smoke on startup?

[ridenrace6]

my 98 5.9 has started smoking on startup, sometimes worse than others and sometimes hardly any smoke at all.
it still runs fine, oil pressure is good and it’s all stock besides the k&n filter, flowmaster muffler, and gutted cat.
my first thoughts are valve seals or possibly rings, anybody have any other suggestions?


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[Yeret]

Blue smoke?

Engine use oil?

 

[Wiggsy72]

I have a 99 5.9, if its the valve seals find a road with a steep hill to drive down and let the engine do the braking. Shift down a gear helps but obviously don’t over rev the engine. The longer the hill the better. Once at the bottom up shift and step on it. If she blows smoke is the valve seals.

 

[dapepper9]

That's not much of a test at all. Better test would be comp check and a leak down test. If compression is good but leakdown test still doesn't look good then it's pretty definitely valve seals.

Also since if it's smoking on startup but not while driving then again probably valve seals. Oil drops down from the valves as the engine cools and the seals return back from their expanded size and that oil collects on the piston. Rings are more likely to smoke while driving.

Valve seals CAN be fixed without removing heads too. Not the easiest thing ever but it's doable

 

[ridenrace6]

yes it’s blue smoke and yes i have to add a quart of oil between changes.
what’s funny is some times it smokes really bad on startup and other times hardly at all but is consistently getting worse i think, however it always quits within a mile down the road or so it seems from drivers seat.
i’ve read elsewhere about a plenum leak causing smoke, can someone elaborate on that as i am not much on the terms and function of certain parts on these newer engines with all the sensors, smog, fuel injection etc. ?


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[Wiggsy72]

That's not much of a test at all. Better test would be comp check and a leak down test.

It’s an easy test without tools. The engine decel causes vacuum through the valve seals pulling oil in if they are leaking which will result in smoke upon acceleration immediately afterward. Its a proven method if you can do it. A compression test of each cylinder would be a given for the piston rings and valve seats.

 

[Okiespaniel]

If it's shootin' the blues on startup it's likely to be valve seals and/or guides. The magnum uses a better seal than the old LA engines but I suppose anything is possible.
I don't recall bad plenums causing start up smoke but your oil consumption suggests it.

A compression test will rule out the rings.
While you can peek into the intake manifold and check for wet or excessive oil caused by a leaky plenum, you can use this test http://dodgeram.info/tsb/2000/09-05-00.htm to determine it.

I'd pop a valve cover and see if there's any pieces of rubber laying on the head. Rubber seals can deteriorate over time.