Pressurized Oil Leak - Need a Little Help

[Bostonian1976]

Those of you that saw my truck on Saturday might have seen the newly-developed pressure leak that I got on the way to the event. It seems to have gotten slightly worse. I used 2 quarts of oil just going to the event and back. It seems like the oil is coming out of the cap and blowing through the engine judging by where the oil is ending up (the air filter hose that leads to the carb, the bulkhead by the fuse box, the air cleaner itself on the top half, and the oil fill stem itself, as well as the top of the cap along the rim, not to mention a good portion of the underside of the truck and engine). Has anyone ever had this before, and if so, my question is..........could the engine suddenly start builing up a lot more pressure and blow the oil out of the vented cap?

A few of you saw the truck and noted that the tube at the bottom of the oil filler tube was bolted off, and the whole pcv valve setup was made inoperable by the previous owner, and it might be the cause. The only thing that makes me think otherwise is that the truck never lost a drop of oil (from the engine anyway) before this - so it's strange that it just came out of nowhere. Does anyone know what may have caused this - I know my solution is to put in the proper non-vented fill tube, but I'm still curious why this just started up when the engine was completely dry for 3 years prior to this. Thanks in advance...

[Donnie]

The PCV system pulls vapors from the engine & re-burns them. In order for this to happen the engine has to be open somewhere for air to enter as to allow the vapors to be run thru the combustion process again..I am unsure of your condition, as I haven't all the facts, but would advise you to check that these are working..

[Bostonian1976]

The PCV system pulls vapors from the engine & re-burns them. In order for this to happen the engine has to be open somewhere for air to enter as to allow the vapors to be run thru the combustion process again..I am unsure of your condition, as I haven't all the facts, but would advise you to check that these are working..

yeah it's plugged off - so the previous owner put a vented cap on the oil fill tube and plugged off the tube on the bottom, as well as the entire pcv system. It's run completely fine for many miles like this with zero leaks, so I don't understand the change...

[yorker]

Sounds like blowby, have you lost power? If you have put the non vented cap on the oil fill AND you have a blanked off PVC system then where is the natural pressure from the crank case going to vent? It needs to be able to relieve pressure, and you sound like you have developed too much pressure to boot... :O

[Bostonian1976]

Sounds like blowby, have you lost power? If you have put the non vented cap on the oil fill AND you have a blanked off PVC system then where is the natural pressure from the crank case going to vent? It needs to be able to relieve pressure, and you sound like you have developed too much pressure to boot... :O

yeah - it's got the vented cap but I think that's the source of my oil - ends up all over the inside of the hood (just towards the very rear of the hood and the bulkhead by the fuesbox - as well as the air cleaner tube to the carb.

[Terrys]

I saw the truck saturday, but wasn't sure who was attached to which.
A simple check of compression may give clues that a ring has failed, causing an increase in crankcase pressure. If blowby is the source, you could re-connect your closed breather system, but you'll likely find your plugs fouling pretty quickly. Also check your top cap, atop the valve cover, to see that it isn't completely fouled.

[Bostonian1976]

I saw the truck saturday, but wasn't sure who was attached to which.
A simple check of compression may give clues that a ring has failed, causing an increase in crankcase pressure. If blowby is the source, you could re-connect your closed breather system, but you'll likely find your plugs fouling pretty quickly. Also check your top cap, atop the valve cover, to see that it isn't completely fouled.

Thanks! The valve cover breather has additional holes poked in it by the PO, and seems to breathe pretty well (I can see steam coming out of it when the truck is stopped and the holes are a decent size).

People were noticing that after I went down a good-sized hill in 1st and low range, when I hit the gas I had a puff of smoke from the exhaust. Does that mean it's my valves (someone else suggested that), and would bad valve seats give enough pressure to do this?

It's a mess - I was actually getting oil drops coming in through my front vents driving down the road

[Terrys]

Does that mean it's my valves (someone else suggested that), and would bad valve seats give enough pressure to do this?

Valve and valve seat condition has nothing to do with excessive crankcase pressure. Rings and bore condition have loads to do with it.
Keep in mind, all engines will have a somewhat pressurized crankcase, irrespective of ring and bore condition, but the crankcase breather system, in most cases, eliminates build up of pressures to the extent you are seeing. Normal pressures are vented, through a positive crankcase ventilation valve, through the intake and out with combustion gasses. You engine has had this removed, and using a vented oil fill cap, is allowing pressure to escape the only way it can; up the oil fill.
My guess is you are fast approaching the time when you need to do a bottom end rebuild.

[Bostonian1976]

Valve and valve seat condition has nothing to do with excessive crankcase pressure. Rings and bore condition have loads to do with it.
Keep in mind, all engines will have a somewhat pressurized crankcase, irrespective of ring and bore condition, but the crankcase breather system, in most cases, eliminates build up of pressures to the extent you are seeing. Normal pressures are vented, through a positive crankcase ventilation valve, through the intake and out with combustion gasses. You engine has had this removed, and using a vented oil fill cap, is allowing pressure to escape the only way it can; up the oil fill.
My guess is you are fast approaching the time when you need to do a bottom end rebuild.

sounds like fun

I'm mechanically inclined but have never done one before. Pretty difficult to do?

[Terrys]

sounds like fun Pretty difficult to do?

Nope.

[jp-]

Might it be that something has clogged up in the oil filter area causing the bypass to endlessly circulate? That could raise the oil pressure somewhat.

Or else you may have blown a seal somewhere.

[LaneRover]

Look on the bright side.... ...At least your Rover is a bit more rust proofed!

Brent

[Bostonian1976]

Might it be that something has clogged up in the oil filter area causing the bypass to endlessly circulate? That could raise the oil pressure somewhat.

Or else you may have blown a seal somewhere.

how would I check for that? remove oil filter?

[jp-]

I think it's in the oil filter housing. Don't have the green book handy. Or it could be in the oil pump itself.

Other than that, did you change anything on the engine that you can remember just before the problem started?

[Bostonian1976]

I think it's in the oil filter housing. Don't have the green book handy. Or it could be in the oil pump itself.

Other than that, did you change anything on the engine that you can remember just before the problem started?

nothing whatsoever, except I think I checked the oil on the way down and added a quart (it was fine at that point, but not fine 20 miles later). I've been driving it all summer exactly as is - put a new distributor in last February that needs a few shims in between it and the block (it's Pertronix and there is a slight gap for some reason), but that has been completely dry all summer too