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overheating at idle

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Dies91

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I have a 91 vro 70hp Johnson i was out on the water today and noticed at idle or low speed the temp gauge is showing pretty hot like on the base of the red on the dial, my water pressure is 10-15 at idle and sits around 25 at Wot. Once I get going though the temp immediately drops almost to the coolest setting on the gauge. I also put a new oem water pump in recently
 
Dies91 said:
yes I did
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Depending upon what you find with the hand held temperature gauge and provided you are absolutely sure that the water pump is good I would check the thermostat ( the manual will tell you the correct opening temperature) and , if applicable the pressure relief valve
 
Why did you replace the water pump? Did you notice the symptoms beforehand? When you replaced the pump, was the impeller all together, or were parts missing? Next, and most importantly, did this occur immediately after the pump replacement? Lastly, is it a saltwater motor? Thanks.
 
Last edited:
Dies91 said:
I have a 91 vro 70hp Johnson i was out on the water today and noticed at idle or low speed the temp gauge is showing pretty hot like on the base of the red on the dial, my water pressure is 10-15 at idle and sits around 25 at Wot. Once I get going though the temp immediately drops almost to the coolest setting on the gauge. I also put a new oem water pump in recently
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So I put it on muffs and ran it till it got to the point on the gauge I saw yesterday and tested with a digital thermometer and it reads from the top cylinder down 155, 165, 172
 
I replaced it because it would take a second when started for the tell tale to start having a steady stream coming off of it, the impeller was not damaged when removed but the metal cup in the housing spun loose from what I saw, the temp gauge i installed after the new water pump so nothing to compare before hand but the water pressure before hand was about 5 psi at idle but the overheat alarm has never gone off before or after the water pump install. motor has only been in freshwater
 
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