Break-in Period for Rebuilt Engine

[DieselScout]

Rebuilt an old D24 NA I had kicking around and installed it this week.
Currently at 400 miles of running time since install.

What is the recommended break-in period for these engines?

I am planning to change the oil at 500 miles, 1000 miles and again at 2000 miles.
How long should I change oil at these shorter intervals? (Using regular oil as opposed to synthetic for break-in)

What is a normal oil burn for a freshly rebuilt engine, and when will it start to level off?
It has burnt 1 quart over the past 400 miles.

[IMG][/IMG]

[ngoma]

Nice cleaning job!

The acorn nuts are also a nice touch!

Oil consumption in the first 400 miles is really not a long enough period for me to opinionate. Actually, not enough info for me to formulate any helpful comments, sorry.

What did your rebuild entail? Pistons? Rings? Bearings? Camshaft? Valves? Did you resurface the cylinders? How?

Have you seen this?

http://www.mototuneusa.com/break_in_secrets.htm

[DieselScout]

The entire engine has been "gone through" (Pistons, blocks, head, bearings, etc...) Block was sent to a machine shop to hone and bore .5mm over.

I have oil leaking from the cam cover cap, is this unavoidable with these engines?

I'll check out the website.

[ngoma]

Originally Posted by DieselScout

Block was sent to a machine shop to hone and bore

OK so reconditioned cylinder walls and new oversize pistons and rings.
You want to create plenty of combustion gas pressure to strongly force the rings into the walls. Don't let it idle, especially at the beginning.

Originally Posted by DieselScout

I have oil leaking from the cam cover cap, is this unavoidable with these engines?

What kind of valve cover gasket? Are the shoulderd studs completely bottomed out in the threaded holes? Usually have to double-nut them to get them all the way in, otherwise they stand too tall and don't allow sufficient gasket compression.

https://www.youtube.com/watch?v=Pvs_EFR-f4E

[DieselScout]

The gasket is the rubber one-piece from Goetze.
Studs are shouldered.

From what I can tell, most of the oil is leaking from the cam cover (refill) cap.
I tried replacing the old (cork?) gasket inside the cap with some rubber, but it only helped a little.

[ngoma]

Is it an actual oil leak or is it just greasy and dirty?

[DieselScout]

The oil consumption has gotten considerably worse, recently.

About a week after switching to the synthetic oil, (Rotella T6 5W-30) the oil consumption has increased to 1 quart every 150 miles. (Versus the initial consumption of 1 quart in the first 400 miles)

The engine power also seemed to decrease.

I did a 1 hour Kano Kreen piston soak the other day.
The engine felt more responsive so I did another 10 hour piston soak yesterday.
The engine power felt significantly better on the 2nd soak, but the oil consumption remained the same.

I am assuming that the oil control rings are the culprit and that the oil is then gumming-up the compression rings.
From what I gather, piston soaks generally only clear the top two rings and do not significantly help the oil ring, is this correct?
Is the oil consumption too high to consider valve seals as a potential culprit?
(The head has new seals, etc..and was checked for leaks prior to installation)

Also, I double-checked my ARP head studs.
They measured 110 ft-lbs (vs the specified 125 ft-lbs)
This may be caused because I did a 5 stage torque sequence vs the ARP directive of a 3 stage sequence, causing an inaccurate reading on my final torque.
Yesterday, I re-torqued the head studs back to 125 ft-lbs.
Any chance that this could have been affecting the consumption or damaged the MLS head gasket?

The oil leak from the valve cover stopped after I removed it and tightened the cover studs.

The car currently has 1,200 miles on the rebuilt engine.

Blow-by is not visible while running with the breather tube connected to the intake. When the breather tube is pinched-off, some blow-by is visible from the dipstick tube, but not from the valve cover oil cap. The cover cap is stationary and does not "dance" when loosened with the breather hose pinched-off.
No visible oil on the intake manifold as with my last engine, which had significant blow-by.

