Oil in bilge - mystery leak

[Two Peas]

My engines are 4.3EFIs. This morning I found what looks like engine oil floating on the little bit of water in my bilge. All told, it appeared to me to be an ounce or so of oil.

I ran the boat on Saturday and Sunday for about 3 hours on each day.

Looking under the port engine, I could see little drops of oil that appeared to be oil spray - but from where?

A cursory examination didn't yield any prime candidates for potential leaks. After checking the oil level in both engines (each was perfect), and the oil level in both trim pumps (at their usual level), I started both engines. Oil pressure was completely normal. I used the boat again today anyway (first 3 day weekend with perfect weather all summer), and found a little more oil in the bilge after the day was over.

Any suggestions on where - or how - to look for the leak?

Thanks,
Andrew

 

[Turtlesboat]

maybe check the trim tab pump and power steering pump and outdrive oil reservoir?

 

[Two Peas]

maybe check the trim tab pump and power steering pump and outdrive oil reservoir?

I looked for the trim tab pump - it sounds like it is behind the engines... any idea on location for it?

My outdrive gear oil looks green/blue in the reservoir, the oil in the bilge looked brown and dirty...

Thanks for the advice.

 

[Turtlesboat]

On my 280, it's behind the port engine mounted on the transom, trim tab pump that is.

 

[SR Tech]

I had this problem on a 07 300DA, Twin 350magsMPI.

The problem was at the oil filter adaptor plate for the remote filter relocation.

This was a brand new boat mind you. But from the factory the adaptor plate had not been tightened down completly, so it didn't squash down the seal to the block, therefore causing a leak. It only leaked under pressure, allthough the gauge read fine.

What a PITA, to just find what the cause was and to replace. The bildge is pretty crowded.

If you have the remote oil filter check the lines to the adaptor plate and also check the seal where it meets the block.

If you don't have a remote then just check the filter seal to the block

 

[Two Peas]

I had this problem on a 07 300DA, Twin 350magsMPI.

The problem was at the oil filter adaptor plate for the remote filter relocation.

This was a brand new boat mind you. But from the factory the adaptor plate had not been tightened down completly, so it didn't squash down the seal to the block, therefore causing a leak. It only leaked under pressure, allthough the gauge read fine.

What a PITA, to just find what the cause was and to replace. The bildge is pretty crowded.

If you have the remote oil filter check the lines to the adaptor plate and also check the seal where it meets the block.

If you don't have a remote then just check the filter seal to the block

Thanks, I do have the remotes - although I gave them a quick look yesterday, I'll go over them more thoroughly next time I'm there.

 

[TimC]

I had what I thought was oil in my bilge but it turns out it was power steering fluid. Check your power steering fluid to see if it's low. My leak was coming from a seal on the rod connected to the outdrive that moves the engine. Sorry I don't have the actual name for it but that's the best I could do. It's a PITA to get back there to replace it.

 

[390pi]

I had the same problem. Could not figure it out. Everything on the motors was totally dry. And I had newly rebuilt motors, so they were suspect.

It ended up being the outdrive reservoirs. Yes, the oil looks a little greenish, but once in the bilge, it looked dirty black.

Check the connection and hose at the bottom of the reservoir on both.

 

[Two Peas]

Thanks again for all the suggestions. I'm looking forward to the detective work now...