Engine/Transmission (1994 - 1998) another blow-by question

[lafinrat]

i'm sure everyone is sick of answering questions regarding blow-by. but i'm confused here.



has anybody here experienced intermittent blow-by? my '96 will one day blow oil all over itself and my trailer--very annoying; and the next day won't lose a drop. it lost a gallon of oil in 200 miles. the oil sure seems to have went out the road draft tube. i was pulling about 10k @ 65-75 mph. so it wasn't being run very hard. two days later i pulled ~6k @ 80-85 mph for 150 miles and lost no oil. the truck runs great, lots of power, no blue smoke. i don't get it.



i am preparing to perform a compression, leak down and crankcase pressure test, but i am very curious if anyone has experienced intermittent blow by.

 

[TRAMPLINEMAN]

Don't have intermittent blow by, but a gallon in 200 miles, wow. Check the color of the coolant.

 

[Dave M]

Well, I don't know if this qualifies as intermittent but I had blowby one weekend and its gone now. It started when my dipstick was down 6 quarts before a trip. I added the oil and kept checking every 50 miles or so and it was still needing oil. I added another 6 quarts in 300 miles for a total of 12 quarts that day. I had oil spraying under the truck and dripping off the front and rear differential and onto the tailgate. I had no engine leaks other than from the blowby tube back to tailgate.



Took it to Cummins and it passed the blowby test with 1 inch at idle and 8 inch (16 is max) at WOT.



That was 6 weeks ago and no blowby since. No way to know what really happened but I figure I was too quick to put oil in as I was concerned about the leak and I kept overfilling the oil. I took the truck on a trip the weekend before and didn't notice the blowby and I remember adding fluid then too.



For my situation I figure I kept overfilling the oil. Cummins said that would cause the oil to start puking out the blowby. Now, I let it set on level overnight before adding oil.



Heres my thread on my blowby if your curious:



http://www.tdr1.com/forums/showthread.php?t=127186&highlight=manometer



Still has me puzzled. Hope that helps. Be careful overfilling the oil.



Dave

 

[Mokerz]

I had the same thing happen to me a month or so ago. I think it was a vaccum line that caused mine. I found one that came off and plugged it in and no more oil all over the underside of my truck. Mabee it was just a quincidence?

 

[Vaughn MacKenzie]

My truck went through a phase where it used a lot of oil, like 2 quarts in 500 miles and spraying oil over the back of the truck. But then it cleared up and I've used maybe 2 quarts in the last 5000 miles with very little out the blowby. Towed a couple weeks ago and worked it fairly hard but didn't use any oil to speak of.



I was figuring the rings were starting to get tired due to the miles but all seems OK for now.



Vaughn

 

[lafinrat]

I think I taught myself a lesson yesterday. I built a crude manometer and was testing the crankcase pressure of my motor. Well it was fairly high:



4" @ idle

10" @ 2500 no load



Well, during the 2500 rpm test I heard a whoosh sound and the meter dropped to zero. Now it builds absolutely no pressure and there appears to be a leak somewhere behind the pump. I pressure washed the entire engine and drove it around. There is no evidence of any leaks but I know I blew something out. Is there a tappet cover or something behind the pump? The leak was definitely above the vacuum/PS pump area and below the dipstick.