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F-90 water in oil-I don't think it's the thermostat

whoano

New member
Hi, I'm new to your forum so thanks in advance for your help
I did a thread search last night and didn't find much information on this issue, so here goes
Went to change the oil in my 2005 F90 the other day and found alot of foam and sludge mixed in the oil. Scratched my head and said a couple of WTF's and hoped it was some sort of fluke. The engine had been bullet proof up until now. It seemed to be running fine when I put it up last fall. my boat lives in the garage during the winter. Last time I remember looking at the oil level was September and I don't remember getting the engine hot after that or ever for that matter. I live in Maine so i put up the boat in early November. Anyway, I wanted to complete the oil change and run the engine a little to try and see if I could flush out any of the sludge that was left behind in the sump. I did a complete oil change including a new filter. Again, I had the same results creamy motor oil. And I think there was way to much of it to be just left overs. I don't use muffs, I have a 20 gallon bucket that I drop the motor into and I run it that way. I don't think it's the thermostat because, the engine seemed to warm up at least the oil filter was warm after five minutes and the water in the bucket warmed up. I also don't think there was enough time to get enough condensation to make the milk shake that I had the second time around. What I didn't do was to check how much extra oil I got after each oil change. I have a six quart drain pan and each time there was room for over a quart. I called my dealer and he said he hadn't heard of anyone having a problem with head gaskets or the "bottom " gasket in a Yamaha. Any Ideas before I have to pay someone $80.00/hr to diagnose my problem. I'm a pretty good parts changer but I'm not a mechanic.
Thanks, Sid
 
Sid, I was about to start a new thread for the same problem,no I mean exactly the same scenario.A friend told me to check the plugs to see if any fouling may be occuring.The engine runs bettr than ever.I have an 01 F115. I know this wasn't any help but I will get to the bottom of this.
Good luck, Moonman60
 
Check my post to moonman. You may also have a t-stat issue and it will take some time to get the sludge gone. Makes a good case for changing oil before you put it to bed for the winter???
 
Sid, Googled "water in oil 115 F Yamaha and it was suggested to check the drainplug copper gasket.I did so and got rid of all the oil including the filter(its still dripping actually) so I'll reply when I feild test it.

Good Luck, Moonman60
 
Sure, it could be compromised head gasket. Do a leakdown test. It could be a cracked block, you live in Maine. It could be a cracked valve seat. It could be alot of things. Get back to basics, the best basic being do a leakdown and check the integrity of the cylinders.
 
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