Boat overheating at idle Motor has been at me for 15 years with no major problems. We have replaced the thermostat first, then the impeller, then the water pump on the engine and finally changed the hoses from the outdrive to the engine. I have had problems overheating at idle. During idle, before alram comes on, the tell tale feels cold then warm to steaming hot. 0 slowly overheating when idling, the temperature increases to over 200F and up, if I rev up the engine to 2000-2500RPM the temperature goes down close to 140F pretty fast. If I am in a long no wake zone, the alarm goes off. May 2, 2004 · Boat is a 1990 Bayliner Ciera 2651 with Mercruiser 5. 0L MPI engine. Removed water jacket and back flushed. Aug 21, 2023 · At low speeds or idle, the engine will cool properly. This spring, I replaced the thermostat and water pump as routine maintenance. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. A water pressure increase (RPM Increase and volume increase) would force water through and cool both banks again. Hi guys, I'm helping out a neighbor with an overheat issue on his mercruiser. May 11, 2021 · My 5. Can run at idle speed and/or high speed indefinitely from that point. Once I get the rpms up, it's fine. But then at the dock, with the throttle down at idle, it almost immediately started overheating again. The original series Cobras impeller is behind a plastic panel at the rear of the upper gear housing, the newer ones have it on the engine like a Volvo. 3 carb, alpha one gen 2 (1995 model year I believe). Apr 25, 2003 · Re: 5. Most boats have a water strainer which catches harmful items before they can cause damage to your engine. If overheating only occurs at the higher throttle, look at one of the above factors for the cause. and also if you have the older thermostat hsg with check balls in the "T"connecter on top of the hsg the balls Dec 14, 2013 · My Merc is new to me (2 months) a 2001 Mercury 50 hp 4-stroke, non-efi (has carburetors), 4 cyl serial 0T229967, SMALL Foot gear ratip is 1. It runs fine at idle or very low speed (under 2500 rpm) but when you get on top, after 100-200yds the overheat alarm goes off and drops the rpms. Jun 21, 2011 · At idle there isn't enough vacuum to pull enough water through but as engine speed increases the vacuum builds and it starts circulating enough water to cool it back down. See full list on godownsize. 7 vortec long block. Running at sub-planing speeds, plowing through the water places a high load on the engine. Before going to the lake, I went ahead and swapped the new 160 deg thermostat with a 140. It cooled a couple hours and when I ran it to go home it started overheating again, I shut it down and did some troubleshooting and couldn't find If they are not hotter than that then it may not be an actual overheat problem. An overheating engine is a problem that can’t be put off, since it leads to major problems that can do some expensive damage. Welcome to TheMalibuCrew! As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account . It runs great at high speeds but overheats at idle. Jul 28, 2003 · Re: OMC Overheating at idle speed only. Took it out tonight and it is still overheating at idle. I have a Yamaha 50 HP 4 stroke outboard F50DET. Recently, I have a problem with overheating at idle speed. does efi have an idle adjustment or is this con*****ed by engine management system. Posted: Wed Jul 22, 2020 7:54 pm . this does not really sound like enough to me. Jun 1, 2017 · Boat is overheating at idle. I have a 2019 BF60a LRT that is driving me nuts overheating. Salt will build up over time, even if you flush regularly. Over time, the inside of a carburetor gets coated in deposits left over by the You may also visit the Boat Motor Manuals section of our site to obtain a Evinrude 115 HP Overheating at Idle. It overheats running at idle and low speeds. I?ve replaced the impeller pump and all grommets, pressure relief valve, thermostat, flushed engine with salt away. Sep 7, 2003 · Hello to everyone. <br />It does have a guide tube but for the life of me could not figure out how it was really helping me. The bypass valve opens at higher speed so that's why it cools fine at