Blue Smoke for first 20 minutes.

[tubpilot]

Sorry if this has been covered before: Universal 5424 (3cyl Kubota) rebuilt 400 hours (2 years) ago, it got new pistons and sleeves, crank bearings and the head rebuilt. Quite a bit of blue smoke now when fist started for about 20 minutes then it goes away. Oil pressure is about 60 PSI. Plenty of power. Any ideas?

[avazquez]

My Perkins smokes white upon startup until it reaches temperature 180. Smoke goes away as temperature rises. I have done all kinds of checks...and smoke still there upon startup. Only thing left for me is to re-torque the head. The engine was overhauled a year ago. Probably 50 hours or so. Anyway this is the place for answers. I am sure you will get valuable info here.

[DeepFrz]

Blue smoke probably means you are burning lube oil. Which probably means it's leaking past the piston rings or the valve guides.

[Alan Wheeler]

Yes the blue smoke is an indication of oil seeping past the rings. This can occur for several reasons, but all of them point toward the cyclinders glazing. There is a good chance this can be reversed.
Here are the rules.
1: Start engine from cold and at idle, allow oil pressure to rise(30secs)then imediatly place into gear. Allow boat to pull on dock lines.
(if you are on a mooring, slip the mooring ASAP and get underway)
2: After only 60secs(oil should be fully circulating by now) take engine to 1000RPM and pull on dock lines. Leave at 1000RPM till engien temp just starts to raise. As soon as temp moves, raise throttle to 50% RPM.
Dock lines will creak, but they will be fine.
3:Once temp gets to 50%, raise throttle just a little further and then allow temp to get to full. You can now raise to full RPM.
4: Raise to full RPM(fully open throttle) but watch for black smoke. As soon as it black smokes, reduce throttle till there is little black smoke. Watch temperature does not go too high. Run the engine hard at this point for a good 10 to 15Mins. Now reduce revs to 1000RPM and allow to run for a minute to fully cool and then shut down.

Doing this regularly will eventually help those rings to bed in.
When you are getting underway, then the goal is to get the boat into gear and upto speed as ASAP.
DO NOT EVER let a diesel "warm up" by idling out of gear in the marina before you get underway. It is death to a diesel.

[tubpilot]

Thanks Alan, I will try what you suggest. I was concerned that that the problem could cause my engine to be unreliable. I am planning to do some extended cruising and don't want to worry about a worsening condition.

[Alan Wheeler]

A Diesel likes good hard work and just a touch of abuse thrown in to make it work well. No mamby pambying around with them.

[Whimsical]

Originally Posted by Alan Wheeler

A Diesel likes good hard work and just a touch of abuse thrown in to make it work well. No mamby pambying around with them.

Sounds like they have a lot in common with women

Mike

[Lancerbye]

Yeah you have to beat them once in a while. Hope my the Admiral isn't reading this post.

[avazquez]

Alan,What do you mean by "cylinder glazing"?

[GordMay]

Cylinder Glazing:

Blue smoke should not be evident at any stage. Blue smoke is caused by engine lubricating oil burning. Blue smoke is often evident at cold start, which can reflect reduced oil control due to carbon fouling deposits around the piston rings and/or cylinder glaze.

An engine may burn oil without the evidence of blue smoke, because good compression burns oil quite cleanly, however, it is not acceptable for any new engine, or engine in good internal condition to burn large amounts of lubricating oil.

Diesel fuel needs to be introduced into an air environment that is under intense pressure, in order for it to burn without an ignition source. When the fuel burns, the gasses produced multiply the compression pressure in the cylinder. Pressurized gasses that escape by means of the compression ring / cylinder wall interface are called blow-by gases.

The blow-by engine oil, lubricating the cylinder walls, will flash burn when it contacts the very hot rings.
This burned oil will leave a hard, enamel like residue on the cylinder wall, commonly known as oil glazing.

