acceptable blowby
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
my 95 gives off a pretty good amount hard to measure but it sometimes let vapro rise right up to my drivers window as my ccv vent right under me.
maybe somebody has a crankcase pressure spec for measuring blow by. deisel have a very high compression ratio 17:1 with very high cyclinder pressures so it won't all stay in the combustion chamber.
maybe somebody has a crankcase pressure spec for measuring blow by. deisel have a very high compression ratio 17:1 with very high cyclinder pressures so it won't all stay in the combustion chamber.
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Senior User
Joined: Nov 2005
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Originally Posted by tjbeggs
my 95 gives off a pretty good amount hard to measure but it sometimes let vapro rise right up to my drivers window as my ccv vent right under me.
maybe somebody has a crankcase pressure spec for measuring blow by. deisel have a very high compression ratio 17:1 with very high cyclinder pressures so it won't all stay in the combustion chamber.
maybe somebody has a crankcase pressure spec for measuring blow by. deisel have a very high compression ratio 17:1 with very high cyclinder pressures so it won't all stay in the combustion chamber.
WHOA!!!...that a lot..(compared to mine) i was just thinking that since it's got all that performance stuff on it...maybe the engine would be worn more than i think. but mines not bad enough that you can see it coming up on the window. thanks for you help!
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
blowby is compression pressure leaking by the rings into the crankcase. this is vented into the intake on stock vehicles that is were the oil residue comes from inside the intake near the turbo. i have vented mine to the air so that i could open up the intake even more. guys with super duties do it to get the oily stuff out of the their intercoolers and tubing. if you ever look at a SD the intake boots are all oily and that is why. the oil is normal and vapor is normal. excess is very hard to tell. i have seen one that was for sure excessive becasue the customer complained of hard starting (ie low compression) and the turbo was dusted and it had a k+n panel filter which all put together equals low compression becuase of dirt entering the engine which scores the cyclinder and allows compression to leak into the crank case and then out into the intake. it had almost a fog going into the turbo.
if your not experiencing any problems don't worry about blowby becuase you can't measure it easily.
if your not experiencing any problems don't worry about blowby becuase you can't measure it easily.
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
oil is not bad its normal, pressure is bad but some pressure is normal. we need to find out if there is a spec for crankcase pressures because i can't tell you how much is too much
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
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From: Cabot, Arkansas
If you remove the oil fill cap when the engine is running, "normal" is just a little smoke drifting up. If there is a lot of it, or if it is chugging (like a steam engine) you potentially have a problem.
Obviously this is not a professional testing method, but it is a quick and easy driveway test that can make you feel better about it...or let you know a problem is developing.
Obviously this is not a professional testing method, but it is a quick and easy driveway test that can make you feel better about it...or let you know a problem is developing.
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Posting Guru
Joined: Oct 2005
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From: Wisconsin
Ohh no. i removed my dipstick and there was a steady stream of steam comming out. i dont know how much is bad but it was comming out good. should i take of the oil fill cap and see? or can i tell by the dipstick?
thanks
mitch
thanks
mitch
Senior User
Joined: Jan 2006
Posts: 349
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From: Louisville
Try the oil fill cap. If it is 'chugging' this is one cylinder hitting and letting a more than normal amount of oil + air mix past the rings. I have seen this first hand on a small block ford gas engine. Kinda neat looking but not a good sign!
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
this is why i nearly didn't post any response to this thread cause now 79 and other reading are all running out and see if they have blowby and asking if its too much and without seeing the blowby its hard to tell anybody if they have a problems or not. that doesn't mean i don't want to help but i have no way to tell you guys if you really have a problems or not.
when the truck is not at operating temps there will be more vapor because there is condensation coming out with cmobustion chamber gases so once the engines warm there will always be more vapor. also if its cold outside the heat coming out will look like vapor too. so you see how this could get out of hand quickly.
i will try to hunt down a pressure spec so we can get some hard evidence!
when the truck is not at operating temps there will be more vapor because there is condensation coming out with cmobustion chamber gases so once the engines warm there will always be more vapor. also if its cold outside the heat coming out will look like vapor too. so you see how this could get out of hand quickly.
i will try to hunt down a pressure spec so we can get some hard evidence!