Thanks again to all those who helped me get my Yanmar 3GMF started (1983 H34). But I have another problem. (This is a long post) Once the engine started I forgot to look at the exhaust to see if water was coming out. The temperature today was a high of 35F with a wind chill of 23F. The water temperature was 38F. I set the RPM's at 1800 and went below to do other things. I kept the engine compartment opened up so I could monitor it. There were no visual problems during the 90 minutes I let it run. She appeared to run beautifully. When I went topside to turn off the engine the buzzer was going off. I didn't hear it below because the engine sound drowned it out. The C.W. Temperature light was on. I then looked over the stern and that's when I first discovered water wasn't coming out the exhaust. There was a little smoke but it wasn't dark or heavy. Just what I'd consider normal. I don't know if water was ever coming out because I initially forgot to look. After shutting down the engine I checked the raw water thru hull. No clogs. Then I went to the strainer. OK. Next the raw water pump. Took it apart and it was OK. Tightened the belts again and started her up. She turned immedietly after 3 1/2 hours of being idle. But still no water out the exhaust (the raw water thru hull was open). The raw water pump seems to be working. I took the exit hose off the pump and water leaked out. I followed the hose up to the fresh water cooling chamber and took that hose off. It was wet. I looked inside the nipple to the chamber and saw the cooling pipe assembly. It too looked wet. I then took the hose off the other side of the fresh water cooling chamber and it was dry as a bone. No moisture at all on that side. I also opened both cooling chamber drain cocks and there was no water. Never did the engine overheat. Again, the other 34 owner said that might be because there was no load on the engine as I was sitting at the dock. I need advice on what I can do to try to find the problem. Why didn't the engine overheat? Why was the rear end of the cooling chamber dry? Could it be the cooling pipe assembly is damaged and the water can't get through? Could it have frozen and been damaged in the cold weather we've been having? Any ideas are greatly appreciated. Thanks, Joe Mullee An
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Don
Joe
Not sure what you mean by cooling chamber - if it's the heat exchanger, it should be wet if for no other reason, condensation, but obviously water isn't getting there. If the exchanger isn't clogged which can be determined by blowing water through a hose through it, I'd suspect the pump. Often the bearings and/or gears are worn such that it may turn with no load but will not pull the load after you put the impellor cover back on. Assuming you can verify the exchanger is okay and that the pump is pumping, check for air leaks at the impellor cover, thermostat or hose cracks - air locks are also a common cause of this problem. good luck Don Illusion
Not sure what you mean by cooling chamber - if it's the heat exchanger, it should be wet if for no other reason, condensation, but obviously water isn't getting there. If the exchanger isn't clogged which can be determined by blowing water through a hose through it, I'd suspect the pump. Often the bearings and/or gears are worn such that it may turn with no load but will not pull the load after you put the impellor cover back on. Assuming you can verify the exchanger is okay and that the pump is pumping, check for air leaks at the impellor cover, thermostat or hose cracks - air locks are also a common cause of this problem. good luck Don Illusion
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Craig
One step but i dont have a clue
could you shut the raw water intake, take that hose and put it in a pan or bucket of water to make sure your raw water inlet from the bottom of the boat isnt clogged? did you take the impleller out and replace? if that doesnt operate correctly, water will not circulate. i am not a pro at this stuff, thats where i would start. good luck and when you fix it , celebrate the victory with some new yrs spirits. craig s/v respite 1987 34 hunter
could you shut the raw water intake, take that hose and put it in a pan or bucket of water to make sure your raw water inlet from the bottom of the boat isnt clogged? did you take the impleller out and replace? if that doesnt operate correctly, water will not circulate. i am not a pro at this stuff, thats where i would start. good luck and when you fix it , celebrate the victory with some new yrs spirits. craig s/v respite 1987 34 hunter
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Scott
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Ed Schenck
Which impeller?
There are two impellers if you have a heat exchanger. Are you checking both? Not really possible to install backwards. You can have the blades misshaped or angled the wrong way when reinstalling. I turn the engine over by hand when reinstalling just to be sure I get the rotation right. Old blades will crack near the hub and look OK until you pull it out and closely examine. Simple check: pull the hose at the inlet to the heat exchanger and have someone turn it over and immediately stop it. If you have good water flow at the inlet then you have a plugged exchanger. But I am betting on a bad impeller.
