My 3GM Yanmar seems to working well, except the Overheat alarm goes off whenever I exceed half trottle for more than 10 minutes. I have checked all the obious areas.....strainer etc.....water pump seems to be pumping well, the closed loop system is fully charged etc. Any recomendations??
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Things to look at...
Try checking the ballcock for any obstructions, like a clam making a new home, or a plastic bag. This may entail removing the hose and opening the valve if not going overboard. Beyond that, I would guess that the impeller has a missing tooth. Steve
Try checking the ballcock for any obstructions, like a clam making a new home, or a plastic bag. This may entail removing the hose and opening the valve if not going overboard. Beyond that, I would guess that the impeller has a missing tooth. Steve
Leif, Also Check The Water Inlet to the
exhaust mixing elbow. It cokes up and restricts the flow of water out of the heat exchanger. If you have ever lost vanes on the impeller, they can lodge in the front of the exchanger. For the exhaust elbow, try taking the inlet off and running a small spring in a drill bit through it while spraying it with carb cleaner. However, it could be the exhaust elbow itself is clogged. They are a service part and its very possible yours needs replacement. Check the archives for mixing elbow or exhaust elbow. You'll find volumes of stuff. Post here your ultimate findings. Rick D.
exhaust mixing elbow. It cokes up and restricts the flow of water out of the heat exchanger. If you have ever lost vanes on the impeller, they can lodge in the front of the exchanger. For the exhaust elbow, try taking the inlet off and running a small spring in a drill bit through it while spraying it with carb cleaner. However, it could be the exhaust elbow itself is clogged. They are a service part and its very possible yours needs replacement. Check the archives for mixing elbow or exhaust elbow. You'll find volumes of stuff. Post here your ultimate findings. Rick D.
overheating 3gm
One addition think to check for is a bad impeller,the bushing slips on the rubber blades.I checked and checked things when mine was running hot and could not find anything wrong put a new impelleer in (even thought the old one was less then 6 months old and looked good)and problem solved !
One addition think to check for is a bad impeller,the bushing slips on the rubber blades.I checked and checked things when mine was running hot and could not find anything wrong put a new impelleer in (even thought the old one was less then 6 months old and looked good)and problem solved !
one more thing to check
check the kind of hose between raw water intake and your water pump. on our 2GM20F, previous owner had replaced hose with automotive kind (without steel reinforcement wire inside) and the hose intermittently collapsed, causing overheating. joe
check the kind of hose between raw water intake and your water pump. on our 2GM20F, previous owner had replaced hose with automotive kind (without steel reinforcement wire inside) and the hose intermittently collapsed, causing overheating. joe
I'd start with the mixing elbow too.
Leif: I would start by looking at the mixing elbow too. This is probably one of the more overlooked spots but is a regular problem. It is NOT difficult to remove the elbow but can be a problem getting it apart. Once you have the elbow and manifold off the engine you will have a good idea if it is the problem or not. Also be sure that your impeller is good.
Leif: I would start by looking at the mixing elbow too. This is probably one of the more overlooked spots but is a regular problem. It is NOT difficult to remove the elbow but can be a problem getting it apart. Once you have the elbow and manifold off the engine you will have a good idea if it is the problem or not. Also be sure that your impeller is good.
Just remember...
that the mixing elbow comes off by removing the four bolts holding the entire device on. You can't remove just the elbow. And you may need a flexible ratchet to access the four bolts.
that the mixing elbow comes off by removing the four bolts holding the entire device on. You can't remove just the elbow. And you may need a flexible ratchet to access the four bolts.
and sometimes, those bolts aren't easy.
Bill is right here. Sometimes the bolts in the block can be difficult to remove too. They tend to be rusty so a little helper on the end of the wrench can sometimes be in order. When you replace the bolts be sure to coat them with never-sieze.
Bill is right here. Sometimes the bolts in the block can be difficult to remove too. They tend to be rusty so a little helper on the end of the wrench can sometimes be in order. When you replace the bolts be sure to coat them with never-sieze.
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