White smoke at highway speeds

[Pos94obs]

I have a 1994 C1500, it's got the 5.7 and the 4L60E. Its got a new transmission, maybe 2000 miles on it. Anyways when I go on the highway (which is once in a blue moon because of this issue) my truck starts to spit white smoke from the exhaust. Not enough to leave a thick cloud, but enough to be noticeable. It starts around 60 mph. Doesn't affect the driving too much, just worried it might be a symptom of a bigger problem. Also idk if this is important but I have a small oil leak but not enough to cause major problems, just makes me refill oil once every 2-3 weeks

 

[Sean Buick 76]

It sounds like the engine is burning oil under load, normally it’s worn out rings and or worn block cylinder walls.

 

[Erik the Awful]

Or PCV issues. Do you have the stock valve covers with PCV baffles, or aftermarket?

 

[Pos94obs]

Or PCV issues. Do you have the stock valve covers with PCV baffles, or aftermarket?

I'll be honest, I have no idea, I'm pretty sure they're aftermarket valve covers because they're chrome. I got the truck from another guy and he didn't give much info. It has long tube headers if that matters

 

[Road Trip]

Or PCV issues. Do you have the stock valve covers with PCV baffles, or aftermarket?

I'll be honest, I have no idea, I'm pretty sure they're aftermarket valve covers because they're chrome. I got the truck from another guy and he didn't give much info

Greetings Pos94obs,

Here's a photo showing the factory valve cover PCV valve baffle that Erik was referring to:

You must be registered for see images attach

(credit: current ebay auction)

Unfortunately most of the aftermarket valve covers don't have this, and when the rpms come up
the oil splash from the nearby rocker arms gets sucked into the PCV valve, and from there into
the intake manifold. You really want a baffle with this factory level of air/oil separation in place. (!)

Of course, visible smoke normally (but not in all cases) is broken out as follows:

* Blue: Oil
* Black: Too rich A/F mixture
* White: Exhaust system condensate steam (cold). Coolant into exhaust. (hot)

NOTE: Some have reported white exhaust from large amounts of raw fuel from
bad injectors? I haven't seen this personally, but if so that's a *lot* of fuel.

****

I share the above in order to ask you to keep careful track of your oil & coolant consumption.
How many miles per quart of oil? 1,000 miles/QT (or better) is considered non-ideal but
healthy enough. Anything below 500 miles/QT needs to be investigated.

How many miles per pint of coolant? Any non-zero answer needs to be investigated asap.

****

At the very least you should remove the valve cover with the PCV valve plugged into it and
see if you have a air/oil separation baffle. Bonus points for taking a photo of what you've got
and post it here.

It goes without saying that the best-case scenario would be to find no baffle in your chrome covers,
you find a set of factory covers in the local treasure yard, clean & install them, and your smoke on
the highway disappears. If this happens, it's a cheap & easy fix...and won't be the first time that
this has happened.

For what it's worth --

 

[95burban]

I bet it’s the valve covers

 

[Pos94obs]

Greetings Pos94obs,

Here's a photo showing the factory valve cover PCV valve baffles that Erik was referring to:

You must be registered for see images attach

(credit: current ebay auction)

Unfortunately most of the aftermarket valve covers don't have this, and when the rpms come up
the oil splash from the nearby rocker arms gets sucked into the PCV valve, and from there into
the intake manifold. You really want a baffle with this factory level of air/oil separation in place. (!)

Of course, visible smoke normally (but not in all cases) is broken out as follows:

* Blue: Oil
* Black: Too rich A/F mixture
* White: Exhaust system condensate steam (cold). Coolant into exhaust. (hot)

NOTE: Some have reported white exhaust from large amounts of raw fuel from
bad injectors? I haven't seen this personally, but if so that's a *lot* of fuel.

****

I share the above in order to ask you to keep careful track of your oil & coolant consumption.
How many miles per quart of oil? 1,000 miles/QT (or better) is considered healthy. Anything
below 500 miles/QT needs to be investigated.

How many miles per pint of coolant? Any non-zero answer needs to be investigated asap.

****

At the very least you should remove the valve cover with the PCV valve plugged into it and
see if you have a air/oil separation baffle. Bonus points for taking a photo of what you've got
and post it here.

It goes without saying that the best-case scenario would be to find no baffle in your chrome covers,
you find a set of factory covers in the local treasure yard, clean & install them, and your smoke on
the highway disappears. If this happens, it's a cheap & easy fix...and won't be the first time that
this has happened.

For what it's worth --

This could not have helped more honestly, thank you so much, I'll be sure to check sometime soon. I love ya man