Re-ring, rebuild questions.

jasantos40 · Sep 22, 2018

Hi, can you help out a newbie on diesel engine rebuild?

After finding out a bent rod I decided to replace the con rod, hone the cylinders and re-ring the 4 pistons with new new bearings.

Cranked the engine some turns without glow plugs to get out some of the excess oil on the piston crowns, installed glow plugs, cranked a bit without injector wiring to build some oil pressure without starting, plugged the injectors and it started.

One of my questions is, I know its normal some smoke at the first start, but i'm getting some injector deviation up to 2.99 -3.01, it's because the rings are being seated to do compression? The engine is quiet, no knockins, no weird noises, no smoke coming from the valve cover.

I haven't installed everything yet, still alternator belt and cooling system to install, had it running only for 30 secs.

After I get the alternator and the cooling system installed, I'm planning on leave it running until it gets to temp service, do you recommend to leave the car at higher rpms than idle? 2000rpms? As it's done with camshaft breaking?

Mongler98 · Sep 22, 2018

2 schools of though on ring break in.

1: Slow and steady.
most common on new engines per manufacturer. vary Rpms for the first 2000 miles and change oil first 50, then 500, then 1,000, then 2,000 on the clock not total.

2: FAST AND FURIOUS
run it hard ad as hot as you can for the first 100 miles.

the reason you would do this is that its about the hone depth.
Things like gy6 engines on scooter and gocarts ect... they need fast break in because the rings will not seat due to low depth on the hone.

If your hone is a deep hone, then go slow, if a shallow hone, go fast and furious. The more depth the hone is the longer the rings have to seat in.

food for thought. i would go slow and steady but i would not baby it as you would on some engines. DONT WOT it for the first 1000 miles though.

oil changes are critical here.

I would seek out the advice of frank and oilhammer on this one.

How did you bend a rod?

jasantos40 · Sep 22, 2018

Mongler98 said:
2 schools of though on ring break in.

1: Slow and steady.
most common on new engines per manufacturer. vary Rpms for the first 2000 miles and change oil first 50, then 500, then 1,000, then 2,000 on the clock not total.

2: FAST AND FURIOUS
run it hard ad as hot as you can for the first 100 miles.

the reason you would do this is that its about the hone depth.
Things like gy6 engines on scooter and gocarts ect... they need fast break in because the rings will not seat due to low depth on the hone.

If your hone is a deep hone, then go slow, if a shallow hone, go fast and furious. The more depth the hone is the longer the rings have to seat in.

food for thought. i would go slow and steady but i would not baby it as you would on some engines. DONT WOT it for the first 1000 miles though.

oil changes are critical here.

I would seek out the advice of frank and oilhammer on this one.

How did you bend a rod?

Lots of oil on the intake by the turbo, turbo has been replaced already.

So it's a bad idea to leave it running, even at higher rpm than idle. From my research I have to put load on the engine right?

About injector deviations at the first seconds of the first start, are they normal because of the building compression?

Mongler98 · Sep 22, 2018

there is no way for the engine to read compression so there is no adjustment for fuel injection. However, lower compression ranges will change the spray pattern slightly but nothing you can do about that.

Define "lots of oil"
Clean out all your lines and intercooler. The way most diesel mechs clean it is to disconnect the turbo and the engine from the pipes and ducktape on some large hose from a shopvac on both sides to elevate the hight of the pipes, pour in 2 cups of laundry detergent and fill with HOT water. now flush it out with a garden hose and drain. now hook up a shop vac to each side one at a time and suck it all out. So that the blow out of the shopvac is pushing air into the pipes to the intercooler and sucking from the otherside. let it run for a few minutes. Now you can hook things up but leave the intake pipe off and start it up and let idle for a minute or 2. Now you can hook it up and let it idle and dont WOT it for a few minutes. You cna break in the rings at the same it. its not going to hurt it to idle for a few minutes to do this. You need to warm it up anyways before you start your break in regardless of fast or slow method.

What was the degree of your crosshatch when you honed?

jasantos40 · Sep 22, 2018

Mongler98 said:
there is no way for the engine to read compression so there is no adjustment for fuel injection. However, lower compression ranges will change the spray pattern slightly but nothing you can do about that.

