Vacuum line replacement

Motor is a 73 18hp, now please bear with me on this description, I am fairly new to boat motors so I will likely not call things by the right names. There is a tiny nipple(1/16th inch) behind the top cylinder above the fuel pump looks like it goes into the crankcase the hose then runs up to near the carb, somewhere near where I believe the reed valves are and connects to a much larger nipple(close to 3/16th inch). I asume I need fuel rated line and something that will not colapse easily? I will try to get some when I get some other parts tomorrow but if that fails I have some silicon hose in a small diameter would that be a suitable replacement. The original is cracking but not leaking yet, since the motor is apart it is getting replaced at this time to aviod impending trouble.

Re: Vacuum line replacement

I can pretty much guarantee you that if the nipples are different sizes then a hose don't run between them. Do you have a manual? That will show the hoses and the routing.

Re: Vacuum line replacement

get a manuel it will make your life a lot easyier.

Re: Vacuum line replacement

Look guys thank you for taking the time to reply but, sometimes there needs to be more of an answer than "buy the manual" I have the Seloc manual and I would call it the equivalant to the automotive Haynes, crap with a little useful info scattered around and poor pics. The best part of the whole thing is in the back with the tables of tuneup specs and torque values. I am mechanically inclined too so the problem isn't my ability. If you can find a diagram of the routing please tell me what page it is on, but I do not think you will find it.

Re: Vacuum line replacement

Gearhead - Just to make sure you have the hose routing right, there should be two hoses not associated with the fuel system (pump and carb I mean). One is an oil recirculation hose that picks up puddled oil from the bottom of the crankcase on the starboard side of the engine down really low, and routes up to the top crank bearing, at the top of the block underneath the flywheel and electrics. This one basically sends puddled oil up to the top bearing, so it can be re-used.It should have been painted with the block if it's original. <br />The other line runs from the front of the intake manifold, just beneath the carb and a little to the starboard, to the intake cover on the starboard side of the engine, just above the fuel pump. This line takes unburnt gasoline from various places where it tends to puddle in the block, and sends it up to the intake cover from where it will go directly into the top cylinder to be burnt. In the old days, they would have simply dumped this puddled fuel out with the exhaust. Rather than dumping fuel/oil into the environment, they burn it on your engine.<br />Sorry for the lengthy explanation. I'm sure you already know half of it, but I want to make sure we're on the same page.<br /><br />Ok, so your question is what type of hose to replace it with. Fuel line works great for both these, since the vacuum and pressure isn't particularly high. I've seen and used various styles of fuel line for these, and really anything works for them - so long as it's fuel rated. I don't believe silicone hose is rated for such use, so forget about it. Actually, it's a very good idea to use fuel rated sealants, line, rubber, etc, everywhere on an outboard since everything will see fuel or fuel vapour at some point.<br />If your having trouble getting the fuel line to fit over the larger nipple, simply warm it up (don't let it burn) and it'll form much more easily. Zip ties or other types of tubing clamps are a good idea even if they weren't originally used.<br /><br />Hope this explains it!

Re: Vacuum line replacement

That was a big help, thanks. Tomorrow I am stopping for the gaskets and carbon seal(another thread) and will see what the repair shop has for small line like this. It is the line from the intake to the top cylinder. I will look for that other one and check it's condition.