speed. Could it be a thermostat if it only happens at idle? I thought it may be the poppet valve but not sure. - If run boat onto trailer, pull out of water, let lower unit drain, back into water again, and restart engine then overheating will occur in neutral. Took the boat out today for the first time since the virus lockdown opened up. I also noticed that the idle was a little slow so I adjusted the carb so the rpm was between 800-900. Put in gear temp normal, back to idle start to overheat. Risers are too hot to touch for more than a couple seconds. Overheating is verified with laser thermometer, over 200°F at the heads, too hot to touch and the alarm itself. You can check by disconnecting the hose at the thermostat housing after the engine is running with the outdrive submerged in water not on the ear muffs, they Jun 27, 2009 · (prob at low ildle for like 15-20 mins). I have a 1994 Force 120 that overheats at idle. 3L overheating at at idle Final update on overheating problem. I have a 2005 Sea Ray with the 5. Jul 31, 2012 · Re: 1975 Mercruiser 165 overheating at idle I've got a 1976 Mercruiser 165, and it runs about 140-150 all the time. Mar 12, 2024 · And, while the thermostat might be partially to blame for an at idle overheat, like you have already suggested, I would also be suspicious of the pump impeller for this. 3 v/6 alpha one i/o mercruiser. We are dying on this one. Let it idle about 15 min, then cruised around the docks and slips for about 30 min since this is Mar 21, 2012 · Thermostats when closed allow quick warm up of the engine and control engine temperature at idle to maintain idle quality. Boat has 156 hours. Got a tow back and loaded back on trailer. 5 psi or Nov 7, 2022 · When this overheating issue was happening repeatedly, I eventually gunned it to get home and it ran ice cold. A thermostat stuck shut causes overheat at idle. It has never been in salt water, garaged and May 13, 2020 · I have a 91 vro 70hp Johnson i was out on the water today and noticed at idle or low speed the temp gauge is showing pretty hot like on the base of the red on the dial, my water pressure is 10-15 at idle and sits around 25 at Wot. Start date Jan 25, 2007; K. At idle it runs at 140 degrees. I learned there's a reason for the order that they have you do things in the troubleshooting guides that helpful folks like Don S post. When I rev the motor the temperature drops but soon after ir rises to 200 Aug 7, 2021 · Here are some protocols to follow if your boat overheats: Shut off the engine. Once you get it above 1250rpm or so (even sitting still), it draws enough water to cool back down and hold 160. as these housings had different amounts of water flow being supplied from the drive. No overheating beep, also the one time I opened the housing and felt the motor, this was at low rpm low speed, it didn't feel hot. at idle it overheats and the alarm activates, if the engine is running 2000 + it runs fine but sometimes the alarm activates at wide open throttle. After things cooled down (<140*), I was able to start the engine while I was still in the river. Sep 6, 2016 · Hello all. The tattle stream is still weak. The cooling system in your outboard’s motor is what to look at if you’re experiencing overheating issues. My 1988 125 hp runs great but the buzzer goes off at idle speeds. Jul 5, 2005 · spent all day sat. Get going again at 3k+ rpm and I can watch it come down. New waterpump kit, two new thermostats, new water poppet relief valve ???? Thanks Jun 25, 2013 · Mercruiser 4. I have re-powered this summer with the 5. Thermostats regulate water flow based on temperature, and circulation slows or stops when they get stuck or fail. If temp is high and the water pump is working properly you may have an obstruction in the water jacket. <br />if it leaks at idle the top stbd cyl wont cool. What I already did: Replaced the impeller Checked water supply Here is the video of water supply hose Oct 22, 2024 · No overheating issues. It would be fine when running at speed and then when back at idle it would start up again. 