Define "lots of oil"
Clean out all your lines and intercooler. The way most diesel mechs clean it is to disconnect the turbo and the engine from the pipes and ducktape on some large hose from a shopvac on both sides to elevate the hight of the pipes, pour in 2 cups of laundry detergent and fill with HOT water. now flush it out with a garden hose and drain. now hook up a shop vac to each side one at a time and suck it all out. So that the blow out of the shopvac is pushing air into the pipes to the intercooler and sucking from the otherside. let it run for a few minutes. Now you can hook things up but leave the intake pipe off and start it up and let idle for a minute or 2. Now you can hook it up and let it idle and dont WOT it for a few minutes. You cna break in the rings at the same it. its not going to hurt it to idle for a few minutes to do this. You need to warm it up anyways before you start your break in regardless of fast or slow method.

What was the degree of your crosshatch when you honed?

The best I could:

Engine cannot read compression but I suppose, since it produces less power and a slight decrease of rpms on a cylinder that has lower compression, it raises the IQ on that injector to get the idle values.

All the intercooler lines are clean.

The engine only idle for 30secs/ 1 min then I turned off. Just need to know if its normal to get a bit of white smoke and some erratic idle just after the rebuild.

GoFaster · Sep 22, 2018

Take it out and drive it. You need to build some cylinder pressure to seat the rings, and that won't happen at idle.

Vince Waldon · Sep 22, 2018

jasantos40 said:
Just need to know if its normal to get a bit of white smoke and some erratic idle just after the rebuild.

In my experience a less than smooth idle is understandable, but of course "how erratic" is in the eye of the beholder, and you don't want it to idle at all really. Ger 'er on the road and once it's up to operating temperature drive it hard for a prolonged period of time to put the rings under lots of pressure.

Also a common idea to use cheap conventional ie non-synthetic oil for the first 500 miles or so (if not an actual break-in oil)... the theory being that you *want* some wear to occur between the rings and the honing, and synthetic is just so darn slippery. You're going to change it really soon, so it doesn't even need to be diesel-rated... whatever you can find in the 5W-40 range that's straight dino juice.

jasantos40 · Sep 22, 2018

Vince Waldon said:
In my experience a less than smooth idle is understandable, but of course "how erratic" is in the eye of the beholder, and you don't want it to idle at all really. Ger 'er on the road and once it's up to operating temperature drive it hard for a prolonged period of time to put the rings under lots of pressure.

To quantify how erratic, sometimes, inject deviation peaks at 2.99 -3.01 then recovers, but as you said, I'll get it on the road. What max RPM do you suggest?

I've read some put weight on the boot to create drag and cylinder pressure, is it worth? I got dozens of old disc brakes lying on the shop to create weight ...

Thanks for all the answers.

Mongler98 · Sep 22, 2018

well, that's less than ideal hone degree, your shooting for 30* give or take 5* . SLOW rpm on the drill with fast up and down motion. looks like it went too fast your your arms didn't move much. Either case it should be fine. Did you bore gauge it and find your egg, taper, and bore at 3 points? Did you even use a feeler gauge and check the ring gap?

If you have not checked the ring gap, go back in and start over. trust me, the one thing you CAN NOT HAVE is improper ring gap. not enough and the rings will bind against each other and you will crack the piston and grande the engine.

But if you have done all that and your ready to go, i would highly suggest go out and drive it at 50 to 75% throttle and avoid much idle time other than to warm it up first.

Go drive the hell out of it and set the rings in fast. The reason is that this crosshatch is week degree and deep AF and will burn in crosshatching faster than the rings can seat. The rings and crosshatching are playing a game of cat and mouse here.
If you take too long to seat them and the crosshatching breaks down before the rings have time to seat, they never will. And the degree that the crosshatching had here is so shallow that its going to happen fast, probably within 500 miles or less. So you have about this much time to seat the rings, this means fast and furious. Change that oil after 25 miles, then after another 100, then after another 500, then another 1000 and then at the last 3,000 miles, change the filter too. Get a pair of right or left handed tin snips and cut the ridge off the filter, wipe the filter off so that no external metal from snipping is present and drain all the contents of the oil you drained though a coffee filter after adding some gasoline or acetone to thin the oil, same with the filter in a separate coffee filter, and inspect the pleats after cutting them free. your looking for brass, aluminum and iron. You should see a fair bit of iron on the first go but it should be finer than pixy dust or powdered sugar.

You need to ass some break in oil additive on the first 3 oil fills. you want plenty of that zinc goodness in there. this protects your engines guts and helps work harden the metal with out scaring. So you will see a bit of glittery like look to the oil that has that in it. your looking for anything and everything. take some pictures of what you find and post them here.

