My Hunter Legend 37 1988 has a yanmar disel 3 cylinder engine "3HM35F" and a old problem has reoccured. I'm not getting any water in my exhaust and my over heated engine alarm goes off. I 've check and replaced my impeller, cleaned out mt raw water filter chamber and checked all hoses including the inlet through the hull valve and water is flowing. I did note, however, that my water pressure from the through the hull valve is not very strong. Water flows ok but not with much force. I also noticed that the incoming raw water dsid not seem to be able to reach my raw water filter chamber. This chamber is about 16 inches above the valve located just slightlym above the engine. Water is supposed to flow into the raw water filter chamber before it reaches the impeller. Tne impeller chamber appeared dry. What's happening? Any help is most appreciated. Thanks Barrie
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Here's one idea
I had a problem with my 3GM30F on my h34 with water circulating. I also checked impeller, filter, etc. All seemed fine, but I still wasn't getting any water flow. It turned out that the gasket at the top of the raw water filter was bad and was leaking air. Now it was still water tight and was not dripping. With the engine running, air would be sucked in past that gasket, and into the pump/empeller. And again: No visible leaks. Repair was easy. I just replaced that gasket. So, one thing to check is: do you have any gaskets or seals that could be leaking. Remember, air molecules are smaller than water, so a leak can break the suction needed for the pump to work, and still not leak any water. Just one suggestion to try.
I had a problem with my 3GM30F on my h34 with water circulating. I also checked impeller, filter, etc. All seemed fine, but I still wasn't getting any water flow. It turned out that the gasket at the top of the raw water filter was bad and was leaking air. Now it was still water tight and was not dripping. With the engine running, air would be sucked in past that gasket, and into the pump/empeller. And again: No visible leaks. Repair was easy. I just replaced that gasket. So, one thing to check is: do you have any gaskets or seals that could be leaking. Remember, air molecules are smaller than water, so a leak can break the suction needed for the pump to work, and still not leak any water. Just one suggestion to try.
Gasket?? What gasket??
Thanks Ron, I didn't even see any gasket material on my raw water filter chamber. I'll look at this right away. Barrie
Thanks Ron, I didn't even see any gasket material on my raw water filter chamber. I'll look at this right away. Barrie
Perko water strainer
Barrie, I have a Perko stainer, and there is a rubberized cork gasket under the lid that lifts, to remove the strainer. I have no idea what kind is on your boat, but the same idea might apply to other brand/design of strainers. Good luck.
Barrie, I have a Perko stainer, and there is a rubberized cork gasket under the lid that lifts, to remove the strainer. I have no idea what kind is on your boat, but the same idea might apply to other brand/design of strainers. Good luck.
I Hate To Say This, but...
..are you sure you are getting flow through the mixing elbow? Carbon deposits will constrict the flow over time and even if everything on the front side of the coolant delivery is OK, it can't flow into the chamber, and you gave an overheating condition under load. I took a stainless steel spring in a drill with carb cleaner once a year, and it made a big difference. Good luck. Rick D.
..are you sure you are getting flow through the mixing elbow? Carbon deposits will constrict the flow over time and even if everything on the front side of the coolant delivery is OK, it can't flow into the chamber, and you gave an overheating condition under load. I took a stainless steel spring in a drill with carb cleaner once a year, and it made a big difference. Good luck. Rick D.
strainer location
just a thought about your location of the raw water strainer, 16 inches above the thru hull sounds high it should be located below the water line. just might be worth checking out. (try bypassing the strainer to see if it help) one other thought is that you water intake hoses could be bad and collape under pressure(suction fron the punp) Hope this has been some help!
just a thought about your location of the raw water strainer, 16 inches above the thru hull sounds high it should be located below the water line. just might be worth checking out. (try bypassing the strainer to see if it help) one other thought is that you water intake hoses could be bad and collape under pressure(suction fron the punp) Hope this has been some help!
more thoughts
Barrie,would you please let us know what was the problem when you get it fixed? I still feel it has to do with the strainer location being to high, it occured to me that you might have to fill the strainer first by hand because it is mounted so high(like you should do for fuel filters when bleading the fuel system) another thought is that the thur hull could be blocked from the outside so either get wet and go over to check it or remove the water hose at the thru hull and clear it with a probe of some sort to make sure it is not restricted. Good Luck!
Barrie,would you please let us know what was the problem when you get it fixed? I still feel it has to do with the strainer location being to high, it occured to me that you might have to fill the strainer first by hand because it is mounted so high(like you should do for fuel filters when bleading the fuel system) another thought is that the thur hull could be blocked from the outside so either get wet and go over to check it or remove the water hose at the thru hull and clear it with a probe of some sort to make sure it is not restricted. Good Luck!
OK, here goes...