Below are my recent compression results. (on a warm engine)

Before 1st Piston Soak
Dry Test
Cyl 1: 410, Cyl 2: 425, Cyl 3: 410, Cyl 4: 400, Cyl 5: 400, Cyl 6: 400
Wet Test
Cyl 1: 480, Cyl 2: 460, Cyl 3: 480, Cyl 4: 480, Cyl 5: 460, Cyl 6: 460

Before 2nd Piston Soak
Dry Test
Cyl 1: 420, Cyl 2: 400, Cyl 3: 410, Cyl 4: 420, Cyl 5: 400, Cyl 6: 430
Wet Test
Cyl 1: 480, Cyl 2: 460, Cyl 3: 480, Cyl 4: 470, Cyl 5: 440, Cyl 6: 480

[ngoma]

Originally Posted by DieselScout

The oil consumption has gotten considerably worse, recently.

About a week after switching to the synthetic oil, (Rotella T6 5W-30) the oil consumption has increased to 1 quart every 150 miles. (Versus the initial consumption of 1 quart in the first 400 miles)

Guessing that the oil control rings are not doing their job. Could be many reasons.
Poor quality
Incorrect size
Incorrect orientation
Poor cylinder prep and/or honing
Faulty break-in procedure

Originally Posted by DieselScout

From what I gather, piston soaks generally only clear the top two rings and do not significantly help the oil ring, is this correct?

Sorry I have no experience with piston soaks, nor about their utility on a fresh rebuild.

Originally Posted by DieselScout

Is the oil consumption too high to consider valve seals as a potential culprit?
(The head has new seals, etc..and was checked for leaks prior to installation)

Not sure

Originally Posted by DieselScout

Yesterday, I re-torqued the head studs back to 125 ft-lbs.
Any chance that this could have been affecting the consumption or damaged the MLS head gasket?

If the head gasket was leaking that much oil externally you should be able to see it pouring down the side of the engine. Or it would be filling the coolant reservoir. Not sure if the oil pressure could get high enough to enter the cylinders.

Originally Posted by DieselScout

The oil leak from the valve cover stopped after I removed it and tightened the cover studs.

This is confusing me. I had recommended double-nutting setting the VC studs but you stated the leaking was at the filler cap.

Are you able to perceive any bluish oil haze in the exhaust?

[DieselScout]

The pistons/rings are from Kolbenschmidt.
.5mm oversized. Block was bored and honed at machine shop.

I made sure all of the rings were orientated correctly/offset from one another.

Cylinder was cleaned with break cleaner and then assembly grease was added to facilitate easier piston install.

I used Amsoil break-in oil, initially.
The car was idling for a while after start while diagnosing a coolant issue. Temperature got as high as 210F. (turned out to be a faulty, DOA thermostat) not sure if that would really affect the break-in detrimentally.

No oil in coolant reservoir and no bubbles through water test.
Oil pressure and temperature are within normal range.

Coolant and EGT temperatures also within normal ranges.

I applied the double-nut technique to the VC studs and reset the cap (I believe the cap gasket leak was because it wasn't seated properly)

The car was producing a blueish haze the past week until I applied the Kano Kreen. The smoke has diminished significantly, but it still produces some white smoke on initial start-up and when going from 1st to 2nd gears. This engine is not producing nearly as much smoke as I'd expect for such high oil consumption and produces significantly less smoke than the engine that I replaced. (which burnt 1qt for 650 miles)

[DieselScout]

Finally found the issue of the oil consumption...

Turns out the machinist I sent the block to last year did a poor job boring and honing the cylinders.
Unfortunately, I didn't have a "base line" for what freshly bored & honed cylinders should look and feel like as this was my first engine build,
otherwise I could've had it fixed before I did the initial engine assembly.

According to the new machinist, it was bored too large for the .5mm oversize, it was slightly oblong and too coarse.
After 5,000 miles of driving, the honing was still extremely rough, which caused significant piston ring wear.

The block was corrected with a 1mm overbore and re-honed.
Engine reassembled and in the past 800 miles, the car seems to have only burned a little, if any oil.

Fingers crossed, but I think it's working AOK.