Yamaha T-50 oil in gas, rings ok???

[Bob_T]

I have a 2000 year Yamaha T-50 (4 stroke, high thrust) that has gas in the oil. The engine has about 125 hours on it now and has very little use in the past two years. I winterize it myself at which time I fog the engine, change the oil and filter, etc.<br /><br />Last summer, I went to check the oil and noticed the oil seemed thin, a little overfilled, and smelled of gas. I changed the oil and didn't think too much more about it it. In the fall, I changed the oil when laying up for the winter and didn't notice (but wasn't really thinking too much more about it) any gas in the oil at that time.<br /><br />This summer, after only a few hours of use, I checked the oil and noticed it was thinned out and smelled of gas.<br /><br />After reading some of the posts here and on other sites, I'm very concerned that I have a major problem, possibly with the rings. I don't beleive this was going on the first couple of years of ownership. Also, I did break the engine as specified in the owners manual. So I'm thinking the rings did get seated properly.<br /><br />The one thing that has been different is I have started to store the boat with the vent cap on the gas tank closed thinking it cut down on fumes in the garage.<br /><br />So, after all of that, I have a couple of questions that hopefully someone can answer for me. First, is it possible that storing the boat with the gas vent closed and the fuel line connected to the engine (I've never disconnected it) could cause fuel to be forced into the carbs and then into the engine when the tanks get warm and expand? If so, or if for some other reason gas is accumulating in the carbs or fuel system, is it possible the fuel would get past the rings even if they were not heavily worn? Finally, will a compression test give me a reasonable indication if the rings are worn, not properly seated or whatever?<br /><br />I was going to test the compression tonight but found out the compression tester I borrowed does not have the right size threads on any of the adapters. I'm planning on buying a new one to test the engine. If all cylinders seem about the same and decent (not sure what it should be), I will change the oil and filter, start storing it with the fuel line disconnected, and see what happens.<br /><br />Any and all thoughts or answers to my questions would be most appreciated. Sorry for such a long winded post.

 

[DJ]

Re: Yamaha T-50 oil in gas, rings ok???

Read this.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=30;t=003494

 

[Bob_T]

Re: Yamaha T-50 oil in gas, rings ok???

I did read the post on the 115 but am wondering if it is possible that I'm having a different issue since it never seemed to be a problem in the first couple of years and about 90 hours of service. Also, I'm wondering if a compression test will verify if the rings are in fact bad.<br /><br />Although I'm new here, I did a lot of searching in hopes of getting some of my questions answered before my long winded post.

 

[JB]

Re: Yamaha T-50 oil in gas, rings ok???

Moving to Yamaha Troubles.

 

[Bob_T]

Re: Yamaha T-50 oil in gas, rings ok???

Thanks for moving this to the right area JB. I thought I was posting it under Yamaha Troubles but guess I screwed up.

 

[LubeDude]

Re: Yamaha T-50 oil in gas, rings ok???

If you have some carb issues, the fuel could drain down past the rings as it is stored, do you store the engine in the down position or trimmed up. I would park it with the engine tilted up so if the fuel was leaving the carbs, it couldnt get into the cylinders. May just need a carb rebuild. You do need to figure it out and keep changing your oil while you figure it out.

 

[Bob_T]

Re: Yamaha T-50 oil in gas, rings ok???

Thanks LubeDude for the thoughts. Yup, I keep the engine stored in the down position so it will fit in my garage.<br /><br />I'm going to change the oil to get the gas out of it but am wondering if I need to change the filter. It only has about a couple of hours on it since the oil and filter was changed. I'm thinking if I unscrew the filter and dump out as much oil as possible and reinstall that I am probably ok. Do you think this is ok or should I just go ahead and replace the filter with a new one?

 

[LubeDude]

Re: Yamaha T-50 oil in gas, rings ok???

Originally posted by Bob_T:<br /> I'm thinking if I unscrew the filter and dump out as much oil as possible and reinstall that I am probably ok. Do you think this is ok or should I just go ahead and replace the filter with a new one?

I am sure you are going to get someone tell you to replace the filter, but I would do as you are saying. The small amount of fuel that is in the oil will not damage the filter.<br /><br />Also, I know that it is the common understanding here that it is a bad Idea to run the fuel out of a two stroke before storing, but I see no reason you couldnt run the fuel out of your fourstroke when done running it. I actually did it for years on a two stroke with no problems, (gaskets drying out, varnishing, etc), You should get more advice, pro and con on this issue shortly.<br /><br />The main thing is finding out why it is happening in the first place.