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Bf90d Over heating

Pchop

New member
Hi there I have a bf90d now sitting at around 120hrs. If I am at wide open throttle for more than 15mins the garmin engine display will alarm with an over temperature alarm at anything from 77 degrees to 83 degrees it will lose power and I will then drop it back to idle the temp seems to come down straight away then I can just put the power back on and away it goes like nothing happened. It will then run for a while and will do it again.
I have pulled both thermostats and checked they open these are good did an oil change pulled the leg and check the pump it looked fine but I did not replace it. I have remove the over pressure valve and cleaned it was fine and removed flushing valve which looked blocked cleaned it up but the problem is still there. I have also replaced the battery as it was getting a bit tired. Went out today on the boat and it ran sweet on the way to our fishing spot about a 25min run most of the way at full throttle but then later we moved spots and 10mins in the over temp alarm came on. Does Anybody.have any thoughts on what might be happening and can Anybody tell me what the normal run temp should sit at in 15 degrees sea water.
 
Hi,

I don't have any service information for this outboard or any experience working on one.

But, IF those temperatures are accurate, then it's not overheating and shouldn't be alarming and going into guardian mode.

Just a guess on my part but check your on board water separator. I have read about those causing false alarms for some reason.

Good luck.
 
You need drH to see where the overheat is. There are four sensors, your NMEA is only showing block temp( yours is fine). More likely an exhaust overheat, possible a blockage in you manifold
 
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