Oil spraying out of valve cover

[turleydog]

After I run my truck around town, a small amount of oil has been spraying out of this left bank valve cover.

I think this is just a breather? It's not connected to anything.

Pretty sure the PCV valve is on the right bank. It has a tube running back into the carb.

Admittedly, I run this thing around revving the heck out the motor, because it sounds so darn good. Am I just over stressing the motor, and the oil is somehow pressured out of this breater?

I also have a related issue of black smoke coming out of the left tailpipe. This is only on initial startup, or when revving it hard.

 

[Bronco Junkie]

A little oil coming out of the breather is not that big of a deal....that looks to be a little more than I usually see. You may need a new PCV or maybe the breather is saturated?

 

[AZ73]

A little oil coming out of the breather is not that big of a deal....that looks to be a little more than I usually see. You may need a new PCV or maybe the breather is saturated?

I would say both. The breather is saturated because the PCV isn't working/mostly likely blocked so the pressure in the engine looks like it's escaping through the breather. Check your WHOLE PCV line. I've had the port at the intake blocked with carbon so then I replaced the PCV, it still didn't work. I had to clean out the port and put a new line on also.

 

[Timmy390]

Baffle missing from the valve cover........is my bet......

Tim

 

[turleydog]

Ok guys, I am buying a gasket kit tomorrow. Then i'm going to open her up and see about baffle in the valve cover, and blockages in the PCV line.

Question - why would there only be a PCV on one bank of cylinders? Maybe I'm missing something, but how would a pressure relief valve on one bank affect the other bank? I'm assuming the valve covers of each bank are independently sealed systems, and a PRV on one wouldn't affect the other?
Thanks - newby to engines, pretty good with pneumatic/hyrdraulics

 

[Viperwolf1]

The two valve covers are not independent systems. The oil pan and valve covers are all open to each other.

If your PCV valve is working then you have just too much blow by in the cylinders.

 

[KyleQ]

Yup, its a possibility that your rings may be worn out. You could always plum both valve covers to a small accumulator and drain it from time to time - turbo guys do it...

 

[BUCKNBRONK]

looks like ur running the pvc hose strait down infront of the motor off the pass side, or it that a heater line?- it should be hooked up the the carb plate..kind a hard to tell from that 100 yard shot.

 

[AZ73]

There isn't one on both sides because it's a circulation system. As Viper points out, the both banks are actually connected through the oil pan. Think of is this way, when the oil drains down from the rockers, it goes through holes in the head, through the block, and into the oil pan. Air does too. Air come into the non-combustion parts of the engine through the breather to replace the air and blow by getting sucked through the PCV into the intake, The breather is like an air filter. If the PCV (or the line to the intake) is blocked, the interior of the engine gets pressurized from the blow by and tries to escape through the breather. Before you take the valve cover off, test the PVC and lines. Save yourself some time and $$

 

[skerrybronco]

When you take the breather cap out can you not see the baffle right there in the hole, with out taking the valve covers off

 

[skerrybronco]

Here's mine

 

[JustinFro]

I had a similar issue with a little oil leaking out the cap. Turned out to be a missing gasket for the cap. Worth a look.

 

[Jeff10]

Hey Guys,

I hope you don't mind a couple of questions.

The PO for the '71 had the PCV hosed from the passenger side valve cover into the vacuum side of the carburetor. There is a breather cap on the on the driver side valve cover that has a hose connection that ties into the base of the air cleaner.

I changed air cleaner housings with the propane setup. I am debating about running the line to base of the air cleaner as I'll need to install a vent connector at that point. From what I'm reading, the breather on the driver side is for drawing air into the motor and the PCV is for exhausting the air into the intake. I'm just wondering if the air cleaner tie-in is necessary.

I am also curious about fitting the PCV valve into the valve cover. The grommet may just be worn, or possibly the PCV and grommet are mismatched. Any quick suggestions on the correct PCV and grommet for cast aluminum valve covers?

Thanks

Jeff

 

[70_Steve]

I'm just wondering if the air cleaner tie-in is necessary.

I am also curious about fitting the PCV valve into the valve cover. The grommet may just be worn, or possibly the PCV and grommet are mismatched. Any quick suggestions on the correct PCV and grommet for cast aluminum valve covers?

The air cleaner tie-in isn't necessary. But the air being drawn into the driver's side valve cover should be clean. I ran a filtered breather on that valve cover. I guess it worked OK, but since there was a little excessive blowby that the PCV valve couldn't handle, I always had an oil film on that valve cover. If you run the fresh air supply to the air cleaner, any excessive blowby will be sucked into the carb.

I ran cheapy chrome valve covers, and picked up a set of replacement grommets the aftermarket parts isle at the local box auto parts store. If you know the manufacturer of the valve covers, you might search for replacement parts that way.

 

[dave67fd]

Try removing the PCV valve and spray it with carb cleaner while holding one end, cover the other end and shake it well then let the cleaner drain out. Do this a couple of times. The valve should rattle freely. Remove the breather and soak with cleaner several times as well until cleaner runs clear. Air dry the breather befor reinstalling.

 

[Hubba]

Remember PCV stands for Positive Crankcase Ventilation.