Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

8

87Chap

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Joined
Apr 8, 2009
Messages
16
I have a 1988 Johnson GT 150 Outboard and that i recently bought with a chaparral. today i took it out for the third time this year. (the previous two times it ran flawless)

We put the boat in the water and let it warm up as i usually do and then headed out. get past the no wake zone and ease onto the throttle we get running good and then all of a sudden its kind of a little bit of a pop and the engine sounded like it was working really hard and then shut off.

it took a few minutes but the engine started back up and was vibrating the whole boat and it took forever to get it back to the ramp. it sounded like metal was hitting metal in the engine (the sound came and went) but the boat was shaking really bad the whole time :mad:

Any help would be greatly appreciated!! thank you
 
T

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

The first thing to do is a compression check. The second thing to do is drain the lower unit oil, and check it for metal.

Unfortunately, if something let loose in the engine (like a broken ring), it was probably severely damaged by running it for so long after it happened. If you get a low reading on one of the cylinders, then take the cylinder head off and find out the damage.

Or if the compression is good, and there is no metal in the lower unit oil, it could be a sheared flywheel key. That's not a huge deal. Just check the compression first.
 
8

87Chap

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Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

thanks i will def. do that and i will let you know how its looking.
 
8

87Chap

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Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

we drained the lower unit and found a good bit of metal shards and some water in the lower unit. we removed the lower unit to find that the reverse gear is completely toasted and the two others are in pretty good condition. but all of the bearings were busted and rolling around in the lower unit. we removed all the extras and cleaned it up.

now i am confused at what i should do. i have it completely apart. so my question is would it be cheaper to buy the parts myself and put it back together (taking apart it was easy, looks like its going to be harder to put it back together) or should i pay some one to put it back together?
 
D

Dhadley

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Feb 4, 2001
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16,978
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

Do you have the shim tool? If so, do it yourself. If you don't have access to one you may want to have someone do it.
 
8

87Chap

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Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

i don't have that tool. what does this tool do? and any ball park figures on how much this might cost at a service shop? thank you
 
F

fixmyevinrude

Petty Officer 1st Class
Joined
Sep 18, 2008
Messages
205
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

That will depend on several things. Do you have a manual? Are you good at reading technical writing? Insurance may cover it if you have insurance. I would think you would have to had hit something for the insurance to cover it though. How much are the parts going to cost you? Are you sure all the bearing surfaces in the LU are OK? Are you sure there is no cracks are fractures in the LU? First thing I would do is get a manual and read the procedure to make sure you are comfortable with the job and that you have the proper tools. Next I would check my insurance coverage. Third I would post some pics and ask the experts here on this forum. Hope it all works out well for you.
 
J

jonesg

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Joined
Feb 22, 2008
Messages
7,174
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

Take a look on ebay and craigslist for used lower units, its usually a lot cheaper than a rebuild even if you buy parts yerself.

Its not so bad, coulda been a $2500 powerhead job.
 
8

87Chap

Cadet
Joined
Apr 8, 2009
Messages
16
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

ya thats what it looks like im am going to have to do. thanks for all of your help. to those who posted! ill let you know how it all goes
 
Sandhammaren05

Sandhammaren05

Banned
Joined
Jul 30, 2008
Messages
172
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

Most likely: broken piston ring.



87Chap said:
I have a 1988 Johnson GT 150 Outboard and that i recently bought with a chaparral. today i took it out for the third time this year. (the previous two times it ran flawless)

We put the boat in the water and let it warm up as i usually do and then headed out. get past the no wake zone and ease onto the throttle we get running good and then all of a sudden its kind of a little bit of a pop and the engine sounded like it was working really hard and then shut off.

it took a few minutes but the engine started back up and was vibrating the whole boat and it took forever to get it back to the ramp. it sounded like metal was hitting metal in the engine (the sound came and went) but the boat was shaking really bad the whole time :mad:

Any help would be greatly appreciated!! thank you
Click to expand...
 
H

HybridMX6

Senior Chief Petty Officer
Joined
Oct 22, 2008
Messages
676
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

Have you not read the rest of the post?

Saying that, did you (87chap) ever do the comp. check? Just curious, hoping it's not a double whammie sort of thing. Hate to drop several hundred on a good used lower only to find out the powerhead has issues too. Better to check now if you can, before dropping money on something possibly not worth fixing.
 
8

87Chap

Cadet
Joined
Apr 8, 2009
Messages
16
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

no i havent donea a compression test yet. i was planning on doing one in the next couple days. But after looking at the lower unit it totally makes sense that this seems to be the problem. i could be wrong (that has been known to happen. but always better to be safe than sorry so i will def. do a compression test while i am working on it to make sure there is no problems.
 
H

HybridMX6

Senior Chief Petty Officer
Joined
Oct 22, 2008
Messages
676
Re: Blown Piston???/ Johnson ENGINE TROUBLE Please Help!!!

I do agree it most likely was the lower unit, but as you said, better to be safe than sorry.
 
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