255 Conquest: Transducer Location Causing Engine Overheating

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Author Topic:   255 Conquest: Transducer Location Causing Engine Overheating

djtdmd posted 05-31-2010 09:50 PM ET (US)
Hello--last November, I placed a post about the optimum transducer location on my 255 Conquest with twin 150 Verado engines. I ultimately found the best location, thanks to several members' recommendations, was as close to centerline as possible, between the engines. It worked great--terrific readings! The problem is this spring, I am having some engine overheating problems, first one engine, than the other. My techs have done all the usual stuff, but the problem is not solved. They said that it is possible the new transducer location is causing interupted water to the engines, thus causing overheating. Are there any 255 owners with twins out there that can help me out here? Here is a link for a photo of where my transducer is mounted.Thanks a lot, Dan
sosmerc posted 05-31-2010 11:46 PM ET (US)
It's not possible to see the transducer location in your picture due to the dark bottom paint or shadow. BUT, it should not be difficult to temporarily raise your transducer such that it is well above the bottom of the boat and therefore "out of the picture" to see if your overheating problems go away.
My gut feeling is that your transducer is NOT the problem.
Your tech should be able to access (using his Merc diagnostic tool referred to as the CDS) the memory buffers for each engine to see exactly when the overheating is occuring and what other conditions are present at exact time of the alarm.
Have you raised your engines on the transom recently? Have you added anything else to the bottom besides the transducer?
Is your boat bottom clean and undamaged?
Do the engines overheat at the same time or does it occur only in turns? We need alot more information here to be helpful.
djtdmd posted 06-01-2010 01:22 AM ET (US)
SOSMERK- To answer your question, bottom is clean, freshly painted. My verado techs have done all diagnostics, and are continuing to try to solve the problem with mercury. One engine is worse than the other as far as overheating goes, and the engines have not been raised. Changed the transducer to current spot last nov., used the boat in NJ until late december, and never noticed a problem till the last trip or two of the season. Only had starboard engine overheat then, so I had my techs change the impellers and water pumps this spring before launch. They got the starboard OK, now the port is acting up. Is it possible the colder water temps in nov/ dec masked a overheating problem? I'm not sure if the incoming water temp can make a difference or not. If you click on my link for the photo, then click on "enlarge photo", it is pretty clear where the ducer is. Follow the transducer cable from the port side, down, and see the black transducer a few inches starboard to the centerline. Hope this helps!
Tom W Clark posted 06-01-2010 01:30 AM ET (US)
http://www2.snapfish.com/snapfish/viewsharedphoto/p=712311275370208420/ l=7649585013/
That's a crock. The transducer location shown in the photo is fine and will in no way interfere with the cooling of those two outboards.
Jefecinco posted 06-01-2010 10:13 AM ET (US)
You had the starboard engine's water pump reworked and the starboard engine no longer overheats but the port engine now overheats.
Is it logical to assume the operating hours and conditions of operation of both engines is similar? If so, is it logical to assume that perhaps it's time to consider reworking the port engine water pump?
I am unable to imagine a scenario in which a center mounted transducer could affect twin outboard engine cooling. As Tom Clark more succinctly puts it "That's a crock."
Butch
boatdryver posted 06-01-2010 10:40 AM ET (US)
Have you thought about the water conditions where you use the boat. Are you sure you aren't sucking mud or other crap into the motors?
JimL
rslsail posted 06-01-2010 07:04 PM ET (US)
Butch's comment seems completely logical to me....sounds like its time to replace the impeller/water pump on the port engine
sosmerc posted 06-02-2010 01:27 AM ET (US)
I have seen electronic water pressure sensors get clogged and then give false readings. If the engine computer doesn't see a given water pressure for a specific rpm it will trip a code and put the engine into guardian mode. Again, your techs should be able to review the fault history buffers and see exactly what was going on at the time of the overheat. It would be most interesting to review these buffers.
sosmerc posted 06-02-2010 01:34 AM ET (US)
It is also conceivable that something is lodged inside your water pickups on the offending engine. This would restrict the volume and pressure of the incoming water. Again, careful review and comparison of the two engines fault buffers should shed some light on the situation.
tom976 posted 06-02-2010 09:52 AM ET (US)
I would say the sensor location is in a great position.
If it were me, new water pumps first then I would entertain changing the thermostats. From there they can take a IR thermometer and go out for a run to get it to overheat. They can get the true temps of the cylinders to see if the alarm is real or bad sensor.
Tom

