Boat Overheats At Idle

When you start the boat in the spring, remember that all of the oil has drained into the pan and let the engine idle for a minute or two to recirculate everything. This has been confirmed in absence of sailing, i. It’s highly recommended to follow the idle mixture adjustment procedures in the factory repair manual. The problem sound just like my two dt140's, and the 115's are just alike. I get plenty of false alarms after throttling down quickly to idle and would prefer knowing the sensor and system are working than waiting and wondering. Never happened before, good water stream coming out of the engine. These compact outboard motors take you to the fun, the fish, or whatever floats your boat – quickly and reliably. MerCruiser Overheating - Merc Cruiser Troubleshooting Guide Troubleshooting can determine faults and help correct mechanical or cooling system problems. We recommend upgrading your browser. Hooked up the diagnostic software and get the overheat grad warning showing up. I had it fixed and all the seals redone in my lower unit. Try slowing to 1/2 throttle a half mile before needing idle. That would not over richen the whole range from idle to WOT. 632 overheating at idle. I've had a couple excursions with no apparent issues, except when at idle. my mercury outboard is overheating. plastic bag overheat syndrome. To enrich the idle mixture, one must first measure the inside diameter of the idle tubes. If you have a blockage or a Chimo/thermo problem I can guarantee it would sound the alarm at speed. Flushing the coolant system actually killed it, but it was merciful. I took the new elbow off, inspected it, and re installed it with a new gasket, thats 2nd time after I have replaced the old ones with these new ones. We recommend NO MORE than 0. (2000 model) F115TLRY Yamaha 4 Stroke Outboard. In my experience as a forensic engineer, there are three main independent modes of electrical overheating that lead to electrical fires: excessive current, poor connections, and insulation breakdown. Overheating at idle is not a common problem with Evinrude E-TEC outboards, some abnomality is causing that. Can do it at the boat ramp sitting at idle or when reducing to idle after cruising. Getting a gaming laptop I expected to be able to play games on it on a whim. This article applies to the Ford F-250, F-350 Diesel (2005-2014). Rich/Lean Adjustment on 1996-1997 25 hp Johnson Outboard INSTANTLY DOWNLOAD outboard repair manuals straight to your computer in seconds. Does it only overheat at idle? Are you sure the fins are going the correct way and all going the same direction when the impeller was installed? Has this always been a problem since you've owned the boat or is it something more recent?. A download outboard repair manual is a book of instructions for learning how to maintain, service, troubleshoot, and overhaul the engine to factory specifications, including procedures for engine overheating Download this book straight to your computer in seconds and fix your problems now. The bypass poppet typically opens around 1800 to 2000 rpm. If I revved the engine really high it would cool off and. Boat keep overheating i'm guessing it could be thermostat or temperature sensor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around. My starboard engine (2007) can push the boat at idle all day long. I have replace the pump checked pop it value do I go to the thermostat next I have no problem while running. clear hose didn't show any bubbles. - Boat runs great at speed and problems begin again when I idle down I don't have a service manual so I've looked on this forum for this same problem, only to find mostly the opposite problem (alarm sounding when getting into the throttle, not at idle only like mine). Outboard download 1980 honda outboard 130 repair manual mercury 1350 engine repair manuals water pump complete installation guide for 1986 mercury 275hp outboard 1998 mercury 51 hp outboard service manual overheating bravo 5. This has been confirmed in absence of sailing, i. 04/03/15 17:54:12 31ZW2600_001. Hello i am having a issue with my 1995 GTX overheating at idle, when i rev it up a little or during normal operating conditions i don't have this problem, if its hooked up to the hose i also don't have this problem, i was wondering if the problem could be the Jet Pump, any feedback would be greatly appreciated. The bypass poppet typically opens around 1800 to 2000 rpm. The water pump is brand new and no wear, (lower unit pulled last fall) new t-stats installed along with a good back flushing. 