I have a Yanmar 3GM30F which was new in 1995. This past season I had overheating problems on and off. More on than off.. By overheating I mean it was above normal but not high enough to set off the overheat alarm... I completely dismantled the Saltwater system (including cleaning the exchanger) and eveything was clean.. In reassembling I replaced the Saltwater Impeller and the Thermostat... At first I thougfht it was OK but then it came back to overheating. Has anyone had problems with the Cam located in the Pump? Understand it is made of bronze and wears out? Is it difficult to replace? Or, anyother thoughts/suggestions.
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overheating 3gm30
Wilkie, how hot does it get?(water temp)Could you be chasing a bad gauge? or sending unit? I'm curious how hot the water temp get and what it is compared to the thermosat range? I had a simular problem but seams I had a defective impeller that was sliping on the pump shaft.Are the hose in good shape and is it possoble one of them could be collapsing?Get back with some answers and maybe we can figure it out.
Wilkie, how hot does it get?(water temp)Could you be chasing a bad gauge? or sending unit? I'm curious how hot the water temp get and what it is compared to the thermosat range? I had a simular problem but seams I had a defective impeller that was sliping on the pump shaft.Are the hose in good shape and is it possoble one of them could be collapsing?Get back with some answers and maybe we can figure it out.
Ye Old Mixing Elbow Trick
Recommend searching in Forum/Forum Archives and enter "mixing elbow heating", or something else similiar. I got 82 hits when selecting searching in "All", "title and message" and "match all words". This could keep you out of mischif for a while!
Recommend searching in Forum/Forum Archives and enter "mixing elbow heating", or something else similiar. I got 82 hits when selecting searching in "All", "title and message" and "match all words". This could keep you out of mischif for a while!
What's "normal" anyway?
How hot was it running? You say it wasn't hot enough to set off the alarm which usually happens at 205 if memory serves. The thermostat should open at 160 or so. Are you running the engine harder when it gets hotter? If it isn't setting off the alarm you might not even have a problem, can you give more details?
How hot was it running? You say it wasn't hot enough to set off the alarm which usually happens at 205 if memory serves. The thermostat should open at 160 or so. Are you running the engine harder when it gets hotter? If it isn't setting off the alarm you might not even have a problem, can you give more details?
Ye Old Mixing Elbow
would be my guess. There is also often a carbon build-up at the injection nipple on the mixing elbow. After figuring it out, I made it a practice of taking a small (3/16?) spring in a variable-speed drill chuck and running it in and out while spraying carb-cleaner into it. Did it twice a year. This only works if the elbow itself isn't restricted badly. The other suggestions already made are equaly valid. I assume you also checked the intake and strainer. Once, I had some growth inside the intake through-hull. Purchased a gun barrel cleaning tool. Took care of that. FYI, there was once an alert for a batch of impellers that spun on their inserts. If it isn't any of this, it's hard to say. Also, may be worth pumping a couple of gallons of vinegar through the system. Good luck. These intermittant deals are a pain. Rick D.
would be my guess. There is also often a carbon build-up at the injection nipple on the mixing elbow. After figuring it out, I made it a practice of taking a small (3/16?) spring in a variable-speed drill chuck and running it in and out while spraying carb-cleaner into it. Did it twice a year. This only works if the elbow itself isn't restricted badly. The other suggestions already made are equaly valid. I assume you also checked the intake and strainer. Once, I had some growth inside the intake through-hull. Purchased a gun barrel cleaning tool. Took care of that. FYI, there was once an alert for a batch of impellers that spun on their inserts. If it isn't any of this, it's hard to say. Also, may be worth pumping a couple of gallons of vinegar through the system. Good luck. These intermittant deals are a pain. Rick D.
Some suggestions
Try to determine if the problem is on the fresh water side or the sea water side. Generally, if you have a good "squirt" coming out then the sea water side is OK and you should then concentrate on the fresh water side & vica-versa. With that I will relate my resolved heating problem. Like yours, the overheating light/buzzer never came on but I did notice some white smoke. Coincident was little exhaust water - just an occasional spray but not the continuous flow that should occur. Turned out to be a crack in the hose right where the hose connects to the inlet of the impeller pump (from the outlet of the strainer). This is the same spot where I remove the hose to flush the engine for winterization so it gets a lot of wear and tear in addition to the normal vibrations. The crack allowed air to come in (try sucking on a straw with a hole above the water). The problem was also intermittant - if the hose moved a tiny bit, the crack would seal itself temporarilly. Roger Destiny (Hunter 37) "Committing solecisms that society will never pardon"
Try to determine if the problem is on the fresh water side or the sea water side. Generally, if you have a good "squirt" coming out then the sea water side is OK and you should then concentrate on the fresh water side & vica-versa. With that I will relate my resolved heating problem. Like yours, the overheating light/buzzer never came on but I did notice some white smoke. Coincident was little exhaust water - just an occasional spray but not the continuous flow that should occur. Turned out to be a crack in the hose right where the hose connects to the inlet of the impeller pump (from the outlet of the strainer). This is the same spot where I remove the hose to flush the engine for winterization so it gets a lot of wear and tear in addition to the normal vibrations. The crack allowed air to come in (try sucking on a straw with a hole above the water). The problem was also intermittant - if the hose moved a tiny bit, the crack would seal itself temporarilly. Roger Destiny (Hunter 37) "Committing solecisms that society will never pardon"
yanmarhelp WEBSITE
Wilkie. There is a super trouble shooting of yanmar it is www.yanmarhelp.com I have the same 3GM30F engine in my 28 ODAY I have had used the website a few times it told me a lot of information about the engine you ask questions and they will answer them good luck FRED PIERCE
Wilkie. There is a super trouble shooting of yanmar it is www.yanmarhelp.com I have the same 3GM30F engine in my 28 ODAY I have had used the website a few times it told me a lot of information about the engine you ask questions and they will answer them good luck FRED PIERCE
Check the obvious
Hi Wilkie, you seem to have some good leads here, but one problem that I occasionally have with my 3HM35f (cousin of the 3GM30) is the input thru-hull getting clogged. I know that you are out of the water, but disconnect the input hose from the thru-hull and ream it out with a wire to see if there's any debris. I have had to do this quite often on mine. I also found out this summer (after 8 seasons) that the input thru-hull diameter is too small. Being small, debris (sea weed, eel grass, etc.) can accumulate easier. There is a step-down nipple on the thru-hull that takes it down to 1/4 inch and should be at least 3/8 inch flow.
