Overheating on Yanmar 110

[walldog]

The Christina Bee is experiencing some overheating when operating above 2200 rpms. At 2600 rpms or above, the temp will increase until the alarm will come on somewhere above 210d. Slowing it down, it will slowly return to 180d or so as long as it is operated below 2200 rpm.

We have examined the exhaust riser, sea strainer, and determined that plenty of sea water is flowing through the exhaust. The output of the seawater from the heat exchanger manifold is running cool. According to previous posts, that indicates that the seawater portion of the cooling system is working and that we have a problem in the fresh water portion. We have added about a quart of antifreeze and removed the thermostat. Still overheating. I checked the thermostat in a pan of boiling water. It starts to open just before boiling and opens to about a 1/4 inch. To be sure it was not the problem, we temporarily removed it from the system without noticing any difference. The v-belt is tight and when looking at the coolant with the cap off and the engine running, the coolant seems to be circulating.

We now need some help. Does anyone have suggestions?

Thanks for your input.

 

[tlkenyon]

Not sure about boats, but if you remove the thermostat from a car, it overheats because of the lack of residence time in the radiator. I would imagine the same principal would apply to a water/water heat exchanger much the same as an air/water heat exchanger.

You might consider a malfunction of the temp monitoring system, but I am not sure how to check that.

 

[rt11002003]

To check the accuracy of your temperature sensing system use an infrared temp sensor. Available at Radio Shack and elsewhere.

Gene

 

[wefings]

When was the last time the impeller was renewed ??
marc

 

[walldog]

OK, on advise of local boat service guru, we removed the intake and outlet from the heat exchanger and back flushed it. We reinstalled the thermostat. We got my digital temperature gun and went out on the bay. After warm-up, we ran it WOT for about 5 minutes. Max temp on top of the thermostat housing was 175d. Cruised for a few miles more continually checking the temps. the seawater plumbing ran from 75 (local water temp) to about 96 max out of the heat exchanger. The heat exchanger was 125 on the inlet side and 165 or so on the outlet side. Running at normal cruise the temp gun showed about 160. We did determine that the analog gauge on the dash runs about 15d higher than the gun.

Longer seatrial tomorrow, but looks like we are back in business on the Christina Bee.

Thanks to all for your suggestions and support.

 

[j&lgray]

On the Laurie Ann, a 2008 R25 with a 110 Yanmar, the same as the Christina Bee, our thermostat opens at about 175 degrees. Close to boiling is not right, I would replace it. In the warmer waters of the Gulf, the engine routinely ran at 200 degrees. Here in the 40-50 degree water of the Pacific Northwest, we run at 175 degree all day long.

If I was having this issue and I have, I would do these in this order: (1) make certain the coolant reservoir is 1/2 full and the V-belt deflects less than a 1/2 inch when it is pressed on, (2) clean out the sea strainer, close the sea cock, run a hose and flush fresh water through the system using a mixture of "Salt Away" to rid the most common kind of gunk of the engine, (3) replace the impeller, a 30 minute job, see our website http://www.laurieann-ranger25.com for my procedure, and (4) replace the thermostat. If the problem persists and the engine has over 500 hours on it, assess the quality of the heat exchanger and exhaust elbow with a laser thermometer when the engine is running fast and hard by taking the measurements those pieces against the temperature of the water. The difference in the water temperature should not be great. Again, look at my website for the recommended temperature differences that I learned from listening to marine diesel mechanic. If that is the problem, take apart the heat changer and the exhaust elbow and unplug it.

Having said all of that, looks you found it! Great job. Steve is my man.

I would replace at the temperature sender in the engine block earlier if the engine hours were few and items 1 to 4 were done. I had a sender go out on another engine when it was higher in hours but only after I did 1 through 4 above. The sender replacement job was a snap once the replacement part is on hand.

 

[steveandtina]

thanks to all for your advice,, BTW, john would the bogus temp rating [10 degrees high at least] be a function of the sending unit or perhaps just the analog gauge itself ?? talk to you later,,, steveandtina 😀

 

[Andrew Custis]

I agree with everything said here. In my book, the first thing I would do is check coolant levels in the engine than the expansion tank. Inspect water heater and cabin heater at connection points for any leaks if your system appears low.

Next thing I would do is check the impeller and replace. An impeller can still push water through the exhaust if a blade is broken off. It might not be pushing enough.

Thermostat is an easy thing to replace and I agree with boiling point being too hot.

Sorry I didn't get back with you sooner Steve! I was on vacation in AZ. If you need assistance, please dont hesitate to call.

 

[RICH002]

Good Morning,
One other possibility on the 110 boats is the circulation pump. On RT Tug #69 it lives on the forward engine room bulkhead starboard side and can be accesed thru the small in cabin engine hatch. We had a very similar problem last year and it turned out to be the circulation pump. The fuse for this pump(on my boat) is behind the dashboard kind of scabbed in to the ignition switch and hanging in the air. We found the fuse blown but replacing it did not fix it. with a multi meter i found the motor was open. Only the 110 yanmar boats use this pump, it provides water flow thru the water heater and cabin heater. It was not a cheap pump but replacing it took care of our problem.
Hope this helps

Rich

 

[doke01]

One thing I didn't see mentioned. Check you bottom for barnacles or anything else that would impede the flow of the boat through the water. It makes a huge difference in performance and we have had the problem ourselves. At lower RPMs there is no problem but once you get to the higher RPMs the engine overheats because it is working so hard. There was nothing mechanically wrong with the engine itself.

