overheating

[Tahiti]

I have 3-350 HP motors that are one year old. They have been randomly overheating for no apparent reason. Has anyone else experienced this?

[Hoosmatroos]

Not much people here have 3x350 behind their boat

[Murray]

Could you have some weird turbulence happening that could be disrupting the water intake? To have all 3 engines overheating randomly that are only one year old seems kind of fishy. Maybe you sucked in some debris that could be effecting all 3 engines???

[artdf175]

Not enough information here to provide much help
how many hours?
what type of service has been done?
give us something to work with
Art

[2014DF25ARS]

I have a friend with a DF25A on his small boat, about one year old. On two occasions, his engine flashed an overheat warning. He pulled the waterpump and didn't find anything wrong. I got Suzuki's diagnostic kit and we scanned the engine for codes. I believe there are two types of overheat condition: First is temperature too high = the obvious one. The other is temperature GRADIENT too high, i.e. the engine is heating too rapidly. In both his overtempt cases it was a gradient warning. Honestly, I have no idea what this tells me, but it seems more likely that the gradient warning might be caused by a faulty sensor or perhaps a bad battery condition. I believe he was trolling/idling in both cases where he saw this warning, but I'm not positive about that.

[LPowers]

I sense a troll...

[Pot Hole]

...... The other is temperature GRADIENT too high, i.e. the engine is heating too rapidly. In both his over temp cases it was a gradient warning. Honestly, I have no idea what this tells me, but it seems more likely that the gradient warning might be caused by a faulty sensor or perhaps a bad battery condition.....

I'm dealing with an over heating problem as well and I have a relatively new impeller in my DF140. I'm curious as to what sensor you might be referring to or how the battery might contribute to this problem? I haven't done a diagnostic test yet, but that is next on my list.

[Moonlighter]

I'm dealing with an over heating problem as well and I have a relatively new impeller in my DF140. I'm curious as to what sensor you might be referring to or how the battery might contribute to this problem? I haven't done a diagnostic test yet, but that is next on my list.

How old is your 140? What year?

When you changed the impeller did you also change the stainless housing it sits in?

When you say relatively new impeller, when was it installed?

When was the last time you checked and changed the internal anodes? How did the water passages they sit in look at that time - evidence of salt/calcium buildup??

A overheat condition can be due to a gradient alarm eg engine temp rises too rapidly although it may not reach the temp absolute alarm level. Gradient alarm may be indicative of an obstruction picked up on the leg that is blocking water flow, or something internal not working eg a stuck thermostat.

The engines are quite voltage sensitive. False alarms can be triggered if there is low or erratic voltage to the ecu. I gather that false alarms are not usually recorded in the ecu log. You will notice this if you hook up to the SDS and check codes.

Anyway it is well worth removing and cleaning the main battery cables as well as the white battery sub-wire that powers the ecu, and also remove and clean the fuse in the wire. And make certain that the battery holds charge under load. This will help avoid false codes.

[Pot Hole]

How old is your 140? What year?

When you changed the impeller did you also change the stainless housing it sits in?

When you say relatively new impeller, when was it installed?

When was the last time you checked and changed the internal anodes? How did the water passages they sit in look at that time - evidence of salt/calcium buildup??

A overheat condition can be due to a gradient alarm eg engine temp rises too rapidly although it may not reach the temp absolute alarm level. Gradient alarm may be indicative of an obstruction picked up on the leg that is blocking water flow, or something internal not working eg a stuck thermostat.

The engines are quite voltage sensitive. False alarms can be triggered if there is low or erratic voltage to the ecu. I gather that false alarms are not usually recorded in the ecu log. You will notice this if you hook up to the SDS and check codes.

Anyway it is well worth removing and cleaning the main battery cables as well as the white battery sub-wire that powers the ecu, and also remove and clean the fuse in the wire. And make certain that the battery holds charge under load. This will help avoid false codes.

The motor is a 2006 model. I bought it used, but I know the two previous owners who gave me the service history on it. The motor cranks quickly and runs great for about 30 minutes then beeps and flashes the temp warning light.

The impeller was changed in 2017 and the work was performed by a marine service center so I do not k now if the stainless housing was replaced as well. There is visible water coming from the discharge hole on the back of the engine.

I have not checked the internal anodes. This motor has never seen salt water. I have looked for obstructions in the water pickup area and found nothing.

I completely cleaned all battery connections (including the ECU white wire) immediately after purchase, however, I will check the fuse connection in the white wire.

I am in the process of troubleshooting this problem now and looking for suggestions of things I can try myself before I take it to a marine mechanic. I appreciate your comments

[Moonlighter]

Impellers on motors that have sat unused for a long time can deteriorate faster than those that are used regularly.

Since you didnt say what the engine usage has been since it was changed, I would suggest installing a full water pump kit anyway - and this is also recommended because you REALLY need to drop the leg and lube the driveshaft splines where they meet the driven gears in the engine, extremely important to do this if you don’t want them to jam in there and never come out.

When the impeller gets a “set” in it due to lack of use, it will usually pump Ok at low revs but not be effective at higher speeds. Anyway its been 2 years so good idea to install a new kit and do a service.

Check those internal anodes, its a quick job and they do perform a vital task. When removed you get to see what the internals look like.

[Pot Hole]

Impellers on motors that have sat unused for a long time can deteriorate faster than those that are used regularly.

Since you didnt say what the engine usage has been since it was changed, I would suggest installing a full water pump kit anyway - and this is also recommended because you REALLY need to drop the leg and lube the driveshaft splines where they meet the driven gears in the engine, extremely important to do this if you don’t want them to jam in there and never come out.

When the impeller gets a “set” in it due to lack of use, it will usually pump Ok at low revs but not be effective at higher speeds. Anyway its been 2 years so good idea to install a new kit and do a service.

Check those internal anodes, its a quick job and they do perform a vital task. When removed you get to see what the internals look like.

This motor saw little use since the impeller was last changed, so my plans are to change it out and see if that remedies the problem. I will also lube the driveshaft while I'm at it. I'll have to look up the internal anodes as I am not familiar with their removal. Thanks for the comments. I'll try to post up my results

[Pot Hole]

A overheat condition can be due to a gradient alarm eg engine temp rises too rapidly although it may not reach the temp absolute alarm level. Gradient alarm may be indicative of an obstruction picked up on the leg that is blocking water flow, or something internal not working eg a stuck thermostat..

I ordered a new impeller, but have not had time to put it on and see if it effects my over heating situation. Rummaging through the internet, I did find this video where someone with a similar motor found his exhaust manifold temperature sensor was bad after he had replaced and checked all the other potential sources of the problem. He replaced the sensor and that fixed his over heating problem. I just wonder if a computer system diagnostic check would reveal a code that indicates this sensor is bad? Thoughts? https://www.youtube.com/watch?v=xeOjSgJxJt8

[Moonlighter]

Get a full water pump kit installed including the housing. Not just the impeller.

Many examples where a small invisible imperfection in the housing caused suboptimal pump performance.

[Pot Hole]

Get a full water pump kit installed including the housing. Not just the impeller.

Many examples where a small invisible imperfection in the housing caused suboptimal pump performance.

The kit I purchased has all the components to replace the pump including the housing. I hope to get this done over the weekend

[Solarman]

A weak water pressure valve, and/or sometimes thermostats can also play a part on some overheating problems.

Just thoughts. Good luck.