For Three years now I have been chasing an overheating engine.. We have owned the boat since new (1995) and had no problems until three years ago... Up to 2600 RPM it runs fine (180).. As soon as it hits 2650 it starts ti climb... Eventually getting to about 210+... I have a Temp guage and have checked it with a laser temp meter for accuracy.. The standard warning buzzer does not go off.. In the three years I have, replaced the mixing elbow, new water pump, replace all hoses, checked strainer, replaced belts, replaced thermostat (right now I have removed the thermostat) The engine does not smoke and sounds very healthy... There are times it starts hard... Yesterday I was checking temps all over with the laser guage and found the top of the injectors showed a temp of 125 on two and 145 on the other.. Any connection? The engine has 1400 hours and has had oil & filter changes as required.. We are now in FL for the winter (on our boat) Hope someone could give me some ideas!!!! Wilkie
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Have you checked the heat exchanger?
I didn't see that in your list of things you've checked. You might want to pull the core out of the heat exchanger and be sure some of the tubes aren't clogged with something.
I didn't see that in your list of things you've checked. You might want to pull the core out of the heat exchanger and be sure some of the tubes aren't clogged with something.
Heeat balance ......
FIRST check the outlet exhaust water flow at normal high cruise rpm. Run the engine and with a bucket and a stopwatach measure to see if you're getting about 5 gallons per minute out the back end. If much less than 5 GPM chase down a restriction in the system --- broken pump vane or vane that has migrated and jammed somewhere in the piping, exhaust manifold that has begun to degrade internally, etc. etc. etc. IF you get ~5 gpm out the back end at you normal high cruise rpm. THEN... consider that the heat exchanger is fouled. If fouled drain the raw water circuit and add/use Marsolve (marsolve.com) or Rydlyme boiler descaling compound (Put n in the circuit and let soak). Another souce of fouling of the raw water circuit is the internals of the exhaust manifold. Best is to disconnect the raw water intake hose from the throughhull plus remove the connection between the exhaust manifold and the injection elbow on the water lift muffler; join these two hoses together in a bucket and let the engine pump the marsolve, etc. until the engine is totally full.... then shut down and let soak for several hours. Dont use acids to descale/de-salt the engine as they will dissolve the engine's 'base-metal'. hope this helps.
FIRST check the outlet exhaust water flow at normal high cruise rpm. Run the engine and with a bucket and a stopwatach measure to see if you're getting about 5 gallons per minute out the back end. If much less than 5 GPM chase down a restriction in the system --- broken pump vane or vane that has migrated and jammed somewhere in the piping, exhaust manifold that has begun to degrade internally, etc. etc. etc. IF you get ~5 gpm out the back end at you normal high cruise rpm. THEN... consider that the heat exchanger is fouled. If fouled drain the raw water circuit and add/use Marsolve (marsolve.com) or Rydlyme boiler descaling compound (Put n in the circuit and let soak). Another souce of fouling of the raw water circuit is the internals of the exhaust manifold. Best is to disconnect the raw water intake hose from the throughhull plus remove the connection between the exhaust manifold and the injection elbow on the water lift muffler; join these two hoses together in a bucket and let the engine pump the marsolve, etc. until the engine is totally full.... then shut down and let soak for several hours. Dont use acids to descale/de-salt the engine as they will dissolve the engine's 'base-metal'. hope this helps.
Just went through this!
Afternoon Wilkie: This past week end, one of my dock mates was having a heat problem with his Yanmar. The problem was solved but due to unusual reasons. We took the discharge hose loose from the raw water pump then the hose loose from the exhaust elbow and back flushed the system. This got out three vanes from an old impeller that had blown previously. While we were at the raw water pump, we went ahead and put in a new impeller. Still overheated and it appeared that there was a reduced amount of water coming from the exhaust. The heat exchanger had been checked and was clean. There were no signs of build up in the exhaust elbow that would restrict water flow. Checked the raw water filter and found nothing. This left the through hull intake. Closed off the through hull and took the hose off. What we found was an acorn and a small piece of drift wood. Apparently it had been sucked up into the hose as flotsam. They were small enough to get through the through hull but big enough not to go through the strainer connection and there was not enough water to wash it out by back flow when the engine was shut down. They were acting like an anti-backflow valve, allowing just enough water through to keep the engine from burning up but not enough to keep it from running hot. Runs fine now. This may not be the answer to your problem, just my way of saying check for restricted water flow from the through hull through the entire system. Lotsa Luck!