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Author	Topic: 255 Conquest: Transducer Location Causing Engine Overheating
djtdmd	posted 05-31-2010 09:50 PM ET (US) Hello--last November, I placed a post about the optimum transducer location on my 255 Conquest with twin 150 Verado engines. I ultimately found the best location, thanks to several members' recommendations, was as close to centerline as possible, between the engines. It worked great--terrific readings! The problem is this spring, I am having some engine overheating problems, first one engine, than the other. My techs have done all the usual stuff, but the problem is not solved. They said that it is possible the new transducer location is causing interupted water to the engines, thus causing overheating. Are there any 255 owners with twins out there that can help me out here? Here is a link for a photo of where my transducer is mounted.Thanks a lot, Dan
sosmerc	posted 05-31-2010 11:46 PM ET (US) It's not possible to see the transducer location in your picture due to the dark bottom paint or shadow. BUT, it should not be difficult to temporarily raise your transducer such that it is well above the bottom of the boat and therefore "out of the picture" to see if your overheating problems go away. My gut feeling is that your transducer is NOT the problem. Your tech should be able to access (using his Merc diagnostic tool referred to as the CDS) the memory buffers for each engine to see exactly when the overheating is occuring and what other conditions are present at exact time of the alarm. Have you raised your engines on the transom recently? Have you added anything else to the bottom besides the transducer? Is your boat bottom clean and undamaged? Do the engines overheat at the same time or does it occur only in turns? We need alot more information here to be helpful.
djtdmd	posted 06-01-2010 01:22 AM ET (US) SOSMERK- To answer your question, bottom is clean, freshly painted. My verado techs have done all diagnostics, and are continuing to try to solve the problem with mercury. One engine is worse than the other as far as overheating goes, and the engines have not been raised. Changed the transducer to current spot last nov., used the boat in NJ until late december, and never noticed a problem till the last trip or two of the season. Only had starboard engine overheat then, so I had my techs change the impellers and water pumps this spring before launch. They got the starboard OK, now the port is acting up. Is it possible the colder water temps in nov/ dec masked a overheating problem? I'm not sure if the incoming water temp can make a difference or not. If you click on my link for the photo, then click on "enlarge photo", it is pretty clear where the ducer is. Follow the transducer cable from the port side, down, and see the black transducer a few inches starboard to the centerline. Hope this helps!
Tom W Clark	posted 06-01-2010 01:30 AM ET (US) http://www2.snapfish.com/snapfish/viewsharedphoto/p=712311275370208420/ l=7649585013/ That's a crock. The transducer location shown in the photo is fine and will in no way interfere with the cooling of those two outboards.
Jefecinco	posted 06-01-2010 10:13 AM ET (US) You had the starboard engine's water pump reworked and the starboard engine no longer overheats but the port engine now overheats. Is it logical to assume the operating hours and conditions of operation of both engines is similar? If so, is it logical to assume that perhaps it's time to consider reworking the port engine water pump? I am unable to imagine a scenario in which a center mounted transducer could affect twin outboard engine cooling. As Tom Clark more succinctly puts it "That's a crock." Butch
boatdryver	posted 06-01-2010 10:40 AM ET (US) Have you thought about the water conditions where you use the boat. Are you sure you aren't sucking mud or other crap into the motors? JimL
rslsail	posted 06-01-2010 07:04 PM ET (US) Butch's comment seems completely logical to me....sounds like its time to replace the impeller/water pump on the port engine
sosmerc	posted 06-02-2010 01:27 AM ET (US) I have seen electronic water pressure sensors get clogged and then give false readings. If the engine computer doesn't see a given water pressure for a specific rpm it will trip a code and put the engine into guardian mode. Again, your techs should be able to review the fault history buffers and see exactly what was going on at the time of the overheat. It would be most interesting to review these buffers.
sosmerc	posted 06-02-2010 01:34 AM ET (US) It is also conceivable that something is lodged inside your water pickups on the offending engine. This would restrict the volume and pressure of the incoming water. Again, careful review and comparison of the two engines fault buffers should shed some light on the situation.
tom976	posted 06-02-2010 09:52 AM ET (US) I would say the sensor location is in a great position. If it were me, new water pumps first then I would entertain changing the thermostats. From there they can take a IR thermometer and go out for a run to get it to overheat. They can get the true temps of the cylinders to see if the alarm is real or bad sensor. Tom