Brand New Yanmar smoking and acting sluggish

[zstine]

I also agree that white smoke indicates a lean mix, lack of fuel (or head gasket). If I were to troubleshoot that, I would disconnect the fuel line from my Racor pre-filter going to the engine and drop the fuel line in a jerry can and run the engine off that. If the problem goes away, you know you have an issue with the vents, or between the pickup and up to and including the pre-filter. If the issue persists, then you have eliminated those components as the problem. This assumes you do not have a lift pump in your tank. Also, pinch/clamp off the lines before disconnecting so you don't get fuel everywhere and you don't get air into the lines.
best luck
Zach

[reed1v]

Originally Posted by sailorchic34

At 33 hours, the engine is not broken in yet. Per yanmar, new engines should be operated at about 70% of max rpm from 10 hours to 50 hours. There is a guide in the engine owner manual on break in rpms. Generally you have to vary the rpm a bit every so often for the rings to set. You do not run at a constant rpm for 7 hours though.

If it's not ring/ cylinder scuffing, you might have picked up a bit of line on the prop.

Yup, good advice. Sounds like fried cylinders or blown head gasket from not breaking in the engine. If it is the prop, then the rpms in gear vs out of gear should be different. But who looks at instructions anyhow? They are for wussies.

[jkishel]

Several incorrect comments above, white exhaust is unburned fuel. This is caused by excessive fuel in the cylinders or inadequate combustion. Check injectors first (excessive fuel), then check combustion; low injector pressure, bad fuel, low compression, head gasket.

[Fishman_Tx]

Originally Posted by jkishel

Several incorrect comments above, white exhaust is unburned fuel. This is caused by excessive fuel in the cylinders or inadequate combustion. Check injectors first (excessive fuel), then check combustion; low injector pressure, bad fuel, low compression, head gasket.

Yep. See my post #2...

FIRST THINGS FIRST STAY CALM

Always check the fuel condition and filters FIRST. One step at a time with a logical progression. Eliminate the simplest things first. Fuel condition, pressure and flow, venting, and filtration before you even THINK about the hard stuff. I tend 14 permanent gensets and 2 portables for AT&T, but I'm no expert, either. Check the obvious first. There are many SIMPLE causes to this than burnt cylinders or a bad break-in.

Just sayin'!

[reed1v]

Originally Posted by jkishel

Several incorrect comments above, white exhaust is unburned fuel. This is caused by excessive fuel in the cylinders or inadequate combustion. Check injectors first (excessive fuel), then check combustion; low injector pressure, bad fuel, low compression, head gasket.

Guess you are one of the clueless also. White and also black smoke can represent unburned or partially burned fuel. White also can represent cooling water that has gotten into the cylinders(think head gasket). So white smoke can represent not just fuel but water, usually water vapor.

Condensation is normal on cold mornings and white smoke just means the engine is blowing out the condensation. However this should not affect the engine's performance. The conditions described sure do not look like excessive fuel from injectors for that would result in Black smoke, not white smoke. Better luck next time.

[jkishel]

White smoke is unburned fuel. Black smoke is partially burned fuel. White steam is water vapor.

Unburned fuel (white smoke) occurs either because too much fuel gets to the cylinders (bad injectors) or combustion is incomplete because of low compression, bad fuel, etc.

Partially burned fuel (black smoke) occurs because not enough air is getting to the cylinders, often because there is too much load on the engine (classically a fouled prop).

Steam (visually distinguishable from white smoke) occurs when cooling water boils in the exhaust system, typically clogged intake, strainer, bad impeller, fresh water problem, etc.

[Aqualibrium]

There seem to be many conflicting theories here,

Normally black smoke indicates incomplete or poor combustion often caused by overloading, ie Overpitched prop or rope around it but the vibrations are normally a giveaway with that.

White smoke as different to steam, check for water flow from exhaust and feel temperature of exhaust after engine and salt water injection point, if cold and good water flow it wont be steam.
White smoke can be due to excessive unburnt fuel and lube oil.

A 75 HP Yanmar will not have manual decompressors so that wont be the cause unless an exhaust or inlet valve is not closing, seems unlikely on a new engine.

