Suggestions or tricks to reduce blow-by?

[Cheaper Jeeper]

Anybody got any? My 4x4 duallie is condensing a fair amount of oil vapor into liquid oil residues in the intake. I'm a little worried about what it is doing/going to do to my turbo. I've seen pictures of erosion from water/**** injection systems installed upstream from a turbo and I wouldn't think the condensed liquid oil would be much better for the blades.

Naturally I'd like to reduce the blow-by for other reasons too - like the fact that it is burning up the oil. I've already cleaned the CDR really well. I'm thinking of enlarging the air hole in the back side of it a little so the diaphragm can close a little faster/easier. Also wondering about installing some kind of oil trap that could let it drain back into the engine.

I haven't checked compression yet, so I don't know how bad the rings are. Is there even a decent chance that they're just gummed up? Any suggestions on products to try to free them up if they are? I'd like to put off doing a rebuild for a while if I can.....

 

[93_E_350]

Hey Cheaper,

The CDR does not close until you get above 2000 rpm, so like mine yours probably never closes. I had replaced my CDR and increased the small hole you speak of – basically removed the paint which increased the hole times 2. Overall I don’t think it did much. I run 5w 40 shell RT synth oil which may become airborne a little easier but once it gets down a half qt it stays there and really doesn’t use much after that. I don’t have a turbo on mine so I can’t test it my self but have you tried disconnecting the CDR and plugging the holes or reducing the hole on the inlet side of the CDR so it can’t suck so much oil out? The reason I ask is my brother in-law has a 99 psd that’s drinking 4 qt’s a week through the turbo - according to the stealership… Are there seals that would let that much oil escape from the turbo, if so maybe it’s a turbo issue?

93

 

[Agnem]

Your best bet is to get creative with a road draft tube. I'll have to snap a pic of my N/A Moosestang intake, so you can see what the intake should look like.

 

[Cheaper Jeeper]

Hey Cheaper,

The CDR does not close until you get above 2000 rpm, so like mine yours probably never closes. I had replaced my CDR and increased the small hole you speak of – basically removed the paint which increased the hole times 2. Overall I don’t think it did much. I run 5w 40 shell RT synth oil which may become airborne a little easier but once it gets down a half qt it stays there and really doesn’t use much after that. I don’t have a turbo on mine so I can’t test it my self but have you tried disconnecting the CDR and plugging the holes or reducing the hole on the inlet side of the CDR so it can’t suck so much oil out? The reason I ask is my brother in-law has a 99 psd that’s drinking 4 qt’s a week through the turbo - according to the stealership… Are there seals that would let that much oil escape from the turbo, if so maybe it’s a turbo issue?

93

I don't think the oil is escaping through the turbo, since it it pooling up in the intake tube leading to the turbo. I'd think airflow into the turbo would keep it from getting out of the turbo and into the intake tube. My CDR should be closing, at least on the highway, because the way I'm geared 2000 RPMs = 60 mph, 2200 RPMs = 65 mph, and 2400 RPMs = 70 mph. Also, when I open the oil filler there is a pretty constant stream of oil vapor coming out. Don't know that there is much pressure, or even all that much airflow, but there's a pretty steady stream of visible oil vapor.

I thought about the road draft tube agnem, but my thinking was that if it is going to be pushing that much oil vapor out, I might as well be burning it as fuel insted of wasting it onto the road! On the other hand, without the suction of the CDR, maybe it won't push so much through the tube. Any ideas on a way to make a road draft tube with a "trap" to return the oil to the crankcase?

 

[smokin_stroker00]

take the oil out

 

[Cheaper Jeeper]

take the oil out

Ummm.......yeah.......

 

[Exekiel69]

As Mel already said, put on an rdt, that way You will not get oil in the turbo nor the intake. Now You want to point that hose away from the engine compartment or everything will have a oily film covering it (You can figure how I know ) You can follow the frame rail to either side using 1" OD hose.
Mine has a lot of blow by but it only has 40k on this engine (sig) also Darrin's new engine have a similar problem, You can always pull the valve covers and the a look maybe the valve seals are the problem if the comp test doesn't point out anything.

 

[Cheaper Jeeper]

Well guys, the news isn't very good at this point. Before dinner I pulled all the glow plugs and started testing compression. Only got the PS bank done before the wife called me in for dinner, but I was pretty dissapointed with the results

1&2 were both 350 psi, 3 was 320 psi, and 4 was 360 psi.

IIRC the compression should be above 400 psi, right?

I'm thinking of giving some Rislone or Restore a shot & see if maybe the rings are just gummed up. At this point I can't see where I have much to loose....

 

[caterpillar]

What i did on my pickup was take a hose and fitting and run the blow by down out the bottow for the truck, you get wierd looks cause of the oil vaper at stop lights but oh well no biggie, I figure its what they do on tractors so i'll do it to my pickup

 

[Cheaper Jeeper]

What i did on my pickup was take a hose and fitting and run the blow by down out the bottow for the truck, you get wierd looks cause of the oil vaper at stop lights but oh well no biggie, I figure its what they do on tractors so i'll do it to my pickup

Yup, that's the RDT or Road Draft Tube that Exekiel69 and Agnem are suggesting....

 

[6.9poweredscout]

seesh and when i had the crappy nissan diesel in my scout we were trying to ELIMINATE the road draft tube and go to CDR's, now it's backwards! WILL THE CONFUSION EVER END???!!!
i think i'll be ok with the REbuilt 6.9 i'm building for the scout.

-Jon

 

[Exekiel69]

Well guys, the news isn't very good at this point. Before dinner I pulled all the glow plugs and started testing compression. Only got the PS bank done before the wife called me in for dinner, but I was pretty dissapointed with the results

1&2 were both 350 psi, 3 was 320 psi, and 4 was 360 psi.

IIRC the compression should be above 400 psi, right?

I'm thinking of giving some Rislone or Restore a shot & see if maybe the rings are just gummed up. At this point I can't see where I have much to loose....

I would worry if one cylinder where much lower than the rest but if all have similar # only says the engine has some use.

 

[Agnem]

That's what I'm thinking. It's more important that they are within 15-20% of each other than all of them being high. Did you take your readings with the engine hot? That's also a requirement if you want to go by the book.

 

[Cheaper Jeeper]

Nah, I was taking the readings with the engine dead cold - hadn't even been started in 4 or 5 days. It would be pretty hard to take them hot. With the time it takes to pull off all the turbo intake stuff and the GPs, it would be have cooled down quite a bit no matter how warm it was when you started!

 

[MIDNIGHT RIDER]

Excessive blow-by is what finally pushed me to swap in the Cummins.


Mine got so bad that other truckers would comment to me about it on the radio.

The engine ran strong and started easier than any other glow-plug engine I ever dealt with.

For the last few years, the blow-by got bad enough that I could wipe fresh oil out of my nose, after climbing a grade, and a white fog would pour out from under the truck.

There is nothing that can be done about blow-by other than rebuild or replace; anything else is only a short-lived band-aid fix.