I have an 04 Yamaha four-stroke 150 with 240 hours. It started idling a little rough recently. The mechanic I use said that it was probably an injector problem. Their lot is covered up with boats with ethanol issues.

He said that before taking the injectors off and sending them off to be analyzed that I might first try changing the fuel filters and running some injector cleaner through it, which I did � Seafoam.

After three brief outings running it the motor would run better then idle rough again. On the third outing it seemed to be getting better and better. When we loaded up on the third outing it was idling fine. Other than the rough idle issue it never ran bad above idle. The motor was running great.

We went out again the next day. Before unloading the boat I noticed oil in the splash well. I checked the oil and the crankcase is full of watery oil.

I called the shop and talked to the mechanic just minutes before closing for the weekend. He said that just sight unseen that it sounded really bad. He couldn�t think of anything right off hand that could be only minor. He said that I probably ran one of the injectors too lean a little too long.

I won�t have time to get it out to the shop before Wednesday. Does anybody have anything in mind that could be wrong with this engine other than total devastation? Help me sleep between now and Wednesday. Is there anything minor and cheap that could be the problem???

Thanks

Give Tommy a call at Rockwall Marine.

You say the "crankcase is full of watery oil"....is it creamy in color?

Did you drain the filters after each outing?

When was the last time the boat was used, before you started having problems?

The oil was creamy. I did however check the oil the very first time it idled rough. The oil was perfect.

I only changed the fuel filters after the first time it idled rough. I have one of those big Yamaha water separator / filters that goes in-line. It isn't the type of filter with the drain on the bottom. It is just a pretty big filter that resembles an oil filter. It is supposed catch stuff down to 10 microns. Plus there is the factory fuel filter on the motor.

The boat has been out several times a week since the first of May.

I forgot to mention that besides just a little oil in the splash well there is now a great deal of creamy, watery oil in the driveway under the motor.

sounds bad sorry to hear it

It sounds like you have checked the obvious areas....I would give Tommy a call next....he can most likely give you a good honest diagnosis from his experience.

What boat is the motor on?

I hate to bother Tommy since I use a shop here locally. I have known my guys here a pretty long time.

The suspense is killing me. I may not get it to the shop until Wednesday. And they might not get it in for another day or so.

The motor is on a 21' XPress X21B center console boat. I really baby this thing. I bet that probably 70% of my total running time is between 3,000 to 3,200 RPM's. I have thought that was a pretty fuel efficient speed. We do some tubing and ski some where the RPM's are a little higher. I bet that less than 1% of the running has been wide open. I have had the oil changed regularly.

Maybe it will be something minor....let's hope so.

Thanks for the feedback. I was really hoping that somebody could think of something minor that it could be.

Sounds like it blew a head gasket that would be the only way water could get into the oil...OPTI

That was my first thought, but my mechanic said that he doubted that. However, he still hasn't seen it.

I have a compression gauge. Won't a compression check determine if it is a head gasket? The motor otherwise was running like a top when I loaded up the last time.

Thanks Opti!!

yes comp check should tell ya if the head gasket is bad, look for major differences in compression.

I just did the check. I had a little trouble getting the gauge hose screwed in as tight as I wanted. However, it is a new gauge with new o-rings, so I think I got it tight enough. Here are the numbers starting at the top. The readings alone seem inconclusive to me.

1. 130
2. 149
3. 130
4. 139

Now the real kicker -- the top plug was soaking wet with water.

A compression test will show a blown head gasket if it is severe enough but a leak down will tell for sure if #1 is covered in water then it is either a blown gasket or a cracked head or even a stuck or burnt exhaust valve with a bad exhaust valve it could suck water back up the exhaust. One of the three....OPTI

After pondering over this a while I thought about the leak down test. No matter what happens it doesn't sound cheap.

Thanks again for the feedback.

If it were mine I would take it to the Boat Center in Flint.
They have helped me out with several issues in the past, quick turn around and no BS.
903 825 2293
Ask for Brian.