Johnson 4.5 overheat problems

G

golfcarmad

Cadet
Joined
Jul 16, 2004
Messages
13
Hi guys,thanks for all help on Merc 7.5,changed impeller and i have a fine engine. New problem,my Johnson 4.5 starts fine when cold,pees,then water fluctuates between cool and hand burning!!! side plate gets too hot to touch,peeing is still ok however.Pointers please before I strip her down?? thanks from the Paul in the UK
 
E

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Johnson 4.5 overheat problems

Probably poor water circulation. Check the water intake screen above the prop. Replace the water pump or at least the impeller. Try air hose pressure on the water tube.

Make sure that the plate under the waterpump impeller is sealed at the bottom or it can suck air.
 
M

mikesea

Lieutenant Commander
Joined
Oct 1, 2006
Messages
1,830
Re: Johnson 4.5 overheat problems

You dont mention whether the impeller is recent.Its possible its time to change it,are you tank testing?often the intakes grab air,it could be deposits in the side plates but start from the bottom with an impeller,you might want to shoot some water up the tube and see if it feels restricted
 
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