There are two impellers if you have a heat exchanger. Are you checking both? Not really possible to install backwards. You can have the blades misshaped or angled the wrong way when reinstalling. I turn the engine over by hand when reinstalling just to be sure I get the rotation right. Old blades will crack near the hub and look OK until you pull it out and closely examine. Simple check: pull the hose at the inlet to the heat exchanger and have someone turn it over and immediately stop it. If you have good water flow at the inlet then you have a plugged exchanger. But I am betting on a bad impeller.
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Fred Ficarra
Ask yourself what changes did you make
True, you can't put the impeller in backwards but you can put the PUMP in backwards. I managed to accomplish that trick after a haulout in Trinidad. Same simptoms as yours. But again, the first rule in problem solving is asking what changes were made? If there weren't any then 'simple check' should tell you what you need to do. Also check that impeller very closely. (the raw water one. My 3GM30F only has a raw water impeller. Your fresh impeller should be solid) If you ran without water flow, it might be toast, literally. Fred
True, you can't put the impeller in backwards but you can put the PUMP in backwards. I managed to accomplish that trick after a haulout in Trinidad. Same simptoms as yours. But again, the first rule in problem solving is asking what changes were made? If there weren't any then 'simple check' should tell you what you need to do. Also check that impeller very closely. (the raw water one. My 3GM30F only has a raw water impeller. Your fresh impeller should be solid) If you ran without water flow, it might be toast, literally. Fred
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Joe Mullee
Here's What I Know
Thanks to everyone for the input. I pulled the original Yanmar manual and in the diagram they refer to that area where the water enters the engine as the "cooling chamber" I thought it was the heat exchanger too and asume they're one and the same. There is only one impeller between the raw water thru hull and the cooling chamber in my 3GMF. I looked it and and it seems to be in good shape. Prior to the original problem of the engine not starting I never had a problem with the exhaust. Then I went away and didn't get to the boat for seven weeks. It had turned very cold and that's when the engine wouldn't start. I'm going to try unhooking the raw water intake and placing the hose in a large container of water to see if the thru hull may be clogged. I'll also unhook the hose at the cooling chamber (heat exchanger) and see if I have water there. Any more suggestions? Thanks,Joe Mullee
Thanks to everyone for the input. I pulled the original Yanmar manual and in the diagram they refer to that area where the water enters the engine as the "cooling chamber" I thought it was the heat exchanger too and asume they're one and the same. There is only one impeller between the raw water thru hull and the cooling chamber in my 3GMF. I looked it and and it seems to be in good shape. Prior to the original problem of the engine not starting I never had a problem with the exhaust. Then I went away and didn't get to the boat for seven weeks. It had turned very cold and that's when the engine wouldn't start. I'm going to try unhooking the raw water intake and placing the hose in a large container of water to see if the thru hull may be clogged. I'll also unhook the hose at the cooling chamber (heat exchanger) and see if I have water there. Any more suggestions? Thanks,Joe Mullee
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Don Alexander
Lift Head?
Joe, I once had an old Yanmar 2QM which, after launching the boat, did not have enough suction to suck air and so lift the water up to the pump inlet. I revved the motor very briefly and all was well. In reality the raw water impeller looked okay but the side clearance of the rubber, and the pump cover plate, had worn sufficiently to mean the pump was incapable of pumping air but was happy to pump water. May I suggest that after doing all the checks already suggested it may still be an impeller problem. You can check the filter and thru hull by connecting a spare piece of clear poly hose, having the open end above water level and just pouring water in and noting whether it runs away. Also, using the same piece of hose now connected to the the pump inlet with the open end in a bucket of water, you can run the engine and note whether the water is being sucked up. If the blockage is after the pump it may also be necessary to disconnect the pump outlet tube. Lastly it could be a choked water injection bend but it is unusual for these to block completely.
