Recently Burning Oil...
 

Hey guys,

I've got a 'new to me' 66 C20 on my hands that recently began burning oil and having some signs of excess fuel burning as well. My truck has the 283 SBC without modifications.

I began noticing the oil burning increasing about a month ago and checked out the PCV valve first, which was working properly. Being new to this truck, I haven't tried much but that and I also replaced the breather cap on the oil fill pipe because I figured the original one wasn't exactly working well.

One interesting thing is that when I was putting new exhaust on it, I realized that the heat riser was stuck in the up position and it may have been that way for years with the previous owner. I knocked it into the down position, which resulted in more flow out the passenger's side exhaust. That seemed like a good thing, but would that play any role in what I'm seeing?

I should also note:

1. It seems to worsen as the truck warms up.
2. When I hit the accelerator quickly to rev it up, it chokes out
3. When it does get a good rev, it blows both black and blue smoke
4. I noticed that the passenger side valve cover gasket began mildly leaking blue smoke in the past week.
5. The engine does not overheat.
6. The oil pressure used to be in the mid to slightly below mid range, but now it is slightly above mid.
7. Blue smoke is being pushed out of the oil cap breather when running.
8. MPG is about 10.

Those are a few observations. The truck seems to run and drive fine, but isn't always fun driving around wondering how much smoke you're going to be blowing at the person behind you.

Hopefully we can get some thoughts floating around to talk about.

Thanks,

Ryan

Re: Recently Burning Oil...
 

My 1st thought is the drain back passages & pushrod openings are sludged up. Pull your rocker covers & take a look. then pull your plugs & see which ones are oil soaked. Sounds like a 283 re-furb is in your near future!

Re: Recently Burning Oil...
 

Sounds like broken rings to me. I would do a compression check and leak down test. Blue smoke coming out of the valve cover is a severe case of blow by. If you were to pull the dipstick while the engine is running will it do the same thing?

Re: Recently Burning Oil...
 

I'll have to do the dipstick check and get back to you. I'll do that.

Re: Recently Burning Oil...
 

I'm going to pull the plugs to do the Marvel Mystery Oil piston soak before anything, just to give it a shot. I'll check the plug state then.

Re: Recently Burning Oil...
 

I checked the dipstick out last night and didn't see any smoke coming out when I pulled it out and the truck was running. Just checking in.

Re: Recently Burning Oil...
 

if you have blue smoke getting out past the valve covers and the oil fill tube in the intake then no amount of engine additive / cleaner is going to help you . the blue smoke you are seeing is a broken oil control ring and old valve seals its time for a tear down

Re: Recently Burning Oil...
 

The reason I said the engine could be sludged up is cause if the oil can't drain down from the rocker area then when it gets to a level above the valve GUIDE then it will run down the valve STEM into the intake area of the head or into the exhaust. Also, when this area is sludged up the PCV cannot evacuate the blow by in the crankcase & excessive pressure builds up. Very few bolts to remove to check this, and there is ALREADY a rocker cover leaking! 283s are old enough to have been run for yrs with non detergent oil!

Re: Recently Burning Oil...
 

Could this be a reason why my oil pressure is now higher than it was a few weeks ago? It was running at a steady 30 all the time in the past, but now it fluctuates between 30 and 45 depending on engine RPMs.

Today on the highwayat 55mph it was 45, but rolling around town it was 30. Any insight on this?

Also, it seemed like after driving it a little while, the oil burn decreased a bit.

Thanks for your help!

Re: Recently Burning Oil...
 

Obviously I want this to be wrong, but I'm prepared for it to be right. It will turn into a winter project.

The only thing I'm wondering is if the engine will have to be pulled out to have work done to it associated with replacing the rings?

Re: Recently Burning Oil...
 

Yes it will have to be pulled .. and a complete rebuild is in order when it's apart you will want to have the valve seats done on the heads too . Because of the crap fuel we are being sold

Re: Recently Burning Oil...
 

Any chance you can hit me with a rough cost estimate on this? Consider that I'll do any labor outside of something that a shop NEEDS to do.

Also, a family member owns a NAPA, so that is going to help too :)

Re: Recently Burning Oil...
 

Assuming you want it done right you're going to need 2 put the engine in the Machine Shop have it hot tanked also having the heads done will be at the machine shop as well I'm not sure what prices are where you live at machine shops and they will fluctuate from shop to shop your best bet is to call around machine shops telling them what you want and getting the best price however I also highly recommend that you do your own research on each machine shop online to see if there are any negative complaints about bad workmanship coming from their establishment sometimes the cheapest isn't always the best route you're going to need to get the heads done the engine hot tanked you may need to bore over a little if the broken ring or rings have damaged the Piston walls so I can't really comment on the cost for that you can get a full set of rod bearings and main bearings for about $200. A double roller timing chain set for like $90.00 rings set $100 the engine gasket kit I've gotten for like $60.00 but you have connections at Napa all those prices I gave you 4 those products are probably going to be reduced because of who you know so again probably not much help to you but it gives you a ballpark this is just my opinion so some may disagree with me and that's okay but in my opinion while you have it all down I would also put a new cam and lifters in it might as well have everything new and have it last you a long time then to use old parts just my opinion I've never really much cared for using old camshaft and lifters on a fresh rebuild

Re: Recently Burning Oil...
 

Based on those numbers and that every part will be at cost to NAPA, that isn't as bad as I was hoping. I was expecting to be told a couple grand.

