Oil Burning...where?

[RLDSL]

My '92 f350, 7.3 non turbo about 250,000 miles on it, eats oil like crazy, it has since I got it and it's getting worse . It goes through a qt or two everytime I go anywhere.

It starts right up no problem and has plenty of power. Blowby doesn't seem excessive ( I did the oil cap off check, steady light tea kettle like smoke at idle, dissappears above about 1800rpm ) CDR and tube are new. No strange noises or funny behaviors. Steady oil smoke out the exhaust pipe while driving ( none at idle )

I just ran the compression ( not exactly hot, but mildly warm, it only gets up to about 145 when fully warmed up and that takes a while of driving, I fired it up till the idle kicked down and ran it a few miles around the block before tearing into it )
#1) 410
#3) 420
#5) 405
#7) 305
#2) 400
#4) 405
#6) 380
#8) 305

Aside from the two back holes being a tad out of range for difference between cylinder, Does this look like anything that could be causing that much oil consumtion, or am I more likely needing a new set of valve stem seals or just go ahead and get the heads done with new guides?

Thanks---------Robert

 

[OkieGringo]

Steady oil smoke out the exhaust pipe while driving ( none at idle ) #7) 305 #8) 305

I think you've found the problem. Rings or valve guides on these two cylinders. OkieGringo

 

[Magoo]

Does your tester allow you to hook air to it? If you can pressurize those cyls, listen in the intake, at the exaust pipe and the oil filler to hear where the air is comming from. If your burrning oil, rings or guides.

 

[pafixitman]

Since it is 7 & 8, would a plugged / bad CDR have contributed to the low numbers? Just asking and trying to learn!

 

[RLDSL]

Does your tester allow you to hook air to it? If you can pressurize those cyls, listen in the intake, at the exaust pipe and the oil filler to hear where the air is comming from. If your burrning oil, rings or guides.

I'll have to take a look . it has some non standard connectors on it, but if I can adapt it, I can try presurizing to see if there's excessive ring leakage, but those compression figures don't seem low enough to account for that much oil.

 

[RLDSL]

Since it is 7 & 8, would a plugged / bad CDR have contributed to the low numbers? Just asking and trying to learn!

That could be a possibility. When I pulled the old CDR it was packed with sludge ( it was flowing air, but couldn't tell if it was closing all the way ) I had to really clean it out good to even tell if it was working. , then i went ahead and bought a new one just for safety sake.

 

[RLDSL]

Does your tester allow you to hook air to it? If you can pressurize those cyls, listen in the intake, at the exaust pipe and the oil filler to hear where the air is comming from. If your burrning oil, rings or guides.

A tad rusty here, to review, if it's the guides/seals , with the valves open I should get air leaking out at both the intake manifold or exhaust pipe and the oil fill at the same time Right???


----------Robert

 

[Mr_Roboto]

Air leaking at intake / exaust for valve or valve guide leak. Air leaking at oil fill for piston ring leak. Valves closed and piston at TDC.

Kind of wierd, I have two 7.3's with 250K plus. They both use oil, but not in those quantities. Clogged oil drain back holes in the head would be a possibility. They might flow enough to drain the oil at idle, but not enough to drain it all when running at higher RPM's, making the oil cover the valve guides where it is sucked in en-mass.

 

[DeepRoots]

let the oil run low for a bit.

my truck, when the dipstick reads "add" it is full.
If I add any more, it burns off REALLY fast, roughly the rates you mentioned.

 

[RLDSL]

let the oil run low for a bit.

my truck, when the dipstick reads "add" it is full.
If I add any more, it burns off REALLY fast, roughly the rates you mentioned.

If I let it run low, it wil be down to empty in short order. I ran about a 230 mile trip with it down about a qt to start with and near the end of that run, the gauge started swinging to zero pressure and I had to stop and put about a gal and a half in the thing..

--------Robert

 

[obinella]

air press. in the cyl. is not going to tell you much as far as oil consumption. burnt or damaged valves will leak air, a guide could be shot and the cyl. still hold air press,air that does leak past the valve seat goes out one of the manifolds and doesant tell you anything about the conditon of the guide. compression can be high and still have high oil consumption, its the job of the oil controll ring to controll the oil on the cyl.wall. only two ways for oil to get out----leak it or burn it. to burn it has to get past the oil controll rings or the valve guides . pull the valve covers check for sloppy guides ,check all of them,not just the ones with lower compression.

 

[LUCKY_LARUE60]

If you are useing that much oil and you say it is not leaking it then it is going out the exhaust, no other place for it to go. If it is going out the exhaust you would be seeing it, there is something being missed here......... Jim

 

[NJKen]

let the oil run low for a bit.

my truck, when the dipstick reads "add" it is full.
If I add any more, it burns off REALLY fast, roughly the rates you mentioned.

My 90 did that. I had to run it on the add mark. If filled to full it would dissapear in short ordr and stop at add.
The funny thing about it is my 02 powerstroke is the same way must be a Ford IH thing.
Ken

 

[NJKen]

If I let it run low, it wil be down to empty in short order. I ran about a 230 mile trip with it down about a qt to start with and near the end of that run, the gauge started swinging to zero pressure and I had to stop and put about a gal and a half in the thing..

--------Robert

SOmething is realy weird here. If you used 6 qts in 230 miles you would be smoking like a factory. If it was leaking you would have a big oily mess all over the back and bottom of the truck. Try changing to a different brand of oil next time you change it and see if that makes any difference. My 90 did not really like Delo but seemed to retain Rotella better.

Ken

 

[RLDSL]

SOmething is realy weird here. If you used 6 qts in 230 miles you would be smoking like a factory. If it was leaking you would have a big oily mess all over the back and bottom of the truck. Try changing to a different brand of oil next time you change it and see if that makes any difference. My 90 did not really like Delo but seemed to retain Rotella better.

Ken

Like I said, It has steady oil smoke out the exhaust while driving. I know it's burning it, just trying to pinpoint where it's getrting in.
I think I'm going to go ahead and pop some valve seals in the thing first, doesn't look like to painful a job on the engine and definitely the least of a project for the moment. If it doesn't work, I'm only out some time and about $20 for seals.

Thanks---------Robert