I have a problem. I had a leak in a radiator and I had an employee who ignored a temperature gage in a 1991 Ford 460. The result was 2 cylinders toasted, ex-employee and a junk yard engine.

The junk yard engine runs really well. It is stronger, and smoother than the original engine. It is cleaner and just better in all areas but one. There is one problem. With highway running, it loses oil like crazy – 3 quarts a day. Around town- no problem, highway – big problem. So this is what I think. I think that high revs (3000-4000) mean high crank case pressure and high oil flow. The higher pressure and flow and finding away past the pvc valve or a valve seal or an oil ring. Please check my thinking.

There are no leaks that I can see. The radiator is new – no oil in the coolant. I think it is finding its way through the exhaust. I THINK there are only 3 places it can be:

1. Bad valve seals. I think I can replace all the valve seals without removing the head with a spring compressor, some compressed air and time.
2. Bad rings, I guess this would mean I screwed up and bought the wrong engine
3. PVC valve or plumbing is bad? New PVC valve?

How can I tell? If I pull the plugs, and do a dry compression check and the ring/s are shot, compression would be low – right? If I add oil, the compression would improve? – correct???

If the compression is good, how can I figure out if the PVC is failing and dumping oil into the exhaust or the intake OR it is valve seals?

 

#1, yes you can replace the stem seals.
#2, Yup.
#3 A new PCV is cheap, get a new one.

Yup, do a compression check, dry then add oil.

 

Why is this engine turning 3,000-4,000 RPM on the highway? That's way out of a 460's comfort range.

As mentioned, you should start by making sure the PCV and ventilation systems are functioning properly.

 

If you're losing that much oil it will be easy to figure out where it's going. That's a lot of oil.

Pcv stuck open would be oil in the intake manifold, stuck closed would be oil in the intake (between throttle body and air filter). Oil into combustion chamber (bad rings or a missing valve seal [notice I said missing, that's what it'd take to lose that much oil down a valve stem]) would be evident in the exhaust, and burning that much would result in a clogged cat in no time.

 

Hi

There is no tack on the thing, it is 60mph in O/D and it seems to turn faster than the local trips. The local trips are stop and go, 40mph stuff. I really do not know the actual rpms on the highway

 

You can have great compression and still lose oil past the rings. Start by seeing if there's oil on piston tops. For instance, if it's only a few piston tops then it's likely those respective valve seals. If it's all piston tops, it might be the PCV valve.