GDI engine care.

[GRIFF]

A friend of mine and his wife drive GM vehicles with GDI engines.

GM recommends that they "decarbonize" their engines when performing an oil/filter change at regular intervals. About a $140.00 ticket.

The service tech's explanation is that the GDI engine intake valves do not see the flow of gasoline and included cleaning fluids which assist with build-up around the intake valve assembly and that a regular cleaning improves engine performance and promotes a longer life.

They claim that the build-up comes from the crankcase routed to the upstream intake air/mix stream via the crankcase PVC bypass valve, and certain contaminates coming from the crankcase will end up coating the intake valves and degrading performance.

Just food for thought. Never head anything like this from Hyundai.

GRIFF

 

[Mark_888]

That "may" have some truth to it, but if the gasoline does not reach those areas, how do they do it? I am not sure I would want a Hyundai tech taking apart my engine.

 

[radicaltimes]

When you say GM I bet it is the dealer. Check the owners manual to find out what is recommended. The dealers will sell all types of services that are not required to make more money. I am not saying that are not needed or bad except on the wallet.
Some Honda dealers try to sell transmission flush but Honda does not recommend that .

 

[NSXNEXT]

I'd be curious to know exactly what they do to "decarbonize" the engine.

 

[sluggo]

GM is doing the right thing, but I would treat it differently.

When the crankcase gets pressurized from piston blow-by, the excess air pressure has to be vented somehow or you start blowing gaskets. Long ago the manufacturers would just vent it out to a hose and down onto the road. Now the pressure is vented back to the intake manifold via the PCV valve and a hose.

The air in the intake manifold (normally clean and dry) now has blow-by gases which come with little oil droplets. These oil droplets land on the back of the intake valve where they get baked on. Port-injected engines spray air-fuel mixture on the back of the valve, which cleans this oil off. Our GDI engines don't do this.

Baked-on oil can be blown off with a mild abrasive (like powdered walnut shells) and the abrasive vacuumed out.

A better solution (I think) is a simple oil capture stage in the PCV return line to keep the oil from building up in the first place.

 

[Mark_888]

Some manufacturers are apparently starting to build hybrid direct-injection/fuel-injection engines to solve this problem. Direct injection works at highway speeds and fuel injection in town.

I would definitely use a high quality synthetic oil with any direct injection engine as synthetic oil is known for its superior engine cleaning properties.

 

[GRIFF]

I believe GM Service sprays a cleaning solution in the air stream in the attempt to clean what they can off the intake valves. For me, it will be synthetic from now on. I wonder if Hyundai does have an in line filter to clean the blow-by as it comes then the PCV valve?

 

[RonJ]

Would installing a catch-can/oil separator in the PCV system affect the warranty in any way? Has anyone reading this thread installed one on their GDI Genesis?

RonJ

 

[landtuna]

GM is doing the right thing, but I would treat it differently.

When the crankcase gets pressurized from piston blow-by, the excess air pressure has to be vented somehow or you start blowing gaskets. Long ago the manufacturers would just vent it out to a hose and down onto the road. Now the pressure is vented back to the intake manifold via the PCV valve and a hose.

The air in the intake manifold (normally clean and dry) now has blow-by gases which come with little oil droplets. These oil droplets land on the back of the intake valve where they get baked on. Port-injected engines spray air-fuel mixture on the back of the valve, which cleans this oil off. Our GDI engines don't do this.

Baked-on oil can be blown off with a mild abrasive (like powdered walnut shells) and the abrasive vacuumed out.

A better solution (I think) is a simple oil capture stage in the PCV return line to keep the oil from building up in the first place.

Where was this problem back when PCV's were added to engines in the 60's? If this were a big problem it would have been noticeable way back then when crankcase vapor return lines pumped lots of oil mist back into the intake manifold.

 

[RonJ]

Where was this problem back when PCV's were added to engines in the 60's? If this were a big problem it would have been noticeable way back then when crankcase vapor return lines pumped lots of oil mist back into the intake manifold.

The problem was there to some extent but with a carbureted, TBI or port injection, the gasoline, with it's solvents and cleaners, would wash much of the accumulated oil off the neck of the valve.

With GDI, same oil mist from the crankcase but no fuel in the entering air to wash it off, hence the problem with carbon build-up on the intake valves, just as if the valve seals were bad.

RonJ

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[PMCErnie]

I wouldn't be surprised if GM is only dumping a can of Justice Brothers injector cleaner into the tank and charging customers $140 for privilege.

 

[Mark_888]

I wouldn't be surprised if GM is only dumping a can of Justice Brothers injector cleaner into the tank and charging customers $140 for privilege.

For $140.00, they are not going to take the engine apart to get to the valves.

 

[landtuna]

For $140.00, they are not going to take the engine apart to get to the valves.

Yeah, not that I would want them to do that anyway.

 

[Mark_888]

Yeah, not that I would want them to do that anyway.

Yes, I mentioned that in a previous post that I would not want a dealer tech to start taking apart my engine. My dealer techs cannot even follow directions on the work-order concerning what oil to use on an oil change.

 

[brfatal]

BMW folk have their valves removed and blasted with walnut shells because nothing less really works well.

 

[CanukV6]

I wouldn't be surprised if GM is only dumping a can of Justice Brothers injector cleaner into the tank and charging customers $140 for privilege.

The injector cleaner won't help build-up on the valves if they put it in the tank, for the same reason that there is a potential issue. The fuel doesn't go anywhere near the back of the valves. Only way I can see is to spray some sort of cleaner into the air intake while the engine is running.

 

[landtuna]

The injector cleaner won't help build-up on the valves if they put it in the tank, for the same reason that there is a potential issue. The fuel doesn't go anywhere near the top of the valves. Only way I can see is to spray some sort of cleaner into the air intake while the engine is running.

That's the way we used to clean up engines. Makes a powerful amount of smoke but you won't be bothered by mosquitoes for awhile.

 

[kf4zra]

i have used about 1/3 can of seafoam in other cars every 30-50k miles.
I ran it through the vacuum line going to the power brakes.
suck it in, let it sit for 15-30 min, then fire it up and clear out the whole neighborhood of mosquitoes with the smoke you will generate.

wonder if doing the same thing would help these engines?

Only have 6k mi on mine in the 10 months i have had it, so i am nowhere near that on mileage.

 

[NSXNEXT]

i have used about 1/3 can of seafoam in other cars every 30-50k miles.
I ran it through the vacuum line going to the power brakes.
suck it in, let it sit for 15-30 min, then fire it up and clear out the whole neighborhood of mosquitoes with the smoke you will generate.

wonder if doing the same thing would help these engines?

Only have 6k mi on mine in the 10 months i have had it, so i am nowhere near that on mileage.

Will do nothing to clean the backs of the valves.

 

[RonJ]

Will do nothing to clean the backs of the valves.

It should do something, the SeaFoam (or whatever) is being put into the intake air flow which goes past the valves.

If it was being put in the fuel it wouldn't do anything for the carbon on the valves.

RonJ