15 hp 4 stroke water in engine oil

[tkms002]

I have a year 2000 15 hp 4 stroke that overheated due to a broken impeller some years ago. I have since had a problem with what I think is water in the engine oil. After running it for 2 hours trolling the engine oil developes a butterscotchy yellow color. I don't use it a lot or I would have fixed it long ago. Question is, what is the most likely problem? Head gasket, cracked block. Anything else? Can I test it somehow to know for sure?
Any help would be deeply appreciated. I don't want to take it to a dealer at $175/hour if I can help it. Probably would not get it back for a month at this time of year.
Bruce

 

[alaskanassassin]

Re: 15 hp 4 stroke water in engine oil

It sounds like either a head gasket, warped/cracked head, or a cracked block.
Likelyness in that order. Do not run it anymore like this, water will wash out your bearings in the crankcase. Do a compression test to determine what cylinder the problem is. Buy a service manual and use it. I feel your pain, I am dealing with an overheat myself, but on a late model Merc 200hp with at least a head gasket failure, if not worse! Keep us updated..AA

 

[sschefer]

Re: 15 hp 4 stroke water in engine oil

It's probably normal.. All 4 strokes make oil to some extent when they get older. Some even do it from day one. Change the oil and filter often and you'll probably be fine. My 02 Nissan 18 did it. I'd check the oil frequently and change as needed. The motor ran like a bat out heck and is still running today without any problems. It wasn't uncommon for me to change the oil after 10 hours of run time. Not sure if my brother is changing it that often or not.

 

[alaskanassassin]

Re: 15 hp 4 stroke water in engine oil

My 2005 honda 2hp, 2003 honda 90, and 2001 yamaha 25hp never had water in the oil with a whole season's use. The 2hp eventually started milking up the oil as the head gasket went south. Watery oil in the crankcase or gearcase is not a good thing. I don't think it's "normal"

 

[CRFan1]

Re: 15 hp 4 stroke water in engine oil

That is definitely not "normal"!! I am gonna say you probably lost the head gasket when you overheated it which is the most common thing. A compression test will show if thats the problem.

 

[sschefer]

Re: 15 hp 4 stroke water in engine oil

That is definitely not "normal"!! I am gonna say you probably lost the head gasket when you overheated it which is the most common thing. A compression test will show if thats the problem.

Pull the plugs and look at the piston. If it's shiny clean you have a blown head gasket. If it looks normal then you're just making oil. If you're not making oil at an alarming rate then just change it a little more often. If it bothers you a lot then rebuild it.

Using a little common sense will keep you from lightening your wallet.

 

[tkms002]

Re: 15 hp 4 stroke water in engine oil

Well, the crankcase oil turns butterscotch yellow after 2 hours or less of run time. Didn't have this problem before the overheat. Hoping for the head gasket.
Thanks
Bruce

 

[alaskanassassin]

Re: 15 hp 4 stroke water in engine oil

A head gasket will probably do it. On some motors, it's not that big of a job. Let us know what you find.

 

[tkms002]

Re: 15 hp 4 stroke water in engine oil

If the leak down test is good, what does that tell us?
Bruce

 

[sschefer]

Re: 15 hp 4 stroke water in engine oil

If the leak down test is good, what does that tell us?
Bruce

Rings, cylinder walls, head gasket, head, valves, valve guides, piston, are probably o.k.

 

[tkms002]

Re: 15 hp 4 stroke water in engine oil

So, does that leave us with a cracked block? If so, can I somehow run some stop leak through the system?
Bruce

 

[sschefer]

Re: 15 hp 4 stroke water in engine oil

Honestly, I don't know the cooling system on that engine well enough to say for sure. If the compression test is good and the leakdown test is good then that suggests to me that there's a problem in the block. Problem is, there's only one way to find out.

 

[tkms002]

Re: 15 hp 4 stroke water in engine oil

O.K. so I pulled the spark plugs and the tops of both pistons look quite rusty. Does that tell us anything?
Bruce

 

[tkms002]

Re: 15 hp 4 stroke water in engine oil

Well, I replaced the head gasket and even thought the old one looked fine all is well now.
Thanks
Bruce