Bronco script valve cover oil consumption

[Mikes79Bronco]

Just put a new engine in and took it out for its first long ride over the weekend ~200 miles and when I was checking the oil yesterday I was almost 2qts low. I verified the oil before I left so I know it was lost during that trip and no puddles or leaks. Right now I'm pretty certain that its just pulling the oil through the PCV, the valve and hose are full of oil & the intake has some oil in it as well. At least I'm really hoping this is where its going. I ordered a catch can that I'm going to use to verify that it is or isn't going through the PCV.

Any one else having issues with Scott Drake small block ford covers and oil consumption through the PCV? I've read of a few others having these issues on other sites but I haven't seen a solid solution yet. One guy was modifying the PCV baffle to make it larger but never posted a follow up.

 

[Brush Hog]

I run those valve covers with no issues. 2 qts seems like a lot of
Oil to get pulled out through PCV. Might be some other issues. Is your PCV connected to your carb or intake manifold?

 

[Mikes79Bronco]

I run those valve covers with no issues. 2 qts seems like a lot of
Oil to get pulled out through PCV. Might be some other issues. Is your PCV connected to your carb or intake manifold?

I agree it seems like a ton to get pulled though that quickly. But searching the Internet I don't seem to be the only one with this issue with these covers, even to this extent of oil consumption. So I am crossing my fingers that this is my issue because obviously it's the cheapest & easiest problem that this can be I pulled the sparks plugs last night and all of them had oil on them. Planning to do compression and leak down tests tonight.

The PVC goes directly to the carb.

 

[ba123]

Your valve covers cannot create an oil consumption issue.

If there is oil in your pcv, the pcv is either faulty or you don't have the system properly set up.

Generally speaking, you need one spot for air pressure to come out, and another for fresh air to come in and balance the crankcase pressure.

Maybe post a pic of your engine installed and everything hooked up?

You could try PCV on one valve cover and a regular breather on the other to let air in. That might do the trick.

 

[ba123]

I just did a search for carb pcv and found this scematic. might help.

 

[joebronco73]

It looks like the negative (fresh air) side of the PCV system has a breather/filter on it, based on the photo of the engine on a stand. Unless the PCV is incorrectly routed, this shouldn't be causing an issue. This may seem trivial, but had the engine been run prior to this drive?

 

[Brush Hog]

Yes definitely needs the breather tube on the fill cap side. I had to run mine to the air cleaner like that diagram. A breather cap allowed too much pressure to build up. Don’t know if that was a function of my engine or the new valve covers but my old bent up steel ones didn’t have that problem.

 

[Mikes79Bronco]

Your valve covers cannot create an oil consumption issue.

If there is oil in your pcv, the pcv is either faulty or you don't have the system properly set up.

Generally speaking, you need one spot for air pressure to come out, and another for fresh air to come in and balance the crankcase pressure.

Maybe post a pic of your engine installed and everything hooked up?

You could try PCV on one valve cover and a regular breather on the other to let air in. That might do the trick.

I'll snap some pics tonight. I have the fill cap / breather that comes with them on the drivers side cover and the PCV valve in the passenger cover going directly to the Edelbrock PCV port on the front of the carb.

"It’s a relatively well-known issue with the Drake Cobra valve covers that the baffle acts as an oil storage container and the funneling of air flow allows a lot of oil to be sucked through the PCV. In my instance, I had visible oil in the intake plenum after just 10 minutes of idling and 1/2 mile of driving."

That quote is from this thread:
https://www.vintage-mustang.com/thr...r-baffle-issue-my-potential-solution.1200768/

Baffle design or lack of baffles can create oil consumption through the PCV, just not sure to what extent, this seems excessive. But I've read a lot about these valve covers and this issue and the only conclusion that I'm coming to is that is a real issue with these covers for some people OR there is something else at play maybe bad PCV setups or valves or something. I have read multiple posts of people going through oil this quickly through the PCV with this cover.