1996 Mercruiser 3. When it runs hot and the alarm goes off I can tap the gas and the temperature immediately goes down back to normal. You've eliminated the impeller as another possibility. Flow is good. The motor overheats only at idle (approx 650 rpm factory set). 900 RPM is a bit quick for idle. I fixed the hose and ran the boat. Now it's doing it again. It first shows up after the boat has been run a while when back to an idle to pick up your fallen rider the temp will creep up and set off the temp alarm. it would last longer than Mar 20, 2006 · Re: 2001 135 Optimax overheating at idle The metal plate has a sort of a ramp, that if turn over would shred the impeller if I remember it correctly, so I am pretty sure it is correctly installed. I thought maybe the sender was bad so I bought an infrared temp gauge. for a alpha one . some here corroded enough that we switched to a crank mounted johnson or jabsco and used a thru-hull and strainer. It has fresh impeller, new thermostat, can see water moving in strainer, can’t feel any obstructions in tranny Aug 2, 2023 · Hey there, looking for some help. I have a 1989 Prostar 190 with a INDMAR engine with a ford block in great condition that has developed a crippling overheating problem when at idle, but at speed the temp returns to running temp. The symptoms are that the engine will run at a Feb 18, 2025 · So my boat has been overheating at idle lately after it's been run. is on this engine . New water pump, both new thermostats. Lake test for overheating went excellent. The out drive is brand new, the engine was a long block from Carolina Machine Engines who have built engines for me before with great success. Engine only overheated after a couple of minutes at idle, not at full speed. At idle it overheats. Jan 14, 2012 · Hi guys, I'm fairly new to outboard motors and Im having problems with my Mercury 200hp Black Max. Apr 8, 2010 · Hi guys, I,ve read several of your threads and it looks like you guys have plenty of collective knowledge to help me out. This could be as simple as salt build up. I have minimal water coming out the pee pee hole at idle and I am sure it should be shooting out, boat idles around 1000 rpm little high but i'm not sure if the overheat would cause a high idle or not. Everything is reading 165 or less except the block and heads. I am overheating to 200 degrees at idle up to about 1500 RPM's. Have ordered the temp sensor to replace it. I've replaced the impeller and thermostat. It was fine for a 20 min run. Last year I put new thermostat 140 and it still had problem. Motor has 2,000 hours on it - At idle speeds, very low water flow coming from weep hole, and motor overheat alarm will sound after about 30 seconds of idle. Still overheating. Earlier, while boating, no problems at allWhen I got boat home ,I hooked up the ears with water turned on (few turns)ran engine for like 5-10 mins at idle and temp was fineholding at around 150 Any ideas would be welcomed Nov 21, 2023 · An overheating outboard isn’t just a nuisance; it’s a cry for help from your boat’s heart — the engine. It pees fine all the time and water pump was replaced this past summer! Ay help would be appreciated Aug 24, 2020 · I have a 1994 stingray 719zp that originally came with the 4. The motor was rebuilt over the winter of 2010. sometimes, have to start 3-4 times to stay running and it seems to (flood) thus the rough idle. Re: 2003 OX66 225 overheating@idle Get your hands on a Infrared Temp gun. It is a 1989 4. Popped the thermostat out and it appeared to be stuck. I can run up and down the lake all day at 170 but when I bring her to an idle/in no wake it goes up to 220 but no alarm or limp mode. Clark Roberts: posted 09-26-2010 05:45 AM ET (US) May 6, 2013 · Re: Johnson 150 overheat I have already installed new tstats hoping that would fix the overheat issue. Any ideas? Thanks May 28, 2017 · Unlikely, but what you describe (overheat at idle, fine at other speeds) sounds like a sticky valve. 83:1 (so Not a big foot) , , had been mostly fine, except recently at idle and very low speed, alarm horn under dash started coming on once on while so Aug 15, 2012 · Upon retrieving the boat and dusting it off, I opted for a full service that included a new seawater pump impeller. 