I recently purchased an 89 F250 4x4 w/460, C6 and 3.55 gears. It has 78k original (I'm certain) miles but is burning a quart of oil every 350 miles. The tailpipes are sooty (dry) and there's never any sign of blue/black smoke. I've known the truck since new and am pretty sure it's had good care and maintenance w/oil changes every 5k miles. Why would this thing burn so much oil?? Also, it get's between 8.5 and 10 mpg unloaded while being driven very easily. I wouldn't expect much more, maybe 12. I need some help here experts... What should I check??

Also, a little background:

The truck was driven daily 8-10 miles to and from work (each way) since new.

When I got the truck it would barely heat up past the first bar on the temperature gage. A new 195 degree thermostat and radiator flush improved it some, but it's still only about a quarter of the way into the range of the gage.

Looking into the oil filler there appears to be some sludge build-up on the rocker arms compared to my 95 Windstar w/55k miles that's as clean as a whistle.

Are the problems that appear to be caused by the short trips reversible? Also, I know that short trips are especially hard on catalytic converters. The truck doesn't appear to be lacking power from excess back pressure, but how can I know for sure if the converter is OK? The truck appears to be powerful enough although it seems to be a little less powerful than the 390-4V that was in my 71 4x4.

Your advice is greatly appreciated.

 

You should do a thorough replacement of the PCV system to include a new PCV valve, a new Crankcase Breather Filter,a new Air Filter,and, verify the PCV hose is not restricted as well as the fitting where the hose connects to the intake manifold. The gas mileage you experience is kinda normal for the big 460, maybe some new plugs will really tell the story.
Phillip

 

Im betting the cool engine operation & short trips contributed to the sludge plus like Phillip suggested going thru the Pcv system may alleiviate the oil burning . That engine has a monster 4 core radiator that is designed to keep it cool . Its also possible the valve stem seals may be worn & leaking a little ? Do you notice any puffs of blue smoke on initial start up of the day ? I personally beleive short trips , easy driving is harder on an engine than if the truck was run on a more regular basis .
Paul

 

Thanks Phillip, I'll check the PCV system. Isn't the crankcase vent filter the one that's in the air cleaner box? When I replaced the air filter (with a K&N), seems to me I cleaned it out with some carb cleaner. I'll replace the PCV valve since it's cheap but when I drew vacuum on the existing one it seemed to release OK, and when I pressurized it seemed to seal OK. Not too sure about the hose or fitting though... The plugs were worn but otherwise looked OK, not fouled with oil or gas and not built-up with carbon.

 

Thanks Paul for the advice. I hadn't considered valve guides since, no, there is no smoke on start-up. Like Phillip and you both suggest, I'll check the PCV system. I'm just afraid it might be something worse. It's great to get an older rig (though '89 doesn't seem that long ago)with such low miles, but I guess there's a down side as well. Again, thanks.

 

Thanks Paul for the advice. I hadn't considered valve guides since, no, there is no smoke on start-up. Like Phillip and you both suggest, I'll check the PCV system. I'm just afraid it might be something worse. It's great to get an older rig (though '89 doesn't seem that long ago)with such low miles, but I guess there's a down side as well. Again, thanks.