Hello all, I have the 13 hp 2GMF which overheats after 30 minutes at about 2800 RPM - so far I`ve cleaned the heat exchanger, replaced the sea water pump impeller (the pump still leaks 2-3 drops per second - I still have to replace the seals) cleaned the sea water strainer... I`ve got a spare thermostat which I`ll change next, and do an oil change ( I bought the boat in April and do not know the age or quality of the motor oil)... any ideas as to the cause of overheat will be greatly appreciated, Guy
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Check the mixing elbow.
Guy: Check the mixing elbow. It is quite often the cause of the problem. If you want to know how to remove and replace it you can check the photo forum and lookup ELBOW. I did some pictures when I did mine. Good Luck.
Guy: Check the mixing elbow. It is quite often the cause of the problem. If you want to know how to remove and replace it you can check the photo forum and lookup ELBOW. I did some pictures when I did mine. Good Luck.
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Gene B. s/v Paradigm
Exhaust Elbow Revisited
Check the archives. This subject has been addressed over and over. The exhaust elbow cokes up and has to be cleared or you don't get the cooling flow you need. The archives include some very high quality photos to help you. Good luck!
Check the archives. This subject has been addressed over and over. The exhaust elbow cokes up and has to be cleared or you don't get the cooling flow you need. The archives include some very high quality photos to help you. Good luck!
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Ray
Mixing Elbow
I changed my mixing elbow this year. I bought a 1990 H30 last year and the surveyor said change out the mixing elbow. For a year I ran with the old one and didn't realize how hot the engine was running. I finally changed it out this spring and it has made the world of difference. faster RPM, less smoke, cooler engine temperature and piece of mind. It's not an 30 minute job but taken slowly and with enough band aids for scraped knuckles it can be done. I replaced the exhaust hose at the same time as the old elbow and the hose had become so welded together as to require cutting.
I changed my mixing elbow this year. I bought a 1990 H30 last year and the surveyor said change out the mixing elbow. For a year I ran with the old one and didn't realize how hot the engine was running. I finally changed it out this spring and it has made the world of difference. faster RPM, less smoke, cooler engine temperature and piece of mind. It's not an 30 minute job but taken slowly and with enough band aids for scraped knuckles it can be done. I replaced the exhaust hose at the same time as the old elbow and the hose had become so welded together as to require cutting.
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Kent Wilson
Overheating and weeds
At this time of the year weeds are becoming a problem with water intake systems. The strainer is there to catch them however on the 29.5 (and probably boats of similar size) the intake valve and piping is about a half inch diameter and will plug, or partially plug,with weeds. I have found that I have to push a piece of coathanger through the open valve and work it around to be sure everything is cleaned out. I have figured out how high a "fountain" I will get with a clear system and keep cleaning until I achieve this. In addition I check that the hose between the valve and strainer is clear. The partial blockage can really fool you.
At this time of the year weeds are becoming a problem with water intake systems. The strainer is there to catch them however on the 29.5 (and probably boats of similar size) the intake valve and piping is about a half inch diameter and will plug, or partially plug,with weeds. I have found that I have to push a piece of coathanger through the open valve and work it around to be sure everything is cleaned out. I have figured out how high a "fountain" I will get with a clear system and keep cleaning until I achieve this. In addition I check that the hose between the valve and strainer is clear. The partial blockage can really fool you.
Kent makes a good point!
Guy: Do not forget to shut off the seacock for the raw water intake. Then remove the hose. If you have water flowing freely when you open the valve, then you need to check the strainer which is in the same compartment. Then you can check the flow into the elbow. If this all is flowing well, then you can check out the elbow.
Guy: Do not forget to shut off the seacock for the raw water intake. Then remove the hose. If you have water flowing freely when you open the valve, then you need to check the strainer which is in the same compartment. Then you can check the flow into the elbow. If this all is flowing well, then you can check out the elbow.
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Brian
Jelly Fish
I had a similiar problem with getting water to my A/C. I worrked backwards from the strainer till finally getting to the seacock. Since I had a weed problem in the past, I thought that might be it. I got a coat hanger and and tried to clean it out... nothing happened. I decided force some air through it. I could hear it bubbling under the hull, but water wouldn't still wouldn't flow at much of a rate. Sooo, I jumped into the water and much to my surprise a jelly fish was stuck in the hole and I guess the coathanger was just going right through his "jelly." Water flows great now....
I had a similiar problem with getting water to my A/C. I worrked backwards from the strainer till finally getting to the seacock. Since I had a weed problem in the past, I thought that might be it. I got a coat hanger and and tried to clean it out... nothing happened. I decided force some air through it. I could hear it bubbling under the hull, but water wouldn't still wouldn't flow at much of a rate. Sooo, I jumped into the water and much to my surprise a jelly fish was stuck in the hole and I guess the coathanger was just going right through his "jelly." Water flows great now....
