My 30-foot 1981 Hunter has its original Yanmar Diesel engine, model 2QM15. It runs fine, starts right up, and gets about 5 knots at 2200-2300 rpm. However, after running a while, when I throttle down, such as entering a canal or channel, frequently the overheat alarm comes on and will not go off, even if I run the entine faster. The water in Miami runs about 90 degrees most of the summer. I have removed the thermostat, the water pump is putting out a lot of water, and the engine does not seems to feel overly hot. Is there anygood way to flush the engine case, assuming there is a build-up of salt, or should I just put a cut-off switch on the alarm? I would appreciate any ideas. King Elliott, Miami, FL "King Louie"
Engine Overheat Alarm
- Thread starter King Elliott
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Check the elbow
Check the exhaust(raw water)elbow. Replaced mine last year on my Yanmar and it solved the problem. There was alot of build up and rust. It's worth a check. Peter
Check the exhaust(raw water)elbow. Replaced mine last year on my Yanmar and it solved the problem. There was alot of build up and rust. It's worth a check. Peter
Start with the elbow.
King: Start with the mixing elbow. This is probably the second most common cause of overheating after a impeller. There is a product that you can purchase to flush the salt from the block. It is called Marsolve, but I have heard that they are out of business, or they have changed their name. You can do some research. This product is suppose to be environmentally friendly, but I am not sure about that.
King: Start with the mixing elbow. This is probably the second most common cause of overheating after a impeller. There is a product that you can purchase to flush the salt from the block. It is called Marsolve, but I have heard that they are out of business, or they have changed their name. You can do some research. This product is suppose to be environmentally friendly, but I am not sure about that.
Check the exterior engine intake
Hole... I had the same type problem.. The engine intake hole was half the size it should have been because of all the bottom paint jobs. The engine would only overheat once the ocean temps. rose.. Just something else to check along with the other suggestions. By the way cutting off the engine alarm is NOT a good idea.. and a great way to kill your engine ..it's there for a reason.
Hole... I had the same type problem.. The engine intake hole was half the size it should have been because of all the bottom paint jobs. The engine would only overheat once the ocean temps. rose.. Just something else to check along with the other suggestions. By the way cutting off the engine alarm is NOT a good idea.. and a great way to kill your engine ..it's there for a reason.
Mixing Elbow
I too have a 2QM15 and before I pull the elbow to check was wondering if replacement elbows are still available, anyone buy one recently?? How much were they and where did you get one? Thanks!!
I too have a 2QM15 and before I pull the elbow to check was wondering if replacement elbows are still available, anyone buy one recently?? How much were they and where did you get one? Thanks!!
Over heating advice given to me
About two months ago my 2QM15 over heated at sea from a clogged sea water strainer. I was advised to power flush the engine for over five minutes. To do this disconnect the hose after the water pump and connect it to a shore fresh water hose. I first ran the water through the engine by pass with a closed thermostat. Then after blocking the by pass and taking the thermostat out, water was run through the engine. The water flow seemed strong and should have cleaned out the engine. A good check is taking out the thermostat sensor bolt at the back of the engine, where the water runs last to see if it is plugged up. Mine was at first. I also flush the engine when at sea with vinegar and leave it slosh around for a few hours. This can be done by pumping out of a pail. Another fresh water flush that is worth doing is to run fresh water through the engine after each use. To do this rig a by pass to the engine from the fresh water system. Mine uses the head sink drain as the fresh water source.
About two months ago my 2QM15 over heated at sea from a clogged sea water strainer. I was advised to power flush the engine for over five minutes. To do this disconnect the hose after the water pump and connect it to a shore fresh water hose. I first ran the water through the engine by pass with a closed thermostat. Then after blocking the by pass and taking the thermostat out, water was run through the engine. The water flow seemed strong and should have cleaned out the engine. A good check is taking out the thermostat sensor bolt at the back of the engine, where the water runs last to see if it is plugged up. Mine was at first. I also flush the engine when at sea with vinegar and leave it slosh around for a few hours. This can be done by pumping out of a pail. Another fresh water flush that is worth doing is to run fresh water through the engine after each use. To do this rig a by pass to the engine from the fresh water system. Mine uses the head sink drain as the fresh water source.
Tnx for suggestions on engine overheating
I appreciate the suggestions on how to flush my overheating Yanmar engine. I will definitely check the elbow and follow up on the other ideas. King Elliott, Miami, FL, "King Louie"
I appreciate the suggestions on how to flush my overheating Yanmar engine. I will definitely check the elbow and follow up on the other ideas. King Elliott, Miami, FL, "King Louie"
Checking the elbow...
...sounds like good advice, but removing the thermostat is bad advice. No matter what, the engine will produce a certain number of BTU's of heat. Removing the thermostat will allow the cooling water to circulate unrestricted through the engine. The amount of heat transferred to the coolant is minimal, therefore the coolant feels cool and the temp gauge will read low. However, the engine is actually overheating because it cannot dispose of the heat being produced, eventually doing serious engine damage.
...sounds like good advice, but removing the thermostat is bad advice. No matter what, the engine will produce a certain number of BTU's of heat. Removing the thermostat will allow the cooling water to circulate unrestricted through the engine. The amount of heat transferred to the coolant is minimal, therefore the coolant feels cool and the temp gauge will read low. However, the engine is actually overheating because it cannot dispose of the heat being produced, eventually doing serious engine damage.
yes they are available
Just bought one this summer from Mack Boring, they are good people. Check the link below and give them a call they will know exactly what you need.
Just bought one this summer from Mack Boring, they are good people. Check the link below and give them a call they will know exactly what you need.
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