/heat soaked), let it sit for a certain amount of time, then fire it up and hold RPM somewhere above 1500 for X amount of time... I don't think removing the boot in front of the throttle body and spraying while the engine is running is the correct method. That bypasses the MAF, so I'd expect all kinds of issues. Not surprised it blew a head gasket. I may be wrong on the process for these newer DI motors, as I haven't done this on the newer GenV motors. I've done it numerous times on the Gen 3 LS1/LS6 motors. Blows all kinds of fun smoke out the tailpipe!!

I just did a cam swap on my '16 L83 with about 54k on it. When apart, I looked at the valves. They didn't have what I would call major buildup on them, and for a DI motor, I was surprised at how clean they were. It wasn't enough for me to say "hmm, I think I need to run some top end cleaner through this baby once I get it all back together."

 

Would Berryman's Chemtool be good here?
I remember back in the 70's it was a "cure" for many ills....

 

Hmmmm. No smoke out of the tailpipe on this method. It’s just an aerosol that doesn’t contain any oils. I forget the name of this particular product, but it’s apparently highly recommended by many GDI owners that regularly do this maintenance procedure. Directions say to remove air intake boot and spray directly into front of TB, while at 2k rpm. After entire can is dispensed, give the engine 3 quick revs, and then take the vehicle out for 15 minutes of spirited driving. Removing the MAF for a couple minutes won’t hurt anything, as the engine will go directly into SD mode and run like it never happened. In fact, it doesn’t even throw a MAF code when doing this. Weird. Seems to work according to others in the GDI community. My problem is…I don’t own a GDI engine so I have never had to do this myself, and the only experience I have with this is helping my brother a couple of times.
I do appreciate the info about your 54k mile valves still looking good. That’s the kind of info I’m looking for from GDI owners.

 

Here is an Intake valve from an 85,000 mile 5.3, 2015 DI motor. Engine was in great shape.


Intake Valve

 

That’s not terrible. I’ve seen worse in high mile port injected engines. Perhaps this “problem” isn’t really a problem after all? I’d love to see in intake valve from a 150k-200k mile engine that’s been maintained well. This is EXACTLY the type of info I’m after. Appreciate this!

 

I use the crc gdi cleaner once a year in my gmc 6.2. No idea if it actually works but i figured it can't hurt. I guess i will find out down the road. My neighbor has a 2017 5.3 with over 200000 miles and runs like a champ. It also has had at least 3 different owners and has dents and dings all over it so i don't think it was well taken care of.

 

Trust me, the DI engine valves can get A LOT worse than that one. Until recently, I worked at a shop that did all the maintenance/ repairs for the local phone company, and all of their trucks were Silverados. I've removed the intakes/ heads on plenty of them, and after 100K plus miles, the valves look a lot worse.

Also, the deposits on the valves are really hard, and I doubt any top-end cleaner is going to do much about it, although I've never done a back to back inspection after doing one.

Now, as to how much of a difference it makes: at full lift, I doubt it's a big deal, but when deposits start to really build up, I'm sure that low-lift flow suffers.

 

Thats the stuff, I believe he buys. How do you use it? Spray right into TB?

 

Appreciate the reply. That valve pictured above, was prolly involved in a valve cleaning program, if you’ve seen look a lot worse at 100k.

 

There is a lot of grit on that valve. I can't imagine washing it down into the cylinder. I think keeping the oil out of the intake from the start would be the best solution---and then clean with that spray stuff. If you want, I can take a couple of these valves and spray them with the cleaner and see what they look like---before and after. It won't be the same as the engine running, but see how effective the cleaner is straight on the valve ??

 

That would be interesting to see what the cleaner would do to the valves outside the engine. I agree completely with you about keeping oil mist out of the intake, which is likely most of the cause of this mess to start with. If you decide to spray those valves, post up pictures please. I appreciate all the input here from you guys.

 

Edited original post with more info….

 

The standard process for several euro DI cars is to pull the intake and blast the valves with a media to clean them, they do it one cylinder at a time on TDC.
I believe the interval is about 60K. (So about like a timing belt... )

I've been reading that several marques have or are going to put a injector back by the throttle body to provide a small amount of fuel at cuise above the valves to aid in keeping them clean..

We shall see...

 

Very interesting. So the valve(s) are closed and the media is then vacuumed up with attachments I suppose? I have heard about this “extra” injector also, for cleanliness purposes.
Seems like to me that adding a well designed OEM “catch can assembly system” with some type of filtration to it, along with this rogue injector(s) would end this issue for the automakers.

 

Last fall i added a standard catch can to my wife's 17 tahoe (5.3). I had to empty it every 1.5-2 weeks, probably due to colder weather. In the colder climate you would even run into issues with the catch can lines freezing and then it's even bigger problems.
It was not worth the hassle so i disconnected it. I just can't see folks emptying the can every 2 weeks...and that crap was nasty, mostly fuel and condensation maybe?
Fingers crossed it's not a big issue with higher mileage.

 

Here are a couple of pics of the valves before and after using that GDI spray directly on them. I set them out in the sun to get warm, but not 300 degrees like they would be on a running engine. Can says to spray whole can into intake while the engine is running and 5 minutes afterward, not exceeding 3000 rpm. Then go drive on the highway for 15 minutes---this will remove about 50% of the buildup. I guess you need to purchase 2 cans.
I sprayed the valves 4 times, not letting them dry between sprays. Couldn't tell any difference. I wiped two of them with a rag and some of the gunk came off. The hard baked part stayed on. I suppose the hot running engine might help loosen some of it.
I am curing my genV build by drilling the intake and installing (8) rougue injectors and blocking the DI's. Don't want my shiny new valves looking like this.
I wonder if Meth injection would clean the valves???


I uesd 3 intake valves and 1 exhaust

Pretty dirty

After spraying 4 times, I wiped these two with a rag. Hard stuff still stayed on.

This one was not touched with a rag. Still looks the same. You can see the little amount that came off on the cardboard.

 

The injectors in the 5.3 that I have were impossible to get out. I pulled the heads and beat them out with a punch. Couldn't even turn them with vice grips. The cost on the bigger DI injectors is outta hand also.

 

 

Pretty sure that’s the same product we used.