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Guy LeClair
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Jim McCue
Heat exchanger
I assume you have adequate volume of coolant - which is different from the raw water side of the cooling system. You may want to pull and clean you heat exchanger. Its not hard to do.First drain the coolant reservoir - makes for less dribble of antifreeze. Undo 4? nuts on front cover of enchanger, slide out the cylinder and degrime. Use lysol direct with pipe cleaners. "In advance" make sure you buy yourself replacement gasket for the front of H/E cover. Jim McCue
I assume you have adequate volume of coolant - which is different from the raw water side of the cooling system. You may want to pull and clean you heat exchanger. Its not hard to do.First drain the coolant reservoir - makes for less dribble of antifreeze. Undo 4? nuts on front cover of enchanger, slide out the cylinder and degrime. Use lysol direct with pipe cleaners. "In advance" make sure you buy yourself replacement gasket for the front of H/E cover. Jim McCue
Heat Exchanger Tip!
Just saw something the other nite regarding heat exchanger cleaning. Just pour a bottle of "lime-away" in the fresh water resevoir and let it run for an hour or so. Then drain the system and refill with anti-freeze and water. The author claimed that it cleaned out the system. Please be aware. Lime-away is ACID. When you mix any acid with anything else you must be careful. I also have no idea if this mixture would hurt any internal seals in the fresh water pump or any other internal parts. My guess is that it would be OKAY, but just be aware.
Just saw something the other nite regarding heat exchanger cleaning. Just pour a bottle of "lime-away" in the fresh water resevoir and let it run for an hour or so. Then drain the system and refill with anti-freeze and water. The author claimed that it cleaned out the system. Please be aware. Lime-away is ACID. When you mix any acid with anything else you must be careful. I also have no idea if this mixture would hurt any internal seals in the fresh water pump or any other internal parts. My guess is that it would be OKAY, but just be aware.
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Guy LeClair
Beware of CLR
Thanks Jim and Steve, I had considered using CLR for cleaning the HX, but did it manually instead because CLR is unsuitable for aluminium and copper, which the exchanger is made of. Fouling was minimal, a couple of tubes blocked. It is a rather easy job but I found it much easier to undo both front and back covers and pull out the whole tube assembly, therefore you need both gaskets.
Thanks Jim and Steve, I had considered using CLR for cleaning the HX, but did it manually instead because CLR is unsuitable for aluminium and copper, which the exchanger is made of. Fouling was minimal, a couple of tubes blocked. It is a rather easy job but I found it much easier to undo both front and back covers and pull out the whole tube assembly, therefore you need both gaskets.
S
Steve Fehm
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Tim Leighton
MY EXPERIENCES (NUMEROUS!)
Guy: Steve Dion was right about troubleshooting from the intake to the mixing elbow. When I first got my 31 I had all sorts of overheating problems.. most self-induced. One which hasn't been mentioned here yet is the SW hose which runs from the strainer to the pump on the front of the engine. That hose is a "suction" line and MUST be reinforced. I didn't know that early on (DUH!) and couldn't figure out why I overheated at 2800 rpm but ran fine at less than 2000. I found a mechanic at the marina we were at who took one look, replaced the hose and charged me $40! The best $40 I ever spent!! Highly recommend you check that hose to ensure it isn't collapsing under load. Here are a couple of other things I did to stop overheating problems: 1. Put a "hubcap" strainer on the hull to stop contaminants before they enter the system. Paint it every time I do the bottom and have had no problems since. 2. Increased the size of the thruhull (as recommended previously). 3. Change the impeller every season. 4. Clean the mixing elbow every other year. That keeps it from clogging and "welding" the exhaust hose to the unit. I also clean that small fitting from the exchanger to the elbow every year. 5. The BEST thing I did (but most expensice and difficult) was to move the exhaust from under the transom (what the heck was Hunter thinking?) to the starboard hull near the stern and about 2' above the waterline. Not easy or cheap but I can see whether or not I'm pumping water when the engine is running. LOTS of peace of mind. Good luck w/ your problem! Hope these ideas help. Smooth sailing. Tim (S/V "TIDE")
Guy: Steve Dion was right about troubleshooting from the intake to the mixing elbow. When I first got my 31 I had all sorts of overheating problems.. most self-induced. One which hasn't been mentioned here yet is the SW hose which runs from the strainer to the pump on the front of the engine. That hose is a "suction" line and MUST be reinforced. I didn't know that early on (DUH!) and couldn't figure out why I overheated at 2800 rpm but ran fine at less than 2000. I found a mechanic at the marina we were at who took one look, replaced the hose and charged me $40! The best $40 I ever spent!! Highly recommend you check that hose to ensure it isn't collapsing under load. Here are a couple of other things I did to stop overheating problems: 1. Put a "hubcap" strainer on the hull to stop contaminants before they enter the system. Paint it every time I do the bottom and have had no problems since. 2. Increased the size of the thruhull (as recommended previously). 3. Change the impeller every season. 4. Clean the mixing elbow every other year. That keeps it from clogging and "welding" the exhaust hose to the unit. I also clean that small fitting from the exchanger to the elbow every year. 5. The BEST thing I did (but most expensice and difficult) was to move the exhaust from under the transom (what the heck was Hunter thinking?) to the starboard hull near the stern and about 2' above the waterline. Not easy or cheap but I can see whether or not I'm pumping water when the engine is running. LOTS of peace of mind. Good luck w/ your problem! Hope these ideas help. Smooth sailing. Tim (S/V "TIDE")
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Glenn
overheating
Have had similar problem. Turned out to be a stoppage in the return elbow from the block. Good Luck.
Have had similar problem. Turned out to be a stoppage in the return elbow from the block. Good Luck.
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