Potential Overheating of Engine

[Toucan]

In the PNW, where the water is cold, our R-27 with a VolvoPenta D3 220 HP engine cruises all day normally without overheating. But at 100% RPM, WOT, it will overheat after several minutes, requiring backing off on the throttle. Our raw water intake plumbing is the original 1" size.

In the future, we want to cruise in the southeast: Florida Keys, Bahamas, Great Loop. With significantly warmer water in these locations, we are concerned about overheating issues at lower RPM/throttle settings than 100%. What have other owners experienced operating in the warmer water?

Barry Thompson
TOUCAN, R-27 Classic

 

[Alpina]

What temperature are you reading? I have the D4-300 and it operates consistently at 185 degrees. I boat in Lake Lanier where the water might not be as warm as further down south but it’s plenty warm for swimming hours on end.

My concern has been the heat trapped in the engine compartment. Unless I am running the generator, there is no venting. Over this winter I added a separate 12V blower which I can run when the generator is not operating. I also added a WiFi/Bluetooth temp/humidity sensor from Govee which I use to monitor bilge temp over the winter to make sure everything is OK but will use it to see how hot the engine compartment gets during the summer.

I had an issue with my generator last year where it would overheat after running for a while. The intervals got shorter over time. Turns out that the impeller was all torn up which was surprising since the generator only had ~12 hrs on it. I bought used so maybe it was run dry in the past. I surmise that one of the blades tore and slowly the others followed which is why it degraded over time. Fortunately I was able to account for all the pieces.

When was the last time you checked your impeller? Have you checked your coolant level? I’m assuming it’s a closed loop system like the D4.

Those are the two first places I’d investigate.
Franco


Sent from my iPhone using Tapatalk

 

[FlyMeAway]

When was the last time you checked your impeller? Have you checked your coolant level? I’m assuming it’s a closed loop system like the D4.

I second this. While there are differing opinions as to whether it’s any good for the engine, you should be able to run a diesel at WOT all day long without it overheating.

 

[dclagett]

Barry,

I suspect you have either a clog somewhere or the impeller needs to be replaced as already Alpina stated. I run in the Chesapeake Bay and in the summer the water temperature is 80+ degrees and I can run at WOT without overheating on my D3-150. I would expect you should be able to do the same.

Check your raw water strainer and if is is clean there is an easy check to see if you have a clog in either the oil cooler or raw water pickup. Start the engine and select on the throttle/shifter control “throttle only”. Increase the throttle to max rpm which will be 1500 in this mode. Look in the engine compartment at the hose that goes from the oil cooler to the raw water pump. This hose is fairly soft and any clog prior to the raw water pump tends to collapse the hose. The greater the clog the more the hose deforms. If the hose does not deform, I would check/replace the raw water pump impeller.

If that does not solve the problem then it is time to visually check the raw water pickup and oil cooler. If they are clean you probably have a problem in the heat exchanger. There are threads on this site that discuss how to clean/flush the heat exchanger.

For reference, the D3s seem to vary in engine temperature based on water temp and rpm, unlike the D4s which seem to always run at 185 degrees. My engine at cruise (80% power) in cold water of 50 degrees the engine temperature will be around 175 degrees and in water in the 80+ degree range the engine temperature will be around 187 degrees. At WOT my engine in 80+ degree water will be in the low 190 degree range.

Hope this helps.

 

[gwishon]

You may also want to run some Barnacle Buster through your raw water system to remove any growth/restrictions. We’re on Tampa Bay and regularly see bay water temps as high as 90 degrees in the summer. In our D4-260, I was beginning to see elevated engine temperatures (195-200degrees). After flushing through a gallon of Barnacle Buster, I can now run at 185 degrees all day. This is now a part of our regular maintenance regimen.

 

[knotflying]

I would follow this sequence: Check that raw water intake is clear, Then check strainer is clean. Then check Impeller and pump belt. Then, I think, Volvo has an oil cooler in the system and this can get clogged with grass so check that. Then flush system with barnacle buster of rid-lyme. Then check thermostat.

 

[BB marine]

First question is has the issue progressively gotten worse? Or is this what has always been experienced. What is considered over heat? Alarm or elevated temperatures at or above 200F. Thermostat opening D3 220HP is 176 F, full thermostat opening is at 201F. Max permissible is 208 F. System design is optimal would be 185F . To obtain this it requires clean exchanger, clean after cooler, water pump housing and impeller to maintain proper flow capacities, and properly designed raw water plumbing and inlet size. A properly operating thermostat and proper antifreeze capacity based on manufactures specs. Proper prop sizing allowing the engine to operate within its designed operating range. One item we have no control over, ambient water temperature. The designed cooling system requires no high than 86 F raw water temperature entering the aftercooler. If all of these items are checked off the engine will operate at manufactures recommended temperatures running in the middle of the range. The goal of a manufactures design is to have a service factor built in. If there is no range then if one or two items listed above are marginal there is no room for error.

All the suggestions already posted to this thread are spot on. The D3 220 hp is the maximum HP rated engine for the D3 design. The difference in WOT between the D3 150 hp and 220 hp is 1000rpm and the fuel burn is almost 5 GPH more (220hp). Fuel increase is energy increase = more heat. The 220 and 200 hp D3 will be more susceptible to higher operating temperatures if there is any component of the above items operating in a marginal condition.

The day the R25,R27 or C26 left Fluid Motion ( all non production models now) One of the above requirements was marginal. The D3 raw water intake thru hull sizing was not sized properly for the engines cooling requirements it is 1". The D3 has 1 1/4" inlet and outlet ports on the raw water pump. For this pump to pump to capacity it requires a minimum sized thru hull and plumbing of 1 1/4". There is also design requirements in the plumbing install to limit 90 degree sweeps. The install requirements from Volvo Penta ( Yanmar has the same requirements for the 4BY2) Raw water intake is 1 1/4" for the system to operate at optimal cooling.

Now, the boat is new all systems are in new working order and the boat owners see's that when operating at 80% load or higher there is a slight increase in engine temperature operating range. It climbs above 185F but not much higher than 190F.

Run the same boat in maximum ambient water temperature 20 F higher than normal cruising water. The 190 is now close to 200F, add a small amount of impeller wear reducing the already compromised water flow. Temp climbs a little more. Add a small amount of fouling in the after cooler, reverse gear cooler and exchanger. Load the engine down to the lower max recommended rpm range. Now the system that marginal worked when it was new doesn't work properly. When the engine is brought up to above 80% load it runs at or close to an over heat.

The difference in flow between 1" adding 3 90 degree elbows and a properly designed install with 1 1/4" thru hull is 30% +.

There are many components that lead to an overheat or marginal cooling. I have crossed off all of them and still see 201F in warmer waters low 80's high 70's. The only component that I have not changed is the thru hull sizing. This is not something that one normally has to do with a originally installed power plant in late model boat. The only time I have ever done this is in a re-power.

Barry, I am interested in what other D3 200 and 220 hp owners have experienced. How many are seeing consistent numbers of 190 F and below when cruising in warmer waters?