I would highly suggest putting an oil PSI gauge on. any will do. you may have to switch to a heaver oil depending on what you get.

Mongler98 · Sep 22, 2018

Don't dick around with loading it, Drive it, dont exceed 2500 RPM but i would give it as much variety as you can.

I would drive it as you normally would do but make sure you go a bit heavy on the throttle more than you normal would but dont rev up past 2,500

jasantos40 · Sep 22, 2018

Mongler98 said:
well, that's less than ideal hone degree, your shooting for 30* give or take 5* . SLOW rpm on the drill with fast up and down motion. looks like it went too fast your your arms didn't move much. Either case it should be fine. Did you bore gauge it and find your egg, taper, and bore at 3 points? Did you even use a feeler gauge and check the ring gap?

If you have not checked the ring gap, go back in and start over. trust me, the one thing you CAN NOT HAVE is improper ring gap. not enough and the rings will bind against each other and you will crack the piston and grande the engine.

But if you have done all that and your ready to go, i would highly suggest go out and drive it at 50 to 75% throttle and avoid much idle time other than to warm it up first.

Go drive the hell out of it and set the rings in fast. The reason is that this crosshatch is week degree and deep AF and will burn in crosshatching faster than the rings can seat. The rings and crosshatching are playing a game of cat and mouse here.
If you take too long to seat them and the crosshatching breaks down before the rings have time to seat, they never will. And the degree that the crosshatching had here is so shallow that its going to happen fast, probably within 500 miles or less. So you have about this much time to seat the rings, this means fast and furious. Change that oil after 25 miles, then after another 100, then after another 500, then another 1000 and then at the last 3,000 miles, change the filter too. Get a pair of right or left handed tin snips and cut the ridge off the filter, wipe the filter off so that no external metal from snipping is present and drain all the contents of the oil you drained though a coffee filter after adding some gasoline or acetone to thin the oil, same with the filter in a separate coffee filter, and inspect the pleats after cutting them free. your looking for brass, aluminum and iron. You should see a fair bit of iron on the first go but it should be finer than pixy dust or powdered sugar.

You need to ass some break in oil additive on the first 3 oil fills. you want plenty of that zinc goodness in there. this protects your engines guts and helps work harden the metal with out scaring. So you will see a bit of glittery like look to the oil that has that in it. your looking for anything and everything. take some pictures of what you find and post them here.

I would highly suggest putting an oil PSI gauge on. any will do. you may have to switch to a heaver oil depending on what you get.

5 oil changes to engine break-in?

I didnt measure the cylinders and the rings because i didn't bore it, and the engine had good compression before rebuild: 480psi, the reason I rebuilt it was just because of that bent rod.

jasantos40 · Sep 22, 2018

Mongler98 said:
Don't dick around with loading it, Drive it, dont exceed 2500 RPM but i would give it as much variety as you can.

I would drive it as you normally would do but make sure you go a bit heavy on the throttle more than you normal would but dont rev up past 2,500

Will do it, thanks for the advice.

Vince Waldon · Sep 22, 2018

Just one man's opinion (and there are thousands of them on engine break-in, of course), but I disagree with a 2500 RPM cap.

You want the rings to break in, as fast as possible, so things don't glaze up. In my mind this means they need to see a wide range of temperatures, pressures, loads, and anything else they will be subject to for the rest of their lives.

Are you gonna keep the RPMs below 2500 the rest of your life? Nope!

IMHO once it's up to operating temperature it's not an egg... it's not going to break if you stick your toe in it... and you want it experience life.

Push it, rev it, decelerate hard (to put pressure on the rings in the opposite direction)... all within reason of course. It's also not a dragster, but I bet it's not only going to church on Sunday either.

Work 'er, reasonably hard, before it glazes over. And to me, that's RPMs well over 2500 now and again as you work thru the gears.

(Just my opinion, not gonna argue with anyone about it.

)

AndyBees · Sep 22, 2018

Subscribed ........................ got to see the results.

csstevej · Sep 22, 2018

Same here too.......subscribed

jasantos40 · Sep 23, 2018

So, the best rpm range is 2k - 3k and 75% throttle?

Mongler98 · Sep 23, 2018

jasantos40 said:
5 oil changes to engine break-in?
I didnt measure the cylinders and the rings because i didn't bore it, and the engine had good compression before rebuild: 480psi, the reason I rebuilt it was just because of that bent rod.