3l w/Alpha One gen one raw water pick up. Engine temp Jun 27, 2010 · So I replaced my impeller on my 1998 Alpha one gen 2 3. Temp was reading 140-160deg on heads using laser temp guage. At full throttle it runs at 140 degreesbut at high idle and planing speed 1200-2000 RPMit runs hot as hell >180 degrees. Why Does My Yamaha Outboard Overheat at Idle? An overheating engine at idle often indicates a thermostat problem. At idle it overheats in 3 mins once you go over 1000 rpm's it cools down. New impeller. The temp. Jun 18, 2008 · 2003 Volvo 5. Just to see what would happen, I pulled the thermostat - no difference. Therefore and engine that overheats at idle generally has a thermostat stuck closed. May 27, 2022 · Hi I bought Evinrude 1999 50 4-stroke last year and i was hurry to change the engine to the boat, and i did not have the gauges at the moment. I replaced the impeller, the base, gasket is correct, all hoses are free of Apr 19, 2013 · Re: 2003 Mariner 60hp 4-Stroke Overheating At Idle Why not replace the thermostat before jumping to uncertain conclusions. That was the symptom on my 2007 225. The alarm goes off between 183-195 degrees. Could this be the poppet valve? If so where is Jun 25, 2012 · Mercruiser 6. Sep 29, 2023 · Hi all. 170 while cruising seems high to me, but I dont have a heat exchanger, just straight lake water that is 65-70 degrees. The engine itself is a new rebuilt long block. Are you sure the alarm is not for the O2 sensor. Engine and drive number above in a 2005 boat May 6, 2011 · I have a 1985 sea ray with 260 mercruiser. Engine runs at 150 to 160 temp when crusing above 10 miles/hr. It also has new exh risers and manifolds,with thru haul exh. This problem occured with new and old thermostats and water pump. It then slowly climbed to 180*, after which the temp gauge needle jumped dramatically towards another overheat. Clogged Raw Water Strainer. Water pump was replaced, and thermo's open when put Mar 31, 2013 · I have a 2003 yamaha 150 2 stroke. This will happen regularly when the engine is warmed up and idles for more than 3-4 minutes. Big block 454's were used with alpha's without any cooling/overheating issues back in 88 89 timeframe before the bravo was released!!!! Look for parts descriptions relating to that year and do a part comparision to see what you may need. Understand Mar 20, 2006 · No change. snailman, do you know what year and type of thermostat hsg. Before you go searching under the Apr 27, 2011 · I apologize ahead of time for the lengthy post. Under closer inspection I can see the water intake hose (red hose) which should be a hard hose from what I understand is noticeably deformed and compressed especially while running the Dec 5, 2021 · Hello everyone, I have a general question that someone may have come across before. At idle, this lack of movement is especially problematic because the engine isn’t cooling through forward motion. Changed water pump, poor condition but no better temp when finished. usuall symptom is over heat after 5 min of idling but anything above 1000 RPM is ok. 0 LX/V8 Alpha One engine. If your boat overheats, throttle down immediately. After the repair, the boat ran fine for 6 months. The temp gauge slowly creaps up to above operating temp (usually 160 at idle). new engine water pump and so on. This is my first post after searching all the posts on overheating etc. 7L Merc I/O Overheats at idle. Cools when running. com May 2, 2004 · Boat is a 1990 Bayliner Ciera 2651 with Mercruiser 5. 3 mercruiser. Cools fine under power. Replaced thermostat - No help Replaced impeller - This made the problem worse, overheating at idle now. The flow seemed a little weak but when I increased the rpm it increased. brought the boat home and put it on the water hose. The increased rpm seemingly making the engine temperature go lower does point to a problem with the pump But, if it were me, I would check both and service as needed. May 28, 2011 · Re: 87 Mercruiser overheating at idle (under 1000rpm) OK, I back flushed and then ran the boat with the muffs on and the supply hose off - dumping into the bilge. Aug 15, 2012 · Re: 2009 yamaha 4 stroke overheating alarm when at idle Generally an overheat at idle is due to a