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Discussion Starter · #1 · (Edited)
Completey new here, just been reading posts as a non-member for a long time.

Anyone have experience or advice on how to get rings to seat? Really, really don't want to pull my engine back out and have the bores re-honed.

I just finished re-installing the engine in my truck. It cracked a piston at 405,000 miles, so I built it (Edit: local shop did all the machine work and assembled to short block) to handle more power with good longevity. I replaced the injectors at the same time as 4 of them tested bad after tearing everything down.

My break-in oil was Shell Rotella T4 15-40 with a ZDDP additive. I did not have new tuning upon initial start-up with the fresh engine and 45% over injectors, and it got probably 15 minutes of idle time right away, (broken into shorter segments.) I know this isn't ideal.
I then had to drive it for work, about 700 miles over the course of a week. During this time it developed an oil leak on the turbo, (missed torquing a drain tube bolt) and an up pipe leak. Both of these have been fixed, but it affected how I could drive. After almost 1,000 miles I finally got it tuned correctly.
All this while, I had massive blow-by out the crankcase vent. Enough to make one frame rail oily about 6' back from the hose.

After a lot of reading, I pulled the glow plugs and soaked the cylinders with penetrating oil overnight, then changed the oil to Rotella 10-30, and ran it really hard for awhile. I've put another 250 miles on it, and it still has tons of blowby. If I put my finger over the crankcase vent, it builds about 5 psi in short order, and starts pouring white smoke out the pipe.

Any ideas?? Did I glaze the cylinder walls? Am I screwed and need to start over? And what did I do wrong?
 

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What type or brand of rings did you buy?What I usually do is whenever I buy piston rings I try to find out what grit of honing stone is recommended by the ring manufacturer.

There are another few things it could be.Not doubting your ability at all on this but I must ask.Did you measure end gap when the rings were square in the bore at the bottom of piston travel and were they installed correctly on the piston?Example “dot” facing up,etc.

Another thing that comes to mind is did you see any cylinder ridge at the top when deglazing the cylinders?Whenever I see a ridge I automatically buy .030 /.75mm pistons and get the block bored oversize to make the cylinders perfectly round with no out of round or taper.I’ve seen guys put standard rings in cylinders with a cylinder ridge but to be honest it’s not the way it should be done.

One other big thing is after deglazing a cylinder always clean them with hot soapy water and a wash mit.Then use white paper towels afterward to wipe the bores clean.Keep washing and drying the bores until no grey residue can be seen on the white paper towel.Then you know the bores are ready for piston/ring installation.

Keep using the truck and see if things improve.Maybe switch back to the rotella 15W40 or the rotella straight 30W oil instead.I bought three pails of rotella monograde 30W as thats what I intend to use in my 6.2/6.5/5.7 diesel trucks.

Some rebuilt engines do consume oil until the break-in period is reached.It may take 2000KM or more before break-in is reached.
 
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Discussion Starter · #4 ·
I forgot to put this in the original post
The short block was built by a reputable (or so I thought) machine shop local to me.
Because of the cracked piston and subsequent scoring, the cylinders were bored over .020". And the rings are Mahle as well, they came with the pistons.

The only thing I totally neglected was to clean the cylinders thoroughly before bolting the heads on. This is my first time doing a completely new rebuild, and it's the one thing I hadn't learned about.
 

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Ok.Thanks for that information.Usually if the shop installed the pistons and rings they should have cleaned everything thoroughly before they did anything else.Maybe they did wipe everything down like they were supposed to and perhaps not.There’s no way to know at this point if it was done.If you did ask them they are only going to say it was done.

Not much you can do at this point but Put another few miles on it and see if things improve.If not go back to the shop and see what they say.With the blowby your experiencing you shouldn’t be having excessive crankcase pressure.

The only other thing I can think of is that the .020 overbore they went with wasn’t enough to make the bores perfectly round and true from top to bottom.Usually a .030 overbore will clean things up.

What type of warranty period did they offer you on this repair?
 

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Also another question not related to the crankcase pressure but where did you get your injectors?
 

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Discussion Starter · #7 ·
They offered no specific warranty, as I sourced all the hard parts (rather than wait on their supplier to get them in stock). They will stand behind their work though.

