2016 Ranger on sea trial. Directly after an extended successful high RPM run throttle was cut back and engine threw a "Inlet air temp high" alarm that put the boat into limp mode. Engine temp was in normal operating range. Any thoughts on what causes this? Thanks ahead of time
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High inlet air alarm
- Thread starter RMG001
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What model boat Ranger or Cutwater? The high inlet air alarm is the intake air temperature after it is compressed by the Turbo and then cooled by the Aftercooler. There is an air temperature sensor between the after cooler and the intake manifold. Why would this go off? Many reasons or a combination of factors will cause it to go off. I have found compartments temperatures in my Cutwater, and other Cutwaters to be higher than Volvo recommendations and ABYC recommendations. I have exhausted this subject on TugNuts and with the Factory members. The consensus is we have never had a problem with the boats that we have built in the last 15 years.
The oldest production boat built is a 2008. When a boat and engine are new, cooling systems are clean and operate without restriction. The installed raw water system may be marginal but it works as per specification when new because the system is "NEW CLEAN" Now operate that engine for 5 years and you start to see elevations of operating temperatures because there are now an unavoidable build up in the cooling system. It can still be well maintained but temperatures are higher than when new. The engine manufacture knows this and installs coolers/exchangers that are sized with a safety factor. If the sea water intake, plumbing, sea strainer, hoses are all sized to meet or exceed the engine manufactures installation recommendations. The cooling system will function and maintain engine coolant temperatures within the manufactures recommendations. When a coolant system is fouled beyond the design safety factor it is time for a complete servicing of all components. What does this mean? It means undersized raw water installation works at first but because of its marginal sizing it will prematurely start to fail and cause higher operating temperatures.
This also applies to your problem HIGH INLET TEMPERTURE. One of the creative designs used on a Ranger and Cutwater is the engine compartment has no ventilation. The engine is put in a compartment, insulated for sound and relies on the induction air for the engine to be pulled in through all the nooks and crannies around the Cockpit insert. There is a small area across the bottom of the stern seat that provides most of the induction air. The system design is to let the air in and use the engines induction system INLET AIR to exhaust the elevated compartment temperatures. This system does not meet the installation Guidelines of Volvo Penta or Yanmar. Does this work? Yes all Ranger Tugs and Cutwaters with inboard engines and generators are operating this way. Have there been issues? Some have had generator high air temperature issues. Some have actually increased the fuse size because the elevated temperatures in the compartment has lower the breakers capacity. I have seen engine compartment temperatures in my C26 exceed 160F which puts the engine operating air temperature in the intake at close to derate temperature. Does it go into derate? No not yet!. So I don't have a problem now!!! I installed a complete ventilation system as per Volvo Penta recommendations so I don't ever have to worry about this and the next owner of my boat doesn't either.
What happens as an engine gets older and has more hours on it to the induction system. It gets fouled ! Not fouled enough to cause the engine to perform poorly. Enough to put the engine into alarm because a combination of marginal factors. A fouled air cleaner, a fouled after cooler, fouled sensor element and a marginal at best ventilation system will cause the alarm to go off. Or it could be as simple as a bad sensor? Probably not because it would fail all the time. A full speed engine operation is when the compartment temperatures will need the most amount of ventilation. Even though the engine temperatures maintain the same temperature the exhaust temperatures climb to there highest level. Over 800F. The Turbo is not water cooled and only has a heat shield. This will elevate the compartment temperature. The hot air now needs to excape but has no way to get out except through the engine intake. There is no exhaust ventilation installed in the boat. Just the engine.
Easy test. Sea trial again with the engine hatch opened up. Its is noisy ( I know I operated my boat this way for a full trip on the Tennessee River) but this will eliminate one factor compartment temperature. If the alarm doesn't go off you have removed on element that is marginal ( ventilation design). Next remove the air cleaner ( make sure the bilge area is clean and there is no loose debris.) Close the hatch and operate at high speed does the alarm sound and derate? If no clean the air filter or install a new one. Next remove and replace the air temp sensor. Sea trial. does the alarm go off and derate? No you had a fouled sensor. I don't think it is bad because it would be causing an alarm and derate all the time. Finally remove and clean the after cooler. Reinstall and sea trial.
There is more wrong with the engine than a poorly designed engine compartment ventilation system. There is a combination of factors that is causing the derate. The older and higher hour the Rangers and Cutwaters get that have inboards power plants these marginal installations will start to cause issues. For the average boater you never know they are there until you see an alarm.
