Why wet test an outboard motor while it is in the water? What do I look for?

Question

Why wet test an outboard motor while it is in the water? What do I look for?

Answer 1

you want to see how it runs under a load

they run diferant in water than on land

Answer 2

I presume you have a tachometer on the boat - if this is a fishing motor, maybe the other guys advice is more helpful.

the real basic thing is that at WOT it is supposed to tach at or just below max rated RPM. you can find this in the mfr engine manual or in any of the Seloc manuals - your public library probably has one or can get one by borrowing it from another library.

That's it! - That's all you really want to check in a wet test.

Like one other said, everything else can be done dry - but no kidding don't run it dry without a water cuff attached or you will need a new impeller, maybe more...

Answer 3

outboards have underwater exhaust and the backpressure puts a load on the engine.  The motor might start and sound fine without the lower unit submerged and then run like c**p when you put a load on it.

In fact, many outboards will idle just fine out of the water with one or even two cylinders not hitting at all, and you can't detect it from listening (unless you have a history with that motor and recognize the different sound).

Are you asking what you look for when purchasing a used motor?  It needs to start with a bump of the key (warm start only), idle in neutral and in gear without dying, accelerate smoothly when power is applied, and cruise at full throttle without misfiring.  Depending on vintage (the ignition technology of a particular model), a cold engine might need to spin for 2 or 3 or 5 seconds before it starts.

Never buy a used motor without (at a minimum) checking the compression.  If the lowest PSI cylinder isn't within 5% of the highest, walk away.

If the boats on a trailer, ask the owner to start it up.  If he does so without hooking the lower unit up with a garden hose attachment, walk away - he doesn't know how to take care of an outboard.

Answer 4

Take the cowl off and see if the engine is relatively clean (no oil indicating leaks), pull the plugs and see if there is any indication of lean mixture or too much oil build up. Make sure the engine idles good when you first start it and after the engine warms up, same with high RPM's. Look at the engine again and check for leaks, gas, etc. Put it in gear and make sure there are no funky clunking sounds.

Ask around about a good mechanic and get one to check it out, including the carbs and a compression check.

If you have remote steering make sure the cables are not freezing up, making it hard to steer. Check any under deck foam to see if it is water logged.

Answer 5

Excuse me... but you are asking about a "wet" test are you not?  Luckyone... must indeed be lucky... as you can do all that he mentioned on dry land... and still end up with a motor that runs like c**p - or doesn't run at all when under load.

As for me... well, I agree with you totally... you need to give the engine a very good "wet" test...

Take the boat out, and really put it through its paces... What are you looking for?  You want to make sure it performs up to par... All engines act differently and perform differently when they have a "load" on them... hooking a hose up, turning on the water and starting the engine, and giving it a few "revs" does not put a load on it...

When the engine is pushing a boat - now you have a measure of the engines true performance...

In addition... you want to make sure the engine's cooling system has a good flow on its water pickup and thus, you can see it as it squirts out... Is it a good strong stream, or is it just a trickle?  Does the engine smoke? If so, is it a pack a day... or a 3 pack a day smoker... either case... that's a big clue to something wrong... you also want to make sure it isn't dripping oil or fuel anywhere.

Yes, Murphy and I are old friends... and I am a big believer in Murphy's laws... So, in addition to having your favorite mechanic look at it... take it out and put it thru its paces... that Murphy... he especially loves boats and boating as much as I do, and he is always looking for a new boating friend.

Happy & Safe Boating!