Inlet port clogging - GDI vs propane

[Circlotron]

Just got to thinking about some newer engines with direct injection suffering from clogged up inlet ports because there isn’t any wet fuel spray anymore to keep it all clean from egr and pcv deposits. Wasn’t this ever a problem with propane powered engines? No wet fuel spray there either.

[Circlotron]

Hopefully a new set of eyes will see this.

[rebelrouser]

When I worked at a GM dealer many years ago, we sold trucks to the local propane dealers. After a trade-in I took the propane injection system off the old truck and got it running on gas, and then installed it on the new truck. From my experience the propane engine were very clean, very little carbon in the runners, and very little sludge in the crankcases. If the propane system messed up, I did see one engine damaged by that, but all in all, propane is about a clean burning fuel as you can get. I think one issue is that modern fuel systems are a little complicated to convert to propane. Back when I did it you just bolted a bonnet on the carb, and turned off the gasoline. To get them going on gas again, we put on a new fuel pump, cleaned the fuel tank, overhauled the carb, and it was running on gas again.

[dfarr67]

I have a Honda Accord with the 2.4L/DI, MT6. Honda doesn't have a reputation for these issues, but I installed a air/oil separator in the PCV system due mostly to low temps here and wifey's driving habits- meaning the engine doesn't get warm. Every couple of weeks I take it out on the highway for a few hours, oil gets changed spring/fall, when I empty that separator about 1/2 cup of black crap spews out- water and oil. So maybe it makes a difference, maybe not, either way it's a big job cleaning valves.

[rebelrouser]

That air oil separator is a good idea. Most shops are selling carbon cleaning with a machine that bypasses the fuel system and the engine runs off the cleaner. BG and Motorvac are a couple companies that make them. High mileage engines, direct injected or normal benefit from carbon cleaning. Most common cause of oil consumption in modern engines is the oil drain return holes in the piston lands behind the oil rings plugging up. Many times carbon cleaning can open these holes and stop oil burning. If you look at most new pistons the holes are really small. Many older engine had large slots instead of holes in the lands.