My 89 f250 7.3idi has been using 1 quart every 200 miles for a while now. I've had the truck for almost 10 years and best I remember it used to use about 1 quart every 5,000 miles. So, obviously something has worn out and/or broken.

Just did a 6 stroke compression test (let each cylinder go through 6 compression stokes and wrote down the pressure at each stroke as best I could remember at the end of the test) and was wondering what the Haynes manual means when it says:

"A low compression reading on the first stroke followed by gradually increasing pressure on successive strokes indicates worn piston rings."

Here's my results:
Passenger side front to back
#1 - 300, 380, 400, 420, 420, 420
#3 - 260, 300, 380, 400, 400, 400
#5 - 300, 380, 420, 440, 440, 440
#7 - 300, 380, 400, 420, 420, 420
Driver's side front to back
#2 - 300, 380, 400, 440, 440, 440
#4 - 300, 380, 400, 420, 420, 420
#6 - 280, 350, 400, 420, 420, 420
#8 - 250, 300, 400, 420, 420, 420

Do these results qualify as low on the first stroke followed by gradually increasing pressure?

I've replaced the CDR with a brand new one straight from the dealership. I also put remain'd heads on back in 2008 because of a blown head gasket. I've got only minor seepage of oil from the usual places but she never seeps enough to drip on the ground. Not much smoke from the exhaust, maybe just a really lite/thin cloud that gets a little thicker on start up/acceleration. I do have a carbon build up at my exhaust tip that seems to be getting thicker.

Basically, do y'all think new rings would stop my oil disappearance problem?

Thanks for the help.

 

how hard do you drive the truck? just cruising around can make the rings sticky, my tow truck gets to smoking and leaking oil if I idle it around too much. When I get it on the road I have to remember to drive it hard with the throttle wide open or closed. I've personally only see 4 diesels break the 300,000 mark and they were driven by guys that use the floor board cruise control.
I'm not saying that it will fix it, but should help. Also you should consider valve guides and seals if you are pulling the motor

 

Was the test done with the engine at operating temp? Numbers look pretty even, id say gummed up / bad rings. Its got to be going somwhere, new heads means its pretty safe to assume its not guides. Do you get a puff of blue when you start it?

 

They all started a bit on the low side, but came up rather quickly, and evenly. I would attribute the lower readings to slower engine cranking speed, rather than engine wear. The faster an engine spins, the higher the reading will be, and it takes a couple turns for the starter to get it fully up to speed.
I'm not sure how the 400-440 range you ended up with ranks in this engine, as far as normal/low, but they are fairly even, which is generally a good sign. If the batteries aren't fully charged and in excellent condition, or the starter is getting old, the results will be lower than expected due to slower cranking speed.

 

400+ are really good numbers for a 7.3, some fresh 6.9s can hit 500 but thats pretty rare from what ive seen / heard. You can still have good compression with stuck rings though. The rings are sealing, but not scraping the oil off of the cylinder wall.

 

Those results are pretty good, change the oil and load it and run it hard, it needs to be worked.

 

Replace the rings with a good quality (Dana or Sealed power, or whoever the successor company is) plasma rings. You will find an immediate improvement to ~2000 miles/ quart.

The CDR has nothing to do with oil consumption, so that was a waste of money.

 

The test was done after letting the block heater run for about 24 hours. I wasnt able to drive the truck directly before the compression test because I'm replacing the leak off tees and the fuel line going from the pump to the #1 injector and already had them off. Plus the outside temp was in the 80's, so the block was maybe not in the 210 degree range, but was definitely hot to the touch. I kept the batteris fully charged as well. I should have it back together pretty quick. Then I'll change the oil and run real hard to see what happens. I will say it has the C6 with no O/D so even just cruisin at 55 mph it runs about 2800 rpm, which is pretty high.

Finn, if I replaced the rings I'm guessing I have to have the cylinders hoaned out to match the ring, right? Does a machine shop have to do that?

 

I have heard of just putting new rings in without honing if there is not scoring marks or something you can catch a nail on, but that was in gassers, I would think it would be the same with the diesels, but I am curious too.

I am not using oil like you are, mine uses a small amount of coolant, I am planning on doing a rebuild by the end of summer, going to pull the motor, head gaskets, head studs, oil cooler seals, valve guides/seals, prolly other stuff too, I might be forgetting something.

 

I read that you need to at least flex-hone the walls before putting in new rings -- you need the micro sharp edges so the new rings seat correctly(which are then worn off almost immediately).

 

did my test today, nowhere near as good as jdstudski results, used a camera to record, because i had trouble trying to remember it as it went, if I had a helper I could have read them off as I seen them and they could have written it down.

I do get a very very small amount of bubbles out the radiator when I put a no spill funnel on there, so im assuming needs a headgasket. The passenger side middle two glow plugs were very difficult to remove, like they were rusted in, it took a lot of force to get them to unthread, to the point that I was worried they might snap off, I was lucky though and they came out with the extra force.

how high up should the compression come on a healthy enigne on the first or second stroke? Im assuming mine is indicating worn rings? its a 1993 7.3 NA, the dash says 247k miles but I couldn't guarantee that its the original cluster. (this truck is new to me, ive had it less than a month, in the process of installing an e4od now, this truck does smoke a little when its running, looks light grey, my nose doesnt really work to smell stuff)

was planning on just doing a headgasket job on both heads, with head studs... but now I am not so sure what the best thing would be to do. Mine does get to the 400 mark, and the oil in this thing was pretty horrible when I got it (not just black, but really sludgey), I am thinking I should try some of that Auto-RX stuff... The headgasket isnt to the point that the truck cant be driven, I am thinking finish up the E4OD and try the Auto-RX stuff and see how it does then. maybe the rings are just gummed up is all?

here are mine (fully charged batteries, engine was warmed up overnight with the block heater, radiator was hot to the touch.):

passenger:
1: 220-320-380-400-410-420
3: 200-290-340-360-378-390
5: 180-320-380-422-445-456-462-472-480
7: 220-310-360-390-400-410

drivers:
2: 200-300-360-392-405-420
4: 220-318-362-398-416-422
6: 220-316-358-390-400-410
8: 230-325-370-402-418-422

 

Ive read a lot of posts that say MMO works just as well as Auto-RX, going to give it a shot and will post back with the results. (may take a while, but I will post back once I get those miles on it)

 

I disagree with this statement. IMO you are always going to have low readings on the first few strokes because the hose on the compression tester adds a significant volume to the cylinder. It takes a few strokes to compress that extra volume of air. That's why the tip of the tester has a check valve. Once the hose is pressurized, the check valve holds that pressure so that in next few strokes the cylinder can build "real" pressure.

 

Our Stiction Eliminator will clean and free up gummed up, sticky rings. PM me for more information

 

IMO never use any thing but factory rings, they work fine when you don't baby the rig. try to fix one thing at a time. or you wont know what fixed it. cheap oil, and crap filters will gum up rings, delo 400 and M1-601 power stroke filter....drive it like you stole it...