Engine overheating alarm issue

[Prodock]

Had a great morning, run about 5 miles to the ocean, it handled a rough inlet Wonderfully. We trolled for a bit, caught a meal of Spanish Mackerel, then stopped at a sandbar on the way back in to jump in the water and cool off. We ran the engines and washed the boat a little while parked by the sandbar. Then when we took off to go home, we quickly got an over heat alarm on both engines. We stopped right away and checked the clean out ports, they were clear. Both coolant lines had flow and neither felt very hot. After a couple minutes we started up and ran about a mile before the alarm came back, port engine this time. Stopped again, still couldn’t find anything. After about 10 minutes we took and ran another 3 miles or so and port side alarmed again. We were pretty much back by then, but I still don’t see where there is anything wrong. Ideas? The boat has about 18 hours on it and had the first oil change at 10 hours. No problems until today.

 

[dlkhmk]

Did you check the water intake strainer.

https://jetboaters.net/threads/how-to-clean-the-cooling-water-intake-strainer.1011/

 

[Prodock]

Did you check the water intake strainer.

https://jetboaters.net/threads/how-to-clean-the-cooling-water-intake-strainer.1011/

I’ll check it out. Kind of figured with water coming out the pee holes for both, it must be getting water, but worth a check..,.thanks

 

[Prodock]

Did you check the water intake strainer.

https://jetboaters.net/threads/how-to-clean-the-cooling-water-intake-strainer.1011/

I’ll check it out. Kind of figured with water coming out the pee holes for both, it must be getting water, but worth a check.

Ok, I pulled the strainer, one small hole had a tiny piece of shell in it, but otherwise it was clean. ??‍

 

[Julian]

When you were running the boat at the sandbar, how shallow was it? Is it possible you sucked up a bunch of sand into your cylinder heads and they are packed with sand now? Runs ok at lower rpm as the temp doesnt get that high, but at higher rpm you create an over heat as water cant get to the full head?

 

[Julian]

Watch this video to get a better sense of what is happening under your boat when sitting with engine running:

 

[Prodock]

I would not say that is impossible. It seemed to do better each time we restarted on the way back in, the last time going about 3 miles before throwing the overheat alarm, so hoping everything is ok. It drops off quick where we anchored at the sandbar, but we did back up to and anchor with the swim platform close to shore, so it is possible the some sand could’ve found its way in. Thanks for sharing the video, very informative.

 

[Prodock]

BTW, it did not throw the overheat alarm when we flushed it at home.

 

[WREKS]

Sand can get in easily, but not easily flushed out. You have a new boat. The advice is good. Avoid running the engines in shallow waters!

 

[Prodock]

Sand can get it easily, but not easily flushed out. You have a new boat. The advice is good. Avoid running the engines in shallow waters!

I have been boating these waters for 14 years with a outboard powered bay boat, apparently will have to treat the jet boat more timidly. So far love the boat, except for the pain it is to flush the motors and how finicky it apparently is with sand. Not much for weeds here, so figured I’d be ok. Live and learn.

 

[anmut]

Manual states 3’ of water is as shallow as you can run.

 

[Prodock]

Wow, we are not supposed to run the boat in less than 3’ of water... nearly impossible to get it on and off a trailer in more than 3 feet of water. When I test drive it, the dealer took me through an area that’s only about 2 feet deep, maybe less and I see jet skis all over in less than 3 feet of water. I will approach anchoring at sandbars differently in the future, but if this boat can be ran in less than 3 feet of water, it’s not much good for about 80 percent of the waterways and basically no boat launches. I was just looking for some guidance here from fellow jet boat owners. I apologize for being new to the jet boat...if I’d have known it requires more water than some live aboard trawlers, I probably would have went a different direction.

 

[WREKS]

That's the problem. Most of us have been fed that line and filled our engines with sand. But take heart. These are great boats. And knowing how to utilize them will make it worth the effort. These forums are filled with information on how to maintain and enjoy your boat. You will not regret it.

 

[chris oftedal]

Did you ever resolve this issue?

 

[Prodock]

Did you ever resolve this issue?

I haven’t had the problem again. That day I was able to go farther and farther between alarms, I flushed it good at home without getting the alarms and have had it out a couple times since with no issue.

 

[WREKS]

Good to hear that. I offer this reminder. Overheat Prevention

 

[anmut]

Yes, manual states you shouldn't run in less than 3'. Yes, on plane, you can run in less than 3' without issue. As that video shows, the biggest issue is sucking fine sand while idling in shallow water. Think about your buckets in "neutral" - sand is basically circulating near the intake screen for the block cooling, right? So for me when in shallow water, always have your buckets up in a fwd direction to sweep the sand through and past the grates. When I push off from the sandbar, I start the motors in N (because safety switch) and put them in Fwd asap. Same coming in to the sandbar, in Fwd until i hit that 3' mark on the depth finder, then kill the engines, but keep the buckets open to allow for pass through.