possible cooling system problem?

[Andy9236]

i have a 2003 speedster 240 mercury 240 efi. this weekend i had it out and the continuous alarm came on straight out of the dock, so i returned and shut it down. waited a few minutes started it up and about 2-3 minutes go by and the alarm comes back on. i had a guy come look at it, he said it had to be a cooling problem. does anyone know how much water is supposed to be flowing through the port side head? he disconnected the hose and we cranked the engine and there was water coming out, he said it did not seem like enough but the boat was also just idling there not moving. he said something like the water pressure out of the hose should be 10+ lbs pressure rating? does this sound right? he also said there was a temp sensor on the inside of the head where the cooling system connects and water flows in, but there was not one present. all the diagrams ive seen have the temp sensor in a different location.

even if there is supposed to be a sensor there, the boat has been out 3 times since i bought it and ran fine so im not sure why it would just decided to overheat now without another issue somewhere

 

[Tim75]

From under the boat- look up into the intake tunnel. On the upper left of the wear ring are 5 holes. These are the cooling water holes. Are they clogged? Any debris around the impeller? Small amount of debris can cause a HUGE drop in water flow.

Check all the cooling hoses for obstructions (disconnect one end if needed). Are any hoses pinched or crushed? The pee hole is a magnet for bugs that like to build in small tight places. If you can't get hot water out, you can't get cool water in.

Has the boat ever been run in the mud? The mud can settle in cooling passages and turn to cement.

Do you still have thermostats in either head? Toss 'em. One of the more common repairs is to replace the temp sensor in the head.

 

[Andy9236]

I will check the holes in a little while when i can step away from my desk....there is no temp sensor in the starboard side head...also plan to check in the port side in a little while to see if i there is a sensor in that head and if i can get a part number off of that one and get one for the other side.

would you recommend using an air compressor and blowing air through the holes on the bottom? or is there a way i can hit it from the inside and try to blow air out of these holes?

 

[Andy9236]

i cannot seem to find the holes you are talking about under the boat.

i did however discover there is no temp sensor in either head. i removed the hose from both sides, so it was only connected to the pee hole on the back corner of the boat. i blew this line out and sandblasted myself in the face with all kinds of sand and mud....no fun...but now water will exit freely when i pour some into the hose. i really want to test it out, but i figured it would have to be put in the water to test it. i am guessing the water could not escape.

i also found stick inside the intake grate...pulled that off to get that out. i still would like to check the water intake holes to be sure they are not clogged....will flushing the engine with the flush mount help any with this?

 

[Tim75]

i cannot seem to find the holes you are talking about under the boat.

i did however discover there is no temp sensor in either head. i removed the hose from both sides, so it was only connected to the pee hole on the back corner of the boat. i blew this line out and sandblasted myself in the face with all kinds of sand and mud....no fun...but now water will exit freely when i pour some into the hose. i really want to test it out, but i figured it would have to be put in the water to test it. i am guessing the water could not escape.

i also found stick inside the intake grate...pulled that off to get that out. i still would like to check the water intake holes to be sure they are not clogged....will flushing the engine with the flush mount help any with this?

The 5 holes may be hidden by the random location of the impeller blades. Try turning the engine just a bit and check again.

Sounds like you found part of the problem. While you are at it, check the rest of the hoses. Caution- there are hoses that could back-fill the engine cylinders with water. If you have any doubt about water in cyl., take out all the spark plugs and turn engine over BY HAND. Don't hydrolock your engine and bend a rod or crankshaft.

 

[Andy9236]

i blew out the hose that comes out of the starboard side head, goes over to the port side head, and then goes out the pee hole. That helped a lot. I went ahead and hooked up a hose to it just to see if that helps anything, and that was the first time I’ve seen water come out of the rubber exhaust pipes and the pee hole. I’m guessing this did help some?

I also looked in the nozzle while the water was hooked up. When you flush it, doesn’t the water come out of the cooler holes you were talking about? If so then part of the impeller blade was over the holes.

I also got kind of brave and started it since it seemed to be getting a lot more water from a hose. Ran 2-3 mins and no alarm and the head didn’t even feel hot

Lastly, is there supposed to be a temp sensor in either of the holes on the heads where I removed the hoses?

 

[Andy9236]

The 5 holes may be hidden by the random location of the impeller blades. Try turning the engine just a bit and check again.

Sounds like you found part of the problem. While you are at it, check the rest of the hoses. Caution- there are hoses that could back-fill the engine cylinders with water. If you have any doubt about water in cyl., take out all the spark plugs and turn engine over BY HAND. Don't hydrolock your engine and bend a rod or crankshaft.

Which other hoses should I check?

 

[Andy9236]

Update: the boat does actually have both head temp sensors. The guy who originally helped me on the water was used to a different mercury outboard and was looking in the wrong place. I did not catch him because I am still a newbie to this engine and mercs in general..grew up working on an old evinrude with my grandfather...50 year old engine doesn’t give me near the problems this seadoo has.
Since it does have the sensors and the system does seem to be doing better, I will take it out to the water tomorrow to try it out and see how it’s doing. Will update

 

[Tim75]

Update: the boat does actually have both head temp sensors. The guy who originally helped me on the water was used to a different mercury outboard and was looking in the wrong place. I did not catch him because I am still a newbie to this engine and mercs in general..grew up working on an old evinrude with my grandfather...50 year old engine doesn’t give me near the problems this seadoo has.
Since it does have the sensors and the system does seem to be doing better, I will take it out to the water tomorrow to try it out and see how it’s doing. Will update

Sounds like you just about have your problems licked. When using the normal flushing fitting, there is a fair amount of water that will come out of the 5 holes in the wear ring. That is why running the engine on a hose requires a lot of hose flow... some is wasted thru the wear ring and does nothing to cool the engine. If you are getting water out of the pee hole, you should have enough flow. That does not mean you can run the engine forever on the hose.

You got debris out of the hose, but you could still have some in the engine cooling jackets and passages.

 

[Andy9236]

If I put the air compressor up to the pee hole, while the hoses are attached to the heads, would this help clear out the rest of the cooling lines?

 

[Tim75]

If I put the air compressor up to the pee hole, while the hoses are attached to the heads, would this help clear out the rest of the cooling lines?

I don't think that is a good idea. You will be subjecting the cooling system to 5 to 12 times more pressure than was designed for. I use only a water hose (from a well).

 

[Andy9236]

I ran a hose to it again yesterday, this time for a longer period of time. about 30 minutes i guess. going to take it out today and see if it works, if it does then great ill be happy. if it doesnt then i do not even know where to go from there....will update.

thanks for your help Tim!

 

[Andy9236]

also i just wanted to add that it was the starboard side that was getting hot...so im thinking the hose was blocked off and not enough water was getting to that head...not sure how the cooling works if the water goes up both heads or just one and transfers over to the other