I have a 1989 model F-Superduty (F450). It has relatively low miles (Odometer says 99,000-its probably 199,000, but the title says exempt because of age). I just bought it and on the trip home (300 miles) it burned 11 quarts of oil. I had a mechanic look at it, and he claims that there is nothing wrong with it other than that it is geared extremely low. The oil didn't leak out; it burned out. I was running the truck 65-75 mph down I-95, and the mechanic says that it is built to be run no higher than 50-55 mph. Is this a reasonable explanation for that much oil to be lost? I would appreciate any insight that you guys can provide.

 

i would say 11 quarts in 300 miles is abnormal. do you have a tach, what was it reading? my f-450 uses more oil, after a few thousand miles on the oil. but normally uses 1 quart per thousand miles. you need a second opinion.

 

The tach was around 2500 pretty much the whole way

 

my mechanic says to keep mine at 2200 or lower, but i don't think 2500 would cause excessive oil usage. do you remember your speed at 2200?

 

11 quarts? Did you add oil along the way, or was it completely dry after 300 miles.

Are you sure you're not overfilling the oil? It should not be over the full mark when checked on level ground a few minutes after shutting it down warm. Full when cold is too much.

The other thing is to clean the CDR and see if that helps. It could be staying open and letting a lot of oil through at high RPMs. Check down inside the intake manifold. If it is coated in oil, that's likely the problem.

 

I agree with the CDR valve. If it can be salvaged then clean it out, but if you see chunks of dried up rubber in the intake, than it should be replaced.

What is your transmission and differenial gearing. My tach will not read above 2600 RPM, and can even snag at those high RPMs ocasionally.

 

i keep hearing as how cleaning the CDR is so important. i removed mine to clean it and there is nothing in it. my truck runs fine and i've driven it 40k miles. i mean my CDR is a hollow pipe, nothing there. nada

 

HJ45: I don't remember what the speed was a 2200 RPM, but it was running fine.
TB91: I added oil along the way. When I stopped on the side of the road when it started smoking, I checked the oil and it was a quart low according to the stick. I'll be honest, I know relatively little about engines so what is the CDR and where is it? I haven't the slightest clue what the differention gearing is. I just know that its geared low. Transmission is a 4 speed with overdrive (5 speed).

 

I think the super duties had 4.88 gears standard and 5.13's as an option.
There i nothing wrong with running at 2500 RPM for extended periods. Trucks with 4.10's and 1:1 transmissions do it all the time. If you are using that much oil, there is more wrong with it than just the CDR. Are you getting excessive blue smoke?

The CDR relieves normal pressure built up in the crankcase. It sits on top of the intake under the air filter assy.

Jason

 

I noticed my 6.9 did use more oil if I was running it hard, up to 1 qt per 200 miles (with proper CDR), no idea what the consumption is now because it is a fresh build. But theres no way that high RPM (within the stock governed speed) in itself could cause such high consumption. Even running all day at 3000 RPM should not cause that problem.

If compression is still good than maybe valve guides or seals (or both), but 11 qts? I don't know.

 

27 miles to the quart on oil? At that rate the oil is costing you about half as much as the diesel. Something wrong there.

The CDR should be under the air cleaner on the back side of the opening into the intake manifold (the hole that matches up to the big hole in the bottom of the air cleaner). The CDR is shaped like a jumbo tuna can and is about 5" in diameter and 3" tall - but it is standing on edge (like a tuna can ready to roll across the table would be).

It has two short metal straps attached to it horizontally - one on each side - and the straps have 1/2" bolts going through them securing it to the back side of the intake manifold opening. Once the air cleaner is off, you'll see it easily and you'll also be able to look down inside the opening in the intake manifold with a flashlight and see if there is lots of oil in there. If there is, the CDR needs to be cleaned.

Loosen and remove the two 1/2" bolts that hold it in place and pull straight up on it. It has a short pipe abouit 1" in diameter and 2-3 long inches sticking straight down from the tuna can into a rubber donut in the top of the intake manifold. Just pull the pipe straight out of the rubber donut. There will be another rubber donut gasket that was in between the flat side of the tuna can and the backside of the opening in the intake manifold opening where it was bolted on. Take that gasket off the tuna can and lay it aside.

Once you have the tuna can off, lay it in a container big enough for it to lay flat and deep enough for you to be able to fill the container with clean gasoline and completely submerge the entire tuna can in gasoline and still have a couple inches of depth left for adding more gasoline later. Pour the gas in there and let it sit for a half hour or so while you do other things. Then, lift it out of the gas and dump all the liquid out of it back into your container of gasoline, submerge it again for a couple of minutes and dump it out again. Keep doing this until the gasoline coming out of the part is exactly the same color as the gasoline in the container - by this point it will all be darkened by the oil it has dissolved off of and cleaned out of the inside of the tuna can.

Then hold the tuna can above your container, pour a few more ounces of clean gasoline into the tuna can, swish it around and dump it into the container with all rest of the oily gasoline. Examine the gasoline as it pours out of the tuna can and the oily gas in the container and see if there are any solid pieces of black rubber in it. If so, your CDR is toast and will have to be replaced. If not then chances are about 95% that it is OK and was just gummed up with sticky dirty old oil deposits.

You will want to set it aside for a half hour or so to allow all the gasoline to evaporate out of it before you reinstall it on your engine (straight liquid gasoline into a diesel engine is not a good thing - even in small amounts). Reinstalling it is the reverse of removal. Push the pipe on the one side down into the rubber donut on the top of the engine where it was, put the other rubber donut back into place between the tuna can and the backside of the opening in the intake manifold and reinstall the bolts. Then you can reinstall your air cleaner.

Kind of a long and complicated description for a fairly simple procedure, and one that needs to be done about every 3-4 oil changes (assuming you change your oil every 3000-3500 miles), but you said you know nothing about it so I wrote the instructions to try to cover every detail.

Good luck with it and come back with any more questions you have if you get stuck at some point in the process....