Doug

 

[walldog]

We took about a 40 mile loop a couple of days ago. The temperature was more under control, but still had a tendency to rise at higher rpms. Not nearly as bad as before. So we are fairly certain that reverse flushing the heat exchanger did help. We only used fresh water, so I feel that removal and boiling out of the exchanger is in Steve's near future.

We loaded the Cristina Bee on its trailer this morning and Steve and Tina headed for Port Aransas for a few days. Tina will fly back to California on Monday, and Steve will continue on toward Apalachacola.

While he was here, we ordered him a CF chip with all US for the Raymarine. When we installed it, it would not show the chart, just the base map. We put his West Coast chip back in and it would not load the chart either. He had had someone do some work installing an XM radio and they were working in the areas behind the Chart Plotter. We checked for any loose or disconnected cables, but could find none. His chip has worked previously, but it has been sometime since he checked it and not since the XM was installed. Maybe Marc at Wefings can find someone to check it out while he is there.

Watch for them in Port Aransas and watch for Steve as the traverses Louisiana and on the Forgotten Coast.

Thanks again to all who offered suggestions to help with the overheating.

 

[CaptMac]

If Steve is running the Raymarine chartplotter, check that he has the latest software upgrade. When I bought my Alaska CF chart chip, it woujld not run. After Navionics replaced the chip - it still wouldn't load all the charts. Finally, Raymarine released an upgrade to the software - it now loads.

Mac

 

[JerryE]

My Yanmar 150 has been mildly overheating since I bought it with 19 hours on it. Since the problem was just solved and the solution could affect any Ranger Tug, I'll describe it here (under the Yanmar 110) rather than start a new thread. The engine has been running hot in comparison to the rated 190º at idle to 205º at WOT as shown in the manuals. The new HPCR (High-Pressure Common Rail) fuel delivery systems on the Cummins and Yanmar engines lead to much higher running temperatures. This led to the massive blog I wrote on engine coolants on Tugnuts, but even after getting Yanmar coolant she was still running 209º at 8 knots. BTW, the reason for the HPCR is less noise, lower emissions, and more power. But higher pressure and temps bring on the risk of other problems...

Last week while tootling out of my marina's inlet the temperature shot up and alarms went off, which happens at 226º-not fun and you have to turn off the ignition to reset the alarm which is ear splitting. Got back to the marina at idle speed and went through the list Andrew had recommended:
1. Check coolant level.
2. Check for tight fit on radiator cap.
3. Check for good sea water inflow/outflow (and make sure strainer is clean, etc.)
4. Pull impeller and inspect. (more on that later with photos as cutting fiberglass was involved for access on a R25).

Everything was OK and I reported this to Andrew who, very kindly, responded while on vacation by contacting the Yanmar distributor in Tampa, FL who called me and followed through to get local Yanmar certified mechanics out to the boat for warrantee evaluation. This all happened without much stress thanks either to Andrew's charm or his ability to apply gentle pressure to the Yanmar folks. Hey, who else is buying Yanmar engines for new production boats? Anyway, they were all great and this is what the mechanic found:

After attaching a pressure gauge (again fiberglass cutting and re-plumbing the gauge with an 90º fitting were required for access, I'll eventually post photos of how to do this) to the radiator cap and pumping to 17 lbs. we saw ripples in the pink tinged bilge water around the bilge pump. This suggested a drip forward under the deck about where the fuel tank stops. Note: we never would have seen this with the engine going due to its vibration, but the pressure gauge did the trick by squeezing the coolant without running the engine. Two hoses (outlet and inlet) go from the back of the engine to the Heatercraft heater under the pilot's chair, and both attach to reducers (double-barbed things) near the engine to match the smaller diameter hoses to the Heatercraft. There was enough slack to pull one hose out as the reducer was about 18" down the line from the engine, well hidden under the deck. Lo! There was a pin hole in the hose as well as a loose SS hose clamp on the reducer fitting. The mechanic cut off 8" of hose with the hole and there was enough slack to attach that to the engine and no more leak. Of course, I need to find more Yanmar coolant (mechanic only had Dexcool and we dare not mix) before I see if that solved the problem, but I feel about 98% confident since I was down over a gallon and the system only holds about 2.5 ga.

I had mild overheating problems for hours before it got to a severe stage due to a pin hole leak. As the pressure would build (at higher speeds) the leak got worse. The moral is check those heater hoses routinely; they are the only hoses have I found without double hose clamps used on either side of a fitting and thus they need to be tightened yearly–its hot coolant flowing on-and-off through them when the thermostat throws at 190º leading to expansion/contraction issues. They come out easily when removing the Heatercraft at that end and are easily accessible at the engine side, too if you remove the 4 screws holding the step support. The single hose clamps on either side of the reducers are a natural point for a problem, and indeed one clamp on my boat was completely loose. How a hole got into the hose suggests it must have been near something that was drilled during manufacture and, indeed, the hose was snagged on something until it pulled free with a bit of pressure.

 

[Ainokea]

Jerry,

I have a jug of the Yanmar coolant 🙂

Let me know if you want to borrow it again. Glad this fixed you up as we have cruising on the river to do!!

Frank