Flushing M40 C

[CKboater]

I boat in salt water so, of course, I'd like to flush the engine with fresh water after using the boat. I got a pair of those rubber cups that go over the water inlets and attach to a hose but the water doesn't seem to spit out when I'm using these. I have a new impeller and water spits out fine when the engine is immersed. Any suggestions?

 

[TOHATSU GURU]

Re: Flushing M40 C

You have dual water pickups on that model engine. The cups go around either side. You have to tape off the additional water intake which is underneath the cavitation plate. If you ran it for more than a couple of minutes without taping off the other one....Pull the lowerunit back down and check the impeller for damage.

 

[CKboater]

Re: Flushing M40 C

Thanks Elvin. I was careful to shut off the engine as soon as I saw it was not making water ( no more than 15 - 20 seconds). I'll tape off that additional water intake and try again.

 

[CKboater]

Re: Flushing M40 C

Elvin,

I've been placing the cups over the two large square inlets below the cavitation plate. I see three smallish holes on either side just above the cavitation plate. Is that where I apply the tape?

Bill

 

[boatnmotor]

Re: Flushing M40 C

I don't think the 40C has the additional 3rd pickup under the cavitation plate. That was on 25C/30A and 40/50D models in this range. I think Tohatsu skipped it on the 40C - not sure why. It would be a black round strainer if it were present.

 

[TOHATSU GURU]

Re: Flushing M40 C

Boatnmotor may be right. I remember it being on the 40 C, but the parts books do not show it there. I hate it when I'm wrong

 

[CKboater]

Re: Flushing M40 C

Well then back to my question..... would taping those 3 holes above the cavitation plate be the answer?

 

[TOHATSU GURU]

Re: Flushing M40 C

Nope. Those are drain holes for the water cavity. I'm having Tohatsu check a 40 C housing to see if it does have dual intakes this morning. I'll let you know what they say.

 

[John_S]

Re: Flushing M40 C

I have not had any issues running my 40C on muffs. It does cover both sides of the water inlet. Water sprays from pee hole, prop, and believe the exhaust reliefs. Possible very low water pressure at your hose? If all works fine if you run it in a garbage can, then probably something amiss in the pick-up area. I'd check to see if it has good volume out the pee hole when you are up on plane.

 

[CKboater]

Re: Flushing M40 C

Possible very low water pressure at your hose? If all works fine if you run it in a garbage can, then probably something amiss in the pick-up area. I'd check to see if it has good volume out the pee hole when you are up on plane.

I get good volume out the pee hole on a plane and when running at idle in the water. It just doesn't seem to want to pump with the muffs on. I have very good water pressure and actually thought maybe it was too high. When it was serviced recently the mechanic used muffs and they worked for him. I'm really puzzled. I even bought a second set of muffs and these have water coming from both sides. Perhaps I'm not waiting long enough for the water flow to start?

 

[TOHATSU GURU]

Re: Flushing M40 C

It is confirmed that you do not have dual intakes. If it is pumping in the water than it has to be a muff issue. You may just have to squeeze them tighter.

 

[John_S]

Re: Flushing M40 C

CK, FWIW I just have the single hose muffs. Do you see water coming out the exhaust or exhaust reliefs?

 

[CKboater]

Re: Flushing M40 C

CK, FWIW I just have the single hose muffs. Do you see water coming out the exhaust or exhaust reliefs?

My boat is on a lift so I decided to attach the muffs and lower the engine into the water until the cavitation plate was submerged. I turned on the tap water and started the engine and water flowed. I then raised the boat up so the engine was above the water surface and the water continued to flow. I guess I'll just use this procedure to flush the engine in the future. Thanks for all the suggestions.

Bill

 

[TOHATSU GURU]

Re: Flushing M40 C

The muffs have to be the issue then.