Running the engine under very light or no load also prevents the oil film placed on the cylinder wall from being scraped away by the expanding compression rings. The rings will instead “hydroplane” or ride over the deposited oil film, allowing it to be exposed to the cylinder combustion. The oil film will then partially burn on the cylinder leaving a residue that will build up and oxidize over time. Eventually this leaves a hard deposit on the cylinder wall that is very similar to the glaze left from flash burning.

Once this glaze builds up, the only repair is a labor-intensive process that requires disassembling the engine and re-honing the effected cylinders.

[avazquez]

In my case it smokes white until the engine warms up. It was rebuilt, then the boat sat in the dock without being used for at least 1 year. It has less than 50 hours. It smokes white upon start up, then I simply put it in gear at 1000 - 1500 rpm. After temperature rises it stops smoking and runs great.

[GordMay]

New Diesel Break-In:

During break-in, a small amount of compression blow-by, oil-fuel dilution, and oil consumption will be experienced. This is normal, and quite common in new (or reconditioned) engines. Although acceptable at first, it is imperative that these undesirable attributes be as close to zero as possible, after break-in has been completed.

A break-in period is required, when an engine is new or whenever the cylinder walls have been re-conditioned to accept new piston rings. An engine break-in "seats" the piston rings against the cylinder walls, to minimize both oil consumption and blow-by of combustion gases.

1. DON'T run the engine above 75% rated RPM for the first few (up to 10 Hrs) hours; but DON'T let the engine idle for more than five (5) minutes, at any one time, during these first hours.
2. DO operate the engine at varying RPMs and speeds until about 25 - 50 hours. The idea is to alternately heat and cool the rings under varying RPMs.
3. DO put a load on the engine at around 50 hours, and get the thing hot! Diesels are designed to work, and they operate best under a load. Baptize your engine with a nice "initiation load," to introduce it to hard work. Keep the RPM up near maximum (at least 80%), and make sure the coolant temps rise.
4. After the break-in period, an average cruising RPM is about 80% of the maximum specified engine speed. Properly matched, this should drive a sailboat to hull speed.

[Alan Wheeler]

Thanks Gord. That was spot on.
Avazquez, white smoke is a tricky one. Often what is considered white smoke, may infact only be steam. So the first question is, does it disapate into the air very quickly, as in steam, or does it blow away in the wind as in smoke?
If you really do consider it smoke, the next question is, does it seem to "puff" out the exhaust or is it a continuouse stream.
If it "puffs" it can be a good sign that one cylinder is not firing. White smoke is usually unburn't diesel fuel. The cylinder has not fired and the raw fuel simly gets exhausted out. As it is one or two cylinders, it tends to come out in "puffs". Does the engine run smooth when it first fires, or does it run ruff and smooth out as the smoke disappears.
It is highly possible that the engine is OK and infact does need glow plugs to start correctly. The fact that the engien is in great condition is why the engine starts with no glow plug. If it has plugs, I would use them. This stops the possibility of raw fuel washing down the bore and past the rings into the engine oil.

[cooper]

I agree with Alan on the "white smoke"....if it is fuel and not water you can somtimes smell the vaporised diesel.......

Thanks Gord a copy of your run in notes has just been tapped to my brand new as yet not run in engine !!

[defjef]

I had the top end valvles) of our 1985 Volvo Penta MD17D rebuilt last year. The excellent mechanic said that the lower end... rings were the cause of the grey smoke at start up. First time in the spring is rather smokey!

In my case the smoke stops or becomes almost invisible when the engine get to operating temperature. There is almost no smoke when we start a warm engine, and none when we restart the engine which is at operating temperature.

We do see steam occassionally especially when the air is cool. It is not white smoke as it disappates quickly.

I suspect your grey smoke is from rings or cylinder wall glazing as noted above... and probably subsides when the engine heats up.

I don't know that I would do the rings on this 22 yr old engine. I will tolerate the smoke as long as it performs well in all other aspects. It does.

Jef
sv shiva