Joe, I once had an old Yanmar 2QM which, after launching the boat, did not have enough suction to suck air and so lift the water up to the pump inlet. I revved the motor very briefly and all was well. In reality the raw water impeller looked okay but the side clearance of the rubber, and the pump cover plate, had worn sufficiently to mean the pump was incapable of pumping air but was happy to pump water. May I suggest that after doing all the checks already suggested it may still be an impeller problem. You can check the filter and thru hull by connecting a spare piece of clear poly hose, having the open end above water level and just pouring water in and noting whether it runs away. Also, using the same piece of hose now connected to the the pump inlet with the open end in a bucket of water, you can run the engine and note whether the water is being sucked up. If the blockage is after the pump it may also be necessary to disconnect the pump outlet tube. Lastly it could be a choked water injection bend but it is unusual for these to block completely.
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Robin
impeller
If your impeller is like mine (has an inner metallic circle with a slot where the key that is imbedded into the shaft sits)Check and make sure that the inner part isnt free spinning with the shaft independant of the outer rubber portion. Mine has gone bad like this before. It may even take a lot of force to get the center to spin. I would probably just replace it since it seems like the most likely (and cheapest) problem.
If your impeller is like mine (has an inner metallic circle with a slot where the key that is imbedded into the shaft sits)Check and make sure that the inner part isnt free spinning with the shaft independant of the outer rubber portion. Mine has gone bad like this before. It may even take a lot of force to get the center to spin. I would probably just replace it since it seems like the most likely (and cheapest) problem.
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Craig
put a new impeller in
i would put in a new impeller, lube it to help create suction, remove the raw water intake and put it in a pan or bucket of water, start the engine and see what happens. the impeller is cheap and should at least remove that issue. craig
i would put in a new impeller, lube it to help create suction, remove the raw water intake and put it in a pan or bucket of water, start the engine and see what happens. the impeller is cheap and should at least remove that issue. craig
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Steve
No water out the exhaust pipe
Been there, done that, just in the last two days. Have found engine heats climbing veeerrrrrryyyyyyy slowly over the last three years. And not using the boat much this last year. Went out three days ago, and water heat alarm sounding. Hasn't happened except when sucked up sea grass, etc, when cruising over the past 10 years. So started at the through-hull and clear to the exhaust riser U-elbow. Did you know, that at 2000 rpm that you can shoot water at least 20 feet after disconnecting the raw water hose after the heat exchanger and at the exhaust mixing elbow. Wow, it was exciting. So knew instantly that the problem was downstream from the elbow. Found out when I removed the exhaust elbow system (3 pieces fastened together) that when you remove the raw water elbow and look into the chamber, you should see lots of open space to the left. It wasn't there , and small bladed screwdriver instantly punched through the build up, and after much scaling and improvement, garden hose check, showing it to a sistership owner who has gone through 3 of the things, we said the problem was cured, and to reinstall the item. If you are saltwater, and are at or near 1000 engine hours, time to get the unit off and do some routing out to ensure that the cooling water is not obstructing as time goes on. A quick check of course is to hold the saltwater inlet hose (cold) exchager discharge hose (cold to cool) and feel top of U mixer exhaust pipe (cold to cool). Worked for me and back to lots of water out the exhaust.
Been there, done that, just in the last two days. Have found engine heats climbing veeerrrrrryyyyyyy slowly over the last three years. And not using the boat much this last year. Went out three days ago, and water heat alarm sounding. Hasn't happened except when sucked up sea grass, etc, when cruising over the past 10 years. So started at the through-hull and clear to the exhaust riser U-elbow. Did you know, that at 2000 rpm that you can shoot water at least 20 feet after disconnecting the raw water hose after the heat exchanger and at the exhaust mixing elbow. Wow, it was exciting. So knew instantly that the problem was downstream from the elbow. Found out when I removed the exhaust elbow system (3 pieces fastened together) that when you remove the raw water elbow and look into the chamber, you should see lots of open space to the left. It wasn't there , and small bladed screwdriver instantly punched through the build up, and after much scaling and improvement, garden hose check, showing it to a sistership owner who has gone through 3 of the things, we said the problem was cured, and to reinstall the item. If you are saltwater, and are at or near 1000 engine hours, time to get the unit off and do some routing out to ensure that the cooling water is not obstructing as time goes on. A quick check of course is to hold the saltwater inlet hose (cold) exchager discharge hose (cold to cool) and feel top of U mixer exhaust pipe (cold to cool). Worked for me and back to lots of water out the exhaust.
