Oil on transom 500 efi
 

All of a sudden their is oil from tail pipes all over transom and outdrive. Motor is down half a quart. Did'nt notice any performance loss, and a compression test shows all at 150+-5. Rear plugs show richer than front. Started up and everything seems normal, and no trace of oil comming from exhaust. Anyone have any idea what happeneed? Thanks John

The only thing that can make oil pump out of the exhaust is leakage through the rings or sucking oil in through the valve guides. The guides would have to be really bad for that amount of oil to suck through. I understand that your compression is good, maybe you should try a leak down test. Compression is not 100% accurate in determining the condition of the internals of a motor. Also, are you sure those rear plugs are rich with fuel and not colored from oil??

John B, 1.2 qt. dont sound like too much to be down! Are you sure it is oil? Is the 500 efi equipped with pvc valves? Disconnect the breather tubes from the valve covers and run the motor and see what, if any blow by it has.
steve

[ 09-15-2001: Message edited by: P29 SCARAB ]

Is it possible to suck the oil from somewhere into the EFI plenum. I was making some topend runs when this happened?

How about a leak in the oil cooler? 65 lbs oil pressure and less than 30 lbs of water presure= oil going into the water and out the tailpipes and all over the transom. Has this happened to anyone?

Thanks Landlord, I will test the oil cooler. That's a lot easier than an engine rebuild.

John, Does your 500 efi have the Sea water pumps with the fuel pumps (new style) on them? Its just a shot in the dark, but could the seal have gone bad ,and sucked the gear oil out of the water pump housing?
Is it on both motors, or just one?
Hope its just something simple!
Good luck,
Ron...

Oh yea, just saying that may have been the problem, because it seems that any other problem with the motor would also show water in the oil!
Also it seems that 30 psi of water pressure is high, isn't it ?

30 psi water pressure is to high shouldnt have over 20 psi at full speed if it does you have to get rid of it before your push the head gaskets out of the engine . do you have a see strainor on the boat if you do you can put a pressure valve on this to get rid of the excess pressure through a transom fitting. you could position it on the boat and blow it on the drive :D

Well the oil cooler isn't the problem.Ron, this is an EFI so I don't think there is a fuel pump on the sea pump. Merlin, no sea strainers, max pressure is in the low 20's. The drives are up about 1.75 above the bottom. :eek: The search continues :confused:

John , On some of the later model 500 efi motors, there is a manual fuel pump that runs off the sea water pump, it was supposed to solve the vapor lock problem that Merc. was having with some of the EFI motors , it was added to supply the fuel to the electric high pressure pump.
My 500 efi doesn't have one, but i did see some of the boats at the Daytona race back in april, did have these pumps, and was told that the reason was to stop the vapor lock problem.
Anyone else know of this??? Maybe i am mistaken! :confused:

Ron...

Found the cause!
 

O- ring in the top of the drive was cocked when service was done. Oil was comming out while running and blowing mist of oil and water on the transom and drive. It's OK now, thanks for the tips, I forgot to post the solution last year. Hope this may help someone. JB

How can you test the oil cooler? If it was leaking on a 454 mag, would the oil be more prominent out one exhaust or would the same amount of soot be comming out of both exhausts?

The oil cooler was removed and pressure tested with air to 100 psi. Then we put it in a bucket of water, no leaks.

As to where the oil would go....somewhere in the system and out the tail pipes.

I also had some oil on the other side of the transom. How about a loose oil plug on the other drive.