Blow By Tube

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I read in one of the post ups that there shouldn't be smoke coming from the blow by tube. This is my first diesel and I noticed a small amount of smoke coming from this area (I saw it at night in the headlights)Is this normal or a sign of a problem?Thanks this site rules

 

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Smoke and blow by are virtually one in the same IMHO. Blow by is cumbustion by product that gets past the rings and winds up in the crankcase. The diesel engine does not allow the normal pvc/kv tube arrangement like a gasser so the blow by tube vents the crankcase pressure to atmosphere. This means periodic visible smoke.

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3/4 ton, 5 sp, lsd, 2wd, qcab, guages, Scotty sys. Rhino liner, Blue Box hp enhancement

 

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It also means that you will have oil on your front sway bar and power steering pump which will need to be cleaned from time to time. I have 19K on my truck and I'm hoping it stops soon.

John

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1999 Dodge Ram 3500 Quad Cab 5 spd; 4:10 LSD rear; Mag-Hytec diff. cover; Speedliner spray in bed-liner; Amsoil foam air filter; Smittybuilt step rails; JVC 12 disk CD system; Windows tinted; Manual transmission filter kit; Geno's EZ Drain oil pan plug; US Gear EGT and Boost gauges on a twin A pillar mount. Towing a 31 ft. NOMAD single slideout TT.
Rammin' and Runnin' the roads

 

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The most noticable by-product of combustion in our engines is soot (carbon). If you truely have piston ring blowby, then your oil will turn black in very short order. If it does, then your rings may be worn out AND those by-products will begin to form acids in the oil and become corrosive (a BIG problem for those running extended oil change intervals BTW since no filter will remove the acid).

The color of your oil is indicative of the condition of your rings. Most seem to be reporting "clean" looking oil even after 3-4000 miles. That is quite impressive considering the amount of carbon circulating up in the combustion chambers and a testiment to the high cylinder pressures (which causes the rings to seal tightly) typical of a diesel.

The purpose of the tube is to vent the crankcase of pressurized air, oil and water vapor. What combustion by-products that find their way into the crankcase, should be insignificant.

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'00 2500, 4x4, QC, Cummins ETC/6spd, 3. 54, Camper, Trailer, SLT, 4ABS, BD E-brake, Pullrite 20. 5K 5th hitch, Tekonsha Envoy-SX Tbrake, Flame Red/Silver, Agate

 

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--seen a million posts about the blow-by tube, and the mess that some guys get, but have never noticed, or seen mentioned---24-v only, or both 12 and 24?? I had an episode for a couple of weeks a while back, that might have been blowby making a mess, or overfill of my PS pump simply bubbling out, but none since then... what'm I s'posta think about that???----just need a new excuse to do low-budget tinkering #ad


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98 12-valve qc2500 4x4/kill-switch, K&N,silencer ring hanging in garage,600amp quick-connect jumper cables, 4"straight-thru w/nasty 5" chrome slant-cut outlet,PrimeLoc,Warn Front receiver, 19. 5"Ricksons w/Goodyear Unisteel "UPS Truck" tires, camper shell, Westin step-rail/nerf bars, diamond-plate rail caps, bedliner,ATF dipstick bungee(modified porky system),Tazmanian Devil mudflaps and floormats--"%$*#)%$^#"-(translation:"TAZ LIKE DIESEL")

 

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I think "broken in" or not there will be some blowby on all engines. My truck leaves a small drop of oil on the floor from time to time. You can see some vapor emanating from the tube when idling, although this diminished noticeably after changing to synthetic oil. These engines have very high cylinder pressures and I'm guessing they have very little cylinder leakage in spite of this. I've seen "healthy" Gassers emit vapor out the oil fill hole with the PVC system disconnected, even though cylinder pressure is VERY low (compared to diesels) at idle!

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Vaughn MacKenzie

1998 3/4T QC 4x4 Longbed, 24-valve 5-spd, White over Driftwood, Leather & Loaded, foglights, airdam, DeeZee Running Boards, K&N air filter. 52,320 miles (11/29/99)

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