1st trip with new rebuild 90 johnson

[johnson89]

ran motor across lake and kept it 2000 and less for 1st 10 min.s then moved it up to 2500 for the next 10 min.s..... shut motor off and fished for a few hours...motor started 1 st try...moved the rpm too 2800-3200 to put boat on plane and drove about 15 min.s.....at idle the temp of heads is hot enough to only keep hand on head for about 3-4 sec.s but above 2000 rpms you can keep your hands on the heads....didn't bring my thermometer ......so far have about 1 hour on motor....I rechecked the head bolts and all is well...anything else I should watch close,this is my 1st rebuild....running oil at 25-1....going to pull plugs out Monday if not raining and see how they look

 

[emdsapmgr]

What model/year is this 90? Is it a looper or crossflow? When the powerhead was rebuilt, were new thermostats installed? If the stats are stuck shut, the powerhead will quickly overheat at idle. Once on plane, the crossflow system will open two pressure relief valves in the theremostat housing, flooding the powerhead with extra cooling water-which will keep it cool as long as the boat is planning.

 

[johnson89]

its a crossflow 1989....everything was replaced...I had checked the heads at the ramp, at idle and at 2000 rpm,not in gear

 

[emdsapmgr]

To really validate any cyl head temps, why not rent or borrow a laser temp gun. If you have no access to one, you may want to rent one for the day from the local auto parts store. You really need to know just what the idle cyl head temps are on this new engine. If only for baseline measurments as comparison over your next years of ownership.