But I did have a Yanmar that oversped due to an uncontrolled source of fuel on launch day!!!!
At 1 hr of use it had leaked a large amount of fuel into the sump, so much so that we emptied 600 ml of diesel LO mix out of the plastic silencer box from the air inlet.
This was setting up a smokescreen (White) that a world war ! battleship would have been proud of.

Engine could only be stopped at 4000+ RPM by choking air supply.
Its interesting to note that a diesel dies much more quickly than a human when it stops getting oxygen, the latter observation is only from watching movies.

Yanmar never had the courtesy to inform me of the problem which took over a month to resolve.
Their drawings dont show seals between the fuel pump pistons as in their words it would only confuse people and the pumps should only be pulled apart by Fuel Injection specialists. Agreed.
One of these seals had to be missing to put 4+litres of fuel in the sump in 50 mins of running at very low revs.
Beware of Yanmars, their in factory Quality control is woeful from my experience, two engines two problems.
Spend time watching and feeling around your engine when running; learn your salt and fresh cooling water flow paths and normal operating temperatures, its amazing what you can pick up before it becomes a major and expensive problem!

Learn how to kill your engine if it overfuels and overspeeds, you will not have very long to stop it before it self destructs with potential for boat damage and fire.

Got off the track a bit here, but the white smoke brought back many unpleasant memories on what should have been a day of celebration!

Check oil level closely to ensure there is no fuel going into sump.

Low engine revs and white smoke would possibly indicate one cylinder not firing due to lack of ignition temperature ie: Lack of compression.
If this is the case you will need a good diesel mechanic to help.

[Mike Banks]

White smoke which smells of diesel indicates unburned fuel.

Possible causes:

Wrong grade of diesel fuel being used--hence incomplete combustion at low temperature.

Too little air reaching engine through obstructed inlet manifold--

Injectors delivering too much fuel. Injector Pump needs recalibrating or re-timing.

Camshaft timing has slipped (most unlikely)

Return fuel line from injector pump is blocked or not connected to an open part of the fuel filter (if that is how it is connected) some go directly back to the fuel tank---mine go to the INLET side of the reservoir bowl in the fuel filter.

Glow plugs may need attention if fitted.

Too much oil in sump--this could be a cause as some of this oil vapor and spray may enter the inlet manifold through the breather and oil-recovery system. Easily checked with engine dipstick--

[Uncle Bob]

It's a new engine, someone put it in there, charged for the engine and installation, so take it back and insist that the problem be sorted.

[lateral]

Fugit.
I put my money on timing or low compression/head gasket.
But wtfdik.

I just rebuilt my injector pump system at 500hrs, set up to spec.
I did it cos of black smoke when you gun it.
New fuel lines, filter, lift pump, bleed, exhaust elbow, heat exchange rebuild.
Started instantly, after rebuild now its back to being cantankerous to start.
Dammit!

[s/v Jedi]

You guys are wrong. White smoke means we have a new Pope

[Uncle Bob]

Originally Posted by s/v Jedi

You guys are wrong. White smoke means we have a new Pope

Hallelujah, praise the lord.

[lateral]

Does that mean the OP should pray?

I have sworn plenty, maybe I should change the program?

[boatman61]

You have obviously NOT been following the running in instructions for the first 50hrs as has been stated earlier.. apart from operating the motor at 3/4+ rev's for set periods you are also supposed to run it at the maximum revs for 5mins after each period to clear the build up of crap.. reckon you may have shot your Guarantee..

[four winds]

I believe this is a JH series engine, correct?

Attached is the break in procedure from the operations manual.

Also, I'd like to add quick mention of valve lash adjustment. Initial adjustment is specified at 50 hours. From then on the interval is 1000 hours. This is because the valve seats change dramatically at break in. ( the valve heads "bed in" the new seats) This easily takes up the lash of just a few thousandths.

But from then on the wear is gradual and adjustment interval much greater.

No lash and can reduce compression, burn valve, cause white (light grey) smoke.

Something to consider, especially at breakin, possibly with poor breakin proceedure.