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Marc P
Impeller Ring
Joe I would consider Robins's previous post first. The same thing happened to a friend of mine. Somehow the ring that the impeller is attached to was able to slip relative to the rubber impeller. The pump shaft and ring would turn but would slip inside the impeller so the impeller never rotated.
Joe I would consider Robins's previous post first. The same thing happened to a friend of mine. Somehow the ring that the impeller is attached to was able to slip relative to the rubber impeller. The pump shaft and ring would turn but would slip inside the impeller so the impeller never rotated.
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Jim Haynie
All of the above PLUS
Since I bought a 10 year old legend 37, I had all of these experiences plus a few others in my first 3 years of ownership. A logical approach to troubleshooting this will save you lots of back-tracking and unneeded tests. Check strainer VERY carefully! Visual inspection from outside did not find a piece of plastic bag that had shut down my whole cooling system tight as a drum once. Next, take hose off outlet port of pump and turn start eng run at abt 2K rpm for a few moments--water should not "leak" as you describe--it should gush hard. If not, pump is problem and impeller (even if looks good) is most likely problem. Yes, the metal inner part can certainly break free from an apparently good impeller and spin free--they are cheaper than siezed engine blocks, replace if water doesn't gush. If water doesn't gush after repair to pump, your inlet seacock or port must certainly be plugged--try blowing it out in reverse. You should be able to make bubbles out the back of boat with realtive ease with your own breath--might even blow out an offending clog this way. If water does gush at outlet port of pump, next likelihoods are clogged heat exchanger or clogged exhaust elbow. So, remove hose to elbow and start eng again: Gush = clogged elbow; no gush = clogged heat exchanger. If it is the exchanger, perhaps boiling out like they used to do auto radiators will work, but not always. If it is the elbow, remove whole assembly (impossible to remove a few parts, will be frozen together with rust) and rod it out very carefully. This will work once or twice in its liffe if you are VERY careful. Must make shre that you do not significantly reduce the size or change position of the little lip that separates the wet exhaust side of elbow from the dry (input) exhaust side. If you channge this shape or size, raw water will be sprayed back INTO the ehaust manifold where it will enter exhaust valves and sieze the engine--very dramatic. The whole assembly will cost about 280$ for a new elbow, the stainless part between it and the other casting and a casting that holds that assembly to the exh manifold. I successfully cleaned mine out twice, but could see changing shape and just replaced tha whole deal. If ambient temp was as cold as you say it was, and you were only idling under no load, you may not have hurt anything yet, but two cautions remain. First, never leave the eng running until you have made certain that water is coming out exh, AND 2) should not allow eng to idle under no load anhyway--worst thing for a diesel. Better to run it on up to smoothest RPM close to about 2K if you must charge bats or other uses. This will help blow water and exh on out of system instead of letting them collect and cause the crud that is probably stopped up the elbow in the first place (a mixture of carbon, salt water, and rust). The engine cylinder walls are also damaged by idling--they aren't helped by running under no-load at any RPM, but idling is the worst. Should also change the RPM periodically rather than just letting coast at any speed. And, racing it a couple of times just before shutdown will also help blow out the exhaust. These tips came from a Yanmar clinic I attended first year of ownership.