And my injectors are from Lincoln Diesel Specialties.

Thanks for your input. I posted in another forum, and they guessed a broken oil control or by piston to wall clearance.
Either way it's probably going to have to come back out.
 

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No problem.Anytime.Looks like your injectors were bought from a reliable source👍

Yes it’ll have to come back out regardless to investigate the issue.It’s certainly a royal pain in the behind to deal with.Let us know what you find out.
 
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Sounds like you have bigger problems than just a break in not going as planned. I can relate, in a way. I've rebuilt about two dozen engines total. Everything from a 125cc honda atv to a 7.2L Cat 3126, as well as cams and bearings on many Mack E7s. One was a 3.6L V6 out of a GMC Acadia. Everything did not go well (fall 2020- winter 2021). By the time I got enough parts and finally was able to test drive it I had the engine out for 4 months. Initial warm ups went great, first couple drives did as well. Then I finally took it over 4,000 rpm and had a catastrophic failure (spun a rod bearing). I still can not figure out what went wrong. Took it all back apart to replace crank, bearings, rings, and do a lot of cleaning. Second go around went perfectly. Sucks, but it is bound to happen. Everyone has a bad day, or some project that doesn't want to go right. Only takes a tiny mistake to become very expensive and time consuming.

All that said, I can tell you how I learned to break in an engine. I had a great Auto Shop teacher in high school until he retired, (the second was very good also). I went to Wyotech for Auto/Diesel technology. The way he taught me was the same as they taught me in college. In college they didn't spend much time on the subject because it is a very small part of Auto Service in reality, but the instructor for the class just happened to do a bit of drag racing as well, and was into the subject more than the curriculum was, and I was interested so we talked further about it. Anyway, best way I was taught was to first wear in cams, then load the rings. Incase anyone found this thread on a search I'll add a guide. This is my own, more in depth guide. So a step by step would be;

1. Pre-lube
2. Start, get oil pressure, shut off, check for leaks.
3. Start, bleed cooling system, run to temp, varying rpm 1,000-2,000 while warming, shut off. Wait 5 min.
4. Start, run to temp at idle, then vary rpm from 1,000-2,000 for 20 min, shut off, wait until cool (overnight).
5. Start, run to temp, drive. Normalish (not only highway or stop and go traffic) driving for a few miles, then check over.
6. Seat the rings by loading. Highest pressures at the lowest rpm you can get. Manual transmission is easy, up shift and put the foot to the floor. Auto is more difficult, you need to load the rings as much as possible without upshifting. Best is to Load for 10-15 seconds at a time, then coast for 15-30 seconds. Repeat for 20-30 minutes. Keep on eye on the temp gauges, full throttle is good, but keep RPM under 2/3 of full (approx 4,000 for gas, 2,500 for small diesel, 1,800 for large diesel). The goal is to get the rings to seat into the cylinder walls, ie knock off the microscopic ridges created while honing the cylinder and create an almost perfectly flat face on the ring to provide a nearly perfect contact between the ring and the cylinder wall. The cylinder wall should have microscopic valley's left to hold a tiny amount of oil to provide enough lubrication to prevent wear without having so much that it is able to burn off during combustion. If I remember correctly the cylinder walls should look like an AC voltage graph cut off at 0 volts, showing flats with valleys that are far too small to hold any debris or enough oil to burn.
7. Do several very short full rpm sweep runs. Most vehicles now break the speed limit in 2nd gear and won't let it get to a high rpm in first. But the idea is to shake out any problems that might occur during a passing run, so do what you can.
8. Change the oil and you're good to go. Recommend changing the oil again after 500-1000 miles of normal driving. Fewer if only in town, longer if only highway.

