2003 sport jet 240 overheat on hose only, while flushing

[Blackbird8907]

hey fellas, new here but have a decent amount of time around pwc's and jet boats. short story here is that this motor and drive came from a donor boat and was brand new (accident at the dealer in 03) i was lucky enough to find it and swap it into an 01 challenger 1800 that needed a power head. everything went smooth (gas tank never even had a drop of gas in it from the 03!!) but since the install its always overheated on the hose. However on the water she's a dream, never a problem. the boat was intended as a flip so coming time to sell id like to sort the issue out. any advice is greatly appreciated.
thanks in advance,
mike

 

[Coastiejoe]

Ok, the Merc products are different than the Seadoo. So what I am about to say MAY be wrong. When flushing the engine in a hose the water die NOT cool the engine. When connected to the hose you should not run for more than a minute. Two main reasons. While on the hose the water ONLY goes through the exhaust and the jet pump area. And the second reason is, while in the hose the carbon seal is. It cooled and will destroy itself due to friction/heat.

Again, this being a Merc I may be wrong. Someone that knows for sure will chime in.


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[Blackbird8907]

hey coastiejoe, thanks for the quick response!! I was surfing through the manuals and they recommend flushing for atleast 10 min esp after use in salt water, but i usually run into an overheat condition at about 4 minutes... these models don't have a carbon ring as the drive and the powerhead sort of sandwich the hull with a rubber gasket. As of now I'm sort of wondering if there is supposed to be any kind of one way device that would stop the water from directly exiting the jet pump as it seems thats where most of the water is going. as I'm typing I'm realizing i should probably check for any blockage in the main line from the flush port to the adapter plate. there is some water coming from the exhaust but not much. I'm just kind of baffled as most people that have overheating problems, usually have it on the water lol. I'm also wondering how critical hose pressure is, i don't think i have poor pressure but again just another variable.
sorry for the rant, hopefully I've given enough info

thanks again,
mike

 

[Coastiejoe]

The Merc engine is a beast all to its own. Hopefully a member with some good knowledge will step in and help. For me, I would avoid the Merc engine for the mere fact few know much about it and the cost to diagnose and repair is considerably higher than the Seadoo products.

Best of luck to you,,,,


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[racerxxx]

The Merc cooling system is completely different all together. I remember Doc saying the house hose pressure doesn't have enough pressure to get the job done properly. It fill from the bottom up from what I can tell.


http://www.seadooforum.com/showthre...lushing-engine&p=306724&viewfull=1#post306724

 

[Blackbird8907]

Yeaa it almost didn't make sense to me the way the system is designed to run on the hose, i was almost thinking about re-routing it like dr. Honda was mentioning in those posts. Thanks for the link btw, at least I'm starting to feel like it's not something I did with the engine swap! For the record tho I am using a fat garden hose and I don't feel I have all that bad of pressure, but maybe I'll try to run it on a pump from a different water source this weekend


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[Sportster-2001-951C-Stock]

The cooling water comes from the jet pump during operation, (Incorrect: that line is where you need to connect your water if you want to run on the trailer longer than 30 seconds). The provided flush port is strictly for short running time and exhaust flushing. Without water flushing through the exhaust, backfiring damage to the ride plate is a risk

I believe there is an pisser tell-tale plumbed off the top of the engine block? If yes, and there is water coming from there then the block cooling jacket is full of water covering the cylinder sleeves meaning there's enough water volume to keep the engine cool.

I'm surprised your owners manual doesn't explain this clearly, no wonder there's so much confusion.

I believe this is not true: "that line is where you need to connect your water if you want to run on the trailer longer than 30 seconds."

