I have asked this before on another forum, but didn't really get any answers. I sort of have a favor. My truck has, what I would call a fair amount of blow-by. It is an 08 6.4, maybe 2-3 times more than my 6.0 had. It is enough that if I set the oil cap loosely on the filler, and then rev it it blows off. At idle it wisp's out a fair amount as well. Would anybody mind checking to see how much blow-by comes out of your oil cap? I thought it was supposed to be a tiny amount, like my 6.0 had. Just trying to find out if there is a problem.
Thanks..

 

I wouldnt think thats good i own a 7.3 and mine does it because someone abused my engine. If it puffs like a train your engine is eventually going to fail and loose compression. I would try to get ford to replace it if i were you

 

So I can't believe that I would get a truck with a bad engine already! Is it possible that since my truck has the oil separator built in, that it all comes out there, and none through the intake????? Thanks

 

Am I really the only one who has noticed blow-by out of my 6.4?

 

The idea of taking the oil filler cap off of my engine while running seems highly unusual and I think that nobody would do that, so the blow by, if it exists is something that none of us would discover.

I might try it some time and i'll let you know.

 

Actually, I thought that was a common way to check blow-by?? The reason I checked it on my new truck, is because I was curious to see if it had as much as my 6.0 did, and it had more, so that's why I asked this question. It doesn't seem right, but I was thinking that the 6.4 might run on less compression or something.

 

I know every engine has a degree of blow by, thus the reason for a PCV system. I havent made it a practice to compare blow by between engines by removing the oil cap and with the sophistication of today's engines Im not entirely sure that is an accurate measure of "blow by". These new engines are designed to burn and reburn in the name of emissions. On a gas engine I know crankcrase pressure (which is really what you are experiencing by removing the oil cap) can be altered by the size of the camshaft, the amount of vacuum, whether you run a breather or a PCV system, etc, etc.

I think if you have a true blow by issue on your 6.4 you will experience low boost and/or poor performance. As your boost builds your blow by would get worse and at full boost your crankcrase pressure would be so great that you would be ingesting oil in to the system and probably smoking.

One of the performance tricks on 7.3's and 6.0's is to re-route the blow by tube to the rear of the truck rather than it being fed back in to your intake. I believe there are more in depth threads on this in the tech section of both the 7.3 and 6.0 forums that might provide you with more details pertaining to your concern.

 

Thanks for the info!

 

I checked this on my buddies 08 today when i did his oil change for him. It was the exact same amount of blow-by my 6L emits.

 

How much is that??? Is not enough that you can see it coming out a lot? Or just whisping out a little. I was thinking that the oil separator on the 6.4's might be what makes mine smoke more.