It looks like the negative (fresh air) side of the PCV system has a breather/filter on it, based on the photo of the engine on a stand. Unless the PCV is incorrectly routed, this shouldn't be causing an issue. This may seem trivial, but had the engine been run prior to this drive?

Yes you are correct, drivers side has breather cap, passenger side has pcv valve. Yes the engine was ran and went through a break in before this. It was a quart low before but I had a dipstick tube leak and I thought maybe with the filter taking an extra half quart it wasn't too alarming to me the first time.

Yes definitely needs the breather tube on the fill cap side. I had to run mine to the air cleaner like that diagram. A breather cap allowed too much pressure to build up. Don’t know if that was a function of my engine or the new valve covers but my old bent up steel ones didn’t have that problem.

Interesting, what issues were you having that lead you to adding that tube to the air filter? Do you know what cap you ended up using to do that?

 

[ba123]

That is an interesting baffle design how it’s cupped. If all is set up properly, it should not be an issue but I can see if things aren’t perfect that this might make it worse.

If it were me, I’d simply make a new baffle or flatten that one out. It just needs to be a flat piece, nothing special. You could prob even drill a couple small drain holes in the current one that are far enough away from the opening to let the oil drain, but simply bending it flat would do the job. Most baffles are just flat, at least every one I’ve ever seen.

Obviously just make sure you have clearance from your rockers but if flat, you should.

 

[Mikes79Bronco]

That is an interesting baffle design how it’s cupped. If all is set up properly, it should not be an issue but I can see if things aren’t perfect that this might make it worse.

If it were me, I’d simply make a new baffle or flatten that one out. It just needs to be a flat piece, nothing special. You could prob even drill a couple small drain holes in the current one that are far enough away from the opening to let the oil drain, but simply bending it flat would do the job. Most baffles are just flat, at least every one I’ve ever seen.

Obviously just make sure you have clearance from your rockers but if flat, you should.

I'm probably going to just make a new flat baffle, I just want to confirm that this is where my oil is going first and I was hoping other people on here had dealt with this before.

I think I read somewhere that the baffle design was to help with the clearance issue with these covers and roller rockers. I'm not sure if they changed the design on these at some point. I have a set of cobra covers that I got with another engine that I assumed were Scott Drake covers but after comparing them last night they do have a different baffle and pcv setup. So either they changed the design or the other cobra covers that I have are from somewhere else. I'll post some pics later.

 

[Oldtimer]

Mike,
If you pull your valve covers, post a picture of the baffles, and note which is driver & passenger side if they have different baffle designs.

 

[Brush Hog]

I'll snap some pics tonight. I have the fill cap / breather that comes with them on the drivers side cover and the PCV valve in the passenger cover going directly to the Edelbrock PCV port on the front of the carb.

"It’s a relatively well-known issue with the Drake Cobra valve covers that the baffle acts as an oil storage container and the funneling of air flow allows a lot of oil to be sucked through the PCV. In my instance, I had visible oil in the intake plenum after just 10 minutes of idling and 1/2 mile of driving."

That quote is from this thread:
https://www.vintage-mustang.com/thr...r-baffle-issue-my-potential-solution.1200768/

Baffle design or lack of baffles can create oil consumption through the PCV, just not sure to what extent, this seems excessive. But I've read a lot about these valve covers and this issue and the only conclusion that I'm coming to is that is a real issue with these covers for some people OR there is something else at play maybe bad PCV setups or valves or something. I have read multiple posts of people going through oil this quickly through the PCV with this cover.


Yes you are correct, drivers side has breather cap, passenger side has pcv valve. Yes the engine was ran and went through a break in before this. It was a quart low before but I had a dipstick tube leak and I thought maybe with the filter taking an extra half quart it wasn't too alarming to me the first time.


Interesting, what issues were you having that lead you to adding that tube to the air filter? Do you know what cap you ended up using to do that?

Crank case pressure build up. Was having dip stick popping out when driving wasn’t sounding/running properly. After some research realized the breather cap was too restricted. Used one like this added fitting to air cleaner ran hose between them.

