Rebuilt engine smokin' up a storm

Raindem

Veteran Member
Jun 3, 2012
173
Sonoita, AZ
OK, finally got a chance to do some more work. Here's an update.

Changed oil & filter. This is the first oil change since the rebuild. The old oil was thick and black, but otherwise free of debris or metal shavings. Cut open the oil filter and all I found was a little gritty sludge in the paper. So the engine is not disinigrating.

Cleaned & regapped the plugs. Same condition as previously noted (most had wet oil on the threads and a dry black coating on the electrode). I'm thinking of going to a hotter plug.

Retorqued the intake manifold.

Leaned out the carburetor. I know it's running rich and I didn't want any rich condition black/gray smoke obfuscating the diagnosis.

Started her up and waited for it to come up to temp (remember, it never smokes when cold). While waiting I noticed that #7 plug wire was arcing to ground right at the boot. Upon inspection I saw that there was a small tear in the boot, probably from taking the wires on & off a hundred times. Checked out the rest of the wires and 4 of them had similar damage to the boot and wire #4 was also visibly arcing to ground. So I made a temp repair with silicone and electrical tape. New wires on the shopping list. BTW, those wires ARE new. They're expensive Bosch wires and I'm a little disasspointed in how quickly they failed.

Started it back up and checked the timing. Still at 8 degrees where I initially set it.

Took a vac reading. When the engine was cold the Vac was steady at 16. When it warmed up the needle floated between 15 & 16. That's low. Does it make a difference that I'm at 5,000 ft. elevation?

Once it warmed up I got the blue smoke again. But it's not nearly as bad as it was on the 1st day. It's not bellowing smoke now. It's lightly puffing it out. But it's still there and it's definately blue.

I'm going to put a couple hundred more highway miles on it to see if that changes anything. After which I'll re-do the compression test. And of course pick up a new set of wires.
 

grasmo

Veteran Member
Dec 21, 2005
896
tallahassee, fl
boogie said:
You definitely have a problem with the seals but, it should not smoke as bad as you say even if it had no seals on at all....unless your guides are really shot.

did you check the ring end-gaps?
 
Last edited:

cmonson

Veteran Member
Apr 7, 2006
4,134
Calgary, Alberta
Your rings should seat within the period of the cam break in.

I am still leaning towards your guides are bad. For the couple hours to remove the heads, I would invest that time rather than anything else.

You have a problem that should be fixed unless you want to deal with a smoker and constant oil top offs.
 

Dogwater

Veteran Member
Dec 23, 2010
926
SanAntonio Tx
Here's my guess, broken piston ring or rings. Now I may be wrong but if it doesn't start smoking until its warmed up, seems as thou engine is cold, piston are cold an rings so you would have everything the same temp. A broken ring could be sealing some what. When the engine warms up ever thing expands, cylinders,pistons an so on but a broken ring will loose its seal against the cylinder wall. Do a compression check cold an hot. Just guessing...
 

Raindem

Veteran Member
Jun 3, 2012
173
Sonoita, AZ
grasmo - yes. All gaps were within spec

cmonson - I've heard cases where an engine took several hundred miles to seat the rings. I hope mine is one of those. In any event if I have to pull the heads I'll just pull the whole engine since there are a couple other things I want to do while it's out.

Dogwater - yeah, I was expecting to find pieces of ring in my oil.
 

cmonson

Veteran Member
Apr 7, 2006
4,134
Calgary, Alberta
Your engine is likely not burning oil when cold up as your oil is thicker.

An engine should not take several hundred miles to seat rings, unless the rings were chromoly or stainless.

Seeing that you had valve issues (ie possible binding), perhaps this put a lot of wear on you guides.

Either way, you have an issue. Pull the heads first, if you can't verify the issue, then pull the shortblock out.
 

Raindem

Veteran Member
Jun 3, 2012
173
Sonoita, AZ
OK, took it for a nice long highway drive and we definitely have a pattern here.

- At high speeds (60+) there is NO smoke, whether steady or accelerating.

- At medium speeds (40-50) if I decelerate I'll get a little smoke out the back.

- At medium or low speeds, if I decelerate and then immediately accelerate I get a huge cloud of blue smoke. Even a very slight modulation of the gas pedal will produce a cloud of smoke.

- Whether I'm coasting, accelerating, or decelerating, the smoke is worse the lower the speed, down about 10 MPH.

- Regardless of what speed I'm at, or how bad it's smoking, I can almost immediately clear up the smoke by flooring it.

So with this additional information...rings or guides?
 

Raindem

Veteran Member
Jun 3, 2012
173
Sonoita, AZ
cmonson said:
You may have already clarified this...

by some off chance are your valve covers not baffled for your PCV valve?

Yes, I'm strongly leaning towards guides at this point. The valve covers are stock OEM, and properly baffled.

Quick question... would a leaking intake gasket cause the same symptoms?
 




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