Afternoon Wilkie: This past week end, one of my dock mates was having a heat problem with his Yanmar. The problem was solved but due to unusual reasons. We took the discharge hose loose from the raw water pump then the hose loose from the exhaust elbow and back flushed the system. This got out three vanes from an old impeller that had blown previously. While we were at the raw water pump, we went ahead and put in a new impeller. Still overheated and it appeared that there was a reduced amount of water coming from the exhaust. The heat exchanger had been checked and was clean. There were no signs of build up in the exhaust elbow that would restrict water flow. Checked the raw water filter and found nothing. This left the through hull intake. Closed off the through hull and took the hose off. What we found was an acorn and a small piece of drift wood. Apparently it had been sucked up into the hose as flotsam. They were small enough to get through the through hull but big enough not to go through the strainer connection and there was not enough water to wash it out by back flow when the engine was shut down. They were acting like an anti-backflow valve, allowing just enough water through to keep the engine from burning up but not enough to keep it from running hot. Runs fine now. This may not be the answer to your problem, just my way of saying check for restricted water flow from the through hull through the entire system. Lotsa Luck!
After living with a Hunter installed Yanmar for
19 years, I've been through this too and solved it. Like the guys said, check your coolant raw water flow and volume. Start at the through hull and work your way to the elbow. At the next haul out I would install a filter screen to keep out the debris. Then you can toss the basket. I removed mine 15 years ago because of a screen installation and haven't had anything get past it yet. But I would pass on the Marsolve or similar products. I had my boat in tropical waters when not stored in the off season for 10 years. It did the same thing as yours. The alarm would sound when we reached a certain RPM. After eliminating all of the above possibilities, that left only one thing. It is one of the easiest things to check for too. Just take off the near side cap of the heat exchanger. Look for white calcium built up in the raw-water side of the tubes. If there, go to Home Depots' tool department. Buy a 1/4" very long drill bit. Electrician use them for some reason. Check to make sure that the bit isn't too big by trying to insert it into a tube BACKWARDS. It should just wiggle into a tube. Chuck it up to your drill and have at it. I would take off the back cover too so that the crud has someplace to go. You can do this job in an hour or so. Worked for me. No more alarm and I have an extra long drill bit for some kind of electrical job, once I figure out what that would be.
19 years, I've been through this too and solved it. Like the guys said, check your coolant raw water flow and volume. Start at the through hull and work your way to the elbow. At the next haul out I would install a filter screen to keep out the debris. Then you can toss the basket. I removed mine 15 years ago because of a screen installation and haven't had anything get past it yet. But I would pass on the Marsolve or similar products. I had my boat in tropical waters when not stored in the off season for 10 years. It did the same thing as yours. The alarm would sound when we reached a certain RPM. After eliminating all of the above possibilities, that left only one thing. It is one of the easiest things to check for too. Just take off the near side cap of the heat exchanger. Look for white calcium built up in the raw-water side of the tubes. If there, go to Home Depots' tool department. Buy a 1/4" very long drill bit. Electrician use them for some reason. Check to make sure that the bit isn't too big by trying to insert it into a tube BACKWARDS. It should just wiggle into a tube. Chuck it up to your drill and have at it. I would take off the back cover too so that the crud has someplace to go. You can do this job in an hour or so. Worked for me. No more alarm and I have an extra long drill bit for some kind of electrical job, once I figure out what that would be.
