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I smelt something like burning oil the other day when stopped at a light didn’t think much of it as I had Just topped it up with a quart and a half of oil the day before and some dribbled down the outside of the fill pipe. This morning I got suspicious and took of the oil fill cap while it was running, and the pressure nearly blew the cap out of my hand. Is this normal for this engine?
Yes. You have pistons moving up and down in a long stroke engine and that moves air. It's not pressure in the crankcase, but just air moving around between the bulkheads. If you remove the cap and put a piece of paper over the fill hole, you will actually see the paper being sucked in and pushed out. Four cylinders are really good in demonstrating this phenomenon since you have the outside pistons moving in sync and the inside pistons moving in their sync.
I tried it again tonight I still get a burning oil smell when coming to a stop and the cap is still under pressure. The oil smell could be from the oil I spilled when topping it up but the pressure has me concerned. I agree that it could be a regeneration procedure, but it did it all day long, so it seems less likely to be regeneration. No CEL at all and truck runs like a top, plenty of power..
Possible it’s the brakes, I did have an emergency brake stop a day before. Had to slam them on so hard all the anti locks kicked in and just barely stopped the truck from plowing into the dumb so and so that turned in front of me.
I don't think there should be that much crankcase pressure. I work on bigger engines, but anytime they are able to blow the oil cap off, that's an abnormal amount of blow by, especially idling
check your oil level...too much oil reduces air volume and increases air pressure.
our dip sticks are funky and grab oil going out of the dip stick tube....you basically want a line in between high and low....indications of fully full are problematic since you cant tell how full you are.
why did you have to add oil? are you checking the oil while its running....your are supposed to check the oil at rest.
Not sure why it was down on oil but I use the truck for a trailer towing business so it does a lot of heavy tow work, possibly that’s why. I check oil when it’s not running, and keep it at the cross hatch zone. Oil burn smell seems gone today, in the old days we used to see that the oil was low and first thing was to check for blow by at the fill cap. I was surprised at how much air pressure came out of the fill tube when I took of the cap when it was running, there is a solid whoosh of air that comes out. I don’t know if the fill tube is supposed to be pressurized on these engines. Maybe someone else could try it on their 6.7 when running? I made an appointment with the local dealer for Saturday. They wouldn’t let a mechanic come over to the truck and just take a quick look it would have only been 2 minutes...
Try jamming on the brakes again and see if you get that smell again. Couldn't hurt to be on the safe side. Mine smelled a bit more like tranny fluid at first, if I remember correctly
Ok guys I found the issue and solution, this is exactly what mine is doing! Although not to the point of spitting oil out just yet. My truck has 87,000 miles 2,105 engine hrs and 303 idle hours.Enjoy!
Not a difficult job took about 20 minutes, just awkward, I used a regular 1/4 inch ratchet and 8mm socket. Definitely needed doing, no more pressurized fill cap, if let go too long it would probably blow the oil pan gasket and rear main seal amongst other things. This is going on my maintenance schedule, maybe I will include it with every fuel filter replacement, or every other one. I’ll see how it goes, a good way to tell is take off the fill cap when running, I’ll check it every time I do an oil change. Most painful part is the price, I paid $230.00 from the dealer up here in Ontario. It’s probably cheaper online but I needed to have it now as I’ve got a couple of long hauls next Monday and Tuesday. Part number is FL2077
