• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Smoke coming out of oil filler and intake

RNation

RNation

New Member
Messages
256
Reaction score
0
Location
St.Peters, MO
I have smoke coming out of my oil filler tube and the intake (only when the air breather off). The oil filler cap isn't a regular one, I bought this motor from boyces so I'm guessing it's some military cap. But it looks like a miniature keg in shape, and it's a little bigger than an injector in size. But I'm getting a smoke or smog that comes out of it when I shut the truck off. The smoke isn't "bulky" like what would usually come out of the tailpipe. It's more like the smoke that comes off the end of a lit cigarette.

I'm not sure if this from blow by or not. Also I'm not sure how much blow by would indicate a problem.
 
Sounds like blowby, does it smoke a lot with the oil fill cap off and engine running?
 
I know on a gas motor that can be due to water in the oil cooking off. Is it after a long or short run? Is there a white slimy deposit on the walls of the filler tube?
 
Hvae you changed the oil in it ? If you put your hand over the oil fill with the cap off does it seem to have any "pressure" ?
 
It was too dark when I got home to see the smoke so I'll have to wait till in the morning.

No white slimy stuff on the sides of filler tube. I'll test tommorrow on a short run and long run when I can see the smoke.

I just changed the oil the oil 2 days ago, but haven't payed attention to see if it was still smoking after that or not (I didn't know that could make it stop). I didn't notice any pressure with my hand covering the filler tube but it's hard to tell with the fan blowing all that air around.

I did notice that the oil was pretty low when I channged it. I think it was 2-3 quarts low.
 
Is your entire air intake system intact? GM designed it a certain way. Everything up to and including the air silencer must be in place and hooked up. I thought i could "do one better" and delete that restrictive air silencer, so i did. My CDR stopped functioning. Today i tried something and move my hand close to, but not over the open intake tube. With my hand as a slight "restriction" the blowby vanished from the filler tube. Turns out that intake silencer allows for just enough vacuum at idle for the CDR to work properly. Remove it, and there's no restriction, so the engine smokes from the oil filler since the CDR no longer has the slight vacuum it needs to work properly.

I ended up putting the silencer back today and the blowby i thought was "new" almost vanished from the oil filler(back to the very slight almost not visible state it was in when i bought the truck) since the CDR is working correctly again.

It could be something as simple as that.

Lets not forget. Blowby is going to be natural as the engine wears. These engines start life with none, and usually end life with clouds of it. Blowby gives you a general idea of how well your piston rings are sealing against the cylinder walls. The more blowby the engine has, the worse the rings are sealing. Abuse or infrequent oil changes will just make the engine wear, and therefore the blowby, worse.
 
The intake silencer is going to be the air breather right? If so, then I believe everythings hooked up right. Maybe the CDR is clogged or something, or maybe the air filter is clogged?

I didn't know the blow by was from that. That's good to know.
 
The silencer is that big muffler that goes in-between the port up front by the grille for the plastic tubing and the air filter housing. It's held in place by a band clamp and 2 1/2" or 13MM head bolts. The bracket for the air silencer goes down to two exhaust manifold studs and also has a bracket that goes from the silencer holder to the alternator through bolt for stability reasons.

The silencer doesn't cause blowby. It just provides enough vacuum for the CDR system to work correctly and manage said blowby. If that's all intact and you still have a good bit of blowby coming from the oil filler then it's more than the CDR can handle, which means it's excessive.
 
My silencer is missing then. All I have is the air breather with the open port on it, but nothing connecting to that. Perhaps I should find one.

Also I noticed the smoke coming out of the filler tube with the cap off right after i started the truck.

I'm not sure how many miles are on the motor, I'm guessing theres less than 100k though. I bought the drop in motor from boyces and they said they don't know the miles on any of the motors but they say that they dont really see any motors with more than 50k miles but as low as 12k. I've only put on about 8k since I put it in.

Now that I think about it, I don't see why they don't mark the motors with the miles.
 
RNation said:
My silencer is missing then. All I have is the air breather with the open port on it, but nothing connecting to that. Perhaps I should find one.

Also I noticed the smoke coming out of the filler tube with the cap off right after i started the truck.

I'm not sure how many miles are on the motor, I'm guessing theres less than 100k though. I bought the drop in motor from boyces and they said they don't know the miles on any of the motors but they say that they dont really see any motors with more than 50k miles but as low as 12k. I've only put on about 8k since I put it in.

Now that I think about it, I don't see why they don't mark the motors with the miles.
Click to expand...

If it's open you need to plug it with a frost plug or something similar.
 
Maybe I'm calling it the wrong part. The air breather that sits on top of the intake, has a hole (I called it a port) where it looks like the silencer would connect into. I don't plug that hole right? It would cut off the air intake.
 
So you have basically this.

5820_132313027040_612117040_2829802_7281155_n.jpg


That port is where the silencer attaches.

See the U shaped bracket to the left of the air filter housing opening and in front of the A/C box? That's the "hold down" bracket for the silencer. The bottom 1/2 of the bracket bolts to 2 studs on the exhaust manifold.

Odds are that your CDR isn't functioning at idle due to the lack of the silencer. Try this test. Start the engine with the oil filler cap removed and check your blowby. Then bring the engine just off idle(you can do this from under the hood) and see if the blowby vanishes. That's what mine did. There' wasn't enough vacuum for the CDR to work at idle, but there seemed to be enough for it to work off idle and above. I re-installed it anyways. the engine is so much quieter with the silencer on. Now i just have to listen to the rumble of the exhaust, instead of the exhaust and the ridiculous roar of the intake.
 
How do you check the blow by? I think I read some where that you can take a soda bottle with some water in it and a clear plastic tube. Stick the plastic tube over the oil dipstick tube (with dipstick removed of course). Then rev your motor to 2000 rpms and I think the waters supposed to do something. Anyways is the the tutorial I need to follow for the blow by check or is there a simple faster way? I don't have a rpm gauge so i would have to be guessing. Haha...and let me assure you this drywaller doesn't really know what 2000rpms sounds like.
 
I'm going to have to wait a day or two to do the blow by test. We got a couple inches of snow, 18* weather and 24 mph sustained winds. Haha...and to top it off I've lived in florida my whole life except for the past 4 years, so I'm not completely broken in yet.
 
You must log in or register to reply here.
Back
Top