Running without oil: 90 Mariner 3 cyl: Corrective action?
Hi AllSo after many years of uneventful boating I am now part of the select many who ran his outboard without 2xoil for appr 10 minutes while towing a skier.Although the motor started making a soft but very audible tinny rattling sound after about a minute of running, it was only after the skier was beached about 9 minutes later that oil was seen pouring out the bottom of the cowling.Closer inspection revealed the oil feeding line to be broken off at the oil pump inlet.I managed to replace the piping and while running back noticed the rattling sound to disappear after about 3 minutes.At home I added a little extra oil to the fuel tank and ran the motor the next day on the water for another 2 hours without any problems or unwanted sounds. It runs and idles as smooth as ever.My question therefore is, what parts inside the motor could have been damaged in what way and are there any corrective actions that can be taken at this late hour to minimise or prevent further damage?ThanksD
Re: Running without oil: 90 Mariner 3 cyl: Corrective action?
The damage that would be caused by this is usually scored cylinders and pistons. The only way of really seeing this is to remove the cylinder head.Other than that, do a compression test, and check that all three cylinders are within 10% of each other.As far as prevention, when you maintain your engine (grease and clean etc....) each month, check all rubber hoses for any signs of cracking or hardening.
Re: Running without oil: 90 Mariner 3 cyl: Corrective action?
The first thing that goes without oil is the crankshaft and rod assembly. Then the piston area starts to suffer. For whatever reason, the crank seems to go longer without damage than the piston area. You have no way of knowing what damage was actually done without a complete teardown, but you can remove the head and check things out. If your compression test shows everything fine, you may have got lucky this time. "REAL LUCKY".Just for the sake of discussion, what oil were you using [or not using], when this happened?
Re: Running without oil: 90 Mariner 3 cyl: Corrective action?
Since the reciprocating assembly (crank, rods) is on roller bearings, they are probably okay. The pistons and cylinders could be scored due to scuffing. The fuel/oil mix cools as well as lubricates, the pistons would expand more and possibly make physical contact with the cylinder wall. The gasoline will provide some lubrication on a short term basis. If your motor is still performing the same at the same rpm range, you probably got off wit a bit of cylinder scuffing. Compression check may or may not tell you. Running extra oil won't make up for anything, so you may as well just run your regular ratio, and thank God you were this lucky...
Re: Running without oil: 90 Mariner 3 cyl: Corrective action?
Quote:
Originally posted by Damdan:Looks like I got away with it this time.
I wouldn't be so sure of that. If you have a removeable head, unlike my motor, it would be a REALLY good idea to remove it and have a look...or at the very least barrow/rent/buy a borescope and have a look. I ran my '74 150hp Mercury for about 10 minutes without oil. After I realized the problem and added about twice the usual oil it SEEMED to run ok the rest of the day, but it DEFINATELY was not ok inside. A total rebuild was required. It is very likely that at least one of your cylinders is in very bad condition...be ready for a total rebuild in the near future.
Re: Running without oil: 90 Mariner 3 cyl: Corrective action?
Get a compression test done to confirm one way or the other. Only takes a couple minutes then you can be confident of your motors condition. Don't panic about something you aren't sure about
Running without oil: 90 Mariner 3 cyl: Corrective action?
So after many years of uneventful boating I am now part of the select many who ran his outboard without 2xoil for appr 10 minutes while towing a skier.
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