Barrie. I have a 1988 L37 with the same engine. Your configuration sound to be exactly like mine. I've been thru mine several times over the years, so I'll tell you what to check. First, the strainer, mounted on the port, aft side of the engine compartment should be alright. So disconnect the hose from the hose from the thru-hull (at the foot of the bed in the aft cabin, below the floor boards) and the strainer. Blow thru the hose. It should be clear. Then open the thru hull seacock. Water should come in a pretty good stream. Check the elbow at the seacock to be clear. This is a 90 degree elbow that often gets clogged with anything. OK, now the first segment is clear so connect them back up. Now disconnect the hose from the strainer on the opposite side of the strainer. Then disconnect the other end of the hose at the impeller pump input. Blow thru the hose. It should be clear. Reconnect this hose to the strainer after checking the 90 degree elbow that it connects to. Now two segewnts are checked. Again, check the lid on the strainer to ensure that it seats tightly. If it was not seated properly it would suck air AND leak, also. Watch for these. You changed the impeller? Is it the correct one? Be sure. Does the impeller leak? Is the plate gasket OK?. If it does leak, you'll lose your vacuum (sucking) integrity. Check the hose from the impeller output that goes up to the heat exchanger. Disconnect it and blow thru it. It should be clear. While the hose is off, look into the heat exchanger thru the open nipple. If there's gunk in there, that may be you blockage and have to get it acid boiled to clean it out. After the heat exchanger, is the mixing elbow. The other reader covered that, sooooo...., GOOD LUCK! I hope this helps. This whole process should take you 20-30 minutes to check out.
Barrie. I have a 1988 L37 with the same engine. Your configuration sound to be exactly like mine. I've been thru mine several times over the years, so I'll tell you what to check. First, the strainer, mounted on the port, aft side of the engine compartment should be alright. So disconnect the hose from the hose from the thru-hull (at the foot of the bed in the aft cabin, below the floor boards) and the strainer. Blow thru the hose. It should be clear. Then open the thru hull seacock. Water should come in a pretty good stream. Check the elbow at the seacock to be clear. This is a 90 degree elbow that often gets clogged with anything. OK, now the first segment is clear so connect them back up. Now disconnect the hose from the strainer on the opposite side of the strainer. Then disconnect the other end of the hose at the impeller pump input. Blow thru the hose. It should be clear. Reconnect this hose to the strainer after checking the 90 degree elbow that it connects to. Now two segewnts are checked. Again, check the lid on the strainer to ensure that it seats tightly. If it was not seated properly it would suck air AND leak, also. Watch for these. You changed the impeller? Is it the correct one? Be sure. Does the impeller leak? Is the plate gasket OK?. If it does leak, you'll lose your vacuum (sucking) integrity. Check the hose from the impeller output that goes up to the heat exchanger. Disconnect it and blow thru it. It should be clear. While the hose is off, look into the heat exchanger thru the open nipple. If there's gunk in there, that may be you blockage and have to get it acid boiled to clean it out. After the heat exchanger, is the mixing elbow. The other reader covered that, sooooo...., GOOD LUCK! I hope this helps. This whole process should take you 20-30 minutes to check out.
The thru hull on that model is relatively small
and hose adapters you might have may further restrict the flow. Couple this with the small intake on the 37 Legends and any marine growth you might have in the passageways could be causing the problem. I have experienced this before with barnacles, eel grass, etc. My first tip off is the throaty exhaust heard when i start the engine. You did say this is an old reoccuring problem....
and hose adapters you might have may further restrict the flow. Couple this with the small intake on the 37 Legends and any marine growth you might have in the passageways could be causing the problem. I have experienced this before with barnacles, eel grass, etc. My first tip off is the throaty exhaust heard when i start the engine. You did say this is an old reoccuring problem....
Paul Here again.
Be sure to check the 90 degree input AND output elbows of the strainer. hese are small also and EASILY trap grass seaweed, etc. Also the thru hull input is narrow (1/4" maybe). At the dock, get a plastic high pressure nozzle for your water hose. Backwash the thru hull by inserting the HP nozzle into the barbed nipple on the thru hull from inside the boat) and blast out any obstructions that may be there. Keep us posted.
Be sure to check the 90 degree input AND output elbows of the strainer. hese are small also and EASILY trap grass seaweed, etc. Also the thru hull input is narrow (1/4" maybe). At the dock, get a plastic high pressure nozzle for your water hose. Backwash the thru hull by inserting the HP nozzle into the barbed nipple on the thru hull from inside the boat) and blast out any obstructions that may be there. Keep us posted.