 

[Blackbird8907]

Thanks for all the support so far guys! I haven't gotten back out to the boat yet hopefully tomorrow after work.. There's no other actual hook up other than the flush port on the starboard side of the bot in the rear. The flush port is actually inline with the jet pump supply line, it just follows gravity and heads straight downwards out the jet. I just find it odd, like you had mentioned, that the flush port they specify on the manual (with a picture) that your supposed to flush for at least 10 minutes with, could only be used for such a short time. I thought about making my own flush port further up in the system but hesitate to as I feel it would look somewhat shady in a sale. I really feel like I'm missing something with this system.. I've tried studying the water flow chart tho without any luck.. Im gonna try to hook up a pump to it tomorrow to see if the extra volume helps.


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[Sportster-2001-951C-Stock]

The flush port is actually inline with the jet pump supply line, it just follows gravity and heads straight downwards out the jet.
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10 minute ENGINE RUNNING FLUSH or ENGINE NOT RUNNING FLUSH? Does your manual specify "ENGINE RUNNING"? I think it must not specify? Regardless, if engine block cooling jacket is not filled with water, cylinder sleeves will overheat. :O !!!

I think the current method is not being interpreted correctly or there is something unclear about the instruction from the manual.

I'm not a sportjet guy so I'm thinking in terms of an outboard engine. There's always an air vent at the top of the block. This is the tell-tale "pisser" outlet. When water is coming from this vent, the block cooling jacket is filled with water. In this case, it's safe to run.

Under any circumstances if no water is confirmed coming out from this air vent at top of block, "pisser" I'd say the block will not be cooled. For an outboard, we look to see if water is exiting the pisser at all times and if not, we investigate the cause (usually the seawater pump is not working). The sportjet receives it's cooling water from the jet pump, that is the primary difference between it and an outboard.

So for 10 minutes of flushing while running the engine, you must devise some way of connecting such that the engine block cooling jacket is kept filled with water. Perhaps use a high pressure fire hose, or alternatively by connecting somewhere else?

Facts are facts, poorly written or interpreted instruction manual method doesn't change them. Bean counters don't care much about these details until after the fact when it comes back to bite them (Yamaha has won the majority outboard market).

 

[Blackbird8907]

I'll double check on the pisser tm. The manual says "the engine may be run using the flush adapter". I just feel if it was a misinterpretation there would be many other cases and Ive found hardly any. I just can't believe the manufacturer would design such a useless flush port, I would love to hear from another sportjet owner on how their boat runs on the hose. Thanks again for all the support fellas I'll get back to you on the "pisser".



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[Sportster-2001-951C-Stock]

"the engine may be run using the flush adapter" Perhaps my reading comprehension is weak, I don't see the phrase "10 minutes" in that sentence?

 

[Blackbird8907]

Have you taken a look at the manual on here really quick? It's page 1B-2, I would post the page but I'm sure that's not cool.. However, directly below that in the next step, it says to turn the water on and flush the engine block for 10 minutes, Idk maybe my comprehension is poor, but telling me I can run the engine on the flush port and then telling me to flush it for 10 min implies that it shouldn't be any sort of issue and is normal practice. Anyways, thanks again for tryin to help, I'm hoping a sportjet owner pops up so we can compare running on a trailer.
Thanks,
Mike


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[Sportster-2001-951C-Stock]

Agreed, I'd appreciate hearing from a sportjet owner as well.

Come on guys, throw us a bone here!

 

[Blackbird8907]

Ok Guys, got out there again and checked the pisser tell tale and had nothin at all. Buttt I had water going straight up to the exhaust and nice flow from the exhaust.. For laughs I pulled the pisser line and tried to blow through it... Completely clogged, and being that the water had an easier way out it of course took it. Soo now that the vent is clear she runs on the hose for the 10 min she's supposed to without an issue! Thanks for all your time and info guys!!! I hope this can help someone else in the future.

Mike


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[Sportster-2001-951C-Stock]

Ahh yes, that makes sense. And if the pisser is clogged there will likely be an air bubble trapped in the block as well so it's probably good you investigated and asked questions.

 

[gioakjoe]

i had to put a coat hanger threw my pisser caz it was clogged once it was un clogged never had this problem again.