I've got an old '79 F250 with a 460, an old farm truck that I bought and have been getting running again. After essentially a major tune up, and replacing a few things, she seems to run great - except for some major oil issues that have started...

A few months back one of the heater hoses blew, and she was driven home about 50 miles until it just over heated and refused to continue running. She was pushed home, and let sit over night - I expected her to not start at all let alone turn over, but she fired right up with out any problems the next day.

Recently, I've been noticing some major oil leakage, it turns out that it's not really a 'leak' per say, but that there is way to much back pressure and it's forcing the oil out the dip stick and/or the breather/PCV valve. I replaced the PCV valve (the only part not replaced with the tune up) and the new one I noticed had the infamous milky substance on it when checking it the last week after some cold nights, the original one didn't have this. The radiator was a little low, but nothing major - maybe 1/2 gallon to 1 gallon worth, a couple of inches below the 'mouth' of the radiator.

I'm getting ready to tear her down, if nothing else to just clean her up, and replace the exhaust manifolds with headers - as she has sat on someone's farm for years (wasps nests every where). My question is if the milky substance, along with the back pressure indicates a blown head gasket, cracked block or simply just perhaps some messed up 'clogged' passages or something maybe?

As a side note, besides the oil issue she runs great - she just likes to suck the gas at 70mph (3k + rpm) is the only problem I have seen, no knocking - nothing. When first starting her up, she does blow out a good deal of white smoke, but after that it's clean and doesn't smoke at all. Any ideas of what I'm in for?

 

Driving it overheated like that could have scored the cylinder walls and pistons which would lead to excessive blowby and cause the oil to blow out of the dipstick tube.
I hope it's not that because that's a complete teardown and rebuild.

 

That sucks.

An easy way that works most of the time to tell for a blown gasket is to start the engine cold with the radiator cap removed and watch for bubbles.

Another is with engine off, use an adaptor for each spark plug hole, bring the repective cylinder to TDC and connect the adaptor to an air compressor. Same thing look for bubbles.

Or beg, borrow, rent a cooling system tester.

Other than that, make sure the breather on the opposite valve cover isn't restricted.

Josh

 

Thanks for the input guys, it turns out the problem (so far) are totally shot valve seals, so the major oil leak has actually been coming from the header gaskets..

I've run into a couple of things though, 1st is the PCV setup on this guy - online, manuals, oriellys, autozone, etc.. all say that this guy should only have 1 PCV valve. I've been doing some reading on PCV systems, and it sounds like this should be a closed system - where one side connects to the carb/manifold with a PCV valve, and the other connects straight to the breather? This thing had 2 PCV valves from the get go - one going to the carb, the other the breather. Should it only have 1 and could that have caused the blow back with the oil and dipstick?

Second, I've torn down the valves and all, the manual mentioned nothing about this (at least what I can tell) and with all the oil and gunk I nvr noticed anything until after soaking the rocker arms in cleaning fluid - but it turns out they have numbers stamped into them 1~4? I have no idea which ones came from where, except for which side - the driver side has everything 1~2, while the passenger has 1~4 - are these various thicknesses or something?

BTW - the head gaskets appear fine, ran a compression test and all the cylinders are between 120-140 So far it just looks like these valve seals are the problem as long as I can get it back together, heh.

 

Yes, your truck should only have one PCV valve. It should be on the passenger side. The driver's side should have a hose that goes directly from the valve cover to the air filter housing and hook to a breather filter inside the a/f housing. Don't know if this would cause your oil problem or not, but I doubt it. Regardless though, hooked up like you described wouldn't allow the crankcase to vent properly.
The rocker arms are all the same. It's best to reinstall them in their original location because of wear patterns but it's nothing fatal if they get mixed. You could always take them to an automotive machine shop and get them refaced if you wanted.
Make sure the oil return channels in the heads are clean and not plugged up with gunk and trash from the deteriorated valve stem seals.

 

Awesome, thanks mike for verifying all that

 

I'd do a cylinder psi check first. If they are consistent then remove the intake and look down inside the ports. If the back of the valves are getting gummed up then I'd try a new intake gasket. Sometimes a bad overheat on a big block will start it leaking.

 

Another thing you might consider. FE's pump way too much oil up into the heads. It's very easy to restrict the oil flow to the head with a pair of Holley carburetor jets. You just insert them into the oil galley in the head. No drilling or tapping is required.
The first picture shows the jet in place, I used a #70. The second picture shows that plenty of oil will still flow. This is using a cordless drill to run the pump.

 

Thanks all, after getting everything together again - setting up the PCV system the right way has helped the engine run 100% better 98% of the oil leak has been stopped as well, it seems as though the blow back coming from the dipstick was from the screwed up PCV valves

Although I still have a leak it's coming from the bell housing, assuming it's the rear main seal? In which from what I've been reading, it may be a catch22 - it's a pain but doable because it's a 2 piece setup on the 460's and you only need to drop the pan/rear main to get to it. Although at the same time, I've been reading (from this forum) that those seals go out all the time - and a lot of people are just saying to not bother with it if it's not too bad - when idling, it may drip once every 45 seconds to a minute?

On actually replacing the seal, I've looked into doing this before - I need to jack up the engine, put it on blocks between the frame and the motor mounts and then I can get to to the oil pan to remove it. The one question I would have is do I need to remove the exhaust as well? The drivers side (stock) goes right under the pan, and it looks like it would be a pain even if you even could get it out. I need to replace the exhaust headers as well, as they are completely shot - should I just wait and replace everything at once, or can I get the pan dropped easy enough?

 

Dang, I must be gettin' senile!
Forget my post #8. For some reason I was thinking it was an FE not a 460.
Glad things are looking up for you and it doesn't look like it was anything major.