Hi Wilkie, you seem to have some good leads here, but one problem that I occasionally have with my 3HM35f (cousin of the 3GM30) is the input thru-hull getting clogged. I know that you are out of the water, but disconnect the input hose from the thru-hull and ream it out with a wire to see if there's any debris. I have had to do this quite often on mine. I also found out this summer (after 8 seasons) that the input thru-hull diameter is too small. Being small, debris (sea weed, eel grass, etc.) can accumulate easier. There is a step-down nipple on the thru-hull that takes it down to 1/4 inch and should be at least 3/8 inch flow.
Ditto Paul,
Had a similar overheating problem w/ my 4JH2... OK at lower RPM, but began overheating at higher RPM. Seemed to have an OK "squirt", but I was suspicious. While hauled last month, took intake hose loose and snaked intake line thru the thru hull. Found a plastic water bottle cap that had been sucked into the intake and lodged in the thru hull. Allowed enough water thru at lower RPM, but constricted the volume enough at higher RPM to cause the overheating....... Check the simple stuff first......
Had a similar overheating problem w/ my 4JH2... OK at lower RPM, but began overheating at higher RPM. Seemed to have an OK "squirt", but I was suspicious. While hauled last month, took intake hose loose and snaked intake line thru the thru hull. Found a plastic water bottle cap that had been sucked into the intake and lodged in the thru hull. Allowed enough water thru at lower RPM, but constricted the volume enough at higher RPM to cause the overheating....... Check the simple stuff first......
I have the engine and experience, but...
I've found, that there are two likely causes: 1. the intake strainer basket is full. Here in coastal SoCal we've had lots of kelp the past couple years so I check before any long run. That's "routine maintenance" that takes only a minute or two. 2. the fan belt is not tight enough. I had all my belts replaced last year and the mechanic used what I'll call "lawnmower" belts. (well, maybe not, but it might as well have been <s>) After tighening and retightening belts with improper side angles I finally called my Yanmar distributor and ordered the right belts, then installed them myself and that issue went away for good. FWIW, I've found the 3GM to be a very reliable engine. The overheating issue, while a real drag until solved, can be very inexpensively solved once you figure it out. In my case (1990 V32), I found the heater exchange unit and pump impeller were in excellent condition, with really no signs of wear. Cheers, Rodger Beard
I've found, that there are two likely causes: 1. the intake strainer basket is full. Here in coastal SoCal we've had lots of kelp the past couple years so I check before any long run. That's "routine maintenance" that takes only a minute or two. 2. the fan belt is not tight enough. I had all my belts replaced last year and the mechanic used what I'll call "lawnmower" belts. (well, maybe not, but it might as well have been <s>) After tighening and retightening belts with improper side angles I finally called my Yanmar distributor and ordered the right belts, then installed them myself and that issue went away for good. FWIW, I've found the 3GM to be a very reliable engine. The overheating issue, while a real drag until solved, can be very inexpensively solved once you figure it out. In my case (1990 V32), I found the heater exchange unit and pump impeller were in excellent condition, with really no signs of wear. Cheers, Rodger Beard
Same here Paul.
Paul: Our raw water intake also has this step down fitting for the hose. I have considered taking a cut off tool to cut off the top of the fitting. There would still be plenty of metal to attach the hose but may even double the water flow. We had an incident a couple years ago. We had been stuck on the bottom due to a shoal at our harbor entrance. When trying to get free we must have stirred up the bottom and sucked up some gravel from a recent dredging at the harbor entrance. We left the harbor the following weekend and the engine overheated within about 5-10 minutes of exiting the harbor. We returned to the harbor and pulled the hose from the seacock intake and found the gravel had blocked the flow. We used a piece of wire to clear it and took off for our destination without further incident.
Paul: Our raw water intake also has this step down fitting for the hose. I have considered taking a cut off tool to cut off the top of the fitting. There would still be plenty of metal to attach the hose but may even double the water flow. We had an incident a couple years ago. We had been stuck on the bottom due to a shoal at our harbor entrance. When trying to get free we must have stirred up the bottom and sucked up some gravel from a recent dredging at the harbor entrance. We left the harbor the following weekend and the engine overheated within about 5-10 minutes of exiting the harbor. We returned to the harbor and pulled the hose from the seacock intake and found the gravel had blocked the flow. We used a piece of wire to clear it and took off for our destination without further incident.
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