Kohler generator - Yanmar 4JHLHT-K oil pressure issue

[BartW]

since a few years, one of the Kohler 16,5Kw generators in our boat,
Always’s needs two starting attempts,

When I try to start, the engine starts running, but after 0.5 sec switches off again.
Also when the engine is hot, and after about 1hour not running, it will need two starting attemps to get the engine running again.

After some investigation,
And checking the electric control circuit
it appears to be the oil pressure that goes up too slow,
it doesn’t reach normal operation pressure within the normal starting sequence, so that the stop command is activated automatically.

sensors were swapped, so they are OK.

I’m not sure how this lubrication cirquit on such a engine works,

So
either the oil pump doesn’t give enough pressure (?)
But ones the genny is running, it works without any problem !

Or,
after stop, the oil in the engine is draining from the oil circuit, so that when starting the engine,
the oil pump has to fill the circuit first, before it can raise oil pressure.
(at least the symptoms are like that)

Can someone explain what could be wrong, or what to check ?
The second genny works perfect, and we can measure on the oil pressure sensor, that the normal oil pressure is reached right in time, within the starting. Sequence.

 

[jfm]

Could be one of several things but feels like a weak oil pump. I don't know that yanmar engine: is it difficult to swap oil pumps port -starboard? Or just buy a new one and swap it out to eliminate the pump.
How many hours on the good one and the bad one?

 

[volvopaul]

since a few years, one of the Kohler 16,5Kw generators in our boat,
Always’s needs two starting attempts,

When I try to start, the engine starts running, but after 0.5 sec switches off again.
Also when the engine is hot, and after about 1hour not running, it will need two starting attemps to get the engine running again.

After some investigation,
And checking the electric control circuit
it appears to be the oil pressure that goes up too slow,
it doesn’t reach normal operation pressure within the normal starting sequence, so that the stop command is activated automatically.

sensors were swapped, so they are OK.

I’m not sure how this lubrication cirquit on such a engine works,

So
either the oil pump doesn’t give enough pressure (?)
But ones the genny is running, it works without any problem !

Or,
after stop, the oil in the engine is draining from the oil circuit, so that when starting the engine,
the oil pump has to fill the circuit first, before it can raise oil pressure.
(at least the symptoms are like that)

Can someone explain what could be wrong, or what to check ?
The second genny works perfect, and we can measure on the oil pressure sensor, that the normal oil pressure is reached right in time, within the starting. Sequence.

A good theory bart but I’d say that it’s more a circuit board issue as the oil pressure and water flow sensor don’t activate until the engine is running when the board will take over taking care to shut down if it looses oil pressure or water flow loss.
It will fuel from cranking so as long as fuel is there at the fuel gallery all should be ok .
Question, does it have an electric pump ? Reason is that it has a plastic drive hub which plays part in fuel priming , once running the engines injection pump will suck it’s fuel as it displaces pressured fuel to each injector .

Slacken the bleed screw on the in-line injection pump and crank the engine next time it’s run up to operational temp , you should see fuel spit out .

I had this happen on a job in Spain a few years ago .

 

[BartW]

Could be one of several things but feels like a weak oil pump. I don't know that yanmar engine: is it difficult to swap oil pumps port -starboard? Or just buy a new one and swap it out to eliminate the pump.
How many hours on the good one and the bad one?

yes its quite difficult to replace the oil pumps especially on that side,
the bad one has around 4000Hrs, and the good one around 3500,

The problem is there already since several seasons, but I didn't bother to investigate...
the strange thing is that since very long, the issue has alway's been behaving exactly the same,
(engine starts running alway's after the second starting attempt)

If there is a good chance that the oil pump is warn out, I'll order one, and try to replace it.

 

[jfm]

A good theory bart but I’d say that it’s more a circuit board issue as the oil pressure and water flow sensor don’t activate until the engine is running when the board will take over taking care to shut down if it looses oil pressure or water flow loss.
It will fuel from cranking so as long as fuel is there at the fuel gallery all should be ok .
Question, does it have an electric pump ? Reason is that it has a plastic drive hub which plays part in fuel priming , once running the engines injection pump will suck it’s fuel as it displaces pressured fuel to each injector .

Slacken the bleed screw on the in-line injection pump and crank the engine next time it’s run up to operational temp , you should see fuel spit out .

I had this happen on a job in Spain a few years ago .

paul, all the electronic life (such as it is) is there before starting and the board is activet hen, surely. I'm struggling to see how this is fuel related if Bart has positively established that the oil pressure sensor is not sending an "I'm happy" message within the time limit set by the board, which will for sure cause a shut down. Happy to be enlightened.