Exhaust Water Solution
Thanks again Paul Akers for your excellent advice. I checked my cooling system step by step as you advised and I have water flowing right up to the mixing elbow. Now how the heck does one clean the elbow out? I assume its plugged full of mineral deposits restricting the water flow into the exhaust. My mixing elbow hose connector for the raw water is a 90 degree one and i can't figure out how to get a probe into it to clean t out. I was thinking of pouring some vinegar into the mixing elbow and let it dissolve the minerals, however, is there any possibiliy of the vinegar seeping backwards into the engine itself. Again any advice is most appreciated. Barrie
Thanks again Paul Akers for your excellent advice. I checked my cooling system step by step as you advised and I have water flowing right up to the mixing elbow. Now how the heck does one clean the elbow out? I assume its plugged full of mineral deposits restricting the water flow into the exhaust. My mixing elbow hose connector for the raw water is a 90 degree one and i can't figure out how to get a probe into it to clean t out. I was thinking of pouring some vinegar into the mixing elbow and let it dissolve the minerals, however, is there any possibiliy of the vinegar seeping backwards into the engine itself. Again any advice is most appreciated. Barrie
Barrie: I Hate To Say This (Again)..
..but, it may be time to just take it off and replace it. It is alleged the life is about five years. I think it is more, but the point is, if it is that clogged, it may be better to just replace it now. What I did, however, was to remove the hose barb fitting and use the spring in a drill method from the prior post. You are right about not wanting to 'pour' anything down there. I got ten years out of mine. It clogged at four, but attention to it over the years, and following the manual for keeping the revs within the 80-90% power range when possible, kept it clear. It was an annual clean-out step, tho. Good luck. Rick D.
..but, it may be time to just take it off and replace it. It is alleged the life is about five years. I think it is more, but the point is, if it is that clogged, it may be better to just replace it now. What I did, however, was to remove the hose barb fitting and use the spring in a drill method from the prior post. You are right about not wanting to 'pour' anything down there. I got ten years out of mine. It clogged at four, but attention to it over the years, and following the manual for keeping the revs within the 80-90% power range when possible, kept it clear. It was an annual clean-out step, tho. Good luck. Rick D.
Thanks Rick,
You're proberly right about just replacing the mixing elbow. A bit of expense now to avoid future hassels. Thanks for your advice, Barrie
You're proberly right about just replacing the mixing elbow. A bit of expense now to avoid future hassels. Thanks for your advice, Barrie
Elbow replacement.
Barrie: If your engine is similar to the 2GMxxF and 3GMxxF, the elbow was only about $90. I would recommend that you order the elbow and a gasket (as a minimum). Getting the exhaust manifold and the elbow apart is not a simple task. I would recommend that you have access to a vise and some type of a heating torch. As I remember the threads on the coupler between the elbow and the manifold have opposite threads (so be aware). Because of the heat and the water these thing rust up pretty good so a couple of good pipe wrenchs and some breaker bars are good to have too. I did an editoral on this procedure in the Photo Forum so you may want to refer to this if you have not done it before.
Barrie: If your engine is similar to the 2GMxxF and 3GMxxF, the elbow was only about $90. I would recommend that you order the elbow and a gasket (as a minimum). Getting the exhaust manifold and the elbow apart is not a simple task. I would recommend that you have access to a vise and some type of a heating torch. As I remember the threads on the coupler between the elbow and the manifold have opposite threads (so be aware). Because of the heat and the water these thing rust up pretty good so a couple of good pipe wrenchs and some breaker bars are good to have too. I did an editoral on this procedure in the Photo Forum so you may want to refer to this if you have not done it before.
No Exhaust Water Solution "Results"
Hi Everyone, Many thanks to all of you, noteable Steve Dion with the excellent photo form of the elbow removal process and Rick Dinon, Paul Akers, Steve C. and Ron Dague. I fixed my probelm. First I checked my system piece by piece from the inlet valve to the exhaust elbow and decided to replaced the mixing elbow. My old one was pretty plugged up. Water flowed nicely throughout the system but finally I discovered that besides the mixing elbow problem the raw waterstrainer is also plugged. I removed it, cleaned it out and reinstalled it below the water line because it was above the engine and not working well. I now have more water than Niagara falls coming out of my exhaust. My wife Judy and I went for a lovely sail off Point Roberts on Saturday. Again, Thanks Everyone, you're great. Barrie
Hi Everyone, Many thanks to all of you, noteable Steve Dion with the excellent photo form of the elbow removal process and Rick Dinon, Paul Akers, Steve C. and Ron Dague. I fixed my probelm. First I checked my system piece by piece from the inlet valve to the exhaust elbow and decided to replaced the mixing elbow. My old one was pretty plugged up. Water flowed nicely throughout the system but finally I discovered that besides the mixing elbow problem the raw waterstrainer is also plugged. I removed it, cleaned it out and reinstalled it below the water line because it was above the engine and not working well. I now have more water than Niagara falls coming out of my exhaust. My wife Judy and I went for a lovely sail off Point Roberts on Saturday. Again, Thanks Everyone, you're great. Barrie
Thanks for the compliment
Thanks for the compliment. This just goes to show you the power of a GREAT site such as this where we can all seek and share valuable advice.
Thanks for the compliment. This just goes to show you the power of a GREAT site such as this where we can all seek and share valuable advice.
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