1988 4.3 OMC Cobra I NEED HELP IM NEW TO BOATS. Thank you Fellas!!!

Pedrocasas

Seaman
Joined
Apr 9, 2016
Messages
54
I have been working on boats for years. I work on upholstery.
But I'm new to Engines.

I just bought a 1988 Seaswirl Sierra Cuddy.
Its a I/O Engine. 4.3 Cobra

The previous owner never took ran more than 15 miles per hour. He was to afraid.
Right now the carburetor is rebuilt, fresh tune up, new spark plugs and spark plug cables.

I took it out yesterday 2/12/2017, I had choked the engine. Took us 1 hour to start the engine.
After that we turn it off and on and turned on right away. "we were not experience with a electrical fuel pump"


Ok, So I ran it up to 40 miles per hour, after a good 30 mins It started smelling like burning Rubber. A bit of smoke.
We noticed that the hose clamps were sticking out a lot from (THAT PART CIRCLED IN RED) this is not my own picture sorry but same part.
Im guessing the clamps were super hot that it fried the RED fuel line coming from the gas tank.

Im not sure what the part circled in yellow is called.

But there was hot water leaking a bit from the house and where that part connect. the water was hot too. (is that normal?)

Any suggestions on what I can do? or what caused the hose clamps to get hot.

The smoke would start coming out again, once I would hit more than 20 miles per hours. Under 20 there would be no smoke.

Also, Gas had been in the tank for months already, do I need to clean it out or somet
 

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southkogs

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Jul 7, 2010
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14,785
Welcome aboard -

First guess is that ya' overheated. What was your temp gauge reading? Check your water flow through the engine, and I would look at the impeller and replace.
 

shaw520

Chief Petty Officer
Joined
Aug 27, 2009
Messages
634
The part circled in yellow is the exhaust manifold/riser,.. the parts circled in red a exhaust bellows and clamps,.. after cooling the engine, the hot water enters the exhaust manifold/riser and is expelled through the exhaust bellow and then down out the lower unit. Those bellow clamps may just need to tightened,... keep a close eye on ENGINE RUNNING TEMPERATURES.
 

Tnstratofam

Commander
Joined
Aug 18, 2013
Messages
2,679
Definitely do an impeller change if you haven't. That should be an annual thing. It is located in the outdrive, and if it is bad or fails while underway you will overheat your engine and exhaust manifolds.
 

proshadetree

Lieutenant Commander
Joined
Jul 19, 2008
Messages
1,887
I would think impeller also. It will be the easiest one to change as it is like 5 bolts total. I would obtain the kit that has impeller and housing and seals. When they
get hot enough to smoke the exhaust the pump housing is normally shot. Check those hoses for damage also. When you they get hot they tend to split.
 

Pedrocasas

Seaman
Joined
Apr 9, 2016
Messages
54
Thank you Guys for the quick responses. This Forum is awesome. And the advice is helpful, I will change the impeller, im not sure the previous owner ever changed it. but I will next week.

Thank you Guys again...
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
If things got that hot I'd be pulling those hoses out and inspecting them. If they're crisp and cracking on the inside they should be replaced. If they leak and you don't notice it they could sink the boat. Also there are rubber flaps in there (one on each side) that stop water from backing up into the manifolds when the engine is off.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
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47,306
you have the dreaded bat-wing exhaust manifolds. change them ASAP as when (and not if) they fail, they will take out your motor.

since this is a new to you boat, you need to change the impeller as well as perform all other maintenance (gear oil change, gimble bearing, bellows, engine oil, filter, fuel filter, cap, plugs, rotor, etc.). if you did overheat the motor, the advice above on changing the exhaust hoses is sound and valid.

if it took you an hour to start the motor, you have done something wrong.

its a carburetor without a fast idle cam. here is the starting proceedure.

with a cold motor.
with boat on muffs or in the water (Never start the motor without water, you fry the impeller in seconds)
engage throttle only (either pull handle out, or press button at base of throttle/shifter)
pump it twice - full handle stroke. this sets the choke and primes the engine.
set to about 1/3 throttle
turn key - when motor starts, pull throttle back to about 1500, let warm up at 1500 rpm for about 2 minutes
after 2 minutes, pull back to neutral to re-engage shifing
 

Bondo

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Apr 17, 2002
Messages
70,468
you have the dreaded bat-wing exhaust manifolds. change them ASAP as when (and not if) they fail, they will take out your motor.

Ayuh,.... Ditto that,.... Especially after overheatin' 'em so badly,... probably cracked all to bits,....
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
And the lesson in this is that the issue you had is why the prior owner never went over 10 MPH (because it overheated if he did!). Those gauges on the dash are there for a reason. It costs you money (lots of it) if they are ignored -- or if the theory is "I'll look at this in a couple weeks".
 
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