Smoking Problem

[63rexC10]

Okay, here's the deal... I've been pulling my hair for a couple weeks on this problem. I have a 350 sbc, Holley Contender intake manifold PN300-36, Edelbrock 1406 600cfm, HEI ignition, ramhorn exhaust manifolds and a TH350. Unknown mileage on the motor and tranny. The motor is out of an 83 Blazer.

Originally my carburetor started fuel dumping, but I rebuilt it and now it's fine and the engine is running 20" of vacuum. Added a fuel pressure regulator set at 5.5 psi.

After I rebuilt the carburetor then I started seeing smoke out of the exhaust and it is bluish white. Compression check results showing 155 psi +/- 5 psi. All cylinders within 6.5%.

I Removed the PCV and added a breather, that didn't change anything. Checked the transmission line to the carburetor and that is bone dry also.

When I rebuilt the carb, I changed the cap, rotor, plugs and wires. However, when I did the compression check I found all my plugs to be black and sooty looking.

It seems like the longer I let the motor idle the worse the smoke gets when I rev the engine and let it back down. I've been leaning towards valve seals and guides, but am unsure that all my seals would just go bad at the same time. Also, the smoke can get pretty thick, which means my valve seals would have to be pretty shot to blow that much smoke.

I figure I could replace the heads, but am skeptical that the problem is something else. So I have been kicking around the idea of just grabbing a 290/350 sbc from Jegs or summit, but I am also worried that it might be some easy fix that I am missing.

Engine ran beautiful until the fuel dumping issue and I would appreciate any suggestions regarding other things I can check and possible solutions. Especially since Cherry's Jubilee is in a few weeks!

Thanks for the help! This site is awesome because of all the information provided by its members.

[dwcsr]

Oil may be thinned out or the oil is staying in the valve cover and running into the guides. Take off the Valve covers and see if the oil is being trapped. A leak down will tell you if your burning oil. HAve you changed the oild since you had the carb trouble? Put you PVC bak on. Its there to get the gas fumes out of the pan.

[63rexC10]

Originally Posted by dwcsr

Oil may be thinned out or the oil is staying in the valve cover and running into the guides. Take off the Valve covers and see if the oil is being trapped. A leak down will tell you if your burning oil. HAve you changed the oild since you had the carb trouble? Put you PVC bak on. Its there to get the gas fumes out of the pan.

Sorry, forgot to mention that I put the PCV back after the breather didn't change anything, as I didn't want oil all over the place and I did an oil change after the fuel dumping problem. I'm pretty sure that I'm burning oil, just not sure how or where.

I'll pull the valve covers off and have a look see and I'll post an update tomorrow.. Thanks for the speedy reply.

[ed70]

how much did you drive it with the fuel dumping problem... is your carb ajusted right.... it might be burning to rich...

[cdowns]

do you have baffeled valve covers?? no baffels the pvc sucks oil to burn

[63rexC10]

Originally Posted by ed70

how much did you drive it with the fuel dumping problem... is your carb ajusted right.... it might be burning to rich...

I drove it a couple miles home when it began the fuel dumping problem and the carb is adjusted correctly. I believe that black smoke means it is running rich.

Originally Posted by cdowns

do you have baffeled valve covers?? no baffels the pvc sucks oil to burn

Valve covers are baffled, I actually removed the PCV for a while and the smoking never stopped. So, I think that can be eliminated from the equation.

I've been googling like crazy over the last couple weeks trying to find a solution and so I have worked through these couple suggestions, but thank you both for your responses, I really appreciate it.

[Lee H]

A leak down test will ID an internal engine problem. There are only a few places the oil can be going (ignoring on the ground), past the rings, down the valve guides, sucked past PVC, leaking intake or head gasket pulling oil into cylinder.

[ed70]

my truck did the same thing (my dodge) when i had bad gas in it... turned out to have water in it... or something dont know if it helps.. i ran some heat through it and it ran better... just another idea...

[63rexC10]

Originally Posted by Lee H

A leak down test will ID an internal engine problem. There are only a few places the oil can be going (ignoring on the ground), past the rings, down the valve guides, sucked past PVC, leaking intake or head gasket pulling oil into cylinder.

If my intake manifold was sucking oil from the galley, would I notice on my vacuum reading, and how much oil could my engine consume this way? Just a thought.

