How long can an outboard motor run outside of the water before it
damages the engine?
For those who are answering, have you ever had a boat with an outboard
The one in question is a trimaran, if that matters (and even if it
I don't know, but assume whichever would be damaged first. (That's
just waster-cooled, I'll bet.) What's the minimum time an outboard
can run without water and be damaged by the lack of water? I'm sure
it's longer than a microsecond, but I don't know how long.
Depends on the engine (how much thermal mass) and at what power. At
idle it will last longer than at speed. And remember, you can damage
the motor without damaging the engine. Running dry will often damage
the water pump and seals before it will damage the power head.
I personally have run a 100HP Evinrude V4 for more than a minute at a
time without water but that was a bare powerhead - no water pump or
lower unit attached. To run more than that I attached the garden hose.
This was a "TV court" case where Seller was selling his boat to Buyer,
and B backed out after the sea trial, and S was suing B for damaging the
engine at the end of the trial by starting it when it was still in the
water but after S had already lifted the engine out of the water, while
B was looking around up front. S and B seemed to agree that S had
yelled at B to turn the engine off and B did so immediately.
S said that the engine can be damaged in 5 to 10 seconds.
That didn't seem believable to me.
B said he backed out of the dealt because he had smelled burning rubber,
and S admitted he had stepped on some wires coming from the battery and
they, the insulation, started melting, but S said he had fixed all that,
and while B just wanted his 100 dollar deposit back, S wanted 400
dollars, 200 because he got 1300 instead of 1500 from the guy he
ultimately sold it to. and 75 for the part he had to replace plus labor.
I would give the rubber water pump impeller a few seconds only. ( if
it has one) That one was already wet so give it a few seconds more.
The motor might have been warm, but I would give it 30 seconds to a
minute w/o damage.
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I believe my brother started up our boat after we bought it, and it was
used. On first launch, I didn't notice heat rising. Motor sounded odd, and
I then noticed the gauge. Turned it off. Got tow. Brother had warped head
fixed. Been fine for 20 years now. Some pump impellers might fair better
than others. Don't try it.
OK - MANY inboards use an automotive style water pump where there is
no contact between the vanes and the housing. Running dry will
EVENTUALLY take out the seals, but you are talking at the very minimum
tens of minutes - possibly over an hour of running "dry" - much longer
than it will take to overheat the engine. MOST outboards use a
positive displacement vane pump which will fail in a matter of minutes
at best if run "dry" - usually significantly faster than you will
overheat the engine (from cold).
On Wednesday, December 3, 2014 2:42:26 PM UTC-5, firstname.lastname@example.org wrote:
My boat had inboard 454's, and the sea water pumps were of the contact
type. The impeller was flexible, rubber like material that was
firmly in contact with the housing. Ultimately, it doesn't matter
what most have or don't have, just what the one in question had. And
that unfortunately, we'll never know.
I forgot. He did mention the impeller. The judge called it the
propeller, with a quesiotn mark, and he repeated impleller. And that
sounds like a part that could be $75 and need no other parts with it.
I was thinking that too.
She ended up deciding based on someithing else, that the purchase was
contingent on B liking it in the sea trial** and B didn't like it, so
that settled it that B didn't owe for the lower price received. In
the possibly-edited version they show on TV, she pretty much ignored the
damage to the boat, but could have reasonably conclused that, since B
was the one piloting the boat during the test, which was undisputed, it
was negligent of S to take the engine out of the water without telling B
first or simultaneously.
So B got his 100 dollar deposit back and didn't have to pay anything.
**This was the second sea trial. It didn't run or run well the first
time, and the seller did some repair between the first and second.
On Tuesday, December 2, 2014 11:12:49 PM UTC-5, micky wrote:
I agree with Clare, that the water pump impeller could be the first
to fail. IDK how they work on outboards, but on my boat with inboards
the impeller fits tight in the housing and required water for lubrication.
Other pumps, eg pool pumps, spa pumps, etc that I've seen, the impeller
itself is clear of the housing. In those you could trash the seal, but
not the impeller itself. On the boat inboard impeller, I think you could
fail it in a matter of seconds without water.
Regarding the cost, it's not just the cost of the impeller. I guess in that
case the seller replaced it himself? Otherwhise, labor would be more than
That's what I was thinking too, when I first read your story. Generally,
it's pretty vague as to when you can back out of a boat contract like
that with sea trial and all. Who's to say what is or isn't acceptable?
How in the world could the seller be there, in a position to start the boat and
not know that it had been taken out of the water?
From what I heard so far, I would have also given the deposit back, but
made him pay for the cost of the repair. Assuming he had legitimate proof
for the purchase of the impeller or whatever else he fixed due to the
buyer's negligence. Seller admitting to starting the engine while it was
out of the water, resulting in needing a new pump impeller sounds
reasonable to me.
On Wednesday, December 3, 2014 5:11:26 PM UTC-5, micky wrote:
That would depend on what is or isn't stated in the specific contract. Most
times the buyer probably can get out, no matter what. But a buyer
certainly could sign a contract with limited options after the sea trial.
And ultimately it's a judge that has to decide in cases like this that
wind up in court.
Then it's still his fault for not turning around to look. It's like
starting any piece of motorized equipment, without checking if it's in
drive, safe to start, etc. Like a 50 year old car, prior to lockouts,
when it's in gear. If you did that and the car hit something or
someone, who's fault would it be?
If the seller started the engine with it out of the water, regardless
who took it out of the water, it's HIS impeller. ID10T clause comes
If the BUYER started the engine with the engine out of the water, a
case MIGHT be able to be made for the buyer to be at least partly
responsible. Note I said MIGHT. If the buyer claimed he thought the
engine was running a bit warm on the sea trial, it would be pretty
hard for the seller to prove the impeller had not partly failed
The seller should have removed the key from the ignition when the unit
was raised out of the water to prevent it being started by himself or
CYA and all that.
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