Puddle of oil in bilge

[scottinsydney]

Checking 12v71 engines today after being away and the starboard engine room had different smell. Dipstick showed oil was way way below the low mark. I had checked oil ok previously 2 weeks ago and had not used boat since. My engine bilges are always as clean as possible

Then I saw a big puddle of black oil in the bilge. Checked all oil hoses and fittings. And gearbox hoses and fittings. Filters were tight. Few drops on bottom of manifolds, but they are always there and not bad enough to put 1.5 gallons of oil in bilge. An oil smear was under where starter motor bolts to bell housing. Where else is possible?

Am using boat this weekend and have oil pads everywhere to find source.

Any suggestions please?

[Dan Mapes]

Turbo return lines? Hopefully the oil pan didn't rust through but that is a thought. Once cleaned up I'd be looking around with a mirror and bright light.
1.5 gallons lost while sitting around is quite a bit!

[dottieshusband]

Scott, if it's leaking oil just sitting these, then a few things to check... Oil exchanger connection to oil pan, and line. Lower oil pan drain plug. Lower Pan gasket. Lower forward flat plate on upper oil pan gadget. Dip stick connector to upper oil pan. Upper oil pan gasket (hope not), rear crank seal. but like the say, if it doesn't leak, it doesn't run!

[Pascal]

That’s a lot of oil just sitting. I d think twice about leaving the dock ...

Did you check the plug or valve or oil change hose connection? That s the only thing that could leak that much oil without running

[kelpy]

1.5 gallons or 1.5 drops of oil is too much leakage from an idle engine. The oil level when full should be below the pan - block interface. The turbo lines are empty. Yet you say engine oil level is low. It would have to be coming from somewhere below the top edge of the pan. Drain plug loose. Oil change line split or loose though there should be a valve at the pan that only gets opened when changing the oil. What else is there?

[racclarkson@gmail.com]

1.5 gallons or 1.5 drops of oil is too much leakage from an idle engine. The oil level when full should be below the pan - block interface. The turbo lines are empty. Yet you say engine oil level is low. It would have to be coming from somewhere below the top edge of the pan. Drain plug loose. Oil change line split or loose though there should be a valve at the pan that only gets opened when changing the oil. What else is there?

Turbo drains on 1271s are below full oil level and are a common leak. Possible one of the two 3/8” bolts loosened?

[DCMY #92]

After checking all the other suggested items, it's possible the pan is leaking. If the 12-71 is like the 6V53 the pan is cast iron about 3/8" thick, so there is not much chance it will rust through, but it could crack. When I bought our Hat 30+ years ago the oil pans were seriously rusty, so I jacked up the engines and removed the pans to clean and paint them. I discovered that the starboard 6V53 oil pan had a 3" long through-wall crack at what appeared to be the seam in the sand mold used to cast it. I sealed the crack on the outside of the pan with JB Weld and fiberglass web. No more leaks.

[kelpy]

Some are cast iron and some are cast aluminum. The engine tag will specify which. In all cases, they are a PITA to remove.

[oscarvan]

Some are cast iron and some are cast aluminum. The engine tag will specify which. In all cases, they are a PITA to remove.

Does the engine have to come up?

[kelpy]

It will have to come up if it is a v configuration to remove it. You might be able to lean it over if it is a inline block. I have done it both ways.