help! i am a novice. i have recently bought a 1984 oday 28. it has a universal m12 diesel engine. last summer i experince overheating. this spring i have done the following: flushed cooling system, replaced internal and external impellers, v belt, sea water pump, fresh water pump, coolant cap, thermostate, hoses and clamps, oil filter. seawater is pumping outexhaust great, no white smoke. any suggestions
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Vic
Did you back flush the heat exchanger?
... that is said to be one of the problem areas if you had a raw water impellor break up and perhaps a couple of pieces of the impellor or maybe something else got through the filters. But if you are getting plenty of water out the exhaust that may not be the answer. or perhaps your temp sender is defective. But wait a minute ... you are overheating at what temp ... I run 160 at cruising, 180-190 pushing it wide open. By the way have you had problems with the wiring harness to the start panel? I had to rewire mine. Vic
... that is said to be one of the problem areas if you had a raw water impellor break up and perhaps a couple of pieces of the impellor or maybe something else got through the filters. But if you are getting plenty of water out the exhaust that may not be the answer. or perhaps your temp sender is defective. But wait a minute ... you are overheating at what temp ... I run 160 at cruising, 180-190 pushing it wide open. By the way have you had problems with the wiring harness to the start panel? I had to rewire mine. Vic
B
bob
vic
i have not had any problems with wire harness. i removed the heat exchanger today and flushed. i was told today that the problem is the exhaust manifold needs to be replaced.
i have not had any problems with wire harness. i removed the heat exchanger today and flushed. i was told today that the problem is the exhaust manifold needs to be replaced.
V
Vic
What was the logic behind replacing the manifold?
you said you get water out the exhaust. Only needs a few gallons of raw water a minute to keep that engine OK. if you are getting water out ... then water is going throught the raw water side of the heat exchanger and the problem is then on the fresh water side of the engine. only have a couple of problems then ... temp sender, fresh water pump, fresh water side of the exchanger, blocked hoses or passages on the fresh water side. Don't see how the exhaust manifold can enter into this. You got good flow on both the fresh water and salt water sides of the exchanger? I am checking your other string of comments as well. By the way do you have a small 6 gal water heater connected to the fresh water line ... and have you checked the hoses for kinks to that water heater? I think all the cooling water flows though the hot water heater. But if someone took out the heater and didn't join the lines, but capped the ends ... you have no flow through the engine. Keep at it ... it's only a motor after all. Vic
you said you get water out the exhaust. Only needs a few gallons of raw water a minute to keep that engine OK. if you are getting water out ... then water is going throught the raw water side of the heat exchanger and the problem is then on the fresh water side of the engine. only have a couple of problems then ... temp sender, fresh water pump, fresh water side of the exchanger, blocked hoses or passages on the fresh water side. Don't see how the exhaust manifold can enter into this. You got good flow on both the fresh water and salt water sides of the exchanger? I am checking your other string of comments as well. By the way do you have a small 6 gal water heater connected to the fresh water line ... and have you checked the hoses for kinks to that water heater? I think all the cooling water flows though the hot water heater. But if someone took out the heater and didn't join the lines, but capped the ends ... you have no flow through the engine. Keep at it ... it's only a motor after all. Vic
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bob
vic
i removed heat exchanger and flushed from both sides. i do have a hot water heater and i checked it. water runs though hoses fine. i replaced the fresh water pump. the question is, is the engine over heating. if it is then there is something internal fresh water side. if the engine is nit over heating then the sender or gage would be the problem. a man on my dock who has been sailing a long time and is familiar wth this engine said he is quite sure the problem is the exhaust manifold. even though water is comming out of the exhaust, he said it only takes a 25 % blockage in the manifold to cause overheating... your thoughts? i am about ready to have the boat yard look at it. manifolds are very expensive... bob
i removed heat exchanger and flushed from both sides. i do have a hot water heater and i checked it. water runs though hoses fine. i replaced the fresh water pump. the question is, is the engine over heating. if it is then there is something internal fresh water side. if the engine is nit over heating then the sender or gage would be the problem. a man on my dock who has been sailing a long time and is familiar wth this engine said he is quite sure the problem is the exhaust manifold. even though water is comming out of the exhaust, he said it only takes a 25 % blockage in the manifold to cause overheating... your thoughts? i am about ready to have the boat yard look at it. manifolds are very expensive... bob
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Vic
I am trying to remember ... did you check the
themostat near the fresh water pump? you can always pull that out and the water temp will go down without it ... if the termostat is not working right. My thought too is that the manifold is a major undertaking ... is the fresh cooling water running through the water heater tubing too hot to handle? if the engine is overheating that tube should be boiling hot as that is the internal water cooling the engine. On another boat i did have a meter go bad so that may be the problem. I think it is a pretty far strectch to think the manifold is the problem ... as I remember their biggest problem is when they leak. Vic
themostat near the fresh water pump? you can always pull that out and the water temp will go down without it ... if the termostat is not working right. My thought too is that the manifold is a major undertaking ... is the fresh cooling water running through the water heater tubing too hot to handle? if the engine is overheating that tube should be boiling hot as that is the internal water cooling the engine. On another boat i did have a meter go bad so that may be the problem. I think it is a pretty far strectch to think the manifold is the problem ... as I remember their biggest problem is when they leak. Vic
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bob
vic
thanks for the responce. i did not mean the manifold but the black exhaust pipe. i removed it and flushed. it looks to be invery good condition. i am going to check the pressure in and out of the heat exchanger today. if i have cirrculation then i am going to replace the sencor. i think i have done several things out of order, but they needed to be replace anyway. hope this does the tirck.
