25 Yamaha water in oil

[RHeathman]

I have a 2003 Yam T25 4 stroke that is getting water in the oil. Quite a bit of it - enough to turn the oil milky. I doubt that it is "making oil" because I'm putting in 1.4 liters and getting almost 2 back. I used it for about 40 hours mostly *****ing but with about 20-30 minutes high speed running time each day. The motor runs perfectly, no dark smoke, no white smoke, no missing- even at very low rpm. Spark plugs are both identical with normal carbon deposits. I pulled the bottom off and the impeller is in great shape. There are no hot paint issues on the block or any other evidence of over-heating. The temp light never came on. I don't know the number of hours on the motor but it seems in great shape: it had 180# compression in each cylinder about 40 hours back. I haven't done a leak down test.
I pulled the power head off and there is no obvious breach in the metal base gasket. I'm reluctant to go into the head as it has no symptoms of a head gasket breach, and it gets increasingly expensive for gaskets the more I pull it apart. Given the configuration of the oil pan, I have my doubts its the pan gasket.

Given the symptoms above what's the most likely cause of the leak?

[Nadinayammy]

Assuming it is eng oil, not bottom end oil? could it be fuel in the oil? Oil should smell like gasoline? If so....carb float sticking?
If water in bottom end oil...prop shaft seal is leaking. Good luck.

[RHeathman]

Thanks for the response.

It is clearly water in the oil pan. Very milky, no gasoline smell. On this model the shaft does not go through the oilpan, so very unlikely to be a seal on the shaft causing it.

I have now taken the cylinder head off and found nothing amiss. No cracks and no gasket problems. I am now pondering whether to dissassemble the upper leg and take off the pan gasket......

[T'boro Fisher]

Not to hijack your thread but I just found the same issue today with my 2005 T25TLRD. The oil has always remained clean (Yamaha oil and filter) and I change once a year or about 25 hours for me . Went to leave to go fishing this morning and found oil milky. Last couple of times out this year it has only been idled or at most ran at under 2,500 (No Wake areas fished), outside temp was only 40 with water temp of 50 and I'm wondering if it is just condensation? Same as OP the engine starts and runs fine and only thing slightly unusual I noticed was a little extra stream out of the engine last time out.
Did you figure anything out on yours, before I get panicky and start pulling mine apart?

[RHeathman]

That oil looks just about the same as what came out of mine. One last little thing, to make sure you get it all out, the motor must be tipped well over backward (you might have to jack up the tongue of the trailer) and let it drain for a long time. Even a little bit of water left will make it look murky.

[T'boro Fisher]

Thanks for the tip. I drained it today with the motor full tilt down and left it open for about 2 hours but will open it back up and tilt the tongue.
I'm going to grab a couple of quarts of Yamaha oil and a filter this week and probably flush a little fresh oil thru it, then run in in my tank and see if it gets milky again.
Did you find anything on yours that would indicate where it's coming from?

[rodbolt17]

lots of ways to get water in the oil.
one is from long periods of low speed operation with a defective/missing t-stat.
easy check.
another is a head gasket leak.
another is the oil sump to powerhead adapter or powerhead adapter to powerhead.
remember, the oil sump is water cooled.
you cant tell if its leaking by simply looking at it.

[T'boro Fisher]

Ok new information on my issue;
Talked to me local dealer and told him about my concerns, he asked if I had been running the engine at idle a lot and I told him I had and his response was that it was very likely just condensation. Just for information purposes; I have ran this engine in similar conditions for the last 5 years without this problem (if it is one).
So I bought a new oil filter and changed the oil & filter and took the boat back to the lake yesterday (water temp 57 - 58 and air temp 60). I made an effort to run it at full revs and avoid any idling (except to warm up off of trailer). Pulled the dip stick after about 1/2 hour of run time and oil looked fine. Ran about an other 1/2 hour and loaded on trailer. When I got it home and checked oil after it had cooled down the oil was slightly milky. I pulled the plugs today and found the top cylinder plug to be cleaner that the bottom (in my old auto racing days we would assume a water leakage problem / see attached picture). I then pulled a compression check and had 105 psi on top cylinder but could only get 85 psi on bottom. Used my blow-by detector on both cylinder and when I got top cylinder to TDC I had a slight air leak out of weep hole. Tired the same think on bottom and had yet a slighter leak out of weep hole. My automobile engine thoughts would be I have a head gasket going bad, am I guessing right?

[RHeathman]

Looks like you have done your homework to me. I don't know what else you would do to isolate the problem. If you put a new head gasket in it, and the water persists, then you could change out the power head gasket next.

[TownsendsFJR1300]

I then pulled a compression check and had 105 psi on top cylinder but could only get 85 psi on bottom. Used my blow-by detector on both cylinder and when I got top cylinder to TDC I had a slight air leak out of weep hole. Tired the same think on bottom and had yet a slighter leak out of weep hole.

Excuse my ignorance, but what weep hole?

In any case, the compression is low / uneven.

If the weep hole is part/goes into the water jacket, sounds like you found the leak, agreed the head gasket.

Your cleaner, ONE spark plug, also confirms your suspicions...

[T'boro Fisher]

The pee hole I guess would be a better definition.
Yea, as much as it pains me I guess I'll call my dealer tomorrow and ask him about getting it in for a head gasket. I have the service manual and thought about tearing into it myself but not sure I would have the time to get to it.

[TownsendsFJR1300]

Yep, a leak down test with air coming out the pee hole, is NOT good. Hopefully its just a head gasket.

Any overheats???

[rodbolt17]

retest.
place the lower unit in a barrel of water.
tape off the idle relief port and the tell tale.
do the leakdown test and watch for air bubbles from the exhaust.
if you get air bubbles either the head gasket is leaking or an exhaust valve is leaking.
either will allow water into a cyl.

[T'boro Fisher]

OK, just to report on my results; It ended up being a warped head and head gasket issue. The head was about .020 warped in a couple of spots and you could just see a couple of questionable places on the gasket. The cylinders looked great (no ring groove at all). Milled the head, replaced the gasket, and put a new set of plugs in it. Ran it for about an hour in the tank and no water in the oil, mission accomplished.

[rodbolt17]

double check the cam belt.
make sure the deflection is still within spec.
as you mill the head it makes the belt looser.