HX again
Fred's right. In addition to the heat exchanger tubes, there is usually an incredible amount of fouling on either the intake or outlet ports/tubes. Most people aren't aware of this. When we had our old 2 inch HX (on our 1986 Universal M25), I'd have to remove it yearly: the tubes were fine because we replaced the impeller and zinc regularly, but the connection ports, at least one, I forget which, was ALL gunked up with salt deposits. Fred's solution is correct, I used a sharp screwdriver, so it took longer. What we eventually did was replace the 2 in HX with a new 3 inch HX. Nice and cool runnin' now. JB's flotsam in the through hull is another good source of restriction. Many do not prefer an exterior screen, simply because it precludes opening the through hull and sticking a dowel down through it to clean it out. Maybe that's why they call 'em "through" hulls.
Stu
Fred's right. In addition to the heat exchanger tubes, there is usually an incredible amount of fouling on either the intake or outlet ports/tubes. Most people aren't aware of this. When we had our old 2 inch HX (on our 1986 Universal M25), I'd have to remove it yearly: the tubes were fine because we replaced the impeller and zinc regularly, but the connection ports, at least one, I forget which, was ALL gunked up with salt deposits. Fred's solution is correct, I used a sharp screwdriver, so it took longer. What we eventually did was replace the 2 in HX with a new 3 inch HX. Nice and cool runnin' now. JB's flotsam in the through hull is another good source of restriction. Many do not prefer an exterior screen, simply because it precludes opening the through hull and sticking a dowel down through it to clean it out. Maybe that's why they call 'em "through" hulls.
Stu
Fred
If the entrance and exit tubesheet nozzles on a heat exchanger are also fouling it means that the exchanger is thermally fouled or there is a restriction in mass flow of cooling water which retards the heat transfer .... or the heat exchanger is ridiculously under sized. The problem is this: once sea water gets above 150 deg F. the dissolved carbonates begin to precipitate or 'drop out' of solution. The 'cure' is a bigger exchanger or a larger mass flow of cooling water .... to keep the 'interface' temperature well below or near the 'magic' 150 degrees. Whacking at exchanger tubes with a drill or screwdriver although expedient is a good way to damage a tube .... chemical descalers are better at total removal of scale and dont harm or risk the base metal, ......... plus the descalers also remove the same carbonates that are fouling the internals of the exhaust manifold .... which you can't get into to whack-at with scewdrivers, etc. If you have a fouled heat exchanger you WILL also have a fouled exhaust manifold. ;-)
If the entrance and exit tubesheet nozzles on a heat exchanger are also fouling it means that the exchanger is thermally fouled or there is a restriction in mass flow of cooling water which retards the heat transfer .... or the heat exchanger is ridiculously under sized. The problem is this: once sea water gets above 150 deg F. the dissolved carbonates begin to precipitate or 'drop out' of solution. The 'cure' is a bigger exchanger or a larger mass flow of cooling water .... to keep the 'interface' temperature well below or near the 'magic' 150 degrees. Whacking at exchanger tubes with a drill or screwdriver although expedient is a good way to damage a tube .... chemical descalers are better at total removal of scale and dont harm or risk the base metal, ......... plus the descalers also remove the same carbonates that are fouling the internals of the exhaust manifold .... which you can't get into to whack-at with scewdrivers, etc. If you have a fouled heat exchanger you WILL also have a fouled exhaust manifold. ;-)
Rich and Stu
As to the cause of the fouling, I don't know. I only know mine did the same thing in the same place; warm water, that coral like. And Rich, have you priced that chemical cleaning system? I have. Two years ago it was $400.00 for my boat. The drill bit was quicker, more convenient, easier and only cost $3.00. Or just replace the inner tubes. Yanmar exchangers are serviceable. The tube comes out for replacement if need-be. And Stu, this is a case of cause and effect. If you have the screen in place, you don't have to 'rod out' your through hull. I haven't had to.