 

[BartW]

A good theory bart but I’d say that it’s more a circuit board issue as the oil pressure and water flow sensor don’t activate until the engine is running when the board will take over taking care to shut down if it looses oil pressure or water flow loss.
It will fuel from cranking so as long as fuel is there at the fuel gallery all should be ok .
Question, does it have an electric pump ? Reason is that it has a plastic drive hub which plays part in fuel priming , once running the engines injection pump will suck it’s fuel as it displaces pressured fuel to each injector .

Slacken the bleed screw on the in-line injection pump and crank the engine next time it’s run up to operational temp , you should see fuel spit out .

I had this happen on a job in Spain a few years ago .

Its a 26yo genny Paul, I have the electric diagram,
it took me a while to sort out its working, and check all functions on the bad engine, but I was fairly sure that it was the oil pressure sensor.
Then I have swapped the relevant and main PCB's with the working genny and then I was 100% sure it was not in the electronics


that was all done last winter, so I forgot about certain details, and left this as it was.

At the beginning of last summer season, I had to replace the electric starter motor on that genny,
(ordered the spare part, and installed the new starter)
that was more urgent, as it couldn't start anymore, I wanted to have a backup genny during the season,

now in winter mode, I just remembered about the starting issue.

 

[kashurst]

just another idea for the pot - check out the oil pressure relief valve. I have seen similar slow oil pressure rise on old engines with worn OPR valves. Could just be gunged up or could be worn and letting oil leak back when the engine stops.

 

[volvopaul]

just another idea for the pot - check out the oil pressure relief valve. I have seen similar slow oil pressure rise on old engines with worn OPR valves. Could just be gunged up or could be worn and letting oil leak back when the engine stops.

My previous post relates to your job Kevin , remember after filter change on service genny wouldn’t start , my theory wa stat as fuel as already present at injection pump prior to filter change the genny was running on borrowed time , allowing air into the system cut off the supply and as the pump had failed we had the problem.

 

[volvopaul]

paul, all the electronic life (such as it is) is there before starting and the board is activet hen, surely. I'm struggling to see how this is fuel related if Bart has positively established that the oil pressure sensor is not sending an "I'm happy" message within the time limit set by the board, which will for sure cause a shut down. Happy to be enlightened.

Most of Onans and Köhlers I’ve serviced don’t have or need an I’m ok with oil pressure to initially start up , they just give fuel solenoid an open signal when cranking , think about bleeding the system at service, I always remove the starter signal solenoid wire from starter then go to crank mode to bleed most gen sets at service , so I assume from that process I use that the board set up gives fuel and cranking irrespective of oil pressure status otherwise if the board read no oil pressure it wouldn’t crank of give fuel to bleed past the injection pump.

I don’t know what sets you have on the 78 but if your doing DIY service next time you bleed up try my way, might save you a bit of time and fuel spillage if your sets can be fooled into thinking the engine is cranking .

Back to the OP , bart , hang a multi meter or wire a bulb with pos feed and use the earth terminal from the oil p switch and see what happens on cranking , if the light goes out you have oil pressure registration . A 2 wire switch is insulated earth and will be on a loop circuit no doubt in series with the exhaust overheat switch and possibly a sea water flow switch , though flow switches haven’t been around that long .
Just trying .....

 

[BartW]

just another idea for the pot - check out the oil pressure relief valve. I have seen similar slow oil pressure rise on old engines with worn OPR valves. Could just be gunged up or could be worn and letting oil leak back when the engine stops.

thats exactly what the Montenegro (MAN) service guy told me,
because this valve is "inside" the engine, it is quite some work to get at that.
we/they didn'd start that job, as we had other priority's at that moment.

the oil pump or that valve seem to be the two possible options.
will dig in the diagrams when back onboard, and look what's involved to replace these.

 

[BartW]

Back to the OP , bart , hang a multi meter or wire a bulb with pos feed and use the earth terminal from the oil p switch and see what happens on cranking , if the light goes out you have oil pressure registration . A 2 wire switch is insulated earth and will be on a loop circuit no doubt in series with the exhaust overheat switch and possibly a sea water flow switch , though flow switches haven’t been around that long .
Just trying .....

yes I had placed a multimeter over the Oil Pressure switch, and that behaved according the measurements on the PCB (oil pressure comes up only after the second starting attempt

 

[jfm]

Most of Onans and Köhlers I’ve serviced don’t have or need an I’m ok with oil pressure to initially start up , they just give fuel solenoid an open signal when cranking , think about bleeding the system at service, I always remove the starter signal solenoid wire from starter then go to crank mode to bleed most gen sets at service , so I assume from that process I use that the board set up gives fuel and cranking irrespective of oil pressure status otherwise if the board read no oil pressure it wouldn’t crank of give fuel to bleed past the injection pump.

