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I am helping my neighbor.

He has the 6.2 MX. The boat starts runs great. After about 10 minutes of running wide open the motor has a audible bang and shuts off. The temperature gauge reads 175 degrees. There are no warning beeps. Will not restart until temp goes down to about 160°. Boat fires back up and will idle along no problem. Take it back up to wide open throttle and repeats audible sound (bang) and dies again. Cools down, starts and runs great until 175° again.

I don't believe the problem is mechanical. The motor runs great and has no unusual sounds while running until the "bang" at 175°

Any thoughts?

TIA

Tell your Niehbor that without scanning the event for what fault code is occurring your guessing.
My guess is obviously over heat and limp mode is shutting it completely off ( which is not common)
Or maybe it’s just suffering and needs a rest?!
Take it to a Dealer

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Hey rickk

Welcome to the Cobaltchat forum.

Like Matt mentioned, something is clogging the cooling system and she is going into limp mode to save herself from overheating. A good marine tech can scan this and isolate the problem.

Is this engine in a Cobalt? Any pics?

Again, welcome aboard mate.

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Thank you very much fellas for the warm welcome and your ideas. No pictures yet but it is a 26' Cobalt. I agree that she is running hot too. I will have owner take it to marina. Unfortunately, our little lake does not have a reputable dealer.

The impeller had a vein that was split at the core from end to end. I replaced impeller but still is acting the same.

Did they build a 6.2 in 2002? Maybe it's a Merc thing..
Welcome from Oklahoma, and pics or it never happened!

Ytmsn wrote: Tue Jul 02, 2019 6:52 am Did they build a 6.2 in 2002? Maybe it's a Merc thing..
Welcome from Oklahoma, and pics or it never happened!

Yep. They've been building it for some time.

My neighbor Terry pulled boat out and took it to a Merc Dealer this morning. I will report back what they find. Thank you again to all who responded