Engine/Transmission (1998.5 - 2002) smoke from crankcase vent !

[AWeaver]

I was under my hood today re-routing the wires for my electric fans I recently installed and noticed a little smoking from my crankcase vent. It just now started this all of the sudden. Trying to figure out why? The bottle had a little water in it and a little oil as well but just a small amount of both. Is this normal? Like I said before it just now started doing this. Thanks Aaron.

 

[rjrkihap]

That is normal engine/exhaust blowby. Mine looks like a tea pot coming to a boil. It's kinda embarrassing at traffic lights for those of us who have rerouted our breather hoses down by the front axle.

 

[hsmith]

Hopefully not an issue for you, but make sure the crankcase is not getting diluted with fuel from a leaky injector. But with your miles blowby is not uncommon.

 

[DIESELWRKS]

also dont forget its some times can seem worse this time of year to some due to the colder weather outside and you will see more vapor than when its warm

 

[AWeaver]

ok... preciate the input !

 

[BoeingDiesel]

Something else worth checking is the main hose to your vacuum pump. If it's leaking you will get more smoke out of the breather tube.

 

[rjrkihap]

Boeing Diesel, can you help me understand how a leaking vacuum pump main hose will cause more smoke to appear out the breather hose and how to check if the hose is leaking. This is something I might want to look into.

Dieselwrks, funny thing, mine seems to smoke worse on hot summer days here in Oregon. I notice less smoke on the cool damp winter days. Maybe in my case it's because we have less sun in the winter and therefore the smoke is less noticeable.

One undisputed fact in my case, when I had Source divert my breather tube down to the front axle, I noticed much more smoke. The fan must have been blowing it everywhere else with the original breather tube and with the extended tube I can watch a steady stream of smoke blowing out the bottom of the tube.

Ron

 

[Fireman Dave]

That is normal engine/exhaust blowby. Mine looks like a tea pot coming to a boil. It's kinda embarrassing at traffic lights for those of us who have rerouted our breather hoses down by the front axle.

I don't know - I think it looks kind of cool.

 

[JohnBoy5]

rjrkihap That is normal engine/exhaust blowby. Mine looks like a tea pot coming to a boil. It's kinda embarrassing at traffic lights for those of us who have rerouted our breather hoses down by the front axle.

Fireman Dave I don't know - I think it looks kind of cool.

i second that!

 

[NIsaacs]

Something else worth checking is the main hose to your vacuum pump. If it's leaking you will get more smoke out of the breather tube.

Ron, what Boeing is talking about is, if there is a vacuum leak, that amount of air is discharged by the vacuum pump into the crank case. That is where the vacuum pump's exhaust goes. If the system is sealed like it should be there is no exhaust generated. These rotary vacuum pumps can move a lot of volume and can overcome a substantial leak to the point your heater controls still work. It is very difficult to find a leak on our trucks because there is not any tank to hold vacuum after shut down. You need to have the truck running to generate vacuum, then the noise drowns out the leak.



Look real close at all your lines, t's, y's and caps. Also, just a little tidbit of info, the vacuum pump is elevation dependant. At sea level it will pump about 30" of vacuum while at 10,000 feet it might only pump 20".



Nick

 

[champspa]

Cummins has specs on blow by , make an appointment and have them check the amount to see the engine wear.

 

[MRoberts]

Check it out at night with a flashlight!

 

[BoeingDiesel]

Ron, what Boeing is talking about is, if there is a vacuum leak, that amount of air is discharged by the vacuum pump into the crank case. That is where the vacuum pump's exhaust goes. If the system is sealed like it should be there is no exhaust generated. These rotary vacuum pumps can move a lot of volume and can overcome a substantial leak to the point your heater controls still work. It is very difficult to find a leak on our trucks because there is not any tank to hold vacuum after shut down. You need to have the truck running to generate vacuum, then the noise drowns out the leak.



Look real close at all your lines, t's, y's and caps. Also, just a little tidbit of info, the vacuum pump is elevation dependant. At sea level it will pump about 30" of vacuum while at 10,000 feet it might only pump 20".



Nick

Thanks Nick, now I know why the blow by occurs when the main hose comes off the pump. It's been quite some time ago, but when I posted the same question one of the guys came right back telling me to check the vac. pump first. Sure enough, it had cracked and fallen off, but what i didn't initially notice was that the vents had defaulted to defrost. Gotta' love the TDR.