running hot

[dsujen]

I just completed hooking up my 1987 johnson j90tlcur to my boat. Ran it on muffs. Strong tell tale coming out. Thermostats appeared to open because I saw water coming out of the slots after about 60 seconds near the top of the lower unit. Ran it in gear and reved it a few times and let it idle for a bit. Total run time was about 2 minutes 30 seconds. I touched the top of the block on the right side could only hold my hand there for 1 second. The left side about 3 seconds. I'm going to run it in a test tank tomorrow to see if it will run cooler. Don't know if the alarm works. How do I know what is normal?

 

[emdsapmgr]

Borrow or rent a laser temp gun. The palm of your hand won't work if you think you have a temp issue. When the engine is well warmed up and idling, you should see cyl head temps between 140 and 150. Maybe 155 in the dead of summer in a warm lake. When you are on plane on the lake, the planning temps may be as much as 20 degrees cooler. Just because the telltale is strong does not mean that one of the two thermostats is stuck shut, overheating one head..

 

[Auxlarry]

I had the same issue one time and found out the muffs I was using were not supplying enough water to the motor. I purchased muffs that were larger and sealed against the LU better and also make sure my faucet is on all the way. Solved my problem!!

 

[dsujen]

Ran hot in the driveway on muffs again. Removed thermostats and put them in a pot of water on the stove. Only one of the two opened. I heard some old timers tell me to simply leave them out. Not sure if that's a good idea when it gets cooler out.

 

[Bosunsmate]

Ran hot in the driveway on muffs again. Removed thermostats and put them in a pot of water on the stove. Only one of the two opened. I heard some old timers tell me to simply leave them out. Not sure if that's a good idea when it gets cooler out.

Never a good idea, you can have a cold seize and you will also carbon up your motor. It will also be hard to warm up and keep running when cold started, even in the heat of summer.
Maybe the better one is opening too slowly too, if you compare it with a new one

 

[emdsapmgr]

Agree with Bosun. Probably best to install two new stats. Also, check to be sure that the two nylon pressure relief valves are not heat-deformed.