Temp of water coming out of 9.5 HP

[tafische]

I am generally a Mercury guy, but I am helping a young man get his great grandfather's '68 MQ-14E 9.5hp working again...

At first I was a little worried I wasn't seeing water circulating, but then it started. I see this motor has a thermostat, so guessing it finally opened. I am used to luke warm water from my Mercury, but this water is very hot...almost too hot to touch. Is that normal for this Johnson? We will likely replace the impeller and possible thermostat, but trying to understand what to expect - hot water or should it be much cooler? Dont want to overheat this old guy....

 

[oldboat1]

See if the top of the head is too hot to touch (would indicate overheating). Run it in a barrel for testing, with water about half way up the leg.

 

[jimmbo]

The Stat is supposed to open by 140 F, and Water at that temp will feel very Hot, most Home water tanks are set around 140, so hold your hand under the Faucet with only the Hot turned on...

 

[F_R]

There are two cooling water flow paths through that powerhead. One flow path is always open and water flows regardless of thermostat state. The other path is thermostat controlled.

So your description suggests the first path is blocked, since you had to wait for the 'stat to open. My memory isn't good enough to tell you where to look for the blockage. Let's hope you don't have to pull the exhaust covers, a major job.

 

[Crosbyman]

maintenance book on these MQ says they should run between 125 and not over 163..tested using a melting stick but you can get a infra red gun for $20 these days

book says to run the motor 5 min. then check temperatures

 

[Bream Killer]

Just replaced my thermostat and it's at 143 degree. Be careful with the seal, it goes on in an odd way.

 

[tafische]

Thanks all. Good advice and a fun project. Hoping to get this young man into a John Boat and enjoying the water.