"Overheating" On Newish Boat

[korybmd20]

We have a 2020 Nautique GS22 that has about 100 hours on it, which we have properly maintained.

About a month ago (second season in use), we had a strange occurrence. Before starting the engine, we always open the engine cover (in addition to running the blower) just as an extra precaution. Then, shortly after starting the engine, an alert that the engine was overheating came on, telling us to turn it off immediately.

It was a very hot sunny day, so we thought maybe the direct sunlight onto the engine was the cause. We closed the cover, waited a couple minutes, restarted the engine, and it soon cooled off and ran fine.

We ran the boat another dozen days or so with no issues, until yesterday when it happened again. On this day however, it was overcast and not hot. So we're doubting that our original theory was valid. On the initial start, the boat overheated, we had to shut it down, and on the 2nd start the temperature was over 200 degrees but soon cooled down and ran normally.

Has anyone seen this before? Any ideas or suggestion?

Thanks in advance!

[nohlan_4]

Checked strainer? Impeller for water pump still ok? Main seacock fully open? All hoses tight?


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[mlange]

If the boat is on a lift or you are launching you could have an air bubble on the intake side that will cause this. The air bubbles basically causes the intake side to lose its prime. Could be as simple as just remembering to give the engine some RPMs to clear it out or could be a bigger issue where you have a small leak on the vacuum side that is ingesting air into the system that you'll want to fix. When I fought through this a few years back I actually had three separate issues that all contributed to the problem.

When this happens with you is the boat still idling and you haven't gotten up-to-speed yet? If so I'd bet that's your issue.

Mike

[bturner]

The MC Ilmor engines are really bad with the above post. I've been working on a friends for a couple seasons and have dialed it in quite a bit but we have to rev the engine when we lower it into the water off the lift. On that boat you can actually watch the water drain out of the system about 2 minutes after you lift it out of the water. Since yours is doing this only on firts start this would appear to be the same type of issue.

A lot of things to check but the suggestions above are solid. The first being the strainer. Check for daybrie then the seal on the strainer. Next condition of the impeller and the gasket. The idea here is you want the pump working at it's best performance to pull the water in on first start. Next would be any hoses that could be leaking or letting air into the system. Here I would just check for leaks and ensure all the clamps are tight.

[mlange]

Yep. When I was troubleshooting my problem I found a few different issues. I was able to reproduce the problem at will after I understood it and was surprised at how small of a vacuum leak would cause the engine to lose prime.

This was from a post I did on MalibuCrew.com for my old RTXi w/ an Indmar 6L, but lots of cross over here...

I've been fighting a cooling issue for the last three years on my 6.0 and thought I'd share a list of literally everything I went through that helped to solve the problem. This goes from incredibly trivial stuff to the more interesting. Most of the information was pulled from different threads on here so THANKS to everyone over the last three years that provided assistance.

And don't give up. In my case I had three separate problems that all contributed to my issue so when I found one and thought I was good to go I got frustrated that the problem didn't go away.

1. Make sure the raw intake valve is completely open.
2. Make sure all hose clamps are tight. Probably easiest to just trace from the raw water intake through the entire system and check for loose hose clamps along the way.
3. Make sure the transmission cooler screen is clean.
4. Make sure the impeller is good.
5. Make sure the shaft seal is NOT plumbed into the transmission cooler. Mine was plumbed in wrong here. On an L96 the transmission cooler is on the vacuum side of the cooling system so if the shaft seal is plumbed into the transmission cooler you’ll suck air. If it is plumbed into the transmission cooler you can get a brass plug to screw into the transmission cooler and a T from your dealer to plumb the shaft seal into the correct place.
6. Make sure the vent line to transom is clean. On the transom you’ll see a little metal port about the size of a button on your jeans. After running the engine and shutting down it will continue to vent water like its peeing for a few minutes. If it isn’t venting water it’s plugged up. There’s a hose that will run to the top of the engine. Take that hose off and blow it out with compressed air. Mine was plugged up.
7. If you have a heater make sure the heater circulating pump is running. You will get heat even if it isn’t running so don’t make any assumptions based solely on if you have heat. If it isn’t running first check the fuse for it. I had an inline fuse, which was blown. If you don’t have an inline fuse Peter from Smooth Water Sports has said it will use the Fuel Pump #2 fuse in the fuse block on top of the engine. If the fuse is good the pump itself may be bad. I had both a blown fuse and a bad pump.
8. Make sure the thermostat is good.
9. Make sure the temp sensor is good. Hopefully someone else can chime in on an easy way to test it.
10. Check your engine serial number. Indmar published Service Bulletin SB2012-3IN to address a cooling issue with the L96 motor. It affects 2012 and 2013 L96 (6.0) and LS3 (6.2) engines with tube and tube exhaust manifolds and 7-digit serial numbers before serial number 2249300.