Yanmar 3GM30Fe low power when cold

[AA3JY]

Originally Posted by phantomracer

I took the class in 2010. We pulled the injector but didnt pull the precombustion chamber ..

I had RIP Larry Berlin for the instructor and we pulled ‘em..

[phantomracer]

Originally Posted by AA3JY

I had RIP Larry Berlin for the instructor and we pulled ‘em..

I had larry too, we didn't pull them, however. He was a great instructor! Best money I have spent on the boat! I was sad to hear of his passing too!

[sinnerman]

things to do when you remove the injectors:

- Take them to a diesel injector shop to have them tested for :

o Pressure at which they open/fire
o Spray pattern
o That after they fire they seal correctly and do not have fuel dripping

- Adjust the valve clearances
You can rotate the engine easier with no compression due to the injectors being removed...)

- Optional: Check the compression (if engine is new this may be unnecessary)

my two cents

cheers

[phantomracer]

Originally Posted by sinnerman

things to do when you remove the injectors:

- Take them to a diesel injector shop to have them tested for :

o Pressure at which they open/fire
o Spray pattern
o That after they fire they seal correctly and do not have fuel dripping

- Adjust the valve clearances
You can rotate the engine easier with no compression due to the injectors being removed...)

- Optional: Check the compression (if engine is new this may be unnecessary)

my two cents

cheers

that was pretty much going to be my plan.. do the past due maintenance..

should be pretty easy to rotate the engine with no compression while the injectors are serviced.

At idle the engine appears to be OK. It seems it is likely, as been pointed out, the problem is likely compounded by the belt manager on the regulator too high, growth on the bottom and prop, and likely the cold diesel oil in the crankcase.

But will do this to, at least, get the engine to a known good state, and check it out next season.

[Symphony]

Do the simplest test first- get yourself or put a GoPro in the water and check fouling on the prop.

Runs OK with no load? Hmmmmm. A little fouling really messes with everything.

[Dalestr]

This problem would be consistent with tight valve clearance but I’d expect hard starting too. A weak or broken valve spring might be it. It certainly could be an injector problem which seems low hanging fruit. Maybe head gasket leaking until warm. It doesn’t appear to be a low pressure fuel problem but blocking off the recycling/ self-bleed line could be tried in case that check valve is getting stuck, reducing supply to injection pump. I wonder if the ‘smoke’ when pushed might possibly be steam from coolant in the mix. Doubt the alternator or condition of the bottom a major factor.
Too bad the actual fix has not yet been presented to us!

[DirtPete]

Sounds like a fouled (stuck open) thermostat. If the boat performs after warming up for a few minutes then themorstat seems like the logical place to start.

Just my .02

[DirtPete]

Originally Posted by Dalestr

This problem would be consistent with tight valve clearance but I’d expect hard starting too. A weak or broken valve spring might be it. It certainly could be an injector problem which seems low hanging fruit. Maybe head gasket leaking until warm. It doesn’t appear to be a low pressure fuel problem but blocking off the recycling/ self-bleed line could be tried in case that check valve is getting stuck, reducing supply to injection pump. I wonder if the ‘smoke’ when pushed might possibly be steam from coolant in the mix. Doubt the alternator or condition of the bottom a major factor.
Too bad the actual fix has not yet been presented to us!

Smoke is because the malfunctioning thermostat is cooling the intake manifold (as well as the rest of the engine) leading to incomplete combustion. The smoke goes away after the engine is warm because, well it's warm enough to combust all of the fuel.

I sure hope this guy didn't pull the head or injectors before replacing a simple maintenance item like a thermostat.

[skipperpete]

Originally Posted by DirtPete

Smoke is because the malfunctioning thermostat is cooling the intake manifold (as well as the rest of the engine) leading to incomplete combustion. The smoke goes away after the engine is warm because, well it's warm enough to combust all of the fuel.

I sure hope this guy didn't pull the head or injectors before replacing a simple maintenance item like a thermostat.