2010 15 hp suzuki outboard neutral idle; 2011 15 hp suzuki outboards 2004 type of spark plug; 2002 15 hp suzuki overheating; 15 hp suzuki 2007 4 stroke maintenance manual; 15 hp suzuki boat motor free manuals; 15 hp suzuki hot no start; 15 hp suzuki outboard will not idle; 15 hp suzuki outboard wont start; 15 hp suzuki outboard motor idling problem. Please try again later. As we all know the bunny huggers of the world are taking control so the old ways of the presumably dirty engines are gone. The boat was tied up to the dock and let run at dead idle, in gear, for more than 1/2 hour, and no alarm!. just like you. So for long road trips, the engine fine. Get the boat from the shop and can drive it for about an hour. It is then primed so you can idle and not overheat well until you turn off the engine again. A water temperature and possible a water pressure guage are helpful. The fact that I live and work more than a thousand miles from. Hey there We have a 1999 Yamaha 60hp 2 stroke that sets off the alarm at idle. Re: Johnson 115 Outboard overheating Overheating at idle will be the water pump, overheating at speed will be a blockage or a Chimo/thermo problem. The fan clutch did help a bit, though, as it runs on the highway at 210 now. once rpms turn up to about 1500 engine cools to normal operating temp. Took it to the local tech to get the impellor changed (suzuki part). www cruisersownersforum com • View topic - Exhaust Water. how to remove gear housing from 6hp mercury outboard; idle adjustment for johnson6hp outboard; is a 92 mercury 6hp oil injected; johnson 1972 6hp outboard motor service and repair manual; johnson 6hp 2 stroke outboard owner manual; johnson 6hp 4 stroke outboard motor manual; johnson 6hp outboard high idle in neutral; johnson 6hp outboard repair. For what it is worth, when I bought the boat, the PO had a mechanic check the compression in the cylinders and he reported 121 psi in two cylinders and 119 in the third, so I was hoping it was reasonably sound. He had bought a new circulating pump to solve this, I told him unless the circ pump was leaking externally, it would not help and figured it needed a new impeller. Captains for hire to drive your rental boat available for 1/2 day only. This will make little to no noise at idle and make more noise depending on how much load the engine is under. I have noticed that this car seems to run at lower RPM's than all my prior vehicles so perhaps at low revs the vehicle just can't keep cool. Either side it cools off but in this range it warms up fast. " Now that we've completed the sale of my boat, I'd like to take a few minutes to thank you and all the folks at Jordan Yacht and Ship Co. Why does my mercury outboard engine shut off when i put it in foward or reverse. 1991 Mercury 75hp outboard. Click here to enter the site. I wasn't far from home so I let it cool down, buzzer went off so I let it idle for a while, no problems. 2007 Yamaha outboard 4 stroke will not idle and engine dies. A downloadable repair manual is a digitally delivered book of instructions that provides step-by-step maintenance, troubleshooting and repair procedures. Repairing overheating issues requires inspection and testing of both mechanical and cooling system parts. I have run the boat on a stand hooked to a water hose and it is not overheating at all. Does not overheat when traveling a bit above wake speed. understanding your jet boat Most boat owners like to perform at least a certain amount of their boat maintenance themselves to ensure continuing good performance and reliability. An OBDII code checker identifies defects in the exhaust system of the car. I thought it was one of the surpentine belt pulleys squealing. Many cars over the years pick up little annoyances that contribute to overheating. This is at idle, once I take the boat out and the RPMs hit 2500 to 3000 the whole engine overheats to 200 plus, and it does it very quickly. Change Radiator cap 2. A final word of warning: each year, owners (and mechanics) sink boats by leaving the exhaust ports unplugged after disconnecting the manifolds. Find out exactly what is causing the overheating problem with the boat engine and you should be able. Overheating at idle, but not while flushing Hey Gurus, Hope someone has some wisdom for me. (Photo: John Tiger) Back in the day, flushing an outboard with fresh water was done only one way. The engine on my 88 Mariah has been overheating when at idle/crawl. INSTANTLY DOWNLOAD outboard repair manuals straight to your computer in seconds. The indications are that changing out the PRV (Pressure Relief Valve) finally, after two years of frogging around, fixed the overheat problem. We have swapped out the wear ring. I can idle on the side of the road for about 45 minutes before it gets overly hot, less if I run