Before I installed the vent system After a WOT run the temperature of the compartment would climb fast and remain high for a long time unless I opened the hatch. Now I have Two exhaust blowers operating and I see no more than 20 degrees increase and when I bring the throttle back down the air temperature decreases.
I have several Threads about this and Pictures of the install in my Album.
The oldest production boat built is a 2008. When a boat and engine are new, cooling systems are clean and operate without restriction. The installed raw water system may be marginal but it works as per specification when new because the system is "NEW CLEAN" Now operate that engine for 5 years and you start to see elevations of operating temperatures because there are now an unavoidable build up in the cooling system. It can still be well maintained but temperatures are higher than when new. The engine manufacture knows this and installs coolers/exchangers that are sized with a safety factor. If the sea water intake, plumbing, sea strainer, hoses are all sized to meet or exceed the engine manufactures installation recommendations. The cooling system will function and maintain engine coolant temperatures within the manufactures recommendations. When a coolant system is fouled beyond the design safety factor it is time for a complete servicing of all components. What does this mean? It means undersized raw water installation works at first but because of its marginal sizing it will prematurely start to fail and cause higher operating temperatures.
This also applies to your problem HIGH INLET TEMPERTURE. One of the creative designs used on a Ranger and Cutwater is the engine compartment has no ventilation. The engine is put in a compartment, insulated for sound and relies on the induction air for the engine to be pulled in through all the nooks and crannies around the Cockpit insert. There is a small area across the bottom of the stern seat that provides most of the induction air. The system design is to let the air in and use the engines induction system INLET AIR to exhaust the elevated compartment temperatures. This system does not meet the installation Guidelines of Volvo Penta or Yanmar. Does this work? Yes all Ranger Tugs and Cutwaters with inboard engines and generators are operating this way. Have there been issues? Some have had generator high air temperature issues. Some have actually increased the fuse size because the elevated temperatures in the compartment has lower the breakers capacity. I have seen engine compartment temperatures in my C26 exceed 160F which puts the engine operating air temperature in the intake at close to derate temperature. Does it go into derate? No not yet!. So I don't have a problem now!!! I installed a complete ventilation system as per Volvo Penta recommendations so I don't ever have to worry about this and the next owner of my boat doesn't either.
What happens as an engine gets older and has more hours on it to the induction system. It gets fouled ! Not fouled enough to cause the engine to perform poorly. Enough to put the engine into alarm because a combination of marginal factors. A fouled air cleaner, a fouled after cooler, fouled sensor element and a marginal at best ventilation system will cause the alarm to go off. Or it could be as simple as a bad sensor? Probably not because it would fail all the time. A full speed engine operation is when the compartment temperatures will need the most amount of ventilation. Even though the engine temperatures maintain the same temperature the exhaust temperatures climb to there highest level. Over 800F. The Turbo is not water cooled and only has a heat shield. This will elevate the compartment temperature. The hot air now needs to excape but has no way to get out except through the engine intake. There is no exhaust ventilation installed in the boat. Just the engine.
Easy test. Sea trial again with the engine hatch opened up. Its is noisy ( I know I operated my boat this way for a full trip on the Tennessee River) but this will eliminate one factor compartment temperature. If the alarm doesn't go off you have removed on element that is marginal ( ventilation design). Next remove the air cleaner ( make sure the bilge area is clean and there is no loose debris.) Close the hatch and operate at high speed does the alarm sound and derate? If no clean the air filter or install a new one. Next remove and replace the air temp sensor. Sea trial. does the alarm go off and derate? No you had a fouled sensor. I don't think it is bad because it would be causing an alarm and derate all the time. Finally remove and clean the after cooler. Reinstall and sea trial.
There is more wrong with the engine than a poorly designed engine compartment ventilation system. There is a combination of factors that is causing the derate. The older and higher hour the Rangers and Cutwaters get that have inboards power plants these marginal installations will start to cause issues. For the average boater you never know they are there until you see an alarm.
Before I installed the vent system After a WOT run the temperature of the compartment would climb fast and remain high for a long time unless I opened the hatch. Now I have Two exhaust blowers operating and I see no more than 20 degrees increase and when I bring the throttle back down the air temperature decreases.
I have several Threads about this and Pictures of the install in my Album.
Thanks Brian for the thorough explanation, I will look into it more. I suspect that most people do not do sustained WOT runs nor would I really want to. The problem does not really become a problem until it is. Its a Ranger 29CB 2016
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