OH YEA man, you want to change that oil LOTS OF TIMES
standard break in is at least 3 oil changes withing the first 3,000 miles but this is a rebuild with a very poor hone angle. you are going to see lots of break in metal dust in that oil.
The oil is to capture contaminates and you will have LOTS of them. Oil is cheep, use the cheapest oil you can. Oh and another tip, do not run synthetic for the first 2 changes. run conventional oil. NAd go cheep on the filters. there only there to do some work, not last 10,000 miles. Normally you would do about 3 changed but, again, oils cheep and you want to encourage as much ring wear as possible to seat them in.

Did you reuse the old rings? If so, you may have issued reseating the rings.
If new, pull it apart and gap the rings, or you risk a total engine grenade

i was wrong in saying 2500 RPM, yea just keep it under 2500 for the first few minutes of running i mean to say. once you get it nice and to temp go for it.

jasantos40 · Sep 23, 2018

Mongler98 said:
OH YEA man, you want to change that oil LOTS OF TIMES
standard break in is at least 3 oil changes withing the first 3,000 miles but this is a rebuild with a very poor hone angle. you are going to see lots of break in metal dust in that oil.
The oil is to capture contaminates and you will have LOTS of them. Oil is cheep, use the cheapest oil you can. Oh and another tip, do not run synthetic for the first 2 changes. run conventional oil. NAd go cheep on the filters. there only there to do some work, not last 10,000 miles. Normally you would do about 3 changed but, again, oils cheep and you want to encourage as much ring wear as possible to seat them in.

Did you reuse the old rings? If so, you may have issued reseating the rings.
If new, pull it apart and gap the rings, or you risk a total engine grenade

i was wrong in saying 2500 RPM, yea just keep it under 2500 for the first few minutes of running i mean to say. once you get it nice and to temp go for it.

The bore was measured, got 79.50mm and I bought 79.50 piston rings, OEM size.

Don't think I'll be pulling everything apart again just to measure the gap. Also I don't see how would the engine would be damaged by just having smaller rings than it should be (apart from low compression issues and oil consumption) but I would like to understand.

Mongler98 · Sep 23, 2018

jasantos40 said:
The bore was measured, got 79.50mm and I bought 79.50 piston rings, OEM size.
Don't think I'll be pulling everything apart again just to measure the gap. Also I don't see how would the engine would be damaged by just having smaller rings than it should be (apart from low compression issues and oil consumption) but I would like to understand.

too much gap, even 0.010 will cause very low compression and massive oil burning the rings are there to scrape off the oil and there is supposedly like 100 to 300 PSI of oil pressure withing the ring areas that the oil pressure spikes too, Too much gap and your idle will have massive oil burning and when you get on the throttle and rpm and boost come up you will have MASSIVE blow by and thats not good for a few reasons, tdi's can run away with too much oil going into the engine via the turbo and its possible that if you had enough blow by that the CCV would cause a runaway.

Too small of a gap and it will pinch, and try and expand causing the top of the piston to explode.

its procedure on all engine builds to gap the rings. i have never in my life seen a set of rings that comes from the factory thats what i needed. We are taking about 0.005" here. thats not much, one touch of a file can take off 0.003 in one pass. Your tolerance on your measurements is about 0.008+/-

If your gap is supposed to be 79.50 and your tolerance is 0.008 and you gaped them at 79.508, you run a 95% chance that the gap will close up on you and will deform and break the top ridge off the piston causing total catastrophic failure you will not be able to rebuild from, well cheaply any ways.

Pull it apart and regap those rings. i mean geese, just pop the TB belt off, pull the head and drop the pan. its about what, 1 days work? compared to a total loss on the engine?

dont ever trust ring gap, the rebuild fore these engines calls for ring gap procedure. how did you miss this part?

http://blog.wiseco.com/everything-you-need-to-know-about-ring-gap

jasantos40 · Sep 23, 2018

Live and learn, theres no risk in oversized the rings, like I said, i installed the oem ones.

On the first start theres was no smoke coming by the valve cover.

"just pop the TB belt off, pull the head and drop the pan"

It just 8 or 9 hours and new headgasket and bolts. I prefer to do the break in, compression test after.

Mongler98 · Sep 23, 2018

jasantos40 said:
Live and learn, theres no risk in oversized the rings, like I said, i installed the oem ones.

On the first start theres was no smoke coming by the valve cover.