[cableguy0]

Its unlikely for the intake to suck that much oil from the lifter valley. It would be a huge vacuum leak and the truck would run terrible. Lots of fuel dumped into the engine is bad. It tends to wash down the cylinders and cause problems with the rings sealing. A few miles of dumping fuel I wouldnt see doing catastrophic damage so long as it was resolved quickly and the oil changed. I would be worried about cylinder washdown causing your problem though due to the fuel. Its the most likely possibility given the circumstances.

[63rexC10]

Originally Posted by cableguy0

Its unlikely for the intake to suck that much oil from the lifter valley. It would be a huge vacuum leak and the truck would run terrible. Lots of fuel dumped into the engine is bad. It tends to wash down the cylinders and cause problems with the rings sealing. A few miles of dumping fuel I wouldnt see doing catastrophic damage so long as it was resolved quickly and the oil changed. I would be worried about cylinder washdown causing your problem though due to the fuel. Its the most likely possibility given the circumstances.

Wouldn't that have showed up on my compression test? I'm not trying to shoot down everyone's suggestions, I'm just trying to eliminate some things. Thanks

[cableguy0]

Normally it would show lower compression. I guess its possible that maybe only the oil rings got hurt. It would still have decent compression. Its all guesses without putting hands on it but with it starting as soon as the cylinders were washed down with fuel Thats the first thing that comes to mind

[63rexC10]

Originally Posted by cableguy0

Normally it would show lower compression. I guess its possible that maybe only the oil rings got hurt. It would still have decent compression. Its all guesses without putting hands on it but with it starting as soon as the cylinders were washed down with fuel Thats the first thing that comes to mind

Just the oil rings... hmmm. That is definitely something to think about. I'm gonna pull the valve covers and intake manifold this weekend. I will be sure to post updates. Until then, I am open to any and all suggestions. Thanks guys!

[Ticker]

Thinking this through, I think cableguy0's got it - as always. If the oil control rings were shot, this would be the symptom. They're fairly delicate, and as noted if they failed it wouldn't show up anywhere on compression or leak-down.

Your troubleshooting approach is sound, and I'd certainly eliminate the valve seals and guides first.

As an aside, if it was the oil control rings it would be fairly simple to replace them - it's a teardown, but just an "in and out" thing.

[63rexC10]

Originally Posted by Ticker

Thinking this through, I think cableguy0's got it - as always. If the oil control rings were shot, this would be the symptom. They're fairly delicate, and as noted if they failed it wouldn't show up anywhere on compression or leak-down.

Your troubleshooting approach is sound, and I'd certainly eliminate the valve seals and guides first.

As an aside, if it was the oil control rings it would be fairly simple to replace them - it's a teardown, but just an "in and out" thing.

I replaced the intake gasket, just to roll the dice, as I didn't have high hopes that it would solve my problem. I'm definitely going to replace the valve seals this week and if that doesn't work, I'm going to order 290/350 crate.

I figure, if I have to pull the motor, might as well bolt in a new one. Then I can tear this one a part and build me a stroker over the next year or so.

Anyways, the valve seals are the last thing on my list before yanking the engine. Keep your fingers crossed

This is going right into my signature as a quote!
If it was the oil control rings it would be fairly simple to replace them - it's a teardown, but just an "in and out" thing.

Easier said than done, at least for me it is. :lol

Thanks again guys!

[Ticker]

Originally Posted by 63rexC10

If it was the oil control rings it would be fairly simple to replace them - it's a teardown, but just an "in and out" thing.

Easier said than done, at least for me it is. :lol

Thanks again guys!

*chuckle* I hear you - but honestly; if you can change a head gasket, you could swap the rings. I never said it was EASY - just SIMPLE

[ya it is a classic]

if your rings did get washed then put a little oil in each cylinder and see if that seals it up for at least a little while.

[63rexC10]

I only have one word for everyone... valvestemseals! j/k
The culprit was the valve seals, I switched them out today and she quit smoking 2 minutes after I fired her up. I am so relieved; however, I was also looking forward to getting a new motor and rebuilding this one into a stroker. I'll probably end up doing that anyways, but at least I can wait a while.

I really appreciate all the help, thanks again to all of you.

[cableguy0]

Thats a big surprise. Usually valve seals dont just go bad instantly like that. Glad it was an easy fix.

[63rexC10]

Originally Posted by cableguy0

Thats a big surprise. Usually valve seals dont just go bad instantly like that. Glad it was an easy fix.

It may have been the fuel dumping problem that washed all the seals clean But yeah, I didn't have high hopes when I started changing the seals. One thing I know for sure is, I'd rather be lucky than good.