thanks for the responce. i did not mean the manifold but the black exhaust pipe. i removed it and flushed. it looks to be invery good condition. i am going to check the pressure in and out of the heat exchanger today. if i have cirrculation then i am going to replace the sencor. i think i have done several things out of order, but they needed to be replace anyway. hope this does the tirck.
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Vic
You keep this up and you'll have a trouble shot ..
everything that could possibly go wrong. Just think that you could be paying some 18yr. old kid that works for the yard $35/hr to muddle through this stuff. Of course he'd only be making $10/hr and the yard $25. Vic
everything that could possibly go wrong. Just think that you could be paying some 18yr. old kid that works for the yard $35/hr to muddle through this stuff. Of course he'd only be making $10/hr and the yard $25. Vic
L
lnranch
Over heating
We have a 1983 O'Day 28 and had the same problem The system is raw water cooled and it is a closed system until the thermostat opens up and lets addtional cooling water in. The problem we found was the water discharge into the exhaust elbow would get jamed with carbon and the syten would over heat and fry the impeller. I drilled the pipe out and this solved the problem: however, we have found that if we start the engine and immediately go to full power it will overheat before the thermostat opens up. I am not sure wat to do about this. Good Luck
We have a 1983 O'Day 28 and had the same problem The system is raw water cooled and it is a closed system until the thermostat opens up and lets addtional cooling water in. The problem we found was the water discharge into the exhaust elbow would get jamed with carbon and the syten would over heat and fry the impeller. I drilled the pipe out and this solved the problem: however, we have found that if we start the engine and immediately go to full power it will overheat before the thermostat opens up. I am not sure wat to do about this. Good Luck
J
james rohr
I know nothing about the m12, but
My 30 had a raw water cooled engine. What a Freaking nightmare. Any way I now have a fresh water cooling sys. on my engine. From what I've heard you folks discuss so far it sounds as though you might have salt encrustation on the raw water side of the heat exchanger. if this happens you will not have the proper heat transfer across the tubes. There is a solution that the tube bundle can be soaked and heated in to disolve the build up. I know there have been several articles written on this problem. if i can find it I'll let you know. if any one else finds the solution please post it. I'm sure I'll need it in the future.
My 30 had a raw water cooled engine. What a Freaking nightmare. Any way I now have a fresh water cooling sys. on my engine. From what I've heard you folks discuss so far it sounds as though you might have salt encrustation on the raw water side of the heat exchanger. if this happens you will not have the proper heat transfer across the tubes. There is a solution that the tube bundle can be soaked and heated in to disolve the build up. I know there have been several articles written on this problem. if i can find it I'll let you know. if any one else finds the solution please post it. I'm sure I'll need it in the future.
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bobkat
overheating
thank you all for your advise. i built a new exhaust this past weekend, still overheating. I tested the thermostate with a mechanical system (sending unit and thermostate),everything tested ok. i just ordered a new heat exchanger. will keep you informed. put work order in to boatyard just incase - mid june earliest to repair. bobkat
thank you all for your advise. i built a new exhaust this past weekend, still overheating. I tested the thermostate with a mechanical system (sending unit and thermostate),everything tested ok. i just ordered a new heat exchanger. will keep you informed. put work order in to boatyard just incase - mid june earliest to repair. bobkat
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