thermostat that is stuck closed. Team Axis: Joined: Sat Apr 16, 2016 10:30 pm Posts: 79 Apr 5, 2023 · Overheat at idle on a v6 sends me straight to the thermostats. If you’re in safe water, anchor the boat. I did this, but problem is still there. Motor still overheat after 4 to 5 minutes at idle on earmuffs. Btw, idle is around 800 rpm and I was using forward and reverse. Took the boat out this week and the overheating alarm went off after 4-5 minutes of idling. Have to bring to a new mechanic. If I bump it up just a bit to 800+ rpm the motor cools right down to 160-170 on the gauge. Aug 1, 2020 · Has had a weaker telltale at idle as long as I’ve had it, three years. To date I have chased the problem by doing the following: Aug 28, 2011 · - Revving engine in neutral results in return to normal temperature. 0 GL with SX outdrive. at idle there is only about . For example, I will start the boat, could be the 1st or 5th start of the day- it does not matter if boat is cold or warm. Maybe the hot foot needs adjusting. The longer you keep the boat’s engine running, the greater the risk of causing permanent damage. Once I get going though the temp immediately drops almost to the Jul 2, 2022 · Im hoping you can help me with my problem as i have run out of ideas. But when at idle or at low "no wake" cruising speeds the boat starts to overheat. Engine overheating in idle. Drop it back to idle on the pontoon dock at with in 10 mins over heat buzzer goes off. at idle, but goes away when you throttle up. So I think these two problems are fixed. Still same problem. Changed thermostats Jul 24, 2019 · Any RPM past 2000 would slowly get the boat to overheat. Feb 9, 2010 · Re: suzuki df140 overheating Re: suzuki df140 overheating 2002 Suzuki 140 hp overheating, NEED HELP PLEASE! Hello Folks, please I really need further assistance. Telltale has solid stream in neutral but lessens when bumped into idle and will eventually sound the alarm after 7-10mins. Engines Over heating on my 1990 5l merc at an idle. Shop changed impeller, t Feb 16, 2025 · Post subject: Boat overheating in idle after sitting. I kick into neutral and give it some gas it goes off after a few seconds. the cobra drive was very popular with the crabbers. 2L 320 HP I/O Engine Number OW324506 Drive: OW268328 Bravo 1 Seawater/raw water cooled Hello everyone, My first post herehope to provide all necessary info as requested in the sticky, but let me know if you need additional info. There is plenty of water coming out of the pee hole at all times. Water pump was replaced, and thermo's open when put Sep 10, 2011 · I have a 2004 F60TLRC carbed 60hp 4 stroke. is the thermostat hsg. Watch the video above or read on below to learn about several ways to diagnose an overheating outboard engine. I can immediately cool it down by revving the motor up to 1200rpm+. Anyway, If it were me, I would test both thermostats new on not. The number one cause for overheating boat engines is a problem with the flow of water to the engine. Then I put sea water pump in drive. I have replaced the thermostat, water temp Sep 16, 2010 · The boat has had overheating problems since the first time I put the boat in the water. The fact that it overheats at IDLE in the lake and NOT at idle on the hose leads me to believe that you still have a problem with the water pump. 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. I changed the waterpumps Aug 24, 2006 · I saw some other posts on this but here is my solution for others. Check all your hose clamps, water strainer gasket, etc. Also there was an squeaking Nov 30, 2011 · I have a 90 baja 190es boat with a 5. at 3500 rpm and at 30 MPH there is about 6 psi. Oct 8, 2013 · I have twin 250 Yamaha 4 strokes on my boat and recently the overheating alarm has been going off on the portside engine while trolling or at idle speed. Am I missing anything? Outboard Runs Poorly When Idling. there were some flacky problems with the pumps as the units aged. took note of water pressure. May 2, 2022 · My ‘99 Super Sport (EFI GT40) is overheating at idle. Wondering if zebra mussel clog or something. Actions so far: Acid flushed the inside of the motor twice to remove any Jul 13, 