Exactly- they don't need an ok to start. But after a time interval -2seconds ish- the board does look for I'm OK and shuts down (fuel solenoid) if it's not there. That's exactly Bart's observation so this has nothing to do with fuel and everything to do with oil imo.
Kashurst's idea is good.

 

[kashurst]

if the opr valve is buried inside the engine as you describe, and the engine/genny runs second go I suspect its not that bad/worth pulling it all to bits yet. It might be worth fitting an oil pressure gauge to see what the pressure is when its running properly. Eventually the main bearings and big ends will start to knock because of oil starvation on start up. That for me would be the point to either strip and rebuild the entire engine or buy new gennie. I don't think you will get the catastrophic failure you had with your main engine when the harmonic balance failed as in comparison its a tiddler. i.e. the crank shaft wont break or snatch the bearings out.

thinking about it if this gennie is the back up and not used often it will probably run like this for many years. Re rebuild - it could probably be cheaper to buy the short engine and just swap the head and ancillaries.

 

[BartW]

if the opr valve is buried inside the engine as you describe, and the engine/genny runs second go I suspect its not that bad/worth pulling it all to bits yet. It might be worth fitting an oil pressure gauge to see what the pressure is when its running properly. Eventually the main bearings and big ends will start to knock because of oil starvation on start up. That for me would be the point to either strip and rebuild the entire engine or buy new gennie. I don't think you will get the catastrophic failure you had with your main engine when the harmonic balance failed as in comparison its a tiddler. i.e. the crank shaft wont break or snatch the bearings out.

thinking about it if this gennie is the back up and not used often it will probably run like this for many years. Re rebuild - it could probably be cheaper to buy the short engine and just swap the head and ancillaries.

I have no clue how deep that valve sits inside the engine,

you touched exactly the dilemma I'm in right now,
spending more time and money on these old machines, (while both are actually running fine,)
or replace one of them with a new, similar size,

as you say, I would run only the new (less smelly and probably less noisy)
and use the old one as a backup,
and use the rest as spare parts...

 

[MapisM]

you touched exactly the dilemma I'm in right now,
spending more time and money on these old machines, (while both are actually running fine,)
or replace one of them with a new, similar size

At risk of appearing naive, I would consider a third alternative:
Just live with the double startup procedure, which only takes a minute more after all.
Use mostly that genset, preserving the other, and whenever it will give up for good (which might as well take years and another thousand of hours or more!), replace it.

 

[BartW]

At risk of appearing naive, I would consider a third alternative:
Just live with the double startup procedure, which only takes a minute more after all.
Use mostly that genset, preserving the other, and whenever it will give up for good (which might as well take years and another thousand of hours or more!), replace it.

thats what I've doing the last few seasons,
and might continue to do the coming season ;-)

fwiw the double start sequence takes a few seconds more, not a minute.
also my automatic genny start command from the victron battery monitors gives 3 start attempts, (the second and 3th are disabled as soon the genny starts running)

 

[MapisM]

thats what I've doing the last few seasons,
and might continue to do the coming season ;-)

LOL, I can't see any reason for not continuing until hell freezes over!

Are there any occasions when you NEED more than 16kW, hence having to run both gensets together?
I would suppose not, and if that is the case, also by normally running the "bad" genset you would always have a full redundancy at your fingertip.
If everything else is fine, chances are that also the "bad" one will run for a lifetime...
And if some guest asks you why it takes two startups to turn it on, you might as well tell them that it's a characteristic, rather than a defect!

 

[kashurst]

the auto start gives 3 attempts. that's probably a good guide. assuming the running oil pressure is ok, when it takes 3 starts to get it going is the time to sort it. could be years away.

 

[BartW]

the auto start gives 3 attempts. that's probably a good guide. assuming the running oil pressure is ok, when it takes 3 starts to get it going is the time to sort it. could be years away.

exactly !
a good and economic conclusion of this thread

 

[vas]

exactly !
a good and economic conclusion of this thread

if you want to buy a new starter motor every few seasons that is

due to bad bleeding and slight leaking stop solenoid valve washer on my 2cylinder yanmar geny engine, I ended up buying a new starter at 1100h...
Now the el. contact for the stop solenoid broke and I was cranking the shit out of it and (surprisingly) wouldn't start!
Realised it yesterday, so another small repair on the list!

cheers

V.