Normal, or is my engine going

[6.2Blazer]

Several years ago the CDR went bad, or at least I thought, on my truck allowing engine oil blow-by into the intake. At the time I couldn't find a replacement so I swapped in a standard valve cover breather/oil seperator with a hose running down to the frame area.

Since then I've always had issues with blowing oil out of this breather, but not horrid, and some smoke coming out of it. If you sit with the engine idling I can see some light smoke (or some type of vapor) coming out of the end of the hose.

Is this normal? I always racked it up to just being a trait of the 6.2 and not having the enclosed CDR system on it. I'm concerned that maybe it's a sign of engine issues.

It's mainly an off-road rig and gets trailered so not a whole lot of miles put on it but it will probably run at least 6 hours non-stop on the trail when I do take it. It appears to run perfectly normal with no obvious power loss and doesn't get hot or anything even during sustained WOT operation (like trying to get out of a mud hole or up a slippery hill), and I haven't noticed any coolant in the oil or vice versa.

 

[tRustyK5]

I'd think it's pretty normal. There is bound to be some amount of blow-by in any engine, which is what it sounds like to me. You just have it venting to atmosphere instead of routed back to the intake.

Any reason you didn't just chuck another CDR on it? I know they're spendy, but there should be plenty of spares or good used ones kicking around CK5 with all the M1008's and M1009's being bought and parted...

Rene

 

[6.2Blazer]

I'd think it's pretty normal. There is bound to be some amount of blow-by in any engine, which is what it sounds like to me. You just have it venting to atmosphere instead of routed back to the intake.

Any reason you didn't just chuck another CDR on it? I know they're spendy, but there should be plenty of spares or good used ones kicking around CK5 with all the M1008's and M1009's being bought and parted...

Rene

At the time I couldn't find any (NAPA, Autozone, Advance Auto, Auto Value, etc...), plus I was concerned about the fact if it failed again it's really hard to tell unless you specifically go looking for the issue.

 

[MaxPF]

All engines have blowby. Since diesels don't have air throttles and have higher compression than gassers they always have a lot more blowby. Worse yet, since they don't have manifold vacuum there is no way of having a positive crankcase ventilation system like a gas motor, where fresh air is introduced at one side and helps sweep the blowby out. The CDR system is really a poor substitute. What is needed is something like a tiny roots blower that evacuates the crankcase of vapor through a PCV valve (with clean air being admitted to the opposite valve cover just like a gas motor) and discharges the vapor into the intake manifold to be burned. Such a system should be able to generate 15-20 inches of vacuum, so no separate vacuum pump would be needed.

[crazy idea]
Another idea, which I might try, would be a venturi in the air inlet duct. It would generate progressively more vacuum as the engine RPM increases. A smaller booster venturi could be used to generate more vacuum at low RPM for vacuum accesories. Who knows, it could actually work, and no mechanical pumps would be needed
[/crazy idea]

 

[AJMBLAZER]

I have a source for some CDR valves if anyone wants one. They're the military version that the CUCV's and HMMWV's got but I know the civy truck CDR fit mine so they should fit your trucks.

 

[Drey]

I had a breather hose on my K10 like that and it had plenty of vapor and oil come out of it. If you look close to big rigs the majority of them have something similar also.

 

[maynardogle]

Well..according to the shop manual, the CDR valve is actually supposed to pull a couple inches of vacuum into the crankcase, which is good for emissions and to gasket prevent leaks. I suppose a direct vent to atmosphere will also prevent pressure from building in the crankcase, but with no emissions benefits since the oil vapor is not going down the intake. My CDR valve dumps quite the oily mess into my intake. My engine has 175,000, and burns a quart every 1500 so there is probably a good amount of blowby occurring.

 

[AJMBLAZER]

Ever changed out your CDR valve?