As to the cause of the fouling, I don't know. I only know mine did the same thing in the same place; warm water, that coral like. And Rich, have you priced that chemical cleaning system? I have. Two years ago it was $400.00 for my boat. The drill bit was quicker, more convenient, easier and only cost $3.00. Or just replace the inner tubes. Yanmar exchangers are serviceable. The tube comes out for replacement if need-be. And Stu, this is a case of cause and effect. If you have the screen in place, you don't have to 'rod out' your through hull. I haven't had to.
Guys
Rich A 2 inch HX on the M25 WAS slightly small, and that's why the crud precipitated. The larger one is fine. And whacking it carefully didn't hurt the tubes. Fred My reference source was someone in the Chesapeake who had some kinda critters, like jellyfish, get through the exterior screen, stick in through hull, not get up into the strainer, and so he made that recommendation. Other venues may not have the same problems. Stu
Rich A 2 inch HX on the M25 WAS slightly small, and that's why the crud precipitated. The larger one is fine. And whacking it carefully didn't hurt the tubes. Fred My reference source was someone in the Chesapeake who had some kinda critters, like jellyfish, get through the exterior screen, stick in through hull, not get up into the strainer, and so he made that recommendation. Other venues may not have the same problems. Stu
$$$$ wow!
I dont understand as about 2 years ago a gallon of Marsolve was about $16.00 As for the tube replacement, I hope you know how to 'roll' a new tube into place, otherwise you get leakage BTW - exhaust manifolds are notorius for forming huge 'platelettes' of rust that come off the inside walls and partlly block the water passages. Cast iron when poured in a foundry unless very carefully alllowed to cool can form 'casting laps' .... somewhat like the construction of an onion. Once you get ferric oxide / corrosion to form in between the laps, the huge plateletts can quickly form. That's why I always start with the water output value first... to verify that the exhaust manifold is still intact internally. hope this helps.
I dont understand as about 2 years ago a gallon of Marsolve was about $16.00 As for the tube replacement, I hope you know how to 'roll' a new tube into place, otherwise you get leakage BTW - exhaust manifolds are notorius for forming huge 'platelettes' of rust that come off the inside walls and partlly block the water passages. Cast iron when poured in a foundry unless very carefully alllowed to cool can form 'casting laps' .... somewhat like the construction of an onion. Once you get ferric oxide / corrosion to form in between the laps, the huge plateletts can quickly form. That's why I always start with the water output value first... to verify that the exhaust manifold is still intact internally. hope this helps.
Stu, I hate it when that happens!
Kidding, never seen it but it sounds serious. Rich, Yanmars are not built so as to allow raw water to come into contact with cast iron until the exhaust elbow. The heat exchanger tubes are serviced as a unit as a multi gang group of tubes formed in a single larger tube. No corrosion, no electrolysis, no zincs. I can't speak about other engine systems. And I was referring to a on-line price quote from the company marketing the entire 'system', not just the chemical.
Kidding, never seen it but it sounds serious. Rich, Yanmars are not built so as to allow raw water to come into contact with cast iron until the exhaust elbow. The heat exchanger tubes are serviced as a unit as a multi gang group of tubes formed in a single larger tube. No corrosion, no electrolysis, no zincs. I can't speak about other engine systems. And I was referring to a on-line price quote from the company marketing the entire 'system', not just the chemical.
fred, the drill bit is for low voltage wire...
with the long drill bit you can make a hole (3/4") place and bend the long bit in and drill past the sill plate into the basement! there should be a small hole on the bitter end of the bit. just twist your wire on go to the basement and pull your wire through. us alarm guys and cable installers use them all the time. (ps if not sharp the bit part heats up and breaks off!!!!) regards, mike
with the long drill bit you can make a hole (3/4") place and bend the long bit in and drill past the sill plate into the basement! there should be a small hole on the bitter end of the bit. just twist your wire on go to the basement and pull your wire through. us alarm guys and cable installers use them all the time. (ps if not sharp the bit part heats up and breaks off!!!!) regards, mike
Hey Fred!
I just checked Torrensen's web site. They have Marsolve for 27.80 a gallon. What kind of chemical treatment were you talking about at $400.00?? J.B.
