Burning oil??

[badboypolar]

So I have roughly 1700 miles on my new motor. It seems to be losing alot of oil, roughly a quart per 1000 miles, and I can figure out why. It is burning it?

I have a catch can and it is still pretty empty and the hoses coming from it are clean. I have a very small oil leak from what I think is the rear main cover, not the seal, stupid paper gasket. I also have a leak from the trans that I need to fix tomorrow.

[kowalski]

how bad are the leaks...? what kind of oil did you put in it? and did you break the motor in properly? also did you put new rings in or reuse the old ones? what kind of rings did you put in?

[badboypolar]

The tranny leak is medium. The rear main is quite small as far as I can tell. The motor was broke in for 500 miles, with easy driving at varying rpm's not exceeding 4000rpm, and I used straight 30 weight non-degetergent). I am now using Mobil 1 15w50.

I used new rings that where included with the pistons, bought from Bavauto (maxsil pistons, Sealed Power chrome-moly piston rings http://www.bmwpistons.com/).

[Wise Old Dog]

IMO A new engine with new bearings should be plenty tight enough to use 5w30 or another 5w or 0w range. 15w50 is probably too thick for a new engine. As the bearings wear over time then the 15w50 would be called for. I don't know if this has anything to do with your oil burning. A compression check would be my first step in diagnosing this problem.

[jetteman]

have you checked to make sure it wasn't mixing into the coolant?

[badboypolar]

There is no coolant in the oil or vise versa.

[Alpine003]

A compression check would be my first step in diagnosing this problem.

I agree with this as the rings might not be seated or installed correctly.

[badboypolar]

my first compression check came out 220, 215, 215, 240. That was cold I believe. I will run another when I get home and do it while it's hot. Should I also do a leak down?

[shutter]

hmmm they look good except the last cylinder. Maybe retry it, it seems high where the others seem about right? It's 20 above the next closest, and that's not good really. Usually at about a 15 spread there should be some concern. Actually, a lot of people say 10 is too much of a difference.

[badboypolar]

Well I'm screwed. I don't know what happened but
180, 170, 165, 215 (#1, #2, #3, #4).

Yeah I get to rip my motor apart again. :mad:

[shutter]

:( That sucks. At least there are a few positives, like being worth it in the end and getting to be a pro at taking it apart. Good luck man! Keep us in the loop...

[Alpine003]

Well I'm screwed. I don't know what happened but
180, 170, 165, 215 (#1, #2, #3, #4).

Yeah I get to rip my motor apart again. :mad:

Did you seat the rings correctly when you rebuilt it?

[badboypolar]

I thought I installed and seated them correctly. According to the directions with the rings the top was the one with no groove, the middle had the groove facing upwards and the oil ring(s). With the piston facing the correct direction (O --> Front) the top ring opening faces 45 degrees CCW, middle faces 45 CW, and the oil ring is 135 CW.

[mbtech0]

Look at the plugs, that much oil will turn them black and/or wet. IMHO, break-in takes much longer than 500mi, and what I mean is that the rings take longer than that to seat correctly. The harder the rings, the more miles they take. I've found that 10,000 mi is sometimes needed.

As a comparison, my newly-arrived 91 iS had 103,000 on it. I drove it till 105,000, and changed oil & filter, with Castrol GTX 10w/30. I put in 5qts., about 4 tenths-of-a-quart less than capacity. Dipstick showed about a half-quart low after change. I left it that way, rather than break open another quart. Now, there is 109,500mi, and the dipstick says add a quart. It gets changed tomorrow. So, that equates to 4 tenths-of-a-quart of oil used in 4500mi, and I consider that to be outstanding.

I would certainly fix what leaks you find, you could be losing more oil than you think. I have not done much more than slight experimentation with synthetics, but I heard many mechanics say that a new engine should be run in for at least 10,000mi on a good quality multi-grade detergent oil, before switching to synthetic, in order that there is enough friction in the bores to cause the rings to seat. I no longer drive enough miles to make the synthetics' extra cost worthwhile.

[badboypolar]

I think that is one reason why the rings didn't seat correctly. I also found another problem that nothing torqued correctly because of a bad torque wrench. So the mains, rod, and head bolts where all out of whack. I'll have to also check the bearings for abnormal wear.

I also what looks like abnormal wear on the pistons. The sides of them (facing how the crank turns) has some wear on them. I'll post pics of them when I get home.

So I'll wash out the cylinders and pistons, do a thread cleaner and try it again. This time though I'm using ARP head studs (ARP-201-4601 is the part number). FYI that summit has them for $140.39.

[Alpine003]

So the mains, rod, and head bolts where all out of whack.

I also what looks like abnormal wear on the pistons. The sides of them (facing how the crank turns) has some wear on them. I'll post pics of them when I get home.

So I'll wash out the cylinders and pistons, do a thread cleaner and try it again. This time though I'm using ARP head studs (ARP-201-4601 is the part number). FYI that summit has them for $140.39.

:eek: So you had the intention of rebuilding the motor but it might be worse than before?

Also, ARP studs are only worth it if you're planning on high hp motor build. Overkill on a stock motor imo. I would do a OEM Febi-Bilstein headbolt set for $14 and call it a day.

[badboypolar]

Here's the "abnormal" wear on the pistons. There is also some concerning wear on the rod bearing. I will pull the crank later this week and check the main bearings.

http://www.dan-ang.com/images/daniel/pistons_1.jpg
http://www.dan-ang.com/images/daniel/pistons_2.jpg

http://www.dan-ang.com/images/daniel/rod_bearing.jpg

[badboypolar]

Pics added

[mbtech0]

Good pics! The sides of the pistons look scuffed, and that concerns me, but the rod bearing looks like a "dry" start. Bearing need a smear, just a dab of Lubriplate when assembling, enough to lube for 30 seconds, and then wash out. You can tell I'm from the old school......Perhaps the failed torque wrench has something to do with this. Not enough/too much torque can upset things. I'm wondering how the piston pins went in, anything unusual? Did you have a bit of piston slap on a cold start, and did it go away in less than a minute?

[badboypolar]

I put on plenty of assembly lube on everything. No piston slap. Pistons went in fine. I had a little trouble getting it started and running because of fuel and the timing chain went off by one tooth, which would explain the dry start, It didn't really get running until a couple of times.

[shutter]

How do the bores look and feel?

[badboypolar]

The bores look and feel fine.

However after taking some measurements it seems that piston 1 is .08mm out of round. TIS says that .01mm is out of round. That doesn't give alot of room.

north/south 83.77; east/west 83.69

BTW these are MaxSil pistons from Bavarian Engine Exchange.

[shutter]

hmmm, the piston is pretty out of round for a .01 tolerance. At first I thought that maybe you got some wiggle from the bad torque wrench, but now it sounds like that one piston is way out your tolerance range. Even if .01 is a tad low, .08 is definitely too much?

[shutter]

oh yeah, are the other 3 ok in tolerance? Were they similarly worn?