I have a 1992 Yanmar 27 HP 3GM30F ( fresh water cooled) which is overheating. The engine would normally run at 180 Degrees at 2700 RPM. The smoke was clear and and it did not seem to be laboring. This weekend I began to see it head up over 180 and I immediately throttled back or gave it a rest to get the temp down. I have done the following with limited improvement: 1/ Cleaned the sea-cock and strainer to ensure adequate sea water flow 2/ replaced and lubed the impeller and ensured it was pumping 3/ Opened and checked the heat exchanger tubes to ensure adequate water flow 4/ dove and cleaned the barnacles off the prop 5/ I poked around the exhaust mixing elbow to ensure it was clear but I couldn't get it off All of the above seemed to improve both performance and the raw water discharge through the exhaust but it still seems a little low. The engine ran very well when I 1st started out and after about a 1/2 hour period I switched the battery from the start to the house bank to recharge. When the high output generator kicked in the engine heat immediately shot up which I do not recall seeing in the past. A few questions: 1/Could the high output generator/alternator be faulty and causing too large a strain on the engine. 2/Where would be the next logical place to look? 3/I am considering flushing the engine with a descaler- would you recommend flushing both the fresh and raw water side? The fresh water pump has recently been replaced and a new mix of antifreeze added. 4/ What would be the normal operating temperature for this engine and at what point would you be concerned? 5/ How much raw water discharge should there be? Any I have a
Yanmar 3GM30 Overheating
- Thread starter Don 3182
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Don, one more spot to check
is the raw water inlet on the exhaust elbow. Remove the inlet pipe fitting and hog both it and the entrance to the elbow out with a convenient tool. Common restriction. That also accounts for low discharge water flow.
is the raw water inlet on the exhaust elbow. Remove the inlet pipe fitting and hog both it and the entrance to the elbow out with a convenient tool. Common restriction. That also accounts for low discharge water flow.
Try using an infrared thermometer
You can pick one up fairly inexpensively and then you can check various spots on the engine/exhaust for hot spots. Its also a good tool for establishing a baseline for various components in a properly running engine. My guess is you haven't serviced your exhaust elbow and it is causing a restriction.
You can pick one up fairly inexpensively and then you can check various spots on the engine/exhaust for hot spots. Its also a good tool for establishing a baseline for various components in a properly running engine. My guess is you haven't serviced your exhaust elbow and it is causing a restriction.
yanmar 3gm30 overheating
the exhaust elbow should be replaced every three of four years. I suggest you replace the exhaust elbow. it cost a little money, but it is worth it.
the exhaust elbow should be replaced every three of four years. I suggest you replace the exhaust elbow. it cost a little money, but it is worth it.
One more check
I had the same problem two summmers ago. I changed the impeller, the hoses T stats and the heat exchanger but I still was overheating. I finally found a piece of old impeller lodged in the elbow just past the pump, that you couldnt see. I removed it and tehn the water flow was fine.
I had the same problem two summmers ago. I changed the impeller, the hoses T stats and the heat exchanger but I still was overheating. I finally found a piece of old impeller lodged in the elbow just past the pump, that you couldnt see. I removed it and tehn the water flow was fine.
Need to remove the elbow to inspect.
Don: You really need to remove the elbow to inspect it. You should consider getting a new elbow and manifold gasket. If you elbow is okay, then you can always return the part. It is a very good chance that this is the source of your problem. It is probably the single most cause of overheating other than an impeller.
Don: You really need to remove the elbow to inspect it. You should consider getting a new elbow and manifold gasket. If you elbow is okay, then you can always return the part. It is a very good chance that this is the source of your problem. It is probably the single most cause of overheating other than an impeller.
Elbow, cont.
It's quite true you can't remove it. Try dismantling from the manifold, 4 bolts. May need a squiggly ratchet to get 1 of them.
It's quite true you can't remove it. Try dismantling from the manifold, 4 bolts. May need a squiggly ratchet to get 1 of them.
Thermostat?
Did you check the fresh water side? You did mention a new fresh water pump. Did the problem start then? I would check that and then thermostat, pump installation, belt, etc? The reason I ask this is that you did not mention if it is now smoking or not. FYI, my 3HM35F runs at 160 at 3000 maybe 165 at 3200(no smoke). That is with my new Home Depot Mark 2 Mod 2 elbow. It now has about 30 hours on it with no problems. The stock elbow gave me 160 degrees at 2600 up to 180 degrees at 3000 (with an increase in smoke. We have cold water here though.
Did you check the fresh water side? You did mention a new fresh water pump. Did the problem start then? I would check that and then thermostat, pump installation, belt, etc? The reason I ask this is that you did not mention if it is now smoking or not. FYI, my 3HM35F runs at 160 at 3000 maybe 165 at 3200(no smoke). That is with my new Home Depot Mark 2 Mod 2 elbow. It now has about 30 hours on it with no problems. The stock elbow gave me 160 degrees at 2600 up to 180 degrees at 3000 (with an increase in smoke. We have cold water here though.
all those, plus one more
You need to replace the mixing elbow, the sleeve and the manifold plate = $200 from Torreson, or whomever is licensed by Yanmar for your location. Also, check the hose from raw water hull inlet to raw water pump. When we bought our 1986 31' Hunter and had same trouble, we did all those things and still had intermittent overheating. Previous owner had put auto-style hose on, which collapses under load! Keep us posted on the results. Good luck, Joe
You need to replace the mixing elbow, the sleeve and the manifold plate = $200 from Torreson, or whomever is licensed by Yanmar for your location. Also, check the hose from raw water hull inlet to raw water pump. When we bought our 1986 31' Hunter and had same trouble, we did all those things and still had intermittent overheating. Previous owner had put auto-style hose on, which collapses under load! Keep us posted on the results. Good luck, Joe
Patrick, pictures,,,,,
I'm not going to give you peace until you post some pictures of your elbow.
Don, for info, I tested my thermostat on the stove with a thermometer. It's 160 degrees. For what it's worth, that is. Also, If good 'ol Patrick, bogart's his new setup and doesn't show us how he did it, you might consider what I did to my last elbow. Ceramic coating from JetHot. Picture #6 among others on my web site.
I'm not going to give you peace until you post some pictures of your elbow.
Don, for info, I tested my thermostat on the stove with a thermometer. It's 160 degrees. For what it's worth, that is. Also, If good 'ol Patrick, bogart's his new setup and doesn't show us how he did it, you might consider what I did to my last elbow. Ceramic coating from JetHot. Picture #6 among others on my web site.Thanks to All for the suggestions
I will begin by flushing the raw water system and ensure I have adequate flow coming out of the heat exchanger. I will try and remove the exhaust elbow and if it appears plugged I am told to replace it as if it fails and water gets back into the cylinders it could cause major problems. I will let you know the results. I believe the consensus is that it should run at about 160 under normal load. The high output alternator put a heavy load on and when that is in the charging mode I will run at lower RPM's
I will begin by flushing the raw water system and ensure I have adequate flow coming out of the heat exchanger. I will try and remove the exhaust elbow and if it appears plugged I am told to replace it as if it fails and water gets back into the cylinders it could cause major problems. I will let you know the results. I believe the consensus is that it should run at about 160 under normal load. The high output alternator put a heavy load on and when that is in the charging mode I will run at lower RPM's
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