the A/C. The water flow was measured and was around 8. Outboard Motor - Overheating Problem When at full throttle, after about a qtr mile, the motor stops spittin water and if I dont cut the throttle back the overheating alarm starts to sound. Does it only overheat at idle? Are you sure the fins are going the correct way and all going the same direction when the impeller was installed? Has this always been a problem since you've owned the boat or is it something more recent?. the motor is freshly rebuilt and the lower unit was recently replaced as well. I hope to get this fixed tomorrow afternoon. Usually, it happens as I'm approaching my marina slip, idling just in gear as I enter the approach. They charge your vessel's battery(s). Runs perfect. Can do it at the boat ramp sitting at idle or when reducing to idle after cruising. If the engine overheats a few minutes after start up, the most probable cause is a defective thermostat. Does not overheat on trailer when flushing after many many minutes. Impellar need replaced? Mechanic's Assistant: Sometimes things that you think will be really complicated end up being easy to fix. I also know this from my own experiences with overheated engines, clogged risers, etc.   I like Bob’s suggestion about a coolant circulation. Refuel outdoors, in a Breathing carbon monoxide can well-ventilated area, with the cause loss of consciousness and may engine stopped. A deeper gearcase and a four-blade, high-thrust propeller with matching gear ratio for precise trolling control. ) and nothing worked as engine would still overheat at idle and would only run at normal temp at ~2000 rpm and above. At idle it would get up to about 170-180 but at speed temp would barely register. speaking re impeller changes on generators and mains. Overheating at idle, but not while flushing Hey Gurus, Hope someone has some wisdom for me. However, enough information in 70HP outboard repair manuals is given for do-it-yourself or apprentice mechanics to correctly and safely perform repair work to their 70HP outboard motor and components. It can also be a problem with the engine itself. I've checked for spark on all the plugs and thats fine. Of course, you should never overlook the possibility that the water intake is plugged. Running at idle or at operating rpm does not alter the condition and the engine heats to alarm. What is the correct height to mount the engine on the transom? For a propeller to best satisfy particular boating needs, the engine must be attached to the transom at the correct height. It only used a raw water pump (no circulating pump). So for long road trips, the engine fine. Re: Yanmar 2QM15 Overheating at Idle I dont have the specs for the 2QM15 but for the 2QM20, the raw water output at the exhaust exit is 3 gallons per minute at 2000 rpm. I wasn't far from home so I let it cool down, buzzer went off so I let it idle for a while, no problems. Please consider this when you are making a reservation, the more weight on the boat the slower it will be and lower it will sit in the water. The Honda BF2. Does the repeated throttle lever pumping prime the system with fuel? With the previous 120 engine, a previous owner put a fuel primer bulb in the fuel line, so I always gave the primer bulb a few squeezes before attempting to start it. Ask the experts on our Johnson Forum for repair issues, diagnosing problems, links to diagrams, suggestions on buying parts and more. plastic bag overheat syndrome. at idle, it will probably overheat and shutoff before 'blowing', probably. How do I check my MasterCraft boat's speedometer calibration?. When on plane the engine is by-passing the thermostat and that water will be a bit cooler. Turn the relief valve in or out until a high-pressure hiss is heard when there is 1/8-inch clearance between the axle stops. i have a 260 mercruiser that overheats at idle. Flushing the coolant system actually killed it, but it was merciful. BMW Forum: car is overheating 1997 BMW 528i?. My truck over heated two times when I was moving my 18 foot Starcraft aluminium boat around the yard. At idle it would get up to about 170-180 but at speed temp would barely register. It always had an issue that when in gear at low rpm, like idle or under 1000 RPM, it will overheat. Outboard Motor - Overheating Problem When at full throttle, after about a qtr mile, the motor stops spittin water and if I dont cut the throttle back the overheating alarm starts to sound. This was all on a boat that was used in fresh water only. Cruised again and the alarm. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. The thermostats were new when I put the boat in, so they swapped out those new ones (just in case they were defective), with another new set, and the engine still overheat. What should I do? I plan to check for air leaks, pull/replace the impeller, and finally replace the thermostat (my understanding that GT40's take a 160 degree thermostat). 4-liter motor. I have a problem with my Mercury 50-HP EFI outboard. You can test this with them hooked up to the boat and the key in the "on" position without the boat running. Need to know when does it overheat, at idle or on plane or both. Turn the relief valve in or out until a high-pressure hiss is heard when there is 1/8-inch clearance between the axle stops. Outboard boat motors are notorious for problems. To troubleshoot the engine, go through a series of checks for specific issues that can occur and fix as needed. Overheating is a problem which can be diagnosed through a process of elimination. May be worth a look before you pull the coolant pump. Often we assume a bigger radiator or a similar big gun solution will fix our problem. Well heres the storyabout a month ago I had a broken water pump base. The temp is coming from the YDS, so I guess the sensor could still be bad, but with the scenario indicated in the live temperature readout, seems unlikely to me. This is called a High Speed Overheat. did not correct problem. What next?. I have to give it 3/4 throttle to get it going when i put it back to idle it dies. I have run the boat on a stand hooked to a water hose and it is not overheating at all. In order to fix overheating problems you first need to do some detective work. The motor was mounted backwards (flywheel forward) with a Paragon manual gearbox bolted to the front of the engine (rear of boat). If you have a stock distributor and know either the timing at idle or the maximum advance at a given engine speed and you have a good timing light, you will have no trouble setting timing. "There is never just one thing wrong with a boat"; -- Travis McGee, main character in a book series by John D. I stared trolling back to the dock at idle speed and the light stayed on but the temp stayed below 170F. The water pump is brand new and no wear, (lower unit pulled last fall) new t-stats installed along with a good back flushing. So for long road trips, the engine fine. " Now that we've completed the sale of my boat, I'd like to take a few minutes to thank you and all the folks at Jordan Yacht and Ship Co. The boat was tied up to the dock and let run at dead idle, in gear, for more than 1/2 hour, and no alarm!. Evinrude Complete Outboard Engines. Slowly remove the radiator filler cap when the engine has completely cooled. Awesome Grappling Hook Kickst. The motor shouldn't be allowed to keep overheating, because permanent damage can occur. I am having an issue with my boat overheating at idle or in drive at the lowest speed (650-800rpm). Re: 70 hp yamaha overheats at idle I am still having overheating problems. The temp would go way up but it never topped out or overheated. Because it plays a crucial role in keeping the engine at a satisfactory temperature, allowing the engine to function, a damaged or otherwise failing thermostat can cause overheating. Mercury FourStroke ProKicker outboard motors deliver superior torque for greater acceleration control. Evinrude complete outboard engines can be a clean, high-performing addition to your boat. Some water does come out the outlet tube, but not as much as used to when it was new. An outboard's computer memory is accessed through the diagnostic port. I idle mine at 600 and never have had a problem. The may come down a little on plane but not much and not always. The poppet valve takes over after 1,500-RPM or around [8-PSI] of water pressure. Low coolant can cause overheating. I have only had the boat for a short while. Rich/Lean Adjustment on 1996-1997 25 hp Johnson Outboard INSTANTLY DOWNLOAD outboard repair manuals straight to your computer in seconds. Flushing the coolant system actually killed it, but it was merciful. Did you also clean the grommit very well and replace the spring? Also, these engines have been known not to produce enough water pressure if you RPM's get as low as 500RPM"s. Hi, My Sizi 175 4st is intermittently but regularly giving an overheat alarm at idle. I know this has probably been discussed multiple times, but my boat 1996 Sport SN (GT40). Heat the bike up, give it a ride for at least 15-20 minutes. Of course be sure the outlet tube and grommet is fitting correctly. Slowly remove the radiator filler cap when the engine has completely cooled. After some inspection we discovered that the impeller in my water pump was. Full weight of the vehicle must be on the wheels. Digital and annolog temp gauge was a. The boat