Rant begin

I've followed this setup on every engine I've done except 2. One really because I wasn't the one that rebuilt it, it was a 115hp evinrude 2 stroke, and I freely admit that me and 2-strokes don't really get along well. Long story shorter, I know my limitations so I purchased a rebuilt boat motor from a marine shop (technically I purchased it from them to be rebuilt by them). They took too long and I saw another motor (nearly identical) very cheap that needed to be rebuilt. I bought that motor, rebuilt it myself over a weekend, for 1/4 the price including rebuilding it. I broke mine in as close to how I'd done every other engine I rebuilt. That was 5 years ago. I still have that motor. It is on a smaller boat that gets 20-40 hours a year on it, with 3/4 of that being as hard of a life as I could think of for a boat motor, all out pulling a tube with teenagers on it. The motor runs perfectly. Better than any 2 stroke I've ever seen. If it weren't for that, I'd have given up on 2-strokes all together 5 years ago. When I finally received the other motor, they had a very specific break in process (and oil) that I had to follow, that was nothing like my usual process. It took it easy for a long (very long) time, such as 2-3 hours at 1,000 rpm, then 2-3 hours at 1,500 rpm, etc. After the break in, that motor went on to my pontoon, which sad to say hasn't been used much since we got the smaller boat. What a waste of money. I bet it has only seen 30 hours since the rebuild 5 years ago. Despite being almost an identical motor, it has been nothing but problems. Some can't be contributed to the person that rebuilt it directly, such as coils going bad, a lower unit leaking, or carbs that need cleaning (he just didn't do a comprehensive rebuild, more of a remanufacture in my mind). But despite that, it has always been really tough to tune and not ever run just right. I don't know if they did a bad job, or the type of break in just wasn't as good. I can tell you that as of a few weeks ago, that engine had 105-115 psi of compression on all 4 cylinders, while the one I rebuilt has 120-130psi of compression. Both technically within specs, but why would a professionally rebuilt boat motor have consistently lower compression than one rebuilt by a Med/Heavy truck tech that probably shouldn't be rebuilding 2 stroke boat motors. While also having about 1/5 the number of hours on it.

Rant end

I've read of many different ways to break in an engine. I've been given instructions for other ways when installing a rebuilt engine (which I've ignored). I do spend a relatively large amount of time breaking in an engine. With the exception of the one, I've never had a problem I still attribute that problem to my ongoing physical and mental problems. I've only rebuilt two for work many years ago because it is cheaper for a shop to get a rebuilt engine and install it, than to rebuild it themselves. Most I've rebuilt were mine, or friends. I still own a few that I've rebuilt, with the most recent being my Wife's duramax. Just passed 2,000 miles and working perfectly. I did an in frame overhaul on my dump truck (7.2L cat) last summer, then hauled 500 yards of gravel to my place with it with no problems. My point is that I've heard of many different ways, in instructions or on the internet. But my adapted way is the closest to the way I was taught, and hasn't failed me yet. No engine that I've rebuilt burns oil or has low compression and I still know the person who has that first ATV that I rebuilt 25 years ago in high school.
 

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Discussion Starter · #10 ·
Appreciate that. The real world experience helps much.
 

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Partly could be contributed to the idle time before actually using it. When I put my engine together and got it in the truck (no overbore, original 266k mile pistons with new rings and honed walls) it ran for maybe five minutes before I took it out and drove it. And I put some boost to it right away too. My friends at Fleece said run it and get the cylinder pressures up to help seat the rings. I drove it about 60miles total, then hooked to a sled and it seems to be fine after 28k miles Maybe a slight oil smoke on a cold start, but its hard to tell if its oil or just fuel smoke, doesn't really smell like oil

Have you had the cylinder pressures up yet, with high boost or heavy throttle input? After 1k miles I would assume so, but if you haven't- load it with a heavy trailer and run it hard and see if that helps seal it
 

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Discussion Starter · #12 ·
I have towed 12k with it a couple times now, and about 25k for a short distance. As well as a lot of holding it on the floor up long hills.
I did learn about cylinder pressure and how it forces the rings against the cylinder walls harder, to help with seating. I think I've done pretty well at that.
 

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Well, if you've done that and it still has blow-by then about the only thing left is to pull it back out and tear it down again. Maybe a ring broke? Have you done a compression check to see if its one cylinder? Balance rates give any indication of one cylinder being out of balance with the rest?
 

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Discussion Starter · #14 ·
Balance rates show no indication to speak of, my spread is +1.25 to - 1 in park, +.90 to -1.25 in gear.
I haven't had time to check compression yet, but it has started to almost feel like it's missing at idle, so I am suspicious of just one piston.
 
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