Still losing oil

[kbenz]

These are my compression numbers.
I fixed the oil leak but I’m still going through a lot of engine oil. 3.5 quarts in 100 miles. Pulling a 20’ steel decked trailer and a 5500 pound truck. When you put it to the floor thick black smoke. Less than 3000 miles on pump and injectors. It’s the same wether I’m running diesel or wmo. There is no oil on the truck or trailer. Any input? I’m kinda lost on this one.
93 7.3 non turbo. (Edited to add mileage). Around 270,000 miles
Thanks

 

[ihc1470]

General rule of thumb is no more than ten percent variation from high to low. Half of yours are at the low limit or lower. Next thing I would do would be a cylinder leakage test to see where you are loosing it at. Could be rings or valves. How many miles on this engine?

https://www.ebay.com/itm/307189719976?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20250417133020%26meid%3De76a595041454f5ebed1f27e649de157%26pid%3D102726%26rk%3D1%26rkt%3D1%26itm%3D307189719976%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3DRecentlyViewedItemsV2DWebWithPSItemDRV2_BP%26brand%3DSnap-on&_trksid=p4375194.c102726.m162918

I own a tester like this and have used it several times over the years to test diesel engines. Use the same adapter that you used for checking compression just get the same fitting as Snap-On used. It is a common air fitting as I recall.

 

[kbenz]

General rule of thumb is no more than ten percent variation from high to low. Half of yours are at the low limit or lower. Next thing I would do would be a cylinder leakage test to see where you are loosing it at. Could be rings or valves. How many miles on this engine?

https://www.ebay.com/itm/307189719976?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20250417133020%26meid%3De76a595041454f5ebed1f27e649de157%26pid%3D102726%26rk%3D1%26rkt%3D1%26itm%3D307189719976%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3DRecentlyViewedItemsV2DWebWithPSItemDRV2_BP%26brand%3DSnap-on&_trksid=p4375194.c102726.m162918

I own a tester like this and have used it several times over the years to test diesel engines. Use the same adapter that you used for checking compression just get the same fitting as Snap-On used. It is a common air fitting as I recall.

It has around 270,000. I ordered that leak down tester

 

[Nero]

Definitely check compression as well. The first engine in my old mans crew cab ran beautifully, but burned oil as bad as yours, turns out it had 3 bad holes from dirt ingestion.

 

[kbenz]

Definitely check compression as well. The first engine in my old mans crew cab ran beautifully, but burned oil as bad as yours, turns out it had 3 bad holes from dirt ingestion.

I did a compression test. Posted a picture. I got 4 holes that are way different

 

[Nero]

Shoot how did I miss that.. Anyways, leakdown will tell you if your rings are worn or not.

 

[Olds64]

X3 on running a cylinder leak down test.

If she's burning the oil (I.e. not dripping it out of the oil pan or oil cooler) you might clean or replace your CDR.

 

[kbenz]

X3 on running a cylinder leak down test.

If she's burning the oil (I.e. not dripping it out of the oil pan or oil cooler) you might clean or replace your CDR.

I cleaned it not long ago. Be a good time to do it again though

 

[lotzagoodstuff]

You might have some stuck rings. Before you tear it down, you could put in a dose of AutoRX and pull/load it hard and see if your compression numbers change. If you see any change for the better in the first 100-200 miles, leave it in as directed and let it keep cleaning. When I did my old IDI, the oil came out black as India ink and I could pull the same hill entering my neighborhood one gear taller than before. My truck had like 220K on it, worth a shot at least before you tear it down and do any genuine machine work/rebuilding.

 

[lotzagoodstuff]

It's interesting that your lower compression numbers are all on the corners/longest intake runners from the intake manifold air inlet.

 

[DirtyWood]

FWIW AutoRx is a slow cleaner. A faster option is Kreen from Kano Labs--it's solvent based and stinks something terrible but before I rebuilt my heads I tried some and it did improve how the engine ran. I still had valve guide problems but the Kreen seemed to be a legit product. I ran it as a flush where I used the maximum dose and just let the engine idle for 45 minutes and then drained the oil.

 

[ROCK HARVEY]

I would pull the heads. My bet is that your valve guides are worn and letting oil past. You can check them with the heads on, but if you pull the heads you can also get a good idea what’s going on inside the cylinders, and also see whether the head gasket is letting some oil past. You might even have a cracked block or head. IMO pulling the heads is going to be the fastest way to get to the bottom of it.

 

[Smitty 90idi]

I would pull the heads. My bet is that your valve guides are worn and letting oil past. You can check them with the heads on, but if you pull the heads you can also get a good idea what’s going on inside the cylinders, and also see whether the head gasket is letting some oil past. You might even have a cracked block or head. IMO pulling the heads is going to be the fastest way to get to the bottom of it.

Valve guides do not stop oil from getting into the cylinder. That what the valve seals do. Valve guides just guide the valve. Worn valve guides cause a loss of compression because the valves do not seat properly. However it’s the seals that keep the oil in place. A bad valve guide will kill a seal. But yes they may be worn out. Very easy to see by pulling the covers.

 

[Nero]

If I remember right, a stock unopened idi does not have valve stem seals, they have these goofy little plastic umbrella splash guards on them. Known to burn some oil, but not drink it by the quart.

Luckily, they can be upgraded to stem seals, did it on both my rig and my old man's.

 

[lotzagoodstuff]

If I remember right, a stock unopened idi does not have valve stem seals, they have these goofy little plastic umbrella splash guards on them. Known to burn some oil, but not drink it by the quart.

Luckily, they can be upgraded to stem seals, did it on both my rig and my old man's.

There used to be lots of deep thoughts on gassers using umbrella seals vs oring style valve seals, especially during the “just post leaded fuels” era. “Do you accept letting some oil pass below the seals for the sake of lubrication” was the argument, but different valve seats and bronzed guides replaced all the leaded heads during valve jobs so nobody but old remember this stuff.

For the record, IMNSHO no seals at all wouldn’t drink a quart of oil in 100-200 miles, but it could be contributing small loss of oil.