Hey guys...been awhile since I've been here =D

I've recently had my engine rebuilt in my 87 F-150. Carburated 302. I had a problem at first with my PCV valve blowing out, and subsequently oil followed it. I got a new grommet, and now it stays in place. Problem now is..it's coming out of my filler cap. It's a chrome vented filler cap with chrome valve covers. I'm afraid to plug it off with a non-vented cap due to my oil pressure. I don't want it blowing out my gaskets or somewhere else.

When I start my truck, I'm at 80 lbs of oil pressure, and by the time it's warmed up (10 mins), it will go down between 60 and 70. I've heard that's good oil pressure, but OTHO it shouldn't be that high. I'm not sure if my mechanic put in a high-flow oil pump or something, but I'm afraid to plug that leak, for chancing that it might find another place to blow the oil out.

It's becoming quite a smoking problem...not to mention it's costing me in oil like crazy.

Thought I'd come here first...what do you guys think? Thanks in advance =D

 

Sounds like the crankcase is pressurized more than normal. Could it be blowby?? What is your compression when the engine is warm?? Is the PVC and hose obstructed??

 

I'll have to go check my hose and PCV valve, but I have no idea about my compression. I'm pretty much a mechanical newb

At least I knew what blowby was

 

PCV and hose are clear...although the PCV looks pretty rough. Parts of it are cracked...they're pretty cheap, I might go get another.

 

Your engine oil pressure has nothing to do with your crankcase pressure.
Sounds like a bad PCV.

 

PCV replaced...still having the problem. It only spits it out when I rev...so I've just been trying to keep it as low RPM's as I can. Any other thoughts?

Oil is Mobil 1 10W30

 

Ok, a few things are not lining up here.

Your truck should have an EFI engine, not a carb. What's up with that?

Your oil pressure is too high. Your mechanic installed a high pressure oil pump. I don't know if it will hurt anything, but that's a lot of pressure.

You must have an aftermarket oil pressure gauge. Did you install it? Why?

The only reason for it to be blowing oil out of the cap like that is because of very high crankcase pressure. The most likely source is from the combustion chamber, which means you probably have a broken, missing, or incorrectly installed ring. This shouldn't happen on a new engine.

A compression check will pinpoint the problem for you. It's not hard to do, but if it's a new engine that your mechanic installed, you shouldn't have to. Take it back and have them fix it. They should cover this under warranty.

Did they rebuild the engine for you? Or did you buy a reman engine from a parts store?

 

Ok...regarding the EFI. It once had EFI on it, and that was a project that another mechanic did for me to take it off, the computer out, and turn it into a carbureted system.

The aftermarket oil pressure guage was put in by my dad long ago (on a different engine). I don't know why he did..he never mentioned why, and I never asked. In fact..up until we changed out the EFI...my old pressure guage also worked, and they were both pretty accurate...so that one puzzled me.

My mechanic was a friend of my dads that used to work for Ford. He built a shop and bought a lift for it, and has started his own business out at his home. In other words...this is not warrantied.

He had the block sent to the machine shop...and I don't remember the exact things he did (it's been over a year now), but I know there was a valve job, honing of some sort, new pistons, rings, and some other things that I can't remember.

The worst part about this all... I just recently lost my job, and my room-mate got her Jeep repo'd, so my truck is a daily driver for both of us. I can't afford to take this to a mechanic to get it fixed...especially if it's going to involve a complete teardown.

Can I do the compression check myself? I assume I would need to go buy a compression tester?

Thanks everyone for the input. This was my mom's old truck, and she recently passed, so this truck means ALOT to me. In that regard...there is nothing I won't do to get this fixed, but at this point in time, I'm very limited on funds to back that up.

 

You need a compression tester.

Remove all the plugs, and take the coil wire to distributor off the truck. Prop open the throttle body so the truck isn't starved for air.

One at a time, plug the compression tester in and crank the engine over. You'll see the gauge climb up as you crank the engine. When the gauge won't go any higher, that's the compression for that cylinder.

Write them all down. On a new motor you should see close to 180psi on each cylinder. On an older engine, lower numbers are fine, as long as the numbers are within 10 to 15 psi of each other.

My guess is that you will find one cylinder with either very little or no pressure. That's your problem cylinder. If the fuel injector is dumping fuel into the cylinder, it will get into the oil and ruin it. If you run it with thinned out oil long enough you will trash the bearings. Although from your oil pressure, it doesn't sound like that's happening.

Let us know the results. It's not complicated, but it does take some time to get to all 8 cylinders.

 

assuming 80psi is correct - thats gonna grind up the soft distributor gear a lot faster.

a high vol pump may or maynot have been used, but a hi-pressure spring was

oil oozing out filler caps and pcv valves (and I bet $5 the CVS breather as well) is a lot of blowby

 

Chrome valve covers. Does the oil fill cap mount on top of one of the valve covers? Doesn't the original valve cover( the one that the oil fill cap goes on) have a baffle to prevent oil from splashing up? Maybe the chrome valve cover(s) is the problem. Also on some older carbureted V-8s, the oil fill cap had a large vacuum hose coming out of it that went back into the intake. Just some thoughts I had.
I may be completely off base here with my ideas.

 

I could change the filler cap so that it wouldn't leak oil...but if I have alot of crankcase pressure, wouldn't it find another place to escape, IE, my valve cover gaskets. It is synthetic oil, on chrome valve covers, nonetheless.

No headway on compression test so far... soon to come.

Question... If I did the compression test, and they were all within 10psi or so of each other, would it be safe to assume I could get a new filler cap and solve the problem? I don't know much about crankcase pressure, etc...

 

If you have that much crankcase pressure, something is wrong with your engine. Putting a different cap on the oil filler is just a band-aid.

 

I have to agree with the others that said you have a blow by problem, connecting a vacuum gauge would verify that real easy. Then yea the compression test.

Sealing the leaks at the valve cover will surely blow a seal someplace else.

If a low cylinder is found adding a teaspoon or two of oil down the plug hole and retesting again will give a indication of how bad it it. If the added oil significantly raises the value it could be a sign the rings just didn't seat properly. If the value does not increase at all it is a sure sign severe mechanical failure. IE: hole in piston, broken rings.....

How was the motor broken in? Was it driven never holding the throttle steady running at one speed? Either accelerating or decelerating for the first 500 miles or so staying under 3/4 throttle? Then 500 of more normal driving but only short burst of WOT? and so on to allow the rings to seat?

I also agree the oil pressure is to high as stated above, could cause it to "float" or "spin" a bearing. To much oil pressure tends to force oil in under the bearings. Causing it to spin with the shaft blocking the oil passage hole through the bearing itself, then running the bearing "dry".

I would definitely check that out before running it much, find out exactly what was installed. A new motor with proper clearances throughout doesn't need a high pressure or high volume pump.