Hey all I know there is a great section on the infamous plenum issues but this question is about how many out there have not had to fix theirs??? I have a 99 heavy 3/4 2500 (8800) with 360 that has 156K on it and as far as I know the plenum has not been repaired of course I have not pulled it off to see but the truck runs great I have not had any O2 issues or fouled plugs and as far as oil useage about a quart between changes 3500-4000 miles, is this possible to run without having a plenum repair? anyone else out there? Thanks for taking the time to read this and answer......

 

Losing a quart of oil between oil changes at 156k miles is not good. Your plenum is either bad or you might wanna do some compression testing... or you have a leak that you're not mentioning. It takes 2 minutes to pull the throttle body and check the plenum. But yes, it's possible to not have a blown plenum.

 

A quart between changes is not good imo. If you cant pull the tb, get a mirror and look insode, or take a magnet and see if it sticks to the plenum going through the TB. Mine had @175k, and my plenum was original and I had a small amount of oil in it, so I never changed it. Transmission went out before the plenum did...lol

 

Let me rephrase on the oil consumption...not quite a quart if I tow it will use a quart but I am gonna look into the plenum and see if there is oil inside anyway I love the old truck and it runs so well and the best part is its MINE!!! no payments!!! The worse part of course is it thinks a lot of the gas I get 10.5 around town maybe 12-13 on the interstate but with 410 gears I guess that's bout right and weighing 8800lbs....thanks for the information guys

 

it doesnt weight 8800 pounds.... thats the gvw. meaning the total weight of the truck cannot exceed 8800 pounds when loaded.

 

thanks for the correction......your right GVWR

 

There are some misinformed people here. Burning a quart of oil in 3500 miles is completely normal and in fact low consumption in the general scheme. Since you are experiencing no adverse effects it sounds like your truck is running just fine and the plenum gasket is not an issue.

 

Burning a quart of oil every 3500 miles is NOT normal. Neither of my trucks burns oil like that. One of them has 140,000 miles and the other nearly 290,000 miles.

 

It is widely known that car manufacturers will not do anything in the way of warranty work / repairs if a car is burning less than 1 liter per 1000 miles, which is deemed "acceptable". This is for a new, tight motor. Think about how many revolutions a single piston makes in 5k kms, multiply by 8. A liter burnt for that amount of miles is not much at all.

 

When they are new, the expect them to burn a bit, till they are broken in good, and the rings have taken a seat. After that though, going thru a quart every 3K miles IS 'excessive'. On a high mileage motor, it doesn't really surprise me. On a newer, low mileage motor? Totally unacceptable.