12v71TI Oil Leak

[scottinsydney]

The starboard engine has always leaked some oil into the bilge. Over the past couple of years this seems to be increasing. Today I now have more than a gallon of oil in the bilge and I have watched the dipstick oil level go down after a recent 4 hour run.. Not good. There is obviously a very good drip of oil.

But I cannot find the leak! There are small drips here and there but nothing obvious. Ive bought an inspection camera today to view under the motor but it all seems dry with the exception of the inacessible sump oil drain fitting which has a hose connected to it for sucking out the oil. Maybe thats it.......

Where else do I look? Gearbox is dry. Airbox drains? Rocker gaskets? There must be some known trouble spots on the 12v71?

There is some blue smoke that clears when starboard motor is run up. Turbos were recently inspected by mechanic and oil free.

A new mechanic is booked for August (our winter) to remove and service starboard intercoolers. We can check blower seals at the same time.

But for now any and all suggestions to find the oil leak are welcome.

Thanks.

 

[Captain Ralph]

but it all seems dry with the exception of the inacessible sump oil drain fitting which has a hose connected to it for sucking out the oil. Maybe thats it.......

.

Well, That is one of the main issues of the turbo oil drain/return hoses that fraking return to the oil sump. If not the hose, the hose-nipple adapter to the sump wall is leaking.
It is rite at the cold (not running) sump oil level and its old paper gasket will start leaking (pouring) when the hose gets leaned on (like for a turbo inspection?).

Order fresh gaskets, next oil change, pump the oil out, replace the gaskets, reassemble.
Just remove the two bolts that bolt the nipple plate to the sump.
Do not try to remove the hose from the hose nipple. Do not bent that hose. Pandora's box will explode on you and you will be replacing the hose.

As long as I'm talking about that turbo oil return hose, Never, never, never let a hose shop make new hoses with new hose end fittings.
The original hose end fittings have a special thread, and must be re-used.
Also the exact lengths must be kept, not 1/2 inched longer or shorter.

I opened this Pandora's box on my 12V71TIs near 20 years ago. I have warned many about this. Some listened.

 

[SKYCHENEY]

Look at exhaust manifolds too. They tend to warp over time and start to leak usually at the aft end. If you do change those gaskets, check the manifolds for warp. They may need to be machined before they go back on.

 

[scottinsydney]

Capt' Ralph.... is it this gasket? from DieselPro. I wil go look for that sump fitting next time I'm at the boat.

 

[scottinsydney]

OK. Thank you Sky. I will go back into Diesel Pro and have a look see.

 

[Captain Ralph]

Capt' Ralph.... is it this gasket? from DieselPro. I wil go look for that sump fitting next time I'm at the boat.


View attachment 73839

That looks just like it.

 

[madhatter1]

My suggestion is to buy several spray cans of contact cleaner or brake cleaner. Spray down everything to make as clean and dry as possible. Then clean up 100% under the engine and lay down new white oil pads. Then run a bit and it will lead you to the leaks.

 

[scottinsydney]

Capt' Ralph: I took a good look at the big hose running down from the turbo. The areas where it attached to the sump was clean and dry. Good news.




Sky: I took a good look at the manifold and its dry everywhere.

Mad Hatter: With my new inspection light and TV monitor I worked upwards. The oil sump suction drain turned out to be compression fittings and metal pipes so oil leak is unlikely to be from this.

Going upwards I followed the oil..... it was seeping around this fitting which was close to the end of the engine where it bolts to the gearbox. The oil did not appear to be coming from this.



And so up I went with the inspection light probe in the valley between the motor and the gearbox. The device has a one metre bendable rod with small light and camera lens on the end. The light illuminates say a 3" area seen by the eyes or shows the same on the colour TV monitor. A cool piece of kit.


Up I went and there, hidden by hoses, air seps and grunge was the source of the leak spurting upwards from behind a small flange. Oil was not coming from the rocker cover gasket.



So I have purchased some 1mm paper gasket material and will fix the leak tomorrow.

There are some other minor leaks around the oil dipstick.

Everything has now been cleaned off with brake cleaner. . Unfortunately the leaking oil must have got warm from the manifold and misted. The engine room, outside hull vents and motor need a good clean. I am wondering if the oil made it into the last exhaust port and is causing the blue smoke.

Time will tell.

(I should also say that the motor was last cleaned down about 5 years ago in preparation for the on board visit of Mr and Mrs Scarlett for their tour of Sydney Harbour.)

 

[Captain Ralph]

Outstanding good news.

 

[yachtsmanbill]

Flourescent dye in the oil and a blacklight flashight will remove all doubt in 2 minutes of idling. Any oil leaks on the inlet side (blower, turbo's etc) will cause a really fast idle leading to a runaway condition upon failure. Removing the silencers and looking in the blower inlets will show seal leakage too. All the ex-spurts will know this.

 

[Captain Ralph]

Flourescent dye in the oil and a blacklight flashight will remove all doubt in 2 minutes of idling.

That 3rd picture in post #8 is not from idling. High volume of oil at higher RPM, is pooling in that lower corner of the head, just before it's normal oil drain path down, back in to the block.
This does concern me a little. The oil usually does not pool this high.
The good news is the valve cover gasket is not leaking just above it.
One morning after a few days of not running, replace that gasket, clean the area well and lets watch it.

The next time that valve cover is off (tomorrow, in 2 years), please look over that oil drain area and ensure there is no path restrictions at the oil drain area/path.