440 mag smoking

[PLUM70GTX]

Engine rebuild has less than 5k on it. Previous owner had it done so I am out of the loop on details of the rebuild.

Passenger side tail pipe smokes at idle after car has completely warmed and been driven. Definitely oil smoke.

Does not smoke at start up.

My first thought was valve seals, but I am told it would smoke a lot during start up.

Any thoughts of where to start diagnosing.

 

[jason lewis]

Run a leak down test.Possible rings have lined up on one or more cylinders,a broken ring.Pulling oil in from the intake sealing surface.Pull the intake and valley pan and set the intake on and use feeler gauges to see how the intake sets on the heads.Which is to say if the intake is setting flush with the heads.It can pull oil from from the bottom of the intake ports.My .2 cents.

 

[lewtot184]

Run a leak down test.Possible rings have lined up on one or more cylinders,a broken ring.Pulling oil in from the intake sealing surface.Pull the intake and valley pan and set the intake on and use feeler gauges to see how the intake sets on the heads.Which is to say if the intake is setting flush with the heads.It can pull oil from from the bottom of the intake ports.My .2 cents.

this is good advice.

 

[PurpleBeeper]

Run a leak down test.Possible rings have lined up on one or more cylinders,a broken ring.Pulling oil in from the intake sealing surface.Pull the intake and valley pan and set the intake on and use feeler gauges to see how the intake sets on the heads.Which is to say if the intake is setting flush with the heads.It can pull oil from from the bottom of the intake ports.My .2 cents.

I agree.... excellent advice. Leak down test first & maybe check the plugs for oil while doing it. If you pull the intake, maybe look for signs of oil seeping in on the bottom of the intake runners.

 

[bigmanjbmopar]

bad valve guide?

 

[gtxno1]

Valve guides or seals usually smoke during decel

 

[badlite]

Valve seals smoke worst on startup.

 

[PLUM70GTX]

Update on this idle smoke issue.

1. Fouled plug
2. Found compression on that cylinder was 11 pts lower than the rest of cylinders. 109 PSI vs 120 PSI on other 7.
Could be time for new rings.
3. When I bought it we did a fresh oil change with 10W-30. Weight too light according to my mechanic. Changed using 20W-50 with Rislone Zinc additive.

No smoke, runs great.

 

[69roadr]

No smoke, runs great.

changing the oil fixed it?

 

[AR67GTX]

I once (1987 to be precise) bought a BB Chevrolet with few miles on a rebuild that went through about 4 quarts of oil just getting it home from a 300 mile drive on the Interstate. Once I changed the oil, it dried up and still runs good 30 years later - no smoke, decent compression and leak down figures. I think the interstate drive seated the rings. Sometimes a change in oil can do strange things - probably only to a recently rebuilt motor that may not have been broken in completely. It may have something to do with the type of rings too.

 

[1967coronet]

I have to comment on the oil change also, I have never brought it up because I figured everyone would think I was nuts. LOL

One of my pickups 2000 ram with 360, has a little over 100K on it. will normally use a qt of oil in 1000 miles.
One oil change I did we were out of 10 - 30 at the shop, so I stuck 5 qts. of 5 - 30 in it same brand of oil as the 10 - 30 I normally use. The same day my pickup was putting out oil smoke. I thought for sure something internal had worn out / broke , ect.

I a few days later switched it back to 10 - 30 just to see if it would help and all symptoms & smoke went away.

 

[AR67GTX]

I have to comment on the oil change also, I have never brought it up because I figured everyone would think I was nuts. LOL

One of my pickups 2000 ram with 360, has a little over 100K on it. will normally use a qt of oil in 1000 miles.
One oil change I did we were out of 10 - 30 at the shop, so I stuck 5 qts. of 5 - 30 in it same brand of oil as the 10 - 30 I normally use. The same day my pickup was putting out oil smoke. I thought for sure something internal had worn out / broke , ect.

I a few days later switched it back to 10 - 30 just to see if it would help and all symptoms & smoke went away.

I know the feeling. But, it sometimes happens

 

[Richard Cranium]

https://www.youtube.com/watch?v=wVOa3xhl0bg