Motor running hot

[rick_26S]

I have a 1994 Honda 7.5 on my Mac 26S. Recently, it overheated, so I changed the impeller which didn't look bad at all. I suspected this was not the problem, so I removed the thermostat to have a look. It was basically a ball of barnacles so I replaced it with a new one.

We went out Saturday and it ran normally in the morning, which was just to get through the channel leading out to Pine Island Sound from the Caloosahatchee River. I didn't notice any problem. After spending some quality time sailing and lounging on the beach at Picnic Island, we had to motor all the way back to the dock. It was against a strong east wind and outgoing current, and we had to run the motor at a little more than half throttle for two hours. I noticed the motor seemed hot on the way, but the pee stream was strong so I kept going. When I approached the dock, I turned the throttle back to idle and the motor died instantly. I would not refire, so I removed the cover. It was pretty hot, including the carburetor. I think it was vapor locking, because after we let it cool for a while, it started right up.

My question is this. I suspect there might be some debris blocking some of the water passages in the head. What is the best thing to use and the proper way to flush it out? I thought about using a strong solution of CLR. Any ideas?


Thanks
Rick

[restless]

clr??
careful with solutions in ally!
If it was my only engine and I'd removed a ball of barnacles/hardstuff from the internals then I would take the head off and poke around the cooling spaces with a wire and an airline to make sure I could rely on it! I'm assuming it is a 2 stroke, in which case the job is not difficult. If not... erm make friends with a marine mechanic
Give the bolt heads a good sharp hit with a hammer n drift after an evening of soaking with a penetrating oil. If any of the bolt heads break off, don't worry as you can always take it to a tig welder who should be able to weld a bit of stud on so you can wind a nut on instead. Try to not shred the gasket on lifting the head... the odd break won't matter too much but the less the better. Reseal with silicon and bombs away!

[Lloyd Franks]

If the boat is on the trailer you might try running the engine in a barrel or large can and add white vinegar to the water. Don't let the water get hot, and keep adding vinegar as the water sloshes out of the can. Do for 10 or 15 minutes. The mild acid in the vinegar breaks up unwanted deposits (salt, lime, etc.)

[Capt Capsize]

My brothers 26D with a 1987 7.5 Honda 4 stroke and a similar problem. After tearing it down we found the previous owner had put a new impeller in the water pump. It seems the prior impeller disintegrated and little pieces of rubber were found clogging the cooling system in a couple of places. The biggest jam was where the vertical tube meets the engine block and makes a 90 degree turn.
I sure wish we found all the clogs on the first tear down. The first tear down we removed the head and found blockage at the intake cover. The second we removed the engine block. This effort is definitely only for the mechanically inclined. I used this website to get gaskets and parts and see exploded engine views.
While I have no affiliation with the following site I did get good service. http://www.boats.net/parts/search/Honda ... parts.html
Good Luck

[oemoemonue]

I have a mercury 4.5 and had the same problem that debris from the old empeller was plugging the water flow. I cleaned them out but I still watch for pieces I may have missed. Check to make surethat your fuel line is in tight . There is a screw that holds the attachment in place and if that get loose it may be .

I have a 1994 Honda 7.5 on my Mac 26S. Recently, it overheated, so I changed the impeller which didn't look bad at all. I suspected this was not the problem, so I removed the thermostat to have a look. It was basically a ball of barnacles so I replaced it with a new one.

We went out Saturday and it ran normally in the morning, which was just to get through the channel leading out to Pine Island Sound from the Caloosahatchee River. I didn't notice any problem. After spending some quality time sailing and lounging on the beach at Picnic Island, we had to motor all the way back to the dock. It was against a strong east wind and outgoing current, and we had to run the motor at a little more than half throttle for two hours. I noticed the motor seemed hot on the way, but the pee stream was strong so I kept going. When I approached the dock, I turned the throttle back to idle and the motor died instantly. I would not refire, so I removed the cover. It was pretty hot, including the carburetor. I think it was vapor locking, because after we let it cool for a while, it started right up.

My question is this. I suspect there might be some debris blocking some of the water passages in the head. What is the best thing to use and the proper way to flush it out? I thought about using a strong solution of CLR. Any ideas?


Thanks
Rick

[Bleakco]

Same problem on my fishing boat,,,,found the critters in the t-stat well and also in the water tube from the pump up to the motor,,,,,cleaned out the tube with an old speedometer cable and cordless drill,,it really whips around in the tube and makes it look new inside...