Hi there, I am just about to purchase a 1977 Hunter 27, and I have a 200 mile sail to bring it home. After checking it out, it seems that the motor is running pretty hot after a 10 minute run, the cooling intake is OK, and the impeller has been replaced, it might seem like the engine can not manage to "push" the cooling water out, anybody have any ideas what I should check? I am not at all familiar with this engine, and I will need it running good for a bit of intracoastal travel...
Cooling Problem, 8hp Yanmar
- Thread starter Toby11535
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Things to check
pump belt tension heat exchanger scaled up broken bits of old impeller lodged in the heat exchanger manifold(S) kinked hoses - thru hull to mixing elbow The belt and hoses are easy, the heat exchanger requires you to drain the anti and take it apart.
pump belt tension heat exchanger scaled up broken bits of old impeller lodged in the heat exchanger manifold(S) kinked hoses - thru hull to mixing elbow The belt and hoses are easy, the heat exchanger requires you to drain the anti and take it apart.
Try this
I have a YSM12 on a 1979 Hunter 30' Start the engine and run at low rpm. Lean over the stern and check for water coming out the rear. If you do not see water in three to four minutes, pull the stop wire and close down the engine as you have a problem. Start with the water intake. Pull the hose off after the sea cock. Open and check the flow. If you have water- no blockage, close and double clamp hose. Open raw water filter and pull screen. Clear debris and return. Check gasket- you might need to replace. (replace anyway- its worth the $10) clamp down tight to keep seal. Open rear of water pump and check impeller. note- use vise grips to break screw heads instead of phillips screwdriver. Brass screws strip. This should be filled with water and the vanes ok. If not replace the impeller- (replace anway- they are inexpensive) greese and seal with gasket. Note- look for worn grove from impeller on back case. If you see a circular groove, polish other side and reverse install. Note- if this leaks air at this point- you can loose the engine's prime and it will stop pumping. After you repace, suck on hose to pull water through system to prime. Hey, its only water. The next place to check is the mixing Elbow on the exhaust- this is a raw water system. To get to it, you might need to pull the steps and the cabinet behind it. You will want to bang on this, and do to the age of the boat- replace due to the length of your planned trip. Three parts- about $300 from Yamar dealer. This goes from the inside and snaps- it happened to me. If it is blocked- this could be your problem. In fact this might be the first place to start. Good luck Ian Meant to Be
I have a YSM12 on a 1979 Hunter 30' Start the engine and run at low rpm. Lean over the stern and check for water coming out the rear. If you do not see water in three to four minutes, pull the stop wire and close down the engine as you have a problem. Start with the water intake. Pull the hose off after the sea cock. Open and check the flow. If you have water- no blockage, close and double clamp hose. Open raw water filter and pull screen. Clear debris and return. Check gasket- you might need to replace. (replace anyway- its worth the $10) clamp down tight to keep seal. Open rear of water pump and check impeller. note- use vise grips to break screw heads instead of phillips screwdriver. Brass screws strip. This should be filled with water and the vanes ok. If not replace the impeller- (replace anway- they are inexpensive) greese and seal with gasket. Note- look for worn grove from impeller on back case. If you see a circular groove, polish other side and reverse install. Note- if this leaks air at this point- you can loose the engine's prime and it will stop pumping. After you repace, suck on hose to pull water through system to prime. Hey, its only water. The next place to check is the mixing Elbow on the exhaust- this is a raw water system. To get to it, you might need to pull the steps and the cabinet behind it. You will want to bang on this, and do to the age of the boat- replace due to the length of your planned trip. Three parts- about $300 from Yamar dealer. This goes from the inside and snaps- it happened to me. If it is blocked- this could be your problem. In fact this might be the first place to start. Good luck Ian Meant to Be
Ian and Bill, Thank you much, I will try this
Thank you much for your postingd, I belive I will do the deal on Saturday, looking forward to it, and cant wait to own this boat, to me it looks like a fantastic boat, will keep you posted, thank you again!!!
Thank you much for your postingd, I belive I will do the deal on Saturday, looking forward to it, and cant wait to own this boat, to me it looks like a fantastic boat, will keep you posted, thank you again!!!
I do have water
I do have water coming out, just not to much....., as far as I can se, not enough
I do have water coming out, just not to much....., as far as I can se, not enough
Further to Ian's suggestion
On a trip last year we found there was a lack of raw water coming out of the exhaust. I disconnected the hose between the water strainer and raw water pump and plenty of sea water came out, so that was not the problem. I disconnected the hose from the raw water pump to the heat exchanger and blew into it by mouth, could hardly force any air through. I then disconnected the hose from the heat exchanger to the exhaust manifold and could easily blow lots of air through, so the heat exchanger was not blocked. Then I tried blowing through the exhaust manifold and could not, so the blockage was in the exhaust manifold or downstream of it. I took the hose off the (water) exit side of the exhaust manifold and there was the problem, scale and crud blocking the outlet. I broke it all loose and then blew it out with fresh water WHILE DISCONNECTED FROM THE MIXING ELBOW - problems all went away. The point is that you can tell a lot by just blowing through sections of the system. The reason for shouting about DISCONNECTED FROM THE MIXING ELBOW is you don't want to do anything that risks filling the exhaust manifold with water (via the mixing elbow) and forcing it back into the engine.