2008 · Re: 87 Mercruiser 4. The risers Apr 18, 2005 · Re: ProV 150 overheat at idle? biggest problem aside from a pump is the pressure control valve grommet. A Bayliner mechanic instructed me to change water impeller. Boat has new risers and manifolds too. Removed exhaust manifolds and elbows and then gave them the acid treatment. A rapid buzzer after a couple of min. If one hangs open the opposite three cylinders (bank) might sound the alarm due to lack of flow at idle. 7 VP overheats at an idle only after a run (never from cold start up). Problem is there is an overheating alarm that goes off if the motor is ran under about 1000 rpm for about 6-8 min. Check your heads at idle. Team Axis: Joined: Sat Apr 16, 2016 10:30 pm Posts: 79 Jun 25, 2014 · I have a 2004 Volvo Penta 5. For marine professionals, understanding the intricacies of an outboard motor’s Mar 15, 2010 · Re: Mercury 150 Overheating Many things can cause overheating, retarded timing, leaking heat gaskets. needs to be replaced and the pocket cleaned every other year with the pump. Sometimes it holds at 145 degrees, but most times it will continue to climb all the way to 210 degrees. After overheating at idle replaced water pump with entire new kit and changed thermostat. Over winter I’ve replaced plugs, low pressure fuel filter and external fuel filter, drained VST but not changed HP filter, fitted new impeller and housing and had lower unit rebuilt and pressure tested at a local If there were plugged cooling passages and/or a wrong thermostat, wouldn't the problem show up even more at speeds above idle? In the first two hours I used the motor I had two instances where I had to thread a wire into the telltale because the stream had been plugged. Exactly what might happen with a kink in the hose! It needed the water pressure from higher RPMs to open up the kink and let water through! Jul 21, 2006 · Hey guys we have a 1990 mercruiser 305 with an alpha 1. So far I have changed impeller system, circulation pump. 5 psi read by the system. My problem Im having is it overheats from idle to about 2000+/- rpms when under way. still getting hot at idle. gauge indicates that it overheats at low rpm or idle on the lake or on the motor flusher. I've had the thermostats changed. I guess I'll never know what really fixed the overheating. At high speed the thermostat is a restriction so the pressure relief valve opens to allow more water through the engine. 0l mercruiser and it is overheating at idle speed goes up to 200-210 in the lake. I have a 1990 150 pro v that runs like a top. Thread starter Kevin F. I can run it for only 2 - 3 minutes, or 60 minutes, and it will run just fine under throttle, but then if you throw it in neutral and your idling around, the engine (right one mainly) will overheat in about 5 minutes or so. I have a 2002 Suzuki DF140 that is overheating. Jun 17, 2023 · My friend has the same year, same boat, same motor but he gets an overheat alarm at idle too after running fast. Customer: This is an inboard outboard 5. Before you go searching under the Apr 25, 2011 · I am having an issue with my boat overheating at idle or in drive at the lowest speed (650-800rpm). 0L motor in a Four Winns Mechanic's Assistant: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. Jun 6, 2016 · 470 overheated the end of last season due to loss of coolant from a hose that broke. Boat runs great then still overheats only at idle. Dec 12, 2020 · Here are a few reasons why your boat may be overheating and how to fix it: 1. 2020 Moomba Kaiyen with Raptor 400 engine. I read that 140 degree thermostat is an option. I cleaned it up real good and took it home and Nov 6, 2022 · And the motor was overheating at idle, but running cold at speed. Everything is new, water circ pump, impeller in stern drive, intake manifold, exhaust manifolds, risers, thermostat housing with 140f thermostat, sensors in Cleaned water passage, water passage diverter in good condition. On test after the work, the mechanic reported that the boat would overheat at idle and at 2000rpm while in the water on the trailer with adequate exposure for the seawater intake. or for a alpha one gen II. Stb bank running @ 105 degrees and port running @ 60 degress. Any suggestions on how to improve cooling? He has also replaced the impeller. fishing without the first overheating problem. 