25 hp Johnson 1975 overheating problem

[Sotey]

I had a problem overheating at the lake today. I was running it as usual but didn't seem to have good water flow. It suddenly died and smoked quite a bit. It didn't seize but I can't get it started back up. It wants to turn over but just won't get there. Is there a possibility I burned something up? ie. solenoid or coil? I plan on changing the water pump and impeller but that shoudn't stop it from starting, right? Any help would be greatly appreciated.

 

[OBJ]

Re: 25 hp Johnson 1975 overheating problem

Welcome to the forums Sotey....<br /><br />At the very least, take a compression test on each cylinder and a spark test before trying to fire it back up. And if you don't know how long it's been since the t-stat was changed out, change it out also along with the pump. <br /><br />Keep us posted....thanks.

 

[The Marine Doctor]

Re: 25 hp Johnson 1975 overheating problem

Can you tell us what RPM range you were running when the stall occured...Idle Midrange Highspeed.<br /><br />Is there any discoloration of the head? <---place where the sparkplugs are.<br /><br />Did you mix the oil in with the gas?<br /><br />TMD

 

[Sotey]

Re: 25 hp Johnson 1975 overheating problem

Yes, TMD there is discoloration on the heads. The once green paint is now burned and a brownish color. I was running it close to wide-open. It burned up in about 60 seconds of running mid-range to high. I thought it may be possible that I had my fuel too rich but I think I mixed it okay. Could be wrong tho. Too much gas not enough oil maybe..huh?

 

[Solittle]

Re: 25 hp Johnson 1975 overheating problem

Do the compression test as OBJ has suggested and tell us what the plugs look like.

 

[Sotey]

Re: 25 hp Johnson 1975 overheating problem

I took the head off and the cylinders were both just fine, luckily. The coil casings looks like they got pretty hot also but no wire damage. <br />I inspected the impeller and it was just fine also. When I was taking the lower end off I believe the water feed tub wasn't inserted all the way to the flange/seal, suspected reason for overheating. Going to replace the head gasket as it wasn't in too great of condition anyway. I have no way of performing a compression check so hopefully after I get it back together she'll fire up. If not I'll have to find someone to do the checkout.