Blew up engine. What happened??

[Jonzed]

I have a 97 hydra sport with a 97 evinrude 115 on it. Me and my cousin was fishing a tournament Saturday and running up the lake at wide open throttle. Then it happened! Motor immediately bogs,knocks and shuts off! It starts back but is running bad. Get it home run a compression check and # 4 had only 30 psi compression. Tore it apart today and found that #4 top ring had broken and and ruined cylinder, piston and head. Why did this happen???? I know for sure the oil/ gas mixture was good because the VRO is removed and I mix it every time I use it. Looking for answers because I don't want this to happen ever again. How much does this cost to get fixed?

 

[salecreekaviator]

Don't know the cost but wrenchin2 is your man with plan!!

 

[SNUFFY]

the carbon buildup behind the ring finally pushed it out far enough to catch the edge of the port as it went by ! Sad to say but is very common occurence in the older Johnson 4-cylinders.
You can use a carbon guard type additive and decarb regularly will probably keep it from happening again.
Also I switched to using a sythetic oil to mix. Much less carbon !
If it didn`t score the cylinder too bad, you can probably hone it out or bore it and oversize the piston. Heads and parts are pretty plentiful for those engines because they made millions and a lot of years interchange. My thinking on these is if you have split the cases you should do a complete rework of the engine because the gaskets set it fairly expensive. That`s not to say you have to replace pistons and everything but get with some that can evaluate tolerances and that kind of thing. Rings and bearings are relativly cheap insurance to keep from having to do it again and keeps everything in more balance powerwise.

 

[EricM]

Good advice.

 

[fischnrod]

http://chattanoogafishingforum.com/forums/thread-view.asp?tid=66772&posts=5

 

[488.5]

SNUFFY - 9/23/2012 10:27 PM

the carbon buildup behind the ring finally pushed it out far enough to catch the edge of the port as it went by ! Sad to say but is very common occurence in the older Johnson 4-cylinders.
You can use a carbon guard type additive and decarb regularly will probably keep it from happening again.
Also I switched to using a sythetic oil to mix. Much less carbon !

YEP. Carbon buildup has destroyed more engines than anything else. It is absolutely necessary to decarb these motors yearly unless you are using XD100 or other synthetic oil. Sorry for your misfortune.

 

[michael]

I feel your pain I have blown 4. 1st-$2400 2nd-$2800 3rd-$3000 4th-$3600 all because they were not put back together rite. make sure you have a dependiable mec. like wrenchin2 who knows what hes doing .He told me why mine kept blowning and its the best its ever been emoWorthy 2 years and counting

 

[dragfish]

Oh- I miss the old days when Wrechin would have been on this like mexicans on a mini-van! He would give you a reply longer than one of JMax's fishing reports!
Look him up and I hope you find him, he is thorough and resonably priced.

A lot of the old veterans have faded away from the site-and I'm sure a few are waiting for me to! emoToast

 

[derek81]

dragfish - 10/4/2012 5:58 PM

Oh- I miss the old days when Wrechin would have been on this like mexicans on a mini-van! He would give you a reply longer than one of JMax's fishing reports!
Look him up and I hope you find him, he is thorough and resonably priced.

A lot of the old veterans have faded away from the site-and I'm sure a few are waiting for me to! emoToast

I've wondered what happened to him, I know he went back to work full time but I never see him post any more.