I just checked Torrensen's web site. They have Marsolve for 27.80 a gallon. What kind of chemical treatment were you talking about at $400.00?? J.B.
Those guys had their own web site.
I'm not sure of the name. They were marketing a system that is installed on the engine. It was meant to be permanent and left in place. It consisted of a 12 volt pump and closed/open system valves. It let you clean your stuff off coral juice and then remove the acid, somehow. I looked at the price and left. That's all I know. Rich, Oh,Oh. That's all I can say. I also removed my tubes during my rebuild to make sure they were good to go. They were. No need to replace the entire manifold. It should last a lifetime. It should even survive a hard freeze. The radiator cap should open as the ice expands. P.S. Rich, are you saying that engine was raw water cooled? Some of them are built that way. Those are not what we are talking about.
I'm not sure of the name. They were marketing a system that is installed on the engine. It was meant to be permanent and left in place. It consisted of a 12 volt pump and closed/open system valves. It let you clean your stuff off coral juice and then remove the acid, somehow. I looked at the price and left. That's all I know. Rich, Oh,Oh. That's all I can say. I also removed my tubes during my rebuild to make sure they were good to go. They were. No need to replace the entire manifold. It should last a lifetime. It should even survive a hard freeze. The radiator cap should open as the ice expands. P.S. Rich, are you saying that engine was raw water cooled? Some of them are built that way. Those are not what we are talking about.
HX again #3,486,987.472
Just occurred to me: For years and years and even longer, many of us have been plagued with overheating engines and problems with HXs. And during the same time, many of us have thought (relatively) little about spending say three to five hundred dollars for something, anything, for our boats: GPS upgrades, new electrical gizmos, you name it. Now, a new HX costs anywhere from three to five hundred bucks, including new hoses. So, heretical as it may sound, why don't we just REPLACE the old ones, instead of dragging them off the boat, taking them to radiator shops, etc., slapping them back in, and STILL overheating? I finally figured it out after four years: I bought a new one. Almost seven years of ownership, $379 (overpriced, I should have done better comparison shopping), about $100 per year or less. And I went UP one size and it makes all the difference. Universal M25s had 2 inch HXs. The M25XP, pretty much the SAME engine (+2 HP) had a 3 inch. I now have a 3 inch. Cool - describes the temperature of the engine constantly. Why are we fighting overheating, when a replacement could easily be justified? Just a thought, long time comin' though. Stu
Just occurred to me: For years and years and even longer, many of us have been plagued with overheating engines and problems with HXs. And during the same time, many of us have thought (relatively) little about spending say three to five hundred dollars for something, anything, for our boats: GPS upgrades, new electrical gizmos, you name it. Now, a new HX costs anywhere from three to five hundred bucks, including new hoses. So, heretical as it may sound, why don't we just REPLACE the old ones, instead of dragging them off the boat, taking them to radiator shops, etc., slapping them back in, and STILL overheating? I finally figured it out after four years: I bought a new one. Almost seven years of ownership, $379 (overpriced, I should have done better comparison shopping), about $100 per year or less. And I went UP one size and it makes all the difference. Universal M25s had 2 inch HXs. The M25XP, pretty much the SAME engine (+2 HP) had a 3 inch. I now have a 3 inch. Cool - describes the temperature of the engine constantly. Why are we fighting overheating, when a replacement could easily be justified? Just a thought, long time comin' though. Stu
Prop
The first thing I would check is the prop. Has it been changed? Are you overproped? You haven't changed it! Did someone else change it for you with or without your knowledge? Is there a cause for the drive system to be binding, causing a greater load? Is your bottom in good shape? Since you have changed most of the cooling system, perhaps the problem is not with the cooling system? Jim Kane
The first thing I would check is the prop. Has it been changed? Are you overproped? You haven't changed it! Did someone else change it for you with or without your knowledge? Is there a cause for the drive system to be binding, causing a greater load? Is your bottom in good shape? Since you have changed most of the cooling system, perhaps the problem is not with the cooling system? Jim Kane
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