R21 Overheats at full throttle

[Gerberding]

Hello Everyone,
My name is Dick Gerberding and I am new to the world of Ranger Tugs. I am also new to their problems and would like your help. I have a 2004 R21 with a Yanmar 3YM30 that does not do well at full throttle. It works fine at cruising speed (1800-2000 rpms) but at full throttle the exhaust smoke instantly turns white, the exhaust water turns black, and then after about three minutes the engine over-heats. Does anyone know what is wrong or ever have had these symptoms? Thanks in advance, -Dick

 

[bbrh842]

Dick,

Email me at mike.hollier@kbr.com and I can send you a screen shot of the relevant page of the Yanmar manual.
Or, go to Yanmar.com and you can download the manual in PDF format.
The manual for your engine does not discuss troubleshooting.
I looked at the manual for the 150 HP engine.

However, the first thing to look at when having an overheating problem that occurs only at full throttle, is the impeller in the sea water pump.

Mike

 

[tuggertoy]

Dick,

Mike is steering you in the right direction in regards to the impeller. There are also a few other things that can contribute to this but more information is required.

How many hours are on this engine and what is the service and maintenance history if you know?

Eric

 

[Gerberding]

Mike and Eric,
Thanks for your replies and help. I have the service manual for the Yanmar 3YM30, but as you say, it doesn't help with trouble-shooting. I have replaced the raw-water impeller, checked to make sure there is free flow from the lake through the heat-exchanger. Thanks to the kindness of "The Two Rons" (Ron Cowan and Ron Berberniss), who spent the day today going over the boat, we have come to the conclusion that the next thing to do is to replace the raw-water water pump. I don't know the service history of the boat since I bought it used. It has 1296 hours on it: 50 of which are mine and I have only owned it since late January. Obviously I love it.
Again, thanks for your replies, and if there are any other things you think I should check, I would be very grateful to hear of them. -Dick

 

[Nellie Too]

Dick,
You might look at the thermostat as a last resort. I have the same problem with my R-29 and haven't tried the impeller on the sea water side yet, that is next. Good luck.
Bob

 

[bbrh842]

I think if you figure out the overheating problem, the white versus black part will go away.
You already replaced the impeller.
Some other things to check case you have not already checked:
Is the engine low on coolant?
Is the sea strainer clogged with debris?
Is the sea water intake clogged with debris?
At full throttle, does the engine come up to full rpm?
If not, is the prop fouled with weed or barnacels?
Is the belt to the raw water pump loose?
Is the belt to the coolant pump loose?
Remove the hose that goes from the raw water pump to the heat exchanger.
Look inside the hose. During your boat's past life, one or more vanes may have broken off the impeller. They may be lodged inside the hose going to the heat exchanger.

If it looks like a reasonable amount of water is coming out the exhaust, the raw water pump is probably o.k.
The odds that the entire raw water pump is deffective and needs to be replaced is exceedingly low.
I would look everywhere else first.
There is an easy way to see if the raw water cooling system is doing it's job.
Get a hand held digital temperature measuring device.
You can get one at Sears in the tool department.
Measure the temperature of the fitting where the sea water goes INTO the heat exchanger.
This will be the sea water temperature.
Then, soon as you go to full power, measure the temperature of the fitting where the sea water comes OUT of the heat exchanger and heads for the mixing elbow.
If the temperature of the water coming out of the heat exchanger begins to rise dramatically, you are not pumping enought sea water.
At full throttle the temperature difference between the water going in and coming out of the heat exchanger should only be about 20 degrees.
If the delta is substantially greater then 20 degrees, and you have already checked everything else, remove the tubing bundle from the heat exchanger. The tubes can get blocked with boiler scale over a period of time, or, they can get blocked with pieces of rubber that have broken off the sea water impeller. To remove boiler scale, the tubing bundle will have to be cleaned with muriatic acid. You will need new gaskets to reassemble the heat exchanger.

Good luck,
Mike

 

[K7MXE]

Mike pretty much covered the cooling system angle unless pm has not been done on the elbow. It was one I skipped myself, kinda like removing and cleaning the fuel tank, a bit of overkill.
I thought something else myself and my idea would cost a lot more. I thought some antifreeze might be getting into the top end of the motor causing the white smoke but if its not using any antifreeze scratch that. Black smoke could be from worn valves or problems with a wrong pitched prop or a non clean prop. I had to replace a valve on a BMW D12 and only had 400 hours on it so they go away too. The BMW was a piece of junk from day one however. Rather than changing out the raw water pump you can see how good it works by watching the amount of water in the exhaust. Bob Heselberg in
Eatonville Wa

 

[bbrh842]

Here's what Yanmar says about White Smoke:
Cold Engine
Incorrect fuel
Leaking fuel injector
Injection timing incorrect

Here's what Yanmar says about Black Smoke:
Clogged air intake
Incorrect valve timing
Leaking fuel injector
Excessive exhaust back preassure
Plugged intake ports.

Interesting they don't mention overloading as a cause of black smoke.

Notice Leaking fuel injector is on both lists.

Too bad none of this does much to explain the overheating problem.

 

[rt11002003]

Somehow this post was lost.

Check fuel filter (s). Inadequate fuel flow can cause heating problems and smoking.

Gene