Dirty oil

[fastskipper]

When I purchased my new to me convincor one of the first things I did was change the oil. The oil was very dirty...like black water. Now after two hours on the oil change the oil is black again. Guess I will keep changing every couple of hours till it gets clean. I am using Valeoline 20w-50 racing oil and a Wix 1061R filter. Comments?

[fastskipper]

When I purchased my new to me convincor one of the first things I did was change the oil. The oil was very dirty...like black water. Now after two hours on the oil change the oil is black again. Guess I will keep changing every couple of hours till it gets clean. I am using Valeoline 20w-50 racing oil and a Wix 1061R filter. Comments?

[Eriktheviking]

Thats what I would do.They do sell motor flush solvents,but I'm not crazy about using them, I haven't seen whats out there lately though.If you notice that its getting black again you could put some Marvel Mystery Oil in,run it for a while and dump it.It has cleaning qualities that might work for you.

[JW]

And if the flushing/cleaning doesn't work, then your problem will be weak rings allowing combustion gasses into the crank area and/or too rich mixture in the combustion chamber forcing gases into the crank area. Have you done a compression test since you noticed the oil color? A leakdown test maybe what you need to do. There's a guy on Scream and Fly that sells a nice leakdown tester.

1995 Pulsare 2100BR/1995 Mercury Promax 225 2.5 EFI/ 1.87:1 Torquemaster/ RapidJack Heavy-Duty manual 10.5" setback/ 23" Tempest worked for ski duty

[Eriktheviking]

Fastskipper,is that a fuel injected or carb engine? Have you noticed any black smoke when your running it? You said the oil was like water the first time you changed it. If its thin again this time there's problems like JW talked about.If you run it too long under those conditions you'll eventually burn up the engine. Hopefully,its only a carb dumping too much gas in, which can usually be fixed with a rebuild. One way to see if your rings are bad is to see if there is blow-by coming out of the breather tubes that run to your spark arrestor.If you see a oily film all over everything ,then things are tired. http://www.checkmate-boats.com/6/ws/,s,8626072361/Graemlins/jpshakehead.gif

[fastskipper]

It is a carb engine. The compression test showed 165 to 170 on all. No black smoke from the exhaust, in fact the thing runs great. Pulled the breather and no smoke. On the last oil change the oil was better. It was not as dirty as the last time and was much thicker. I will change it again this week and see what happens.

[JW]

We'll keep our fingers crossed. The only two things that can thin out oil like that is water and gas. Autos can burn the gas out of the crankcase by running a couple hours on the highway at normal engine temps. Your boat can't, runs too cool. If it's water then HOPE it's just a leaking gasket, not a crack somewhere. Good luck!

1995 Pulsare 2100BR/1995 Mercury Promax 225 2.5 EFI/ 1.87:1 Torquemaster/ RapidJack Heavy-Duty manual 10.5" setback/ 23" Tempest worked for ski duty

[fastskipper]

Things are looking better...much better. I have 4 hours on the last oil change and the oil looks clean. The guy I purchased the boat from said he had not used it in a couple of years. Tied with that the boat was for sale. I'm sure with that loss of interest in the boat the oil was not changed when it should be. I think this was just really old and dirty oil that needed to be flushed out.