"just pop the TB belt off, pull the head and drop the pan" It just 8 or 9 hours and new headgasket and bolts. I prefer to do the break in, compression test after.

you mean undersized? right?

yea, do some reasurche on this subject. you may change your mind. unless you measured it with a bore gauge and not a set of micrometers or calipers, you should have a much more refined measurement.

not enough gap and the moment you add boost and get to higher EGT's you will grenade that engine 100%. this is a #1 cause of failure with gass engines and NOS. Too much heat, gap closes.

I would seek out the advice of others who have gaped OEM replacement rings.

The procedure calls for them to be gaped.

When they close the gap, your looking at about 0.003 of a gap left over, much more and you will see uneven wear on the walls and excessive blow by and oil burning as a result.

Good luck, you have been warned.

What positions did you put the rings at? this is nearly as critical as the gap. you wanted to put the top 2 rings opposing gaps and at a 20 to 25* angle from each other and put the gaps at the wrist pins so that they dont wear down the side walls where the most pressure is. Same with the upper and lower oil rings.

Assuming your gap is good enough and it runs, and you worst case scenario put the gaps in the wrong places. given your poor hone job, and lack of proper blueprinting, i gave this engine a 100,000 life or less to it. Hope im wrong

I have been there and done that bro. its not worth skipping blueprinting setps. Did you plastigauge measure the crank?

jasantos40 · Sep 23, 2018

I mean there is no risk of being installed oversized rings, I bought the smallest.

Remember, engine is in good shape, had good compression, I just rebuilt it due to a bent rod.

Gaps were installed away from the thrust sides.

Don't worry about it, if it ends up with blowby I'll rebuilt it again.

turbocharged798 · Sep 23, 2018

My opinion is that you first need to get the engine under load and up to temp. Too much idling and low RPM will result in wet-stacking and unseated rings.

Secondly, a compression test will be telling. My suspension is that your injector imbalance is due to FOD that got introduced in the injectors when they were removed. That would also cause white smoke as well.

jasantos40 · Sep 25, 2018

Ok last night got everything installed, all the cooling system, EGR and boost hose, crank pulley, alternator belt, started the engine (much better start then when I had the bent rod) and waited to get to 60°C. Then started to moving, 25% throttle, 2000rpms, when it to got 85/90°C stepped 75% 2000/2500rpms, some gear reduction, some reprises after 1500rpms.

Didn't had the time to run it too much, it was late but ran for about 1/2km, what you guys call about 1/4 mile.

When getting back to the shop, my injector readings were:

No smoke coming from the exhaust pipe.

Idle is higher intentionally with VCDS.

jasantos40 · Oct 2, 2018

Update.

After 200Kms (125miles)
Already had an oil changed has suggested.

@36°C Coolant, I'm getting on injector deviation:
-0.12 -0.07 0.21 -0.02

So it seems well balanced.

Did a compression test today, got:
#1 390PSI
#2 410PSI
#3 420PSI
#4 410PSI

Are those numbers ok for a fresh built engine?

Mongler98 · Oct 3, 2018

GOOD, glad to hear it
pull apart the filter and strain it all though a coffee filter, including what you drained. it helps to thin the oil with gasoline.

jasantos40 · Nov 13, 2018

Ok, just to update, and also for future users looking for answers of this matter.

1500kms (930miles), done a compression test @15°C (60°F), engine stone cold.

#1 440PSI
#2 445PSI
#3 460PSI
#4 460PSI

Inj deviations are between -0.3 and 0.3, right from the start.

Started to go full throttle, until 3000/3500 rpms.

Getting a bit of oil consumption, 1mm drop on the dipstick, since started the hard driving sessions, for the last 200kms/125miles, I'm assuming is still part of the break in.

Starts fine, no white smoke on cold starts, no misfires, pulls ok, not getting the full potential of the engine due to a turbo upgrade, hybrid 1752vb but stock file, only getting 1.5b at 2.5k rpms, just coming on 500rpms later.

Powder Hound · Nov 13, 2018

jasantos40 said:
... engine stone cold.
...

I'd bet the compression numbers go up if the engine is warmed up first.

Cheers,

PH

jasantos40 · Nov 13, 2018

Didn't bother doing it, like you said, numbers would probably go up on a warm engine, also I don't like to pull glow plugs on a warm engine.

In my opinion cold starting issues are more detectable on cold testings. With a bent rod, with no protrusion at all, misfiring when cold, I was getting good compression values across all cylinders on a warm engine but with the engine cold, the problem was unmasked and the compression deviation was 75psi on that faulty cylinder.

Re-ring, rebuild questions.

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