Hello all;

I am having a problem with my truck, it is now wanting to burn oil when I pull. I have a 97 with a 460 and a stick. I pull a 10,000 lb fifth wheel with it regularly. The truck has around 90,000 miles on it and has been well cared for. The last trip I took I burnt about a 1/4 inch on the dip stick in 300 miles.

Any ideas as to the cause?

Additional Info;
1. Generally I tow in 5th with the stick. A mechanic friend recomended 4th as it would be better for the motor and trans.

2. I recently had a O2 sensor go bad on a trip. I was just happy to get home with 5.5 mpg. Could I have damaged something?

3. I think it is entering Via the intake due to heavy oil residue in the "rubber tube" that goes to the throttle body. This is after the enterence of the crank case vent.

I am currently running Mobil 1 10(or 15) w50 oil.


Thoughts????

 

Assuming well cared for also means that it wasn't overheated, my bet would be on the valve stem seals. Heat and age will take them out, and any added sludge trapped in a oil return hole let alone part of the seal itself, only compounds the problem.
First things first tho -a compression, or better yet, a cylinder leakage check. This will get to the root of your blow bye issue.

 

The problem apears only when towing. Running around town, it is fine. You are correct, the truck has never been overheated.

 

If it ran that rich you could have scored some cylinders which had the oil washed off or even stuck a ring or two. Compression test.

 

I tore a bunch of those motors apart and 8 out 10 were bad valves .Iwould check there....

 

A compression test will show either bad rings or valves. A a little squirt of oil will tell you which it is.

 

One might think that towing would build extra heat and with slightly worn parts burn more oil, but I still think it's a valve guide issue. Why? Towing with a stick, especially when decelerating, will raise and hold manifold vacuum high causing the engine to drink more oil.
Go out, hit 65MPH, dump it in third with your foot OFF the throttle and look for the smokescreen in the mirror that is sure to be following you. The higher the revs, the more oil you'll be pullin' in.

 

My 460 has almost 190000 on it. I am never under 12000 GVW with it. If I keep the RPMS down I use no oil. If I rev it up I can use a Qt. in under 100 miles.

 

That's very interesting; I wouldn't have thought about that... Maybe that's another reason automatics are recommended for towing over manuals?
(not that I ever abided by the warning! lol)