Need some advice on my 92 460 f250. 165000 miles, runs great but uses about a quart/500 miles. Compression: 2 cylinders @140, 6 @ 150. Hot Oil pressure is 45 @ idle, 65-70 @2000 rpm. I've replaced leaking seals other than the rear main. Some people tell me to pull the heads and have them rebuilt with new guides and seals while others say that doing this may cause more oil loss by increasing blow by past the rings. I'm not sure when it's too late in an engines life to have a valve job done. Any thoughts? Thanks.

 

I had the same question when I had a valve job done on my 302. Your oil pressure is good and compression is on the low side, but is still ok. What I was told by my mechanic is that excessive oil consumption through the rings is due to people cleaning the mating surfaces with scotch brite pads. I was told if the engine is in decent shape and the job is done right, excessive oil consumption isn't an issue.

 

Compression can be good but the oil control rings are not. They're probably caked with gunk, if that's the case...running it hard is the only way to clean them out without a tear down.

It's not uncommon for a grandpa truck to consume oil for this reason; it's never run hard.

I wouldn't bother doing a valve job unless you perform a leak down test first and confirm the valves to be worn. Smoke on startup is a tell tale sign of valve seals leaking.

 

^agreed. You might try hooking up a trailer and working the truck hard for an afternoon. Oil with good detergents help, and a sea foam oil treatment may help too.

How is the truck used? How do the plugs look? Is one hole consuming most of the oil or is it even? If you remove the oil fill cap with the engine running, is there pressure, nothing, or vacuum at the opening?

Also, static compression readings spark debate on forums at times, when people focus on the number itself. There are a lot of variables. I'd be pretty happy to see 140psi, but I live at 7200' above sea level and have a cheap gauge. I look for differences across cylinders more than anything. A leak down test will tell you more anyway.

 

I imagine something like seafood should clean out the rings a bit. Doing a leak down test is a good idea, but there is certainly going to be some wear on the valves.

 

Would that be shrimp or lobster or? Sorry I couldn't resist.

 

Appreciate the responses. Truck is used for work, hauling wood, trailers, etc but not worked overly hard. It smokes a little once started but I don't see any once it's warmed up. What could a scotch bright pad do to the block that would cause oil consumption when prepping it for new head gaskets?
I know a long block may be in order but I hesitate because I've had bad reman engines which ran far worse than what I've got now. I did replace the pcv valve and associated plumbing. I don't have a leak down tester. I'll check the oil fill for blow by. Appreciate the help.

 

Maybe some whale oil is needed.

 

I honestly have no idea how a scotch brite pad would mess it up but that's what I was told. Personally I would probably dump some cheap high mileage oil in and keep running it as long as it still runs good.

 

Ahhhh.. Opinion time...Lol

 

I had my heads redone on my 460. It didnt change oil consumption at all. It burns a quart of oil every 50 (yes, 50) miles. I know I have bad oil control rings on at least 3 cylinders. Id bet your valve guides and seals are probably ok, and since your consumption isnt crazy like mine, a good cleaning/run hard procedure as others suggested may help. Mine had the "run hard" procedure for 250k miles, hence why it does what it does now lol.

 

Amazed that thing still runs worth a damn. Hope you have some cheap oil in your area.

 

The original engine in my truck had a broken oil control ring on one hole, burned a quart of oil every tank or two of gas. I ran it like that for 80k miles, and who knows how long it was like that before I bought it. About every 3-5k miles I had to swap in a fresh #8 spark plug. It ran fine, so I just went with it. I was pretty young too. What eventually forced me to do something was so much carbon built up on the exhaust valve of #8 that it wouldn't fully close and compression went to 55psi.

It's amazing how much oil is slung on the cylinder walls while the engine is running.

 

If it runs might as well just keep going. Oil is cheap if bought in bulk. I'm surprised it didn't ping or misfire like hell. Then again it seems to take a hell of a lot to make these engines not run very well.

 

"Quart every 50 miles" wow. Mines not that bad after all. What's is the reason 15/40 oil was recommended? Do diesel oils have more detergents?