1995 350ci burning oil

95_2500HD · May 31, 2003

I have a 1995 2500 cheyenne with a 350 that seems to be burning oil under certain driving conditions.

I have noticed a smell my truck makes when:

stopping after interstate driving,

stopping after working the engine somewhat hard (flooring it, pulling heavy load up hill...),

and other similar conditions.

So, what would you guess the problems is? Bad seal?

I am just curious what it is going to cost to fix before I take it to my mechanic.

Thanks

Ryan

MarkD · May 31, 2003

Is it smoking (what conditions)?

How much oil are you using?

How many miles do you have on "her"?

BadBowtie · May 31, 2003

The most typical place for these engines to leak oil is the valve seals. They are not hard to replace, but it will take time. You will need to remove the rocker arms and pressurize the cylinders to hold the valves closed.

Before you just replace them, you could go to a mechanic to see if (1) he has the correct air fittings to screw into the spark plug hole and (2) If he wants to check them to see if they are bad.

Chances are with over 100K they will be. As the rocker pushes down on the valvem it also gets pushed sideways slightly, this causes an elongation in the seal, and allow oil to seep down there, causing smoke. They are also the culprit behind the 'GM Engines That Smoke On Startup Syndrome'

-John

97C1500&84Z28 · June 3, 2003

condition only happens when working the engine hard? probably pcv valve, or bad valve cover gaskets. i'd look at those first before tearing into the heads.

americanmuscleman · June 4, 2003

Another thing it could be is an intake manifold leak on the back of the engine, and when the oil hits the Y-pipe its burning and you smell it.

You'll probably have to comb over the engine to see where its leaking from.

If the smell is coming from the exhaust, if you see faint traces of blue smoke after working it hard, I bet its the valve seals. Try revving it up a little and watching the exhaust. If you see blue smoke as the RPM's drop down to idle, its likely your valve seals. If you see some faint black smoke, thats ok as its likely just burnt fuel.

You could also have a partially clogged catalytic converter, or a bad cat.