Oil clean on stick came out milky

[brisboats]

I am stumped I bought a 5.7 liter 260hp mercruiser long block to put in a ski boat. Ran the engine on the stand and the oil was always real clean on the stick. Installed engine and have run on the hose for several at least (5) 5-10 minute intervals. Shut down and upon checking the oil on stick always clean. Today I am changing the oil for this weekend check stick and oil is clean begin to use the oil suction sump and notice it now appears to be coming out light brown. Dump the reservoir and start over thinking there was water in the suction device prior to my engines oil. Remove the remainder of the engine oil and it is milky. Reinsert / Check the stick and it too is all milky, heart sinks and I reach for a beer. Engine did sit for two years before I got it. Can the engine be run without emulsifying water in the crankcase? Tomorrow I will flush change the oil and filter run the engine and recheck. The oil level never rose in the time I have run the motor nor did it turn milky until I inserted the suction device and began extracting. Half thinking I should have left the old "clean" oil in and gone boating as the oil has always been clean and clear until I went to change it.

Any thoughts? suggestions appreciated

Brian

 

[captmello]

Re: Oil clean on stick came out milky

Hummmmm....

You may need to pressure check the block for leaks.

Could your motor have ingested water last time out? May want to pull the plugs and see it there is water or signs of it.

 

[wca_tim]

Re: Oil clean on stick came out milky

not sure i understand exactly, but are you saying you ran it on the stand with no problem, but that it is picking up water in the boat now?

if that's the situation, what's different now? are you using the same exhaust manifolds and so on? and how much water are we talking here? Just a little can come from condensation.

I second the above on checking plugs...

 

[jtybt]

Re: Oil clean on stick came out milky

Just thinking out loud...

It would probably take quite a bit of short start/stop and not letting engine to warm up fully to create as much condensation to cause as much as described...and then it would also show up in places like the oil fill cap.

I can't think of a cause for your problem short of a cracked head/block, head gasket or intake manifold leak just a few seconds before you shut down.



Compression test time!

 

[proxyx]

Re: Oil clean on stick came out milky

for testing you need oil change... suggestion instead of regular oil, dump in 30w hd gasoline grade - from bottom shelf, much cheaper to experiment with (50% less). Could be rain water through the carb/intake in optimistic scenario. The rest as per other posts.

 

[brisboats]

Re: Oil clean on stick came out milky

Thanks for the replies. Think I have this licked or at least hope so. Anyway a little more history..I checked oil level and ran the motor with the center rise cast iron manifolds when I bought it ..no milk. When dressing it out I did change manifolds , But ran the engine with aluminum ski boat manifolds still no milk...Have never had the boat out on the water and when I went to change the oil last night it came out milky but the stick prior to had clean oil...hmm. So last night I drained the oil refilled it and ran this morning on the fake a lake still had light brown oil. Flushed again changed the filter and clear oil ran over 3 times at least ten minutes each so changed out the oil and filter and ran several times again oil is clean and not rising on the stick (three times a charm). In between oil changes I also checked my plugs no water and compression tested 145 pounds all round, my aluminum manifolds were pressure tested too before install. I have not pressure checked the cooling passages of the block to be honest i have never done that and had such a nice block externally that i really wasn't suspect of a problem until last night.

All I can figure is this motor had some water /condensation in the bottom of the pan that did not get agitated until I began to evacuate it even though the motor was run a few times on the stand and when first dropped in . Yes lots of start and stop runs on the motor lately as I dressed the motor to go in a inboard vs i/o and ran it several times in the process but never in the water. I haven't left any opening for rainwater that I know of spark arrestor always in place engine cover on and boat covered but that doesn't mean some hasn't gotten in prior to me buying the engine. I did change out the carb and saw some light rust in the intake so should have been put on notice then but i thought it looked like condensation caused it. Hope I am dodging the bullet and hopefully will water test tomorrow keeping an eye on the stick. Next time I think I'll drop the pan when the motor is out and have a look if I go through this process again. Feel stupid in that changing the oil and filter should have been done from the start but every time I checked the stick there was clean oil and figured I would do it just before the boat hit the water. So far I have run this last batch of fresh oil over 30 minutes without any indication of water. So fingers crossed.

Brian