Since I bought a 10 year old legend 37, I had all of these experiences plus a few others in my first 3 years of ownership. A logical approach to troubleshooting this will save you lots of back-tracking and unneeded tests. Check strainer VERY carefully! Visual inspection from outside did not find a piece of plastic bag that had shut down my whole cooling system tight as a drum once. Next, take hose off outlet port of pump and turn start eng run at abt 2K rpm for a few moments--water should not "leak" as you describe--it should gush hard. If not, pump is problem and impeller (even if looks good) is most likely problem. Yes, the metal inner part can certainly break free from an apparently good impeller and spin free--they are cheaper than siezed engine blocks, replace if water doesn't gush. If water doesn't gush after repair to pump, your inlet seacock or port must certainly be plugged--try blowing it out in reverse. You should be able to make bubbles out the back of boat with realtive ease with your own breath--might even blow out an offending clog this way. If water does gush at outlet port of pump, next likelihoods are clogged heat exchanger or clogged exhaust elbow. So, remove hose to elbow and start eng again: Gush = clogged elbow; no gush = clogged heat exchanger. If it is the exchanger, perhaps boiling out like they used to do auto radiators will work, but not always. If it is the elbow, remove whole assembly (impossible to remove a few parts, will be frozen together with rust) and rod it out very carefully. This will work once or twice in its liffe if you are VERY careful. Must make shre that you do not significantly reduce the size or change position of the little lip that separates the wet exhaust side of elbow from the dry (input) exhaust side. If you channge this shape or size, raw water will be sprayed back INTO the ehaust manifold where it will enter exhaust valves and sieze the engine--very dramatic. The whole assembly will cost about 280$ for a new elbow, the stainless part between it and the other casting and a casting that holds that assembly to the exh manifold. I successfully cleaned mine out twice, but could see changing shape and just replaced tha whole deal. If ambient temp was as cold as you say it was, and you were only idling under no load, you may not have hurt anything yet, but two cautions remain. First, never leave the eng running until you have made certain that water is coming out exh, AND 2) should not allow eng to idle under no load anhyway--worst thing for a diesel. Better to run it on up to smoothest RPM close to about 2K if you must charge bats or other uses. This will help blow water and exh on out of system instead of letting them collect and cause the crud that is probably stopped up the elbow in the first place (a mixture of carbon, salt water, and rust). The engine cylinder walls are also damaged by idling--they aren't helped by running under no-load at any RPM, but idling is the worst. Should also change the RPM periodically rather than just letting coast at any speed. And, racing it a couple of times just before shutdown will also help blow out the exhaust. These tips came from a Yanmar clinic I attended first year of ownership.
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Bob F
Check the Thru-hull valve
I once had a small fish caught in the elbow hose between the thru-hull & strainer. When I opened the strainer it was empty, so I opened the thru-hull and water was coming in ok. But apparently under the suction load of the impeller the small fish would wedge a little tighter and restrict water flow to the engine. After removing all the hose I found the little bugger. Took me over an hour to figure it out.
I once had a small fish caught in the elbow hose between the thru-hull & strainer. When I opened the strainer it was empty, so I opened the thru-hull and water was coming in ok. But apparently under the suction load of the impeller the small fish would wedge a little tighter and restrict water flow to the engine. After removing all the hose I found the little bugger. Took me over an hour to figure it out.
Buzzer is an overheat indicator.
Joe: The buzzer is an overheat indicator. The great thing about these Yanmar panels is that they usually go off before any damage has occured. You could probably run for several minutes without worrying about engine damage. If you engine is idling it takes a long time for it to come up to operating temperature. At 1800 rpm in 38 degree water with an air temp of 23 it is still going to take a long time to overheat. When you checked the strainer did you have the seacock open. I am sort of leaning towards Bob F's suggestion that there is a blockage between the thru hull and the strainer. Even if you have a wet surface when you check at any given point, you really need to check with the hose disconnected after the raw water pump side to check to see if the pump is pumping. I have had this type of problem before and it was a small pebble that was trapped in the thru hull fitting. Water was comming in, but at a very slow rate. The other idea that you may have a defective impeller is also a good possibility. Something that is worth trying is the idea about getting an air pressure tank and blowing air thru the system. The next thing I would do is to remove the front of the heat exchanger and run a rod through the tubes. I have not done this so you may need to have a gasket if you remove the cover when you replace it. If you have air at the temp sensor the overheat buzzer will not go off and the light will not come on. If it does go off, then this usually indicates that the water got how enough to set it off. You can also remove the hose that goes from the heat exchanger to the elbow. Water should pump out of this hose at a good rate. If this is the case, then you can pretty much be assured that your problem is from the elbow to the muffler. This can include the elbow, hose or the muffler itself. If this was actually plugged the engine would probably not run because of back pressure. It will be interesting to see what you find out. Keep us posted!
