oil on water surface of test tank

[321]

my engine is proving hard to start, when she does she will run for a few seconds and cut out. there is a film of chocolate colored oil left on the surface of the water in the test tank. any ideas what could be wrong?

 

[fireman57]

Re: oil on water surface of test tank

What year and hp engine are we talking about. In generic terms I would say that a good carb(s) cleaning/rebuild is in order.

 

[Kevin W]

Re: oil on water surface of test tank

We would most definately need more specifics on what you have for an engine.
It is not uncomon for even a good running 2 stroke to have an oil slick in a small test tank.

 

[321]

Re: oil on water surface of test tank

she is a 50hp johnson 1971. there is a fair amount of oil on the surface also a small amount of fuel. the tarmac under the prop is oil free when she is left in the drive out of the test tank this only happens when i have to crank her over and over again.

 

[red boat]

Re: oil on water surface of test tank

Sounds like a carb cleaning is in order, one of the floats is probably sticking, flooding the cylinder with fuel causing the hard starting and fuel/oil slick in the test tank.

 

[321]

Re: oil on water surface of test tank

how do you get to the carb is it under the flywheel. will the floats be obvious.

 

[Silvertip]

Re: oil on water surface of test tank

Since we have no idea which engine you have we can only make general suggestions. First -- don't even remove the cowl until you obtain a service manual for this engine -- especially if you have no idea where the carbs are. They definitely are not under the flywheel. The float, inlet needle and seat are inside the carb. They need to be completely disassembled, soaked in carb cleaner, every passage, jet and orfice thoroughly cleaned and then reassembled using new parts. Before you start ripping things apart, is the fuel fresh? Has the engine been stored for a long period? Did this problem just occur? Did you do a compression test? What's your starting procedure? Have you pulled the plugs to see what they look like? Lots of things to check before disassembling things.

 

[321]

Re: oil on water surface of test tank

she is a johnson 50hp 1971 as per listing #9. i have a manual in the post which should be here this week, the fuel is about three weeks old but this has happened before with new fuel. the plugs look on but seem to be a bit soaked with fuel.

 

[fireman57]

Re: oil on water surface of test tank

Cleaning the carbs is a pretty easy job. Just take your time and while you have them apart put a rebuild kit in them. They run, if I remember right, less than 20.00 a carb. Set your floats level when the carb is turned upside down. The manual will lead you step by step.

 

[Scaaty]

Re: oil on water surface of test tank

not uncommon for even a good running 2 stroke to have an oil slick in a small test tank.

Yep...I get a good slick in a minute with 2hp in a barrel

 

[321]

Re: oil on water surface of test tank

Cheers chaps, im awaiting my manual in the post. so will get right to it as soon as it arrives.

rob

 

[OBJ]

Re: oil on water surface of test tank

Let me throw a couple other items out to you 321.

Check the compression on both cylinders. They should be within 10 > 15% of each other. This should be in the manual.

Check your manual (when it gets to ya') for checking the engine temp while running. A cold running engine will promote poor combustion which means more unspent fuel in the exhaust.

Also make sure the ignition system is operating up to par and the spark plugs are the correct plugs for that engine and are gapped correctly. Poor spark at the plug can also cause the engine to run poorly and, again, more smoke and unburned fuel at the exhaust.

 

[321]

Re: oil on water surface of test tank

all very helpfull. cant wait to get my hands dirty