Oil blow by

[truckin 79]

In my 79 I have been getting blow by into the air cleaner. I don't drive the truck much it is just my junkyard hauler. I have heard all kinds of things from worn rings, excessive crankcase pressure from carbon build up to bad pcv valve. The truck does not smoke on initial startup but after sitting in junkyard park lot for a couple hours it will smoke for about a minute. It does use oil but I think that is from a oil pan leak that is seen on driveway. Anyone dealt with oil blow by and found a good solution?

[Pontiac1976]

Well you have to try to pinpoint oil leaking in to or from. As you said you have oil in the cleaner maybe check clean or replace PVC & or the rubber tub might be clogged or tub sucking in the sidewalls need new same style tub9 reinforced) A compression test may help tell you if the bores/ or rings are wearing out. It may be time for gaskets& hoses tubs at the girl's age. I'm sure other can give more advise.

[Getter-Done]

I have bought and driven so many trucks like this.

I was trained by the best
I was lucky in my Younger years.

They not only showed me how to Build a Hot Rod.
They showed me how to keep A Well Used one Running.

So here is my Well-Educated option on running (Well Used) Trucks.

#1= The valve cover has a Hole in It. That is for pouring oil in it.

#2= I do Not Believe in (Snake-oil) cures for pour in treatments.
With that said Lucas Oil Treatment helped a truck of mine last a year with a rod making a Noise.

# 3 = This is Probably the most Important. If you have time to take the Valve covers off, You need to make sure the drain back holes are clear ,These are the ones that let the oil drain back to the pan.
They are in the Front and Rear of the head.

Just my 22 Cents.

[Dead Parrot]

For an occasional use truck, if it is otherwise running well enough to do the job, don't worry too much about some blow by or oil leaks. Just make sure you have a couple bottles/cans of oil in the truck to make good any leaks.

That said, make sure the PCV valve is good, the hose is good and clear and the carb fitting is clean. The carb passages for the PCV gasses can get clogged and limit the effectiveness of the PCV system. Spraying some carb cleaner into the PCV fitting will sometimes clean things up a bit.

A common source of oil loss is bad valve cover gaskets.

Another possibility is worn valve seals.

You can spend many hours and a lot of money chasing oil leaks and blow by and not make the truck much better at its job.

[truckin 79]

Yeah that is true I have to remember that this almost 50-year-old truck is going to have problems and I should just put up with them. Like dead parrot said as long as it keeps running and driving I should be happy. I guess I will start with valve covers and see where that goes
Thanks for all the advice

[RustyPile]

Originally Posted by truckin 79

Yeah that is true I have to remember that this almost 50-year-old truck is going to have problems and I should just put up with them. Like dead parrot said as long as it keeps running and driving I should be happy. I guess I will start with valve covers and see where that goes
Thanks for all the advice

Read the replies again.. All, including myself, have said to start with the PCV system. Check the hoses, the little filter inside air cleaner housing and the PCV valve itself.. Start there and then move on to the valve cover gaskets. If you don't make sure the PCV system is functioning properly, new V/C gaskets will soon start leaking again.

[truckin 79]

I checked the PCV valve by the standard shaking it to see if it rattles, it did check. I checked the hoses and didnt find any holes or obvious cracks. I replaced the rubber ring on passenger side metal tube and added new air cleaner filter. I was going to replace valve cover gaskets anyway as I currently have cheapo chrome valve covers. I recently found some thick aluminum Chevrolet valve covers but need to add some baffles to them first.
Slowly trying to eliminate one thing at a time

[RustyPile]

Shaking the valve only determines whether it's clogged or not, says nothing about how well it performs.. PCV valves are cheaper than valve cover gaskets. Buy one along with those gaskets.

[Getter-Done]

Originally Posted by truckin 79

I checked the PCV valve by the standard shaking it to see if it rattles, it did check. I checked the hoses and didnt find any holes or obvious cracks. I replaced the rubber ring on passenger side metal tube and added new air cleaner filter. I was going to replace valve cover gaskets anyway as I currently have cheapo chrome valve covers. I recently found some thick aluminum Chevrolet valve covers but need to add some baffles to them first.
Slowly trying to eliminate one thing at a time

The most important thing you need to look for when you pull the valve covers / Is to make sure the drain holes in the front and rear of the Cylinder Heads are clear. If these holes are clogged it will cause oil to go places that are not Normal.