So basically, this isn't the end of the truck for me like I was thinking it may be. That is good news, because I want to slowly restore this truck, but be able to drive it during that time as well.

Re: Recently Burning Oil...
 

Another idea and maybe a better one is ask how much NAPA sells long blocks for . Because then your getting a engine with a warranty. And it's ready to drop in and go . And you would be a 350 chevy small block .. then you could spend all the time in the world doing what ever you wanted to the original 283 engine and still have a running truck . That is another route

Re: Recently Burning Oil...
 

Don't jump to conclusions.
Your oil smoking might be caused by fuel wash on your rings. Your carb might be flooding(the black smoke). Oil pressure might change due to change in oil viscosity. Oil/fuel mix.
Change the oil and check for fuel in it.

What pcv are you using?
Is it in a valve cover or attached to the road draft connection at the back of the motor?
.

Re: Recently Burning Oil...
 

Geezer,

The PCV valve is mounted on an elbow coming off the carb and the hose coming off the PCV is mounted to the back of the intake manifold. It should be the hole on the far right of this manifold picture:

http://i.ebayimg.com/images/g/JqEAAO...oZh/s-l300.jpg

My first inkling was the PCV valve, so I did some trouble shooting. I first removed the hose from the valve on the back of the carb. That made the engine idle up a little and also idle much smoother. The valve had good vacuum when exposed to the atmosphere from removing the hose.

Due to that, I thought the hose might actually have a clog in it or something. So I disconnected the hose from the other end and took it off completely. The other end was attached to the backside of the intake manifold as far as I could tell. It's back in there under the distributor. I couldn't get to the clamp on the hose so I just took off the actual mount hose mount instead. It was shaped like a dome with a pipe for the house to mount on and a hole in the top of the dome for breathing.

After I took it off, I pulled the hose off and it was not clogged. I actually got a new PCV valve too, so I tried putting it on. I actually let the engine run idle with no hose and no valve on the carb and it idled even higher being it was a completely open system. It idled too high and was popping a little out the pipes.

Anyways, I put the new valve on, and when I pushed the hose onto the new valve, that actually killed the engine. There was probably not enough vacuum to open the valve, so no air was getting to the carb at all. After that, I just put everything back together how it was originally so the truck could still run.

I will say these things:

The truck has smelled 'gassy' from time to time, but I thought it was maybe just due to the tank being right there behind the back seat.

Also, when I quickly hit the gas to rev it up, it hesitates and sounds like it's going to die before actually revving.

Also, there is definitely black smoke that blows out when I do give it a good rev, along with blue. In general, the more I rev it up, the more it smokes blue, but also gets dusty/blackish.

From what I can tell, I'm getting about 10mpg, which I was told seemed low. That would make your idea seem possibly right.

Any thoughts? If I were to let some oil drain out, what would it look like if it had gas in it?

Re: Recently Burning Oil...
 

One thought!
Need some pics.
That dome is the old road draft tube connection. The later 283's that were converted to a pcv used that cap. There's a canister/baffle inside under the intake. It's there to only allow vapors into the pcv. That canister can become clogged up with carbon like stuff if the motor has been neglected and had very few oil changes.

Have you looked in the carb while it's running? Any excess fuel?
Also your stumble could be caused by a lack of initial timing.
What's your initial timing?

Fuel in oil looks like small light colored rivers. Put a little gas in some water in a bucket. Looks the same. And you should smell it on the dipstick.

Your only problem might be a poor pcv system. Carb could be good.
A few diagnostics can save you a bunch of money.

Re: Recently Burning Oil...
 

Geezer brings up some super good points. :metal:

Re: Recently Burning Oil...
 

"Also, when I quickly hit the gas to rev it up, it hesitates and sounds like it's going to die before actually revving." Sounds like the accelerator pump in the carb ....... Another thing that will suck oil and cause blue smoke on an OLDER engine is bad INTAKE valve seals (O-RINGS)

Re: Recently Burning Oil...
 

There was definitely sludge under that dome.

Would a good test be to pull the hose off the PCV valve and go for a drive and watch the exhaust?

Re: Recently Burning Oil...
 

Wouldn't hurt! Might not show any difference. But try anyway.
Plug it off though so you don't get a big vacuum leak.

To see if there's any oil being pulled thru the pcv hose, I've used clear hose.
Bought at the hardware store in the plumbing section. Only a temporary test. Those clear ones soften quicker.

Are you gonna burn us off some pics?

Re: Recently Burning Oil...
 

Geezer, what would you like pics of? I can do that, yes.

Also, you're saying I need to take the intake manifold off to get at that canister, right?

Sounds like I have some projects ahead of me:

Remove valve covers to check for sludged up ports.
Remove intake manifold to check for PCV-related sludge.
Check the look of the oil.
Check the look of the spark plugs.

Those are looking like ones I can do on my own. With the help of a friend I can probably do the compression test and leak down test.

Sound about right?

Re: Recently Burning Oil...
 

Thank you! My brother-in-law and I are prepared to replace the valve seals, which many people are saying is the issue due to more oil burn being present during engine braking.

Re: Recently Burning Oil...
 

Pics of your motor and pcv set up.
Try the clear hose test first. Don't pull the intake yet.

Another thought!
Now that you're diverting all that heat under the intake by closing the heat riser, maybe that's part of your problem. Too much heat causes stumbles and if the oil seperator plate on the bottom of the intake is seperated or cracked you could be drawing some oil in there.