Water in oil

[gleneagle]

I have a 2004 nissan 6 hp 4 stroke. It runs and starts really well, 1st or 2nd pull and idles and accelerates great in a tank with no smoke or missing of the engine, but my oil is milky and bubbly. I've change the oil several times. My first thought is a blown head gasket or a cracked head. Is there other options as to what or how water could be getting into the oil? Also what would someone expect to pay to have a head gasket changed?

Thanks for any help,

 

[pvanv]

Re: Water in oil

Possible bad head gasket, or base gasket, or a crack in the block or head. If you idle extensively, especially in very cold water, too much blow-by could cause oil gain and frothing. What is the level on the dipstick? Should be about half way. Labor varies, but can be upwards of $100 per hour.

 

[gleneagle]

Re: Water in oil

Possible bad head gasket, or base gasket, or a crack in the block or head. If you idle extensively, especially in very cold water, too much blow-by could cause oil gain and frothing. What is the level on the dipstick? Should be about half way. Labor varies, but can be upwards of $100 per hour.

The last time I changed the oil I filled it up to the minimun mark and ran engine engine about 20 minutes , idle, half speed and full throttle) and oil level had risen to the top full mark. what is the base gasket? sounds like it might be worth doing a leak down test on before taking it to a shop? Would engine run as well as it does if the block was cracked? there's no sign of any leak under the cover either.

 

[gleneagle]

Re: Water in oil

Possible bad head gasket, or base gasket, or a crack in the block or head. If you idle extensively, especially in very cold water, too much blow-by could cause oil gain and frothing. What is the level on the dipstick? Should be about half way. Labor varies, but can be upwards of $100 per hour.

The last time I changed the oil I filled it up to the minimun mark and ran engine engine about 20 minutes , idle, half speed and full throttle) and oil level had risen to the top full mark. what is the base gasket? sounds like it might be worth doing a leak down test on before taking it to a shop? Would engine run as well as it does if the block was cracked? there's no sign of any leak under the cover either.

 

[pvanv]

Re: Water in oil

A leak-down test (assuming you have a leak-down tester) would help to identify a cracked head or bad head gasket. If you got that much water in the oil in that short a time, it should be reasonable to find the leak. There is a gasket where the powerhead attaches to the exhaust housing, and also one at the bottom of the block, where the oil pan attaches. Either of those could cause a problem such as yours. Yes, if compression is good, and the leak is strictly from the water jacket into the oil, it should still run OK. Are there any indications of water seen on the plug ("steam cleaned" look" or condensation droplets)?

 

[gleneagle]

Re: Water in oil

The plug looks normal with no effidence of steam cleaning. I have had 2 people suggest it could be a thermostat? Is that possible?

 

[pvanv]

Re: Water in oil

Doubtful. If your stat stuck shut, the motor would overheat. If it stuck open, the motor would run too cold, especially in winter. While a cold motor would promote condensation, it could also cause plug fouling, and might require extra choking. You indicated that the plug looks normal, and you haven't mentioned needing a lot of choke. An IR thermometer can tell you a lot about crankcase temperatures, but I would not be expecting a stuck-open stat with your symptoms.

 

[gleneagle]

Re: Water in oil

So I took my thermostat out and it is open. I assume upon shutting the engine off the thermostat would automaticly close? There was some debri in the thermostat also. I do not need very much choke to start or run the engine, it idles very well also. usually starts cold with choke out and only takes a couple pulls. once started push in choke half way and run for a few seconds then push it in all the way in. starts next time without choke.

 

[pvanv]

Re: Water in oil

You can test a stat by putting it in a pan of water, and warming it up to about 150F on a stove top. Should be closed at room temperatures, and fully open by about 160F.

If it is stuck open, you need a new one. 3H6010300M, THERMOSTAT, $30.07, available from any dealer, including me. While you're at it, get a gasket for the stat cap as well: 346010320M GASKET, THERMOSTAT, $1.30

 

[gleneagle]

Re: Water in oil

Have one on order, there's no dealer in my area. I'm obviously no outboard mechanic but I still have a hard time believing that this is causing water in the oil?

By the way thanks for all the help.

 

[pvanv]

Re: Water in oil

You probably have more than one problem. If the stat is bad, get a good one installed, and then continue to diagnose. Is the telltale flowing properly? Was the motor ever overheated (could cause a thermostat failure, and could cause a bad head gasket)?

 

[gleneagle]

Re: Water in oil

Not sure if it was ever overheated, I just bought the motor and forgot to take a look at the oil before purchase. We ran it at the time and it ran so good I didn't think to look at the oil. The previous owner stated it was to short for his transom for the reason for selling. Possible if motor was cavating because of being to short that it might have overheated? I'll put a new thermostat in and see what happens. Telltale is good, plenty of water flowing.