0 osi engines (2) 720 & hrs over-heating at idle - occurrs in-gear and in neutral - revving engines in neutral and putting boat under way at 1500 RPMs returns temp to normal, 160 or cooler - started with strbd engine and 3 hours later with port engine - recirc pumps changed a year Mar 27, 2011 · I have a 1992 50hp Mariner outboard and while at a idle and trolling the overheating alarm keeps going off. . I have had my outdrive rebuilt with new impeller housin, plate etc and it still didn't bleed right, meaning very little water was getting pulled up. When the overheat at idle problem started, the telltale was working fine. No kinks or May 1, 2024 · It's been overheating at idle for around 7 years now. Apr 27, 2011 · I apologize ahead of time for the lengthy post. it also increased my wp by about 5# thanks again! now, what about a rough idle, low idle on start-up. The motor overheats only at idle (approx 650 rpm factory set). I have a 2003 Yamaha 4stroke F200TXRB that is overheating at low idle. At 2000 RPM's, she's 160-165. Mar 1, 2008 · I own a 1983 Ski Supreme with ford 351PCM. The poper thermostats are in the proper "Hello, I have a 1990 Bayliner "Hello, I have a 1990 Bayliner trophy hardtop with a 4. Used the boat twice this summer with no problems, until a few weeks ago i drove into a bay and reduced the speed, after Jul 18, 2004 · Re: Sucked up mud, now overheating above idle !! FIXED- Update!! Probably the first thing to check is the raw water impeller. Everything is new on the engine, Timing is Flush, complete water pump housing, and new thermostat. Ski boats have a motor mounted impeller like bravo's. _____ Apr 5, 2009 · Re: Volvo Penta overheating at idle Well, as promised, I wanted to post back with what I found on my overheating issue so that it might benefit the next guy with the same problem. I have replaced the impeller, housing etc. Running pressures at WOT at only 13 also indicate a low flow from your water pump. The end of the summer went pretty nice with "new" engine, only occasional 3000rpm limits usually when i shut down the engine for 15mins or 30min. But if I take the throttle to about 1500rpm it cools right back down to 150-160. Seems simple enough. I can turn the engine off an back on and the alarm will stop for a minute or so but then will reactivate once again. It seems to be fine if I go pedal to the metal, but in no-wake zones I overheat. engine would not overheat on the garden hose but still noted only . Checked the poppet valve (not blocked). Feb 6, 2004 · Re: OMC 305 OVERHEATING AT IDLE & HIGH RPM hello<br /> not knowing what drive you have I am going to assume its a raw water cooled cobra. It shoots out a great stream of water. So if it's a clog, you'd think I would have flushed it out but that doesn't seem to be the case. However, there's one more thing you can do to troubleshoot an outboard that runs poorly at idle: Clean the Carburetor . Otherwise, aim to idle the boat to a safe location. Temp never got above above 145. Thermostat or poppet valve maybe. 7 SBC with some performance work done to it, cam, light head porting and alum intake. At higher speeds and on plane, will run fine all day long. Engine was originally raw water cooled but has an aftermarket fresh water cooling system in place. WTF. I disassemble the water pump, but found it all there I am in the final stages of rebuilding a 1989 Sea Ray 230 from a shell and a whole lot of boxes of parts. The checklist for an outboard that remains running poorly at idle is the same as for when it stalls while idling. Removed lower unit and flushed head unit with a decalcifier for four hours with a pump. Mar 5, 2025 · Post subject: Boat overheating in idle after sitting. I let it idle for a few minutes, and the temp slowly climbed to normal operating temp (165*). Dec 2, 2015 · anyone had an issue with a df250 overheating @ idle ?? Will run fine all day over 1200rpm. Jul 6, 2007 · Frustrating problem with overheating on a 2004 F225.
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