worked on 160-180F now is up to 210F I saw a bulletin 10/28/14 a overheating at idle change of thermostat was requiered don't know if that is realted to it. 3l engine and an alpha gen 1 outdrive. Ask the experts on our Johnson Forum for repair issues, diagnosing problems, links to diagrams, suggestions on buying parts and more. They can answer questions for any Honda outboard model or horsepower. Cover your boat with shrink wrap from Americover. what is the consenses re changing impellers when running is fresh water only. The temp would go way up but it never topped out or overheated. Depending on the age of the boat and the maintenance history, the most likely cause of an overheat condition is the impeller located in the lower unit of the drive. Of course, you should never overlook the possibility that the water intake is plugged. After the usual parts were replaced and the engine flushed. On an Alpha drive, this pump is in the drive. Used Mercury Verado's For Sale. Took it to my mechanic - he first replaced the water pump, didn't help. And once you've paid a tech to drop the gearcase and. The top of the hose varies from 130-210 degrees at idle, about 140 at cruise while the side where the sensor sits (look right in the picture) is <120 at cruise and 140 at idle. "It seems I have overheating problems every 3-5 years. I know that sounds painfully obvious but I think most of the water from the raw water pump goes out the exhaust while the engine is at idle. A simple way to diagnose whether there is a problem with the fan is to let your car idle long enough to heat up. Low speed overheats on these engines are usually a Poppit Valve problem. If the engine overheats after several miles of driving or only overheats at low speeds, you should inspect the cooling fan operation and radiator. just like you. Suzuki DF 115 Outboard Suzuki’s new DF 115 (and its sister motor, the DF 90) are the first outboards in the industry to use an offset driveshaft combined with a two-stage cam which reduces the motor’s physical size yet increases overall performance. Only at full throttle will it overheat. clear hose didn't show any bubbles. McDonald ***** The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. engine runs cool when flush (muffs) are attached to a hose on land but overheats when splashed. Once you power up, they'll pop open and the motor will cool until you slow down or let the engine cool off enough that it closes again. i have a 260 mercruiser that overheats at idle. 3l w/Alpha One gen one raw water pick up. I have a 2000 Mercury 50horsepower 2-stroke outboard engine. Can do it at the boat ramp sitting at idle or when reducing to idle after cruising. The Evinrude motor uses water to perform the cooling function. The temp is going over 163 after idling for awhile or a slow troll like in a no wake zone, this is not simply a short in the alarm we tested with thermo gun. My 1995 Mercury 135HP 2 StrokeOutboard has decided to overheat whenever the RPMS are around 1200-2000. Rick was the last person on the boat just a couple days before. I have replaced the thermostat since it started having overheating problems and the water pump was replaced this spring. A deeper gearcase and a four-blade, high-thrust propeller with matching gear ratio for precise trolling control. why would both of my boat motors overheat at idle and suck in sea water; will a lean condition cause a rough idle on an outboard; will faulty outboard impeller cause rough idle; will lean carb setting cause idle knock in outboard; will throttle position sensor Johnson idle rough; Johnson 2 stroke outboard idle pilot screw; Johnson 20hp cutting. don't know what to do next. I took the boat out fishing last week. mercury 100hp outboard 1989 down trim selonoid 8996158 merc 20hp outdrive water replacement pump how you hotwire a 1975 50 horse mercury motor what kind of spark plugs to use for efi 300hp 4 stroke suzuki outboard 97 evinrude 50 hp high idle. Yesterday out on the boat, everything running great, until later that afternoon started engine to move away from shore, and the overheating alarm went off and would not go away. Other Key Items There are a few other important things to keep an eye on. Under certain conditions, the engine will cut-out to prevent damage. That said, most would not overheat at idle, and normally temp will be a bit lower then 140. Nevertheless, there is still a difference in the level of quality between these suppliers (whether the replacement parts are new or aftermarket, etc. Overheating at idle is not a common problem with Evinrude E-TEC outboards, some abnomality is causing that. If uncertain about type of hull, please contact boat manufacturer for