Tips for blowby

[Whitaker717]

Hey guys like the title states does anyone have any good tips for blowby? I did Cruisers Modification and have all new Napa Vac harnesses. Really don’t want to put an oil catch bottle in there. It is seeping into my air box and I have some oil coming out of the filler cap in the valve cover. Just seeing what guys have done and if anything has worked. Thanks

[cruiser54]

Have you changed the rear grommet with the plastic tube yet?

 

Dorman 46005.    https://cruiser54.com/?p=121

[75sv1]

I use the Valve cover off a 93-95 ZJ. It has the latter CCV grommets and fittings. I use the latter Tube and fitting to the manifold. Also, the FelPro rubber gasket. I do the Cruiser  Tower mods too. 

[gogmorgo]

Make sure the vacuum lines are good from intake manifold to the valve cover. There’a two PCV lines, the one pulls from the valve cover into the intake manifold. The one from the air box is clean replacement air and should be flowing the other way, from air box to valve cover, so if it’s oiling the filter either the other line isn’t sucking properly (leaking or plugged) or else there’s enough blow by to overwhelm the system. 
If the vacuum lines are all good, if it sat for a while or the maintenance history is questionable you might have some stuck rings that’ll come back if you shoot some penetrating oil down the spark plug holes and let it soak. It’ll smoke like a bastard when you first fire it back up but might reduce your blow by. 

[Whitaker717]

On 12/8/2023 at 6:04 AM, cruiser54 said:

Have you changed the rear grommet with the plastic tube yet?

 

Dorman 46005.    https://cruiser54.com/?p=121

Yes I have. Its the most tight fitting of all of them Cruiser

[Whitaker717]

On 12/8/2023 at 9:01 AM, gogmorgo said:

Make sure the vacuum lines are good from intake manifold to the valve cover. There’a two PCV lines, the one pulls from the valve cover into the intake manifold. The one from the air box is clean replacement air and should be flowing the other way, from air box to valve cover, so if it’s oiling the filter either the other line isn’t sucking properly (leaking or plugged) or else there’s enough blow by to overwhelm the system. 
If the vacuum lines are all good, if it sat for a while or the maintenance history is questionable you might have some stuck rings that’ll come back if you shoot some penetrating oil down the spark plug holes and let it soak. It’ll smoke like a bastard when you first fire it back up but might reduce your blow by. 

All those hvac lines are new Napa ones. It did sit awhile but this is my second used engine. I may try the penetrating oil tip though. 

[Ωhm]

Not trying to be a smart a$$ here, but a filthy air filter can allow manifold vacuum to enter the air box.

[cruiser54]

Another thing I've seen is a clogged vacuum fitting in the intake manifold. 

[Whitaker717]

1 hour ago, Ωhm said:

Not trying to be a smart a$$ here, but a filthy air filter can allow manifold vacuum to enter the air box.

I try to keep mine as clean as I can but the edges get soaked. Then I flip it around till it gets soaked. 

[Whitaker717]

11 minutes ago, cruiser54 said:

Another thing I've seen is a clogged vacuum fitting in the intake manifold. 

Which hose is that cruiser? You have a picture. Can I just blow it out?

[cruiser54]

It's the metal fitting on the intake manifold. Pull the hose off and poke a wire into the fitting to get the carbon out. 

[Pete M]

compression numbers?

[AZJeff]

1 hour ago, Pete M said:

compression numbers?

I was gonna ask this too.   The crankcase ventilation system can handle blow-by to a certain level, and then after that, it's too much, and the usual symptoms show up, like oil out the dipstick tube, leaky distributor, oil soaked air filter, etc.

 

Tell us how healthy your rings are with a compression test.

[Whitaker717]

On 12/9/2023 at 9:25 PM, AZJeff said:

I was gonna ask this too.   The crankcase ventilation system can handle blow-by to a certain level, and then after that, it's too much, and the usual symptoms show up, like oil out the dipstick tube, leaky distributor, oil soaked air filter, etc.

 

Tell us how healthy your rings are with a compression test.

I have never done that. Is it hard to do? Is there a write up somewhere on how to do that?

[Whitaker717]

On 12/9/2023 at 8:05 PM, cruiser54 said:

It's the metal fitting on the intake manifold. Pull the hose off and poke a wire into the fitting to get the carbon out. 

You have a picture of which hose Cruiser?

[AZJeff]

41 minutes ago, Whitaker717 said:

I have never done that. Is it hard to do? Is there a write up somewhere on how to do that?

Here is nice short video on how to do a compression test:

Compression Test

[cruiser54]