Excessive blowby

[malsup83]

I am having excessive blowby. My air filter is getting covered in oil and I decided today to take off the breather hose going from the air box to the crankcase. It seems to me there should be a vacuum here and keep it from going this route.

Would this be the signs of a bad pcv valve?

Also, the oil in the breather hose is getting milky. I'm hoping it's condensation from the weather change and my high humidity area. My drive to work only takes about 15 minutes and I know everything isn't getting heated up enough.

I've seen posts of people getting rid of the breather tube and putting a small breather filter in its place.

Once I get the blowby issue fixed I'm going to add a cold air intake.

 

[crazykid1994]

Pcv may be plugged up. start the truck and put your finger over the breather line and feel if it’s got any suction. Should be a very tiny amount. With the 5.7 you can check the vacuum side as well where it goes into the pcv with the truck off pull the hose and just check inside. Not sure if there is a way to check functionality but i believe it’s built into the intake manifold so not really repairable

 

[ScLeCo]

Maybe you should consider a catch can as well.

 

[malsup83]

The pcv fortunately isn't built in. It costs about 50 dollars. I was thinking catch can too. If I do a catch can, should the oil be dumped back in the crankcase or discarded?

Is the breather filter a good idea instead of having a breather hose?

 

[crazykid1994]

Awesome. I have not played with the pcv on this truck to much but saw it was inside the intake manifold. Good to know it’s replaceable if need be. And catch cans are good. Always dump it out. A lot of it is condensation buildup and fuel vapors as well. I’ve got one on my truck and get about 2 oz every 2000 miles. I don’t run a breather

 

[G-Ride990]

The pcv fortunately isn't built in. It costs about 50 dollars. I was thinking catch can too. If I do a catch can, should the oil be dumped back in the crankcase or discarded?

Is the breather filter a good idea instead of having a breather hose?

Discard the oil in that catch can. You should see what it looks and smells like when it fills up a bit. Not something you want inside of your engine.

EDIT: Crazykid beat me to it, responded as I was typing lol

 

[malsup83]

What is a good brand. Don't want to be too cheap, just don't want to spend a ton. Truck is about to hit 200,000.

 

[crackerjack1957]

I would fine the cause of the blow-by before buying catch can.......catch can will not fix this issue.
I have catch can but I didn't have the blow-by before install.
If new pcv doesn't fix try a can of restore.....if that doesn't work time to trade up, rebuild or crate engine.

 

[malsup83]

What is restore. I have been using seafoam to clean up internals as best I can since I bought it. I've attempted to clean the crankcase with it, put some in with gas, about to put more in, and yesterday sucked about 5 ounces through the brake booster hose. Not as much smoke as I was expecting with the miles it has on it.

This weekend I will check the suction on the breather tube and go from there.

 

[crackerjack1957]

I would not use until you proved the pvc was working.

Restore Engine Restorer and Lubricant is a high performance oil additive that increases compression in older high-mileage engines. The unique CSL formula fills worn areas of the cylinder walls to reduce blow-by and restore compression to near original levels.

https://www.restoreusa.com/index.php

 

[crackerjack1957]

https://cartreatments.com/oil-in-air-filter/

Read this..........
https://www.ramforum.com/threads/oil-on-air-filter.61490/

 

[malsup83]

so, I just went and checked the breather hose. there is no vacuum, I can ever so slightly feel air blowing out of it. does this mean the pcv is clogged.

 

[malsup83]

on another note the I discovered that the temp sensor inside the intake boot that goes to the throttle body looks terrible.

is this the air temp sensor or the intake manifold temp sensor?

 

[Tach_tech]

The breather hose that goes to the air filter box won’t have any vacuum. It’s the breather, not the PCV valve. There will be vacuum at the pcv valve/hose since it goes in the intake manifold. The breather is a vent for the crankcase. The PCV sucks air in through vacuum to get fresh air into the crankcase while the breather side is to vent crankcase gases out, it’s a cycle. That’s the simplest way to explain it.

If you do a lot of spirited driving some oil will get pushed out through the breather, it’s a normal occurrence. However if the PCV valve isn’t functioning properly then excess pressure can build up which will cause oil/moisture to get pushed out the breather.

A catch can may help but it is installed on the PCV side, not the breather.

 

[pacofortacos]

At idle it would be normal on most engines to have just a bit of vac. on the breather hose - should have at least enough to hold a piece of paper against the hose - if the PCV is functioning normally.

 

[crazykid1994]

The breather hose that goes to the air filter box won’t have any vacuum. It’s the breather, not the PCV valve. There will be vacuum at the pcv valve/hose since it goes in the intake manifold. The breather is a vent for the crankcase. The PCV sucks air in through vacuum to get fresh air into the crankcase while the breather side is to vent crankcase gases out, it’s a cycle. That’s the simplest way to explain it.

If you do a lot of spirited driving some oil will get pushed out through the breather, it’s a normal occurrence. However if the PCV valve isn’t functioning properly then excess pressure can build up which will cause oil/moisture to get pushed out the breather.

A catch can may help but it is installed on the PCV side, not the breather.

At idle it would be normal on most engines to have just a bit of vac. on the breather hose - should have at least enough to hold a piece of paper against the hose - if the PCV is functioning normally.

I’m with paco on this. The breather is to let fresh air in the crank while the other side is there to pull the air out. Should always have a small vacuum on the breather side under idle to show the pcv is working. I’m suggesting a new pcv and a catch can as well after. I run one I bought from billet tech. Moes performance sells them. Not cheap but worth it in my opinion

 

[Tach_tech]

At idle it would be normal on most engines to have just a bit of vac. on the breather hose - should have at least enough to hold a piece of paper against the hose - if the PCV is functioning normally.

True, it’s very minimal though, nothing like engine vacuum though.

 

[Tach_tech]

I’m with paco on this. The breather is to let fresh air in the crank while the other side is there to pull the air out. Should always have a small vacuum on the breather side under idle to show the pcv is working. I’m suggesting a new pcv and a catch can as well after. I run one I bought from billet tech. Moes performance sells them. Not cheap but worth it in my opinion

Brain fart. I had the flow reversed in my head for some reason. The minimal vacuum at the breather port will only be present during high vacuum conditions though like idle,cruise or decel. During moderate to low vacuum is when the PCV valve does its work venting gases back into the manifold. During this time crankcase pressure will increase and can cause the pressure to be pushed out of the breather port, which is why oil reside may be seen on the filter sometimes. It becomes even worse once you start getting into forced induction.

 

[malsup83]

Strange system. I'll get pcv tomorrow. And the obvious air filter

Ill grab an air temp sensor too.

 

[Tach_tech]

Strange system. I'll get pcv tomorrow. And the obvious air filter

Ill grab an air temp sensor too.

The intake air temp sensor you’d probably get away with just cleaning it, unless you really want to replace it.