Your diagnosis is more like whats going on with the 2002 volvo that blows white steam or smoke on a recent previous thread, but difficult to justify with a 3GM Yanmar, the air intake on a 3GM is not really involved with the cooling system other than being attached to the cylinder head and Yanmar thermostats normally fail closed ( as do most other wax pellet thermostats)

[Lepke]

In cold weather diesels don't atomize fuel well. If you don't have the problem in warm weather, then everything is probably ok. A block heater run for an hour before starting or so should stop the problem.
Injectors will get buildups on their tips, hurting the spray pattern. Large droplets do not fully burn. But if the problem goes away when the engine is up to normal temp, you don't have an injector problem. You have a cold weather problem.

[DirtPete]

Originally Posted by skipperpete

Your diagnosis is more like whats going on with the 2002 volvo that blows white steam or smoke on a recent previous thread, but difficult to justify with a 3GM Yanmar, the air intake on a 3GM is not really involved with the cooling system other than being attached to the cylinder head and Yanmar thermostats normally fail closed ( as do most other wax pellet thermostats)

Are you saying that an open (faulty) thermostat wouldn't allow water into the water jacket of the block? Like stated above, cold block means cold everything else. If the problem didn't go away after the engine ran for a few minutes (reached temp) then I'd be looking elsewhere.

[skipperpete]

Originally Posted by DirtPete

Are you saying that an open (faulty) thermostat wouldn't allow water into the water jacket of the block? Like stated above, cold block means cold everything else. If the problem didn't go away after the engine ran for a few minutes (reached temp) then I'd be looking elsewhere.

In the old days with copper bellows thermostats…. They failed open so an engine would run cold, when the wax pellet thermostats entered the market there was a new problem, they failed closed and an overheat was more or less inevitable if there was no bypass function to allow a bit of circulation. Big engines often have multiple thermostats, (some at different temps) to avoid a single point failure and a bypass to stop the circulating pump cavitating itself to death, a common failure on cat 3516 engines

[DirtPete]

Originally Posted by skipperpete

In the old days with copper bellows thermostats…. They failed open so an engine would run cold, when the wax pellet thermostats entered the market there was a new problem, they failed closed and an overheat was more or less inevitable if there was no bypass function to allow a bit of circulation. Big engines often have multiple thermostats, (some at different temps) to avoid a single point failure and a bypass to stop the circulating pump cavitating itself to death, a common failure on cat 3516 engines

Not sure what this has to do with a 3GM.

I just don't know how you arrive at injectors before verifying that the thermostat is in good working order. If the alternator was really straining the engine that hard it would be eating belts left and right.

[skipperpete]

Originally Posted by DirtPete

Smoke is because the malfunctioning thermostat is cooling the intake manifold (as well as the rest of the engine) leading to incomplete combustion. The smoke goes away after the engine is warm because, well it's warm enough to combust all of the fuel.

I sure hope this guy didn't pull the head or injectors before replacing a simple maintenance item like a thermostat.

I was actually the guy NOT advising injector removal, the Mackboring students suggested that and I only responded with thermostat advice because of your suggestion that” smoke is because a malfunctioning thermostat is cooling the intake manifold”. I have no doubt that a failed thermostat WILL cause smoke but it’ll be the paint on the engine smoking from the overheat. I still maintain that the OP’s smoke and loss of power is due to a combination of the Balmar reg setting and a lightly fouled propeller, I might be wrong and I often am…..I hope he lets us know how and if he fixes the problem

[phantomracer]

Originally Posted by DirtPete

Smoke is because the malfunctioning thermostat is cooling the intake manifold (as well as the rest of the engine) leading to incomplete combustion. The smoke goes away after the engine is warm because, well it's warm enough to combust all of the fuel.

I sure hope this guy didn't pull the head or injectors before replacing a simple maintenance item like a thermostat.

have done nothing yet. T-stat is about 2-3 years old , yanmar tstat