1999 21v overheating

[impactoffroadlighting]

Hey guys, new to the forum. Been doing a lot of reading but first time posting.I have a 19 9921V and I’m having some issues with overheating. It started overheating last week the boat would run great and then the temperatures would randomly jump from 175 to 200/ 225 at idle. Ill get on a plane and it will drop right back down to 175 for a few minutes and then all the sudden jump right back to 225. I replaced the impeller today and it was shot. Got the new one in and played on the lake for probably 20 minutes wake surfing with no issues. Then it jumped right up to 225. We got the boat on plane and ran for a few minutes before the temperatures dropped to 175. We let the boat sit on the lift for a few minutes and again the temperature would jump to 225. Not sure what to do from here. The strainer is clean and the impeller is brand new

thanks y’all.

[freeheel4life]

Were there pieces of the impeller missing?? If so the are likely stick in the trans cooler downstream of the pump and causing a blockage. This is commonly the issue. Other debris can also get stuck in the cooler so ita worth a look

[impactoffroadlighting]

I’ll take a look.
The old impeller was mostly intact so I didn’t think there would be.

[Bamer]

I’ll take a look.
mostly intact.

Mostly??? or 100% intact? If not 100%, the missing pieces are somewhere and probably causing your problem.


Sent from my iPhone using Tapatalk

[teachercop]

I agree.....thinking the intermittent heating up is some foreign debris is periodically interrupting the flow. I had a 1999 22i with the Mercruiser MPI315. Had the first had pleasure of impeller debris in the circulating system. Break the trans cooler hoses off and hopefully locate some stuff....

[impactoffroadlighting]

Thanks for al the help.
Sure enough there was some debris in the system.

[Bamer]

Hopefully that solves your issues


Sent from my iPhone using Tapatalk