Suzuki DT140 - Bad Cylinder

[Pavu]

I'm new to the forum, and trying to find some help, I've found a lot of good info but I have a couple of questions. I bought a boat with a Suzuki, Outboard, DT140 (140 hp, inline 4), 1998, Oil injected & fuel injected with 296 hours on it. The previous owner (my boss) told that the last time he had it out, that the motor would run at low RPM, but when he would try to get above 3000 rpm it would loose power, he took it to his mechanic and he pulled the head and told him it has a bad cylinder and the others were carbonized and that HE would probably rebuild the whole thing, and the only reason he could give him why it went bad was it must have been some bad oil. My boss had a problem with that since he took good care and good maintainece of the boat and motor, so he sold it to me. ;-)<br /><br />I've removed the head and yes the second from the bottom cylinder has some light grooves in it, however it doesn't look that carbonized to me.<br /><br />My buddy can help me pull the powerhead and we can have the bad cylinder resleaved and fix the problem, however we are concerned that we will only be fixing the problem and not the cause of the problem. I'm new to working on boat motors, so any advice on what to do, what to look for, etc.. would be greatly appreicated.<br /><br />Thanks!<br />Paul

 

[Pavu]

Re: Suzuki DT140 - Bad Cylinder

I had someone tell me that it could be a oil line check valve going to that particular cylinder, but after looking and reading, my particular year and model (98 DT140) only has one check valve going from the oil pump to the VST (vapor separator tank) so I'm still confused as to why one cylinder would have grooves in it and the other three wouldn't.<br />Thanks!

 

[Pavu]

Re: Suzuki DT140 - Bad Cylinder

OK, I have a friend that says he thinks the rings stuck on the piston and caused the scratches, and to spray some decarbonizer on the piston and rings, get a cylinder honer to clean up the cylinder and put the head back on see what she does. If it works, I saved a bunch of time and money, if not I was going to take the motor apart anyway. Does anyone think this is a good idea or bad idea ? Obviously I could hurt the motor but do you think this would totally damaged the motor beyond repair. ANY advice would be greatly appreaciated !! Thanks! Paul

 

[And1fixer]

Re: Suzuki DT140 - Bad Cylinder

Do a search on "rings " and "Cylinder". You will find alot of good information there.

 

[DJ]

Re: Suzuki DT140 - Bad Cylinder

Read this.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000006

 

[rodbolt]

Re: Suzuki DT140 - Bad Cylinder

a hone in place is a bad idea<br /> most the time if it did not take out the crank it was fuel or heat related. suzuki runs a very close fit on the piston to wall. best you can do is a complete dissaasemble. clean and inspect. the crank is a built up model and any suzuki or motor cycle shop can check rod big end play. I usually replace all 4 pistons on rebored cylinders and replace the wristpin bearings if the crank checks out ok. onec its running and you have a new water pump and t-stats run it on 50-1 premix and do an oil consumption test. a clogged vapor seperator filter or an injector filter can run it lean and scuff a piston as well. maybe fridays marine can help more. I dont deal with suzukis mush anymore in this area. no dealers. worked for suzuki when I was in Norfolk VA.<br /> right now you may have something rebuildable. try a hone in place and odds are you will have a junker. is the damage so bad that a .5mm overbore wont clean it up?

 

[Pavu]

Re: Suzuki DT140 - Bad Cylinder

Thanks guys, I had read the decarbing FAQ topic but I wasn't sure if I could do anything else (or better), since I already have the head off. I'll skip the honing and see if the decarbing fixes the problem if not, I go to plan B, tear it apart. It will probably take me a couple of weeks to get enough free time to do this, so if anyone else has any suggestions, let me hear them. <br />Thanks a bunch !!<br />Paul