On a trip last year we found there was a lack of raw water coming out of the exhaust. I disconnected the hose between the water strainer and raw water pump and plenty of sea water came out, so that was not the problem. I disconnected the hose from the raw water pump to the heat exchanger and blew into it by mouth, could hardly force any air through. I then disconnected the hose from the heat exchanger to the exhaust manifold and could easily blow lots of air through, so the heat exchanger was not blocked. Then I tried blowing through the exhaust manifold and could not, so the blockage was in the exhaust manifold or downstream of it. I took the hose off the (water) exit side of the exhaust manifold and there was the problem, scale and crud blocking the outlet. I broke it all loose and then blew it out with fresh water WHILE DISCONNECTED FROM THE MIXING ELBOW - problems all went away. The point is that you can tell a lot by just blowing through sections of the system. The reason for shouting about DISCONNECTED FROM THE MIXING ELBOW is you don't want to do anything that risks filling the exhaust manifold with water (via the mixing elbow) and forcing it back into the engine.
Dont expect to see a lot of water.
Just a cycled squirt. Remove all hoses and check for obstructions and or salt deposits. Check thermostat opening and closing.
Just a cycled squirt. Remove all hoses and check for obstructions and or salt deposits. Check thermostat opening and closing.
raw water flow
I think the main problem was that he has water flow just wasn't sure how much is the correct amount. I have a 78 Hunter 30 with a YSM12. I think the easiest and best answer to your question is to find another boat like yours and see what it does. When I bout mine I had a question with RPM's. Advertised here for someone close who had what I had and paid them a visit. Turned out I didn't have a problem...
I think the main problem was that he has water flow just wasn't sure how much is the correct amount. I have a 78 Hunter 30 with a YSM12. I think the easiest and best answer to your question is to find another boat like yours and see what it does. When I bout mine I had a question with RPM's. Advertised here for someone close who had what I had and paid them a visit. Turned out I didn't have a problem...
raw water flow
I think the main problem was that he has water flow just wasn't sure how much is the correct amount. I have a 78 Hunter 30 with a YSM12. I think the easiest and best answer to your question is to find another boat like yours and see what it does. When I bout mine I had a question with RPM's. Advertised here for someone close who had what I had and paid them a visit. Turned out I didn't have a problem...
I think the main problem was that he has water flow just wasn't sure how much is the correct amount. I have a 78 Hunter 30 with a YSM12. I think the easiest and best answer to your question is to find another boat like yours and see what it does. When I bout mine I had a question with RPM's. Advertised here for someone close who had what I had and paid them a visit. Turned out I didn't have a problem...
Cooling problem
Toby: I have a 2GM 13 HP in my Hunter 27 and had problems with it running hot. 1- Run the engine at low speed for a bit (about 1500-2000RPM) 2- Put you hand on the top of the mixing elbow. It should feel only luke warm if engine is running at normal temperature. 3- You can check flow by removing the hose from the mixing elbow while the engine is running. There should be a good solid flow. 4- On the 2GM the thermostat housing is directional. Both ends look identical but one end is restricted and should connect toward the waterpump side or facing down. If it is reversed, the engine will run hot. I hope this helps.
Toby: I have a 2GM 13 HP in my Hunter 27 and had problems with it running hot. 1- Run the engine at low speed for a bit (about 1500-2000RPM) 2- Put you hand on the top of the mixing elbow. It should feel only luke warm if engine is running at normal temperature. 3- You can check flow by removing the hose from the mixing elbow while the engine is running. There should be a good solid flow. 4- On the 2GM the thermostat housing is directional. Both ends look identical but one end is restricted and should connect toward the waterpump side or facing down. If it is reversed, the engine will run hot. I hope this helps.
check raw water strainer
I had an over heating problem with my YSM-12 and it turned out to be a bad gasket on the raw water strainer cap which caused the pump to suck air,I sealed the the cap with silicne and the problem was gone .
I had an over heating problem with my YSM-12 and it turned out to be a bad gasket on the raw water strainer cap which caused the pump to suck air,I sealed the the cap with silicne and the problem was gone .
I had the same problem
I had the same problem I hire a tech to come to my boat. The fix was easy he ran on and off (Acid) in to the cooling system, lots of crap can build up in cooling systems when the engine is not run often. You could see the crap run out of the system. After this it fine except if you let it run at low RPM's for a long time than it will over heat. So we run it 70 to 80% as often as we can an have had no problem all season. I looked at the thermostat before the acid it was rusted and old. After the acid when through it look brand new. Maybe this is not the only way but it works and was cheap.
I had the same problem I hire a tech to come to my boat. The fix was easy he ran on and off (Acid) in to the cooling system, lots of crap can build up in cooling systems when the engine is not run often. You could see the crap run out of the system. After this it fine except if you let it run at low RPM's for a long time than it will over heat. So we run it 70 to 80% as often as we can an have had no problem all season. I looked at the thermostat before the acid it was rusted and old. After the acid when through it look brand new. Maybe this is not the only way but it works and was cheap.
Thank You all
Thank you all for all your help, after purchasing the boat, I dismanteled the whole cooling system, had just about every part cleaned (sandblasted), it was extremely clogged up, changed the thermostat and sinc, and now it is cooling really well. The engine ended up beeing the original SB8, I originally did not think it was, but it runs great after a big service, including draining and cleaning the fuel tank. I am posting another question about electronics, if any of you have any advise, it will be greatly appriciated
Thank you all for all your help, after purchasing the boat, I dismanteled the whole cooling system, had just about every part cleaned (sandblasted), it was extremely clogged up, changed the thermostat and sinc, and now it is cooling really well. The engine ended up beeing the original SB8, I originally did not think it was, but it runs great after a big service, including draining and cleaning the fuel tank. I am posting another question about electronics, if any of you have any advise, it will be greatly appriciated
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