Overheat

[cdrascic]

Hey guys...I have done lots of research on this topic and want to make sure I am not missing anything.

I have an 07 3.0 in my Maxim 1800MX. The impeller is probably 2.5-3 years old and was done by the previous owner. I took the boat out the other day and was on the water for about 2 hours cruising around. I then had the boat idling for quite a while and noticed the overheat alarm went off after about 2 hours on the water. The temp gauge was up to 230-240 and I could smell some smoke. I let it cool down and tried again and the temp shot up again so I was towed in. I was able to restart and it operated no problem for a couple minutes so I could get the boat on the trailer.

I dropped the lower half and the impeller is intact and pliable, but it does appear to have normal wear and tear. Also, when I dropped the lower half, the exhaust shutter fell out as well. I noticed the guide tube between the impeller and the upper half was melted with a hole in it.

I have got replacements for these parts (except shutter) and plan to replace them. I also plan to replace the shutter as I hear this is an easy job on this motor? Other than doing an engine oil change, is there anything else I should be checking?

I am not sure what else could have possibly caused the overheat, but I expected the impeller to look worse than it does. Hoping somebody might have some insight for me?

Thanks!

 

[Scott Danforth]

you had zero cooling water flow, hence the temp over 180 and the smoke and burnt exhaust bits.

back-flush the cooling system

replace the whole water pump assembly, not just the impeller

check the rubber parts in the exhaust. those burned up along with the shutters. without water, your exhaust temps go to well over 900f

if your coupler went out or the gears in the drive, it would not turn the raw water pump. which could explain why the impeller is still intact.

 

[QBhoy]

Good advice above from Scott. Likely it’s overheated and melted the flapper off and blocked things up.
But if she ran ok last time you used her…and this is your first outing after winter…often your overheat can be caused by a hose or drain plug being left off or loose, from winterising. Just a thought!

 

[Lou C]

Check for water in the cyls and in the motor oil; signs of a blown head gasket