assistance. If the thermostat is stuck closed. Nope apparently it was one of the fuel pumps over heating. Start the engine and allow it operate at idle speed. I have a 2000 Mercury 50horsepower 2-stroke outboard engine. A Mercury, Yamaha, Johnson, Suzuki, Evinrude, Mariner outboard marine engine repair manual is a book of instructions, or handbook, for learning how to maintain, service and overhaul the 35HP outboard motor to factory specifications. An outboard Tohatsu repair manual is a professional book of instructions that list maintenance, repair and overhaul of the boat engine’s main components. Enjoy quick acceleration to go with exhilarating speed. This was all on a boat that was used in fresh water only. l History l Models l Registry l Members' Pictures l Feature Article l Tech Talk]. Getting a gaming laptop I expected to be able to play games on it on a whim. I have a project boat and I knew that when I bought the boat. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around. Never happened before, good water stream coming out of the engine. Newer boats have a warning siren that alerts the pilot that water is not being pumped up from the lower unit. I suspect I've got a water flow problem, but I don't know how to troubleshoot it. Only use the specified type of antifreeze to top off the system. from perhaps 5 to 15 PSI on the manual gauge. now one of the motors is running hot at idle. If you fish in areas where you can pick up a lot of trash or silt you may have blockage in a water jacket somewhere. i have a 2011 etec 225-- just came off warranty; it has run wonderfully for many years but just recently i get the overheat alarm at idle speed sporadically at the dock and underway, in the latter case, it shuts down my engine to low RPMs -- i have not changed my water pump since i bought the engine but she is low hours and her water pump circulation has always been great based upon her pee. It's also done it a couple of times when in gear, but while barely moving along. Other Key Items There are a few other important things to keep an eye on. You've eliminated the impeller as another possibility. However, enough information in 70HP outboard repair manuals is given for do-it-yourself or apprentice mechanics to correctly and safely perform repair work to their 70HP outboard motor and components. High Output Alternators built right in the USA. They charge your vessel's battery(s). Do not rely on a water hose to check your impeller. I plugged the engine on a Honda diagnostic tool to identify any register faults and it showed a problem with the O2 sensor. it's like the pumps stops pumping for some reason after a cooldown the. It should run colder and take longer to warm up. The boat worked on 160-180F now is up to 210F I saw a bulletin 10/28/14 a overheating at idle change of thermostat was requiered don't know if that is realted to it. This will make little to no noise at idle and make more noise depending on how much load the engine is under. The Boating Forum - 01 OX66 250HP Overheating at Idle - Thanks for all the help and suggestions so far. But both the coolant and raw water pump are pumping much less water at idle. Thus the overheat alarm at idle. The temperature guage said that at idle the engine remained at about 175 degrees, but as soon as I planed out the. I have a 2002 90 HP 2 stroke and owned it since 2002. Or thermostat is opening to late. Can do it at the boat ramp sitting at idle or when reducing to idle after cruising. Used Mercury Verado's For Sale. A deeper gearcase and a four-blade, high-thrust propeller with matching gear ratio for precise trolling control. A water temperature and possible a water pressure guage are helpful. Your browser does not support frames. But anyway, I am hoping these hoses will not have any issue if they DO get up to 250+ for a while. Letting your boat sit for a long time without being run is a bad thing. actually if a poppett valve is stuck open it will overheat at idle, also your engine model is included in a technical service bulletin for exhaust tuner corrosion which can cause an over heat issue. My boat is an 87 wellcraft antiqua. Back in the days of carburetors, when engines were made of steel, overheating was much more common, and less damaging. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. my v-drive flat is overheating,the water pump impeller checks fine and water flows thru motor at idle fine but at speed the temp just climbs past 180 and will run upwards of 210 or more if i dont shut it down,engine is hot! steam is rolling out the over flow but water stops flowing out overflow after it gets to about 180. 