HP525 temp sensor?
#1
Platinum Member
![](https://www.offshoreonly.com/forums/images/icons/platinum_member_star.gif)
Thread Starter
Join Date: May 2001
Location: Candlewood Lake, CT
Posts: 113
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
I just launched my boat off the trailer and idled to the dock. While tying off the boat while it was idling, the overheat buzzer went off and the temp gauge went to ~220. The sensor seems to want to stay there although the motor is cooling down.
I had just replaced the water impeller and there was water coming out of the tail pipes. The odd thing is that the motor does not seem to be hot to the touch so I am wondering if it could be a faulty temp sensor?
Any thoughts?
Thanks.
Jamal
I had just replaced the water impeller and there was water coming out of the tail pipes. The odd thing is that the motor does not seem to be hot to the touch so I am wondering if it could be a faulty temp sensor?
Any thoughts?
Thanks.
Jamal
#2
Registered
Join Date: Mar 2009
Posts: 496
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
I just launched my boat off the trailer and idled to the dock. While tying off the boat while it was idling, the overheat buzzer went off and the temp gauge went to ~220. The sensor seems to want to stay there although the motor is cooling down.
I had just replaced the water impeller and there was water coming out of the tail pipes. The odd thing is that the motor does not seem to be hot to the touch so I am wondering if it could be a faulty temp sensor?
Any thoughts?
Thanks.
Jamal
I had just replaced the water impeller and there was water coming out of the tail pipes. The odd thing is that the motor does not seem to be hot to the touch so I am wondering if it could be a faulty temp sensor?
Any thoughts?
Thanks.
Jamal
#3
Platinum Member
![](https://www.offshoreonly.com/forums/images/icons/platinum_member_star.gif)
Thread Starter
Join Date: May 2001
Location: Candlewood Lake, CT
Posts: 113
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Original impeller looked like new and yes that was the first start up after installing new impeller, fuel/oil filters, oil. I pulled out a plug from each bank and they looked good.
Are there two temp sensors on the HP525? The marina tech scanned the motor and there were a lot of fault codes, but many of them are not applicable to my boat. I think one of the faults he mentioned was that the motor was not reading the correct water and air temps.
They let the motor cool down to recheck and everything was the same again...now they say it will not even start. btw, it was in limp mode before when the temp buzzer went off.
What is going on, maybe the ECU is shot? Can one reset the ECU?
Thanks.
Are there two temp sensors on the HP525? The marina tech scanned the motor and there were a lot of fault codes, but many of them are not applicable to my boat. I think one of the faults he mentioned was that the motor was not reading the correct water and air temps.
They let the motor cool down to recheck and everything was the same again...now they say it will not even start. btw, it was in limp mode before when the temp buzzer went off.
What is going on, maybe the ECU is shot? Can one reset the ECU?
Thanks.
#4
Registered
Join Date: Mar 2009
Posts: 496
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Original impeller looked like new and yes that was the first start up after installing new impeller, fuel/oil filters, oil. I pulled out a plug from each bank and they looked good.
Are there two temp sensors on the HP525? The marina tech scanned the motor and there were a lot of fault codes, but many of them are not applicable to my boat. I think one of the faults he mentioned was that the motor was not reading the correct water and air temps.
They let the motor cool down to recheck and everything was the same again...now they say it will not even start. btw, it was in limp mode before when the temp buzzer went off.
What is going on, maybe the ECU is shot? Can one reset the ECU?
Thanks.
Are there two temp sensors on the HP525? The marina tech scanned the motor and there were a lot of fault codes, but many of them are not applicable to my boat. I think one of the faults he mentioned was that the motor was not reading the correct water and air temps.
They let the motor cool down to recheck and everything was the same again...now they say it will not even start. btw, it was in limp mode before when the temp buzzer went off.
What is going on, maybe the ECU is shot? Can one reset the ECU?
Thanks.
#5
Platinum Member
![](https://www.offshoreonly.com/forums/images/icons/platinum_member_star.gif)
Thread Starter
Join Date: May 2001
Location: Candlewood Lake, CT
Posts: 113
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Hmmm, I did have the marina swap the outdrive with a spare that I have. Air pocket's? That makes sense, I'll mention that advice to the marina guy's. Thanks.
Jamal
Jamal
#6
Platinum Member
![](https://www.offshoreonly.com/forums/images/icons/platinum_member_star.gif)
Thread Starter
Join Date: May 2001
Location: Candlewood Lake, CT
Posts: 113
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
The tech went to start the motor today after it has been sitting all weekend and the temp gauge reads 220+ and the oil pressure gauge is pegged at 80lbs before even starting it up.
What besides the ECM would control both of those gauges?
She will idle but not accept any throttle input by stalling out when any throttle is applied?
Thanks
What besides the ECM would control both of those gauges?
She will idle but not accept any throttle input by stalling out when any throttle is applied?
Thanks
#7
Registered
Join Date: Jan 2004
Location: San Diego, California
Posts: 2,777
Likes: 0
Received 6 Likes
on
6 Posts
![Wink](/forums/images/icons/icon12.gif)
This can be a situation that can arise if your engine system ground is not connected or connected improperly or possible loose ground or corroded ground. check the ground connections and tighten everything up, even at the batteries themselves.
Good Luck'
Best Regards,
Ray @ Raylar
Good Luck'
Best Regards,
Ray @ Raylar
#8
Platinum Member
![](https://www.offshoreonly.com/forums/images/icons/platinum_member_star.gif)
Thread Starter
Join Date: May 2001
Location: Candlewood Lake, CT
Posts: 113
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Took the boat to another dealer who is a mercury racing dealer and they finally diagnosed it to be the ECM afterall. Waiting for the new part to arrive. What would cause an ECM to go bad? Any upgrade ECM's out there?
Thanks,
Jamal
Thanks,
Jamal
#9
Registered
Join Date: Mar 2009
Posts: 496
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Well some times things just go out. It would be hard to tell. Their is no up grades that I know of. By the way I am just curious do you have the mercruiser smart craft system on your boat?