# Smoke from valve cover breather



## Ohio66GTO (May 19, 2014)

Got the GTO running after swapping out the 455 with a 428. Took for about a mile ride and when I got back I noticed smoke coming from the breather. Let it sit for a couple days and took it around the development which is a shorter ride and no smoke. Sat a couple days and went the same route as the first time, about a mile, and it’s smoking again. Did some research and sounds like it’s blow-by from a bad PCV valve, or worn rings. I shook the PCV valve and it rattles. From what I’ve read that’s good. My question is, is there another way to tell if the PCV valve is good or bad other then rattling? Are there better PCV valves then others? Not sure what brand mine is. Lastly, is there anything else besides the PCV valve or worn rings that could be causing this? Guy I bought the engine from said it was rebuilt recently with very low mileage. Said less then 3000. I kind of question that but it does look fairly new. Had him run it on his stand for about 20-30 minuets without any issues. It’s a 68 block rebuilt to stock he said.


----------



## deanhickey (Apr 6, 2015)

I would start by replacing the PCV valve, as they are inexpensive. If that is doesn't work on to a compression test. There are more knowledgeable people here than myself who are able to give better advise. How much oil pressure do you have on the engine and this may seem like a silly question but how much oil is in the engine? overfilling may be something to look at. good luck.


----------



## BearGFR (Aug 25, 2008)

Do you have both parts of the PCV system installed and working? The hose with the valve attached is only half of the system. The other half should be a tube/hose from one of the rocker covers that usually attaches to the air cleaner and has a filter at that point.

Like in the attached diagram.


Bear


----------



## Ohio66GTO (May 19, 2014)

Thanks for the reply’s guys. I checked the oil level and it was right where it should be. Replaced the PCV valve and it still smokes.
I looked at your picture and I don’t have the hose that goes to the air cleaner. I probably should’ve been more specific when I said rebuilt to stock. What I meant by that was crank,cam. Basically the internals. It doesn’t have a stock air cleaner. The intake is an Edelbrock Torker 2 with a Weber 750 carb. Not sure if it not being stock changes your thinking with that diagram. There is a breather on the passenger side valve cover and the oil filler cap on the drivers side is vented. Here are pictures of how the PCV valve is attached and the breathers on the valve covers. Also a picture of the air cleaner I’m using.
Oil pressure @Startup @idle is 60psi
Oil pressure @180 degrees @idle is 40 psi
Oil pressure @2500-3000 rpm is 65psi


----------



## My65goat (Jul 26, 2017)

Get a leak down tester. It will show if you have bad rings.

A leak down test is one of the most definitive tests. 

Good luck, hopefully it's not a internal problem. ..


----------



## geeteeohguy (Feb 2, 2008)

My65goat said:


> Get a leak down tester. It will show if you have bad rings.
> 
> A leak down test is one of the most definitive tests.
> 
> Good luck, hopefully it's not a internal problem. ..


This^^^. The only accurate way of determining internal engine condition. If you have more than 25% leakdown, and the air is coming from the breathers, it's piston ring wear/fitment.


----------

