1990 johnson GT150 can it be rebuilt

[sumpenelse79]

I just bought a 1980 mastercraft barefoot 200 with a 1990 Johnson GT150 that needs a rebuild. On the starboard side of engine the head gasket let water into the middle piston and engine died that's what the owner told me. I have some pic from the past owner my question is if water stopped the engine could it have done more damage to bearings in the engine or would just damage the piston and cylinder.

 

[Faztbullet]

Re: 1990 johnson GT150 can it be rebuilt

Looks more like wrist pin bearing or locating pin let loose from the looks of head damage. Crank and rod could be pitted if it has set a while with moisture/water in it. It a fairly simple fix if the other cylinders are still with in spec's. If it need a total rebuild,junk it and find a 60? 150hp or 175hp as they have more torque and better on fuel...

 

[sumpenelse79]

Re: 1990 johnson GT150 can it be rebuilt

thanks for your info Faztbullet but i can rebuild the engine with a mod one port job for around $1700 to $2100 and have more power and a new engine to find another engine would cost from $5000 to $8500 and that's a used engine. So what do you thank my best bet is.

 

[emdsapmgr]

Re: 1990 johnson GT150 can it be rebuilt

Fast has some good obervations. The dents in the head indicate the top ring let go on that cyl. I'm not so sure that the water damage was solely responsible for the heavy grooves in the cyl walls. The rubber water diverters look pretty squished-possible they may be restricting cooling water flow around that middle port cyl. I'd replace them. Possible you can overbore that center port cyl and put a new piston in it. You won't know what condition the crank and bearings are till you pull the engine apart. That's a nice high compession head. It's pretty damaged-has pcs of the ring imbedded in it. Probably should be replaced if you decide to overhaul the engine.

 

[sumpenelse79]

Re: 1990 johnson GT150 can it be rebuilt

thank you guys for the input. I'm trying to get more hp out of the engine. I would like for find some cylinder heads that would help produce more and have some porting done, are the GT150 carbs the same as the GT175 carbs. I'm trying to make more hp because the boat is rated for a 200hp engine.

 

[emdsapmgr]

Re: 1990 johnson GT150 can it be rebuilt

An XP/GT 150 already has some high performance goodies on it. It already has the larger 1 5/16" carbs from an older 175 engine. (smaller than the 1 3/8" GT175 carbs.) Comes with decent high compression heads. The carbs are fine, but you may find an older set of 1979 small bore 235 heads will give you about 10 lbs more compression. (you will probably have to jet up the carbs somewhat if you make the change.) Your current engine will put out 165 hp at the prop and will significantly outperform a stock 150 from the same model year. The 175 GT is a big bore bubbleback engine and most parts won't swap onto your powerhead. Adding a set of (NLA) rubber intake filler (322722) blocks will give you 5-8 more hp. Some composite reeds will make a nice addition.