3l engine and an alpha gen 1 outdrive. Using Your E-TEC Outboard ENGINE OVERHEATING. If you don't have 2 psi at idle, then change the impeller and if it still overheats then change the stats too. Of course, you should never overlook the possibility that the water intake is plugged. The only clue with the boat in the water is after about 5 minutes, I would get a high pitch whine. Overheat at idle, but cool at speed = air leak between the water pick up and RWP. Can do it at the boat ramp sitting at idle or when reducing to idle after cruising. A low engine-coolant level or poor radiator hose connection can lead to an overheating vehicle with a 7. He had bought a new circulating pump to solve this, I told him unless the circ pump was leaking externally, it would not help and figured it needed a new impeller. Any direction would be much appreciated. It's strange because when I'm cruising at a good pace, the engine cools down rather quickly which makes me think that my water pump or impeller is shot. However, enough information in 25 horsepower outboard repair manuals is given for do-it-yourself or. This article applies to the Ford F-250, F-350 Diesel. I have a 2006 Pickup, 5. They come up to that while at idle and stay there on plane. first link sounds exactly like your problem onthe same. Using Your E-TEC Outboard ENGINE OVERHEATING. overheats at higher RPMs, dt115, 140, and many others. Steamy water, antifreeze, or overheating paint smells in the engine space indicate an overheating engine. The odd thing is that the engine never overheats again on the outing, even if it's idling for 15 minutes. It was a direct-drive (not V). Boat is also reading high oil pressure as soon as start up 40 psi , 1500 RPM / 70 psi. Strange stuff, although nice to work with. Once I cut the throttle back it spits water almost right away. Idle the engine when flushing, making sure it doesn't overheat, until the water flushes clean. - - Yanmar 2QM15 Overheating at Idle (https://www. Manged to get back, by nursing it at low RPMs the whole way, but anything close to plane would trigger the alarm. I recently replaced the impeller (which was in dire need of replacement) but the alarm still sounds after a few minutes of operation at idle. - I've been chasing a overheating issue for a few weeks on my 400ci, c6. Re: Johnson 115 Outboard overheating Overheating at idle will be the water pump, overheating at speed will be a blockage or a Chimo/thermo problem. I put in a brand new thermostat that didn't solve the problem, still overheating. Also I have a problem with the coil and electronic ignition overheating. Well heres the storyabout a month ago I had a broken water pump base. "There is never just one thing wrong with a boat"; -- Travis McGee, main character in a book series by John D. I pulled over waited added a lot of coolant and went on my way. at idle, it will probably overheat and shutoff before 'blowing', probably. Just an informative update to a very nagging problem. I have only been on a boat once before where the prop was spunBut today when I went to take the boat out (left out of Kingfish ramp) when I got to the end of the no wake sign, I engaged the throttle and it started to speed up but just as quickly came off and just bogged downIt would idle or just above it but when I got it back to the trailer didnt have enough to get the boat on the. When I run the garden water hose into the thermo housing I get tremendous and uninterupted water flow out base of stern drive at transom. May be worth a look before you pull the coolant pump. Ever wonder why your boat is overheating? Just take a few minutes and listen Justin from SkipperBud's of Madison, WI. ately reduce throttle speed to idle. From what I saw, I believe the overheat at idle is a result of low water flow thru the engine at idle. Engine hours are 2,200. After some inspection we discovered that the impeller in my water pump was. Before starting the engine, position the remote control in neutral, idle speed position, then start the motor. 3 MerCruiser engine rpm is below manufacture specifications at wide-open-throttle WOT (or engine laboring). The indications are that changing out the PRV (Pressure Relief Valve) finally, after two years of frogging around, fixed the overheat problem. Built in a range of sizes, builds, and displacements, durable Mercury engines serve you in a range of applications. Overheats at idle in about 5 minutes with the muffs on. I have a 2003T which runs at 175F even at full power, no sign of overheating, however if she is idling, perhaps in gear, the temperature rises to 190F. Get Engine Troubleshooting tips from other DIY'ers and auto mechanics that answer car problems for free online. It contains information on ever aspect of repair.