Diazel question

[Serge Tremblay]

I own a hunter 40.5 built in 96, Yanmar 50hp has 1400 hours was serviced every year, it starts and runs great with no load but has no guts at all when under load, I've checked exaust manifold and several other items but it remains gutless no tork at all, if alternator is ingaged I can't even leave the dock, I end up turning the key off to get the reaves up, anybody experience this that could point me in the right direction?

 

[Don S/V ILLusion]

Sounds more like an alternator problem than an engine problem ( "if alternator is ingaged I can't even leave the dock"). Bearings???

 

[Serge Tremblay]

Sounds more like an alternator problem than an engine problem ( "if alternator is ingaged I can't even leave the dock"). Bearings???

Thanks Don,
Already removed the alternator and got it checked, everything was fine, changed bearings anyways since I had it out, problem persist!

 

[smokey73]

Serge,

Will it rev normally when in neutral and idle in neutral?

Have you thought about something binding on the shaft?
Siezed or failed shaft bearing
Siezed, dry or overtightened shaft seal packing gland
Something like a line or wire wrapped around the shaft or propeller?

Might want to check those things out before you tear into the diesel.

Smokey

 

[FourPoints]

possible short in the alternator wireing, or problem with an external regulator resulting in the alt operating at max power, thus creating a heavy load on the engine?

 

[Ralph Johnstone]

Perhaps if you listed what has been checked to date, we could give you some insight into what remains to be checked eg. air filter, fuel filters (X2), mixing elbow, throttle/governor linkage, etc.

IMHO I would look within the engine for the problem. If the lost horsepower were going into an external problem, I would be looking at a lot of heat and damage at that point ie. boiling batteries from an out of control alternator, a smoking packing gland which is too tight, etc.

 

[Rick D]

All Good Ideas...

I would also look into a clogged fuel pick up as well as, of course, the fuel filters.

If it were I, I would borrow an electric fuel pump and bypass all the fuel delivery and return lines using a gallon bottle of some type in order to see if the issue is fuel delivery.

 

[Serge Tremblay]

Serge,

Will it rev normally when in neutral and idle in neutral?

Have you thought about something binding on the shaft?
Siezed or failed shaft bearing
Siezed, dry or overtightened shaft seal packing gland
Something like a line or wire wrapped around the shaft or propeller?

Might want to check those things out before you tear into the diesel.

Smokey

Smoky,
The engine starts and runs and revs perfectly in neutral, boat was up last Easter, changed cutlas bearing, realigned the shaft, readjusted shaft seal didn't see any improvement, I dive periodically to clean the prop and able to turn shaft by hand, I do have doubts on the alignment since I get vibrations on low RPM or when extra load from alternator kicks in!
I think the only thing left to check would be the fuel pump not supplying enough fuel under load or one dirty faulty injector or even exhaust manifold, even if I did look in it and could not find any build ups!

 

[Bill Roosa]

The problem is lack of power.
There are only a few reasons an engine will not produce power
Lack of fuel:
1 check the fuel tank vent, could be a vacuum in the tank
2 check the fuel tank strainer and all other filters/valves to make sure they are clean and open
3 check the injector pump, disconnect the throttle cable and manually work the throttle
4 check the injectors
3 air in the lines -- bleed the air

lack of air
1 take the air cleaner off and see if that makes a difference
2 inspect the mixing elbow for clogs. air can't get in if it can't get out too
3 check the valve timing (not likely as she is a diesel and would bend the valves (and you would hear that) if she jumped time)

lack of compression
1 do a compression test

 

[Serge Tremblay]

possible short in the alternator wireing, or problem with an external regulator resulting in the alt operating at max power, thus creating a heavy load on the engine?

I had someone check the alternator but never got the external regulator checked, I will remove and bring to someone to have a look, thanks!

 

[Serge Tremblay]

I would also look into a clogged fuel pick up as well as, of course, the fuel filters.

If it were I, I would borrow an electric fuel pump and bypass all the fuel delivery and return lines using a gallon bottle of some type in order to see if the issue is fuel delivery.

Thanks Rick, I will try that also!

 

[Serge Tremblay]

Perhaps if you listed what has been checked to date, we could give you some insight into what remains to be checked eg. air filter, fuel filters (X2), mixing elbow, throttle/governor linkage, etc.

IMHO I would look within the engine for the problem. If the lost horsepower were going into an external problem, I would be looking at a lot of heat and damage at that point ie. boiling batteries from an out of control alternator, a smoking packing gland which is too tight, etc.

Maybe I trust my mechanic to much, the guy has done the yearly maintenance for the past 5 years, fuel filter, throttle, linkage the only thing I never really paid attention to is the mixing Elbo I presume that could also be a cause!
I remember the boat being able to maintain 6 kts with no effort now 5 kts with clean prop and the wind in my back is the best I can do, I even went down and played with the pitch of the prop to ease the engine, able to maintain 3200 rpm but still no faster then 5 knots!
Appreciate everyone's help, hope I can find a cure soon!

 

[Serge Tremblay]

The problem is lack of power.
There are only a few reasons an engine will not produce power
Lack of fuel:
1 check the fuel tank vent, could be a vacuum in the tank
2 check the fuel tank strainer and all other filters/valves to make sure they are clean and open
3 check the injector pump, disconnect the throttle cable and manually work the throttle
4 check the injectors
3 air in the lines -- bleed the air

lack of air
1 take the air cleaner off and see if that makes a difference
2 inspect the mixing elbow for clogs. air can't get in if it can't get out too
3 check the valve timing (not likely as she is a diesel and would bend the valves (and you would hear that) if she jumped time)

lack of compression
1 do a compression test

Thanks Bill, those items where next on my list, I will proceed whit those test as soon as I get back from holiday in canada, I'm pretty good with gas engines its time I get get in the diesel mode!

 

[FourPoints]

I had someone check the alternator but never got the external regulator checked, I will remove and bring to someone to have a look, thanks!

After rereading the original post, I don't think my previous post is correct, as Bill said, it is a engine power issue, not a alternator load issue.

 

[kloudie1]

Bill is right on, Serge.. If the engine is not making a lot of black smoke when running, the problem is not enough diesel getting to the injectors.. one other thing to have checked is the valve clearance..

 

[Serge Tremblay]

Bill is right on, Serge.. If the engine is not making a lot of black smoke when running, the problem is not enough diesel getting to the injectors.. one other thing to have checked is the valve clearance..

Thanks Kloudie 1, in fact there is no black smoke, I think with everyone's help my issue is in fact lack of fuel, can't wait to get back to Bermuda and start troubleshooting!
Happy sailing!

 

[rivettw]

Serge,
Had it happen to me just like you were saying. 2QM20 Yanmar. Problem I found was a dirt dauber nest/clog in the deisel tank vent . You have enough head pressure in the tank after sitting and just idlling or not much load on but when the load is put on fuel pump really starts sucking, hence, not enough fuel. Cleaned nest out and no more problem. Just sayin'.
Wally

 

[Serge Tremblay]

Thanks Wally, first thing I'm going to check on my return!

 

[Jean Guy]

Hi Serge have you check the inline fuel filter half way between the tank and the engine. If there is dirt in the tank it will slow down the flow of fuel from the inline filter to the engine which make you engine look like it is starving for fuel and loose power. When at idle I never notice it just when I was at 2800 rpm and rpm was going down and back up. Fortunatly my freind is a mechanic and was on the trip with me. It did not take him long to figure it out. I change all the filter and next step is to clean my tank which I did year ago on my H40.5 when the same problem ocur.
Good luck