 

[Pops68]

I'm probably going to just make a new flat baffle, I just want to confirm that this is where my oil is going first and I was hoping other people on here had dealt with this before.

I think I read somewhere that the baffle design was to help with the clearance issue with these covers and roller rockers. I'm not sure if they changed the design on these at some point. I have a set of cobra covers that I got with another engine that I assumed were Scott Drake covers but after comparing them last night they do have a different baffle and pcv setup. So either they changed the design or the other cobra covers that I have are from somewhere else. I'll post some pics later.

Have you thought of swapping the valve covers with your other set and seeing if the problem still exists doing a similar drive???

 

[Mikes79Bronco]

Mike,
If you pull your valve covers, post a picture of the baffles, and note which is driver & passenger side if they have different baffle designs.

I haven't pulled the covers yet but from looking in the holes I'm pretty certain the baffles match the picture below.

Crank case pressure build up. Was having dip stick popping out when driving wasn’t sounding/running properly. After some research realized the breather cap was too restricted. Used one like this added fitting to air cleaner ran hose between them.

Thanks, I got it back together and running tonight and verified that I have vacuum on the fill tube. Its a light vacuum that's not enough to read on the vacuum gauge but I can feel air going in the port not coming out. I also put a vacuum gauge on the dipstick tube with everything together and got no reading.

Have you thought of swapping the valve covers with your other set and seeing if the problem still exists doing a similar drive???

The cobra set that I have has a crack in one of the covers so I can't use those. But I do have a stock stamped set that I can pull off another engine and try, which I do plan to do once I verify weather or not this is actually my issue. I have a catch can ordered that should be here tomorrow, I'm planning to get that installed and take it for a drive and see what happens. I just want to be certain that this is my issue so I know if I should be digging deeper or not.

I did find a small leak on the back of the drivers valve cover, its dripping onto the header and burning off so I am loosing some oil there. But there's no way leak leak dumped that much oil that quickly and it wouldn't explain why all of my plugs were covered in oil. Also found that the bottom of the header flange on cylinder 8 is wet with oil but I'm not sure if if its leaking from the exhaust port or coming from that valve cover leak. If its coming down from the valve cover I can't find the path that its taking, there doesn't seem to be a wet path between the two.

 

[Mikes79Bronco]

I ran out of time tonight so I didn't get a hot compression or leak down test done. I did do a cold compression test though. I stuck a bore scope down all the holes and all of them had black burnt looking oil inside them except 8 but 8s plug had the most black build up on it. I know the hot test will show higher numbers but the results seem pretty inconsistent and low for a fresh rebuild?

Cylinder 1	125
Cylinder 2	135
Cylinder 3	125
Cylinder 4	140
Cylinder 5	110
Cylinder 6	130
Cylinder 7	120
Cylinder 8	135

 

[joebronco73]

I stuck a bore scope down all the holes and all of them had black burnt looking oil inside them except 8 but 8s plug had the most black build up on it

This and the possible exhaust port leak makes me wonder about your rings or valve seating, but how's the oil pressure while at idle and while cruising?

Also, I've got a set of the same valve covers sitting in my garage. I can see how the pcv baffle could collect oil and cause some pcv leakage:

 

[Oldtimer]

Looking at joebronco73's photos, the baffel design is different for the two valve covers.
Which baffle is for PVC and which is for fresh air source?

 

[nvrstuk]

What Old Timer said... I would assume that the deeper baffle should go on the side that goes to the carb base to try to keep the oil farther away from the path of least resistance which is vacuum drawing the oil to the carb base.

 

[DirtDonk]

The deep baffle “chimney“ is the oil fill side. The shallow baffle is the PCV port.
At least that’s how the ones I’ve seen were set up.

 

[fluffybunny]

The deep baffle “chimney“ is the oil fill side. The shallow baffle is the PCV port.
At least that’s how the ones I’ve seen were set up.

I have the cover with the chimney on the passenger side. No issues for me so wondering if swapping them will help you.