7.3 Eating oil

Evening everyone!

So I just recently put a truck i've had over a year on the road now. '91 F350 cab/chassis, 12ft flat bed, 4x4 dually 5spd.

Truck only has 205,000km (128k miles), and by the condition of the truck, and lack of rust anywhere, I have reason to believe that.

However, it does not have it's original engine. Has an engine out of a van, I can tell by the factory timing adapter on line #4 instead of being on #1 like on trucks.

It burns an unbelievable amount of oil. Did a ~300 mile round trip last saturday with it, it ate 12L of oil! Oil is fresh, Diesel 10W30 valvoline.

Intake has little to no oil in it, so it's not CDR related, what can it be? It runs great, idles well and everthing.

I did notice rear cylinder on passenger side, liquid oil seeping out between manifold and head....

No idea on mileage on engine, it is very clean, doesn't leak or even sweat a drop of oil, just burns it all! I was thinking maybe a high idle hours engine from an ambulance or something, but even that wouldn't cause it to burn this much oil...?

Any ideas? Otherwise this engine has to come out, it smokes blue constantly, worst between 1500-1700RPM.




On side note, this is the truck. Awesome what a 60$ tremclad brush and roller paint job can do

Before


After

The paint job looks nice. Doesn't even look like the same truck.

As far as the oil......that is a ton of oil to burn. I don't really have an answer for you. How long was has it been sitting prior to running it? Have you pulled the valve covers? If so, what did it look like?

Never seen it on a diesel, but I had a 360 once that was nasty gunked up inside. The drain ports in the heads were clogged so oil couldn't drain back into pan. It ran great and burned about a quart of oil every 30 miles.
As jayro said, pull the valve covers and see what you can see. With my 360, I took a rag tied to a coathanger and cleaned out the drain ports in the head and reduced oil consumption by 400%.

IDIDieselJohn said:

It burns an unbelievable amount of oil. Did a ~300 mile round trip last saturday with it, it ate 12L of oil! Oil is fresh, Diesel 10W30 valvoline.

Click to expand...

Can anyone else find his problem in this portion of the post?

As you are adding, try using 10w40 and see what happens......

Streight 30wt was an acceptable option for normal temperature use, but yeah, 10w anything is too low for these motors. Try the 15w40 and stay away from Rotella-T.

I've run nothing but diesel 10W30 in my IDIs in winter, never had one burn a drop of it.

This by now should be mostly 15W40 as I've been topping it up with that, and no change at all.

Starts and runs great, not hard to start cold or hot at all so I'll pull a valve cover off this weekend see what I see, if all's good then looks like I'll be pulling this motor out. Thankfully I do have a good one laying around.

Betting you have valve guide seals that are cracked, hard, and not sealing.
To suck that much oil through the engine, there has to be a path of least resistance, valve guide seals would provide that.

Pull the valve covers and have a look. Rest of engine seems to be working to make power, start easily, etc.. but your post says it's blowing oil out at the manifold mate surfaces.. Intake? or Exhaust? Either way, that tells me the oil is being ingested into the intake / intake valve area..

It's just sweating oil between head and exhaust manifold, probably from burning that much oil. Inside of exhaust is very oily as well. It's only seeping from passenger side rear cylinder.

Remove the valve cover and check the valves and guides. You have major problems like a broken valve. Broken valve would make a LOT OF NOISE. Oil is getting into the cylinder(s) and you need to find out how. Good Luck

Engine sounds normal and healthy, i'll pull the valve covers off this weekend, see what I find. Might do a compression check while i'm at at, see if I should put money in this engine or not.

Agnem: What's wrong with Rotella-T?

Many guys have reported the idi's drinking Rotella for some reason more than the other typical oils.

What is wrong with Rotella T is it won't stay in the engine. I'm running 3 trucks now, 2 with 7.3 IDI and one with 6.9 IDI ... I've tried Rotella T in every one of them for multiple oil changes.. In ever case, the truck started losing oil at a high rate.. like from NO oil loss between changes to a quart every 1,000 miles.. or more.

In each case, I switched to Castrol Diesel oil, 15/40, same weight as Rotella T and oil loss went back to zero..

Convinced me.. your own experience and choice may vary..

My Ranch is 110 miles from town, so one trip to town is 220 miles.. not uncommon to rack up 1000 or more miles a week if we've got something happening. Highway miles, at highway speed.

Thanks. I've only had my 6.9 for less than a year but I'd say that a quart per 1k miles is about what it's been using. I just thought that was normal for these. I just changed to the T6 (5-40 synthetic) in hopes of easier cold starts but I'm a little nervous about it potentially causing leaks. Maybe I'll try the Castrol in the summer.

UPDATE,

So I took the drivers side valve cover off (real easy on non AC engine ) and other than slight slugging found on the valve cover, nothing out of the normal, everything is tight, valve seals all look ok from what I can see through the springs.

Unfortunately the problem is on the passenger side, as the more I drive it, the more I see oil sipping through the exhaust manifold where it meets the head. Its getting worst, just idling I see oil bubbling through the exhaust manifold gasket on the last cylinder by firewall.

I haven't had time to take everything off that side to get that valve cover off as I needed the truck all weekend.

I did do a quick compression check of all cylinders on drivers side, and that one back one leaking oil on passenger side, compression is all ok, the oil leaking one is the lowest tho at 380psi, vs. all the others around 410-420psi. Probably sticky rings now with the amount of oil going into it?