Joe: The buzzer is an overheat indicator. The great thing about these Yanmar panels is that they usually go off before any damage has occured. You could probably run for several minutes without worrying about engine damage. If you engine is idling it takes a long time for it to come up to operating temperature. At 1800 rpm in 38 degree water with an air temp of 23 it is still going to take a long time to overheat. When you checked the strainer did you have the seacock open. I am sort of leaning towards Bob F's suggestion that there is a blockage between the thru hull and the strainer. Even if you have a wet surface when you check at any given point, you really need to check with the hose disconnected after the raw water pump side to check to see if the pump is pumping. I have had this type of problem before and it was a small pebble that was trapped in the thru hull fitting. Water was comming in, but at a very slow rate. The other idea that you may have a defective impeller is also a good possibility. Something that is worth trying is the idea about getting an air pressure tank and blowing air thru the system. The next thing I would do is to remove the front of the heat exchanger and run a rod through the tubes. I have not done this so you may need to have a gasket if you remove the cover when you replace it. If you have air at the temp sensor the overheat buzzer will not go off and the light will not come on. If it does go off, then this usually indicates that the water got how enough to set it off. You can also remove the hose that goes from the heat exchanger to the elbow. Water should pump out of this hose at a good rate. If this is the case, then you can pretty much be assured that your problem is from the elbow to the muffler. This can include the elbow, hose or the muffler itself. If this was actually plugged the engine would probably not run because of back pressure. It will be interesting to see what you find out. Keep us posted!
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Eric Swift
Thanks Jim!
Thanks for the systematic description of trouble shooting the salt water cooling system. I would add that West Marine mentioned a solvent that the heat exchanger tubes could be soaked in to remove deposits that accumulate. Might be better than running rods/wire down to clean. Anyone tried that route? What did you use?
Thanks for the systematic description of trouble shooting the salt water cooling system. I would add that West Marine mentioned a solvent that the heat exchanger tubes could be soaked in to remove deposits that accumulate. Might be better than running rods/wire down to clean. Anyone tried that route? What did you use?
Marsolve!
Eric: This stuff is suppose to be a good cleaner for this type of application. The idea of using a rod or wire to clean out the tubes is just a temporary solution. Typically there can be a build up in the exchanger that will need to be disolved. http://www.marsolve.com/
Eric: This stuff is suppose to be a good cleaner for this type of application. The idea of using a rod or wire to clean out the tubes is just a temporary solution. Typically there can be a build up in the exchanger that will need to be disolved. http://www.marsolve.com/
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David
Eric
Unless you are experienced I would not suggest you use a rod or wire to clean the exchanger, that is the easiest way to ruin it. A local auto radiator shop can usually recondition it. I have had a number of them done for a reasonable price.
Unless you are experienced I would not suggest you use a rod or wire to clean the exchanger, that is the easiest way to ruin it. A local auto radiator shop can usually recondition it. I have had a number of them done for a reasonable price.
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John Van Wagoner
Mixing elbow
Joe, your trouble shooting indicates that the problem is in the mixing elbow. Crude builds up where the hose from the heat exchanger enters the exhaust system in the mixing elbow. This crude prevents water from leaving the heat exchanger, building up a back pressure. That is why your hose into the heat exchanger was wet but your hose out of the heat exchanger was dry. If you are not careful, this backpressure will actually blow the hose off the barb at the top of the heat exchanger, as it did to my Yanmar several years ago. The solution is simple. Take of the hose into the elbow, clean out the intake into the elbow with a small screw driver. I had to disconnect the elbow from the exhaust system and completely scrape the inside of the elbow out with a screw driver. Reconnect and you should have water exiting from the exhaust. By the way, whenever the engine is running you should should have water exiting the exhaust.
Joe, your trouble shooting indicates that the problem is in the mixing elbow. Crude builds up where the hose from the heat exchanger enters the exhaust system in the mixing elbow. This crude prevents water from leaving the heat exchanger, building up a back pressure. That is why your hose into the heat exchanger was wet but your hose out of the heat exchanger was dry. If you are not careful, this backpressure will actually blow the hose off the barb at the top of the heat exchanger, as it did to my Yanmar several years ago. The solution is simple. Take of the hose into the elbow, clean out the intake into the elbow with a small screw driver. I had to disconnect the elbow from the exhaust system and completely scrape the inside of the elbow out with a screw driver. Reconnect and you should have water exiting from the exhaust. By the way, whenever the engine is running you should should have water exiting the exhaust.
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Craig
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