Tracking down an oil leak

[Chris Simenstad]

I'm a week into a summer cruise, and have been doing a lot more motoring than I should be. Yesterday I motored 16 hours down the big sur coast in no wind! (should be a NW wind this time of year).

The engine has run perfectly, except after a long trip have a couple of ounces of oil in the bilge. Where should look for leaks? My plan is to put some pads in the bilge under the engine to try and pinpoint the source. Oil pressure is 50 psi. I don't lose enough to notice on the dipstick.

I should mention that to install a polishing filter fitting on the mechanical fuel pump I had to remove the pump bolts a little to back the pump out and get the fitting on.

Anything to keep in mind about oil leaks, where to look for them etc? As I write this the engine is purring along.

[Kurt]

Is there any oil dripping or seeping out of the weep hole of your raw water pump? This would mean the oil seal within the pump has failed.

[Marian Claire]

A real seal leak will tend to sling oil around when motoring. I used lots of paper towels tracking down leaks. Just don’t leave any in the bilge. Good luck and enjoy the trip. Dan S/V Marian Claire

[Chris Simenstad]

It's not the water pump, but it is dripping from the very aft part of the engine, maybe the area between the engine and the propellor shaft flange. I did tighten the bolts in the rear seal a bit to no avail. Anything else I shoid check. The oil is dripping but not flinging.

It's only losing oil under power. No leak while engine off.

[rigspelt]

This may help: http://www.moyermarine.com/forums/sh...=leak#post2325

[Marian Claire]

There are no bolts associated with the rear seal. Many leaks tend to run aft due to the tilt of the engine. Enjoy. Dan S/V Marian Claire

[Chris Simenstad]

I crawled down there with a mirror. It's a small drip from the most aft part of the engine where the shaft exits. The leak is slow. How fast will this seal deteriorate? Do ihave to pull the engine to fix this?

[rigspelt]

I crawled down there with a mirror. It's a small drip from the most aft part of the engine where the shaft exits. The leak is slow. How fast will this seal deteriorate? Do ihave to pull the engine to fix this?

Don posted a PDF on changing the rear seal in this thread: http://www.moyermarine.com/forums/showthread.php?t=867. Apparently it can be done on some boats, depending on access for the operator and the tools.

I'd make sure it was a leak from the rear seal first. One fellow wrapped a 2' wide strip of white bed sheet around the transmission case to confirm oil drip was not from the front of the engine. http://www.moyermarine.com/forums/showthread.php?t=867

See this post: it contains a short post from Don that includes two relevant PDFs and wise advice: http://www.moyermarine.com/forums/showthread.php?t=2950

Regarding whether to interrupt the short boating season to replace a rear seal, this may help a bit, though I don't know all the ins and outs: http://www.moyermarine.com/forums/showthread.php?t=1461

[Marian Claire]

Good info from rigspelt. I ran over two hundred hrs with a leaky rear seal. Just rig something to catch the drip. Is your boat direct or 2 to 1 reduction? Dan S/V Marian Claire

[julian hood]

Had the same problem

Use a flashlight and check the valve stem cover plate behind the manifold. Thought I had a seal problem but turned out to be a loose bolt holding the plate on. You should be able to see oil blowing out if that's the problem. Snug the bolt up tight but be careful not to overtighten.

Good Luck
Julian Hood
Audacity27