Merc 5.7 carb/ alpha 1 - Overheating
 

Went over a large wave yesterday and directly after that I noticed the water
temp was over 200. Out of habit I scan this and the other essential gauges
regularly when running. Up to that point the temp was the normal 160-170. I
went to idle and then turned the engine off since this happened once before
where I probably picked up a plastic bag wrapped around the water intake on
the i/o. I raised the drive and felt around the intake holes searching for
blockages. None found at the holes, but a healthy crop of barnacles were
populating the surrounding areas of the drive. Started it up again and
revved it a couple of times and the temp subsided to normal. Then a few
minutes later the temp was up there again. I stopped. Turned off the engine.
Restarted. And again, back to normal. This happened once or twice more
during my time out but on these later occasions all I did was put the drive
in neutral, rev the engine a couple of times, put it back in drive and the
temp went back to normal saving me from having to get back up to plane from
a dead stop.

The question is, did I cause come damage, say, to the impellor from the
impact on that large wave (this was a wake from a large ship that had passed
about a 1/4 mile away in an otherwise flat and calm sea) or was it just
coincidental that I may have picked up something that would cause random
blocking/malfunctioning of the cooling system (would have to be pretty small
to fit in the intake holes)?

Thanks for your help.

-Mike
1987 Sea Ray Sundancer 250
Repowered with a rebuild last year with 160 new hours on it.

Maybe a sticking thermostat. You have raw water cooling or a heat
exchanger? 160-170 is too high for raw water cooling.

"MJT" wrote in message
t...
Went over a large wave yesterday and directly after that I noticed the
water temp was over 200. Out of habit I scan this and the other essential
gauges regularly when running. Up to that point the temp was the normal
160-170. I went to idle and then turned the engine off since this happened
once before where I probably picked up a plastic bag wrapped around the
water intake on the i/o. I raised the drive and felt around the intake
holes searching for blockages. None found at the holes, but a healthy crop
of barnacles were populating the surrounding areas of the drive. Started
it up again and revved it a couple of times and the temp subsided to
normal. Then a few minutes later the temp was up there again. I stopped.
Turned off the engine. Restarted. And again, back to normal. This happened
once or twice more during my time out but on these later occasions all I
did was put the drive in neutral, rev the engine a couple of times, put it
back in drive and the temp went back to normal saving me from having to
get back up to plane from a dead stop.

The question is, did I cause come damage, say, to the impellor from the
impact on that large wave (this was a wake from a large ship that had
passed about a 1/4 mile away in an otherwise flat and calm sea) or was it
just coincidental that I may have picked up something that would cause
random blocking/malfunctioning of the cooling system (would have to be
pretty small to fit in the intake holes)?

Thanks for your help.

-Mike
1987 Sea Ray Sundancer 250
Repowered with a rebuild last year with 160 new hours on it.

How old in the impeller?

"MJT" wrote in message
t...
Went over a large wave yesterday and directly after that I noticed the
water
temp was over 200. Out of habit I scan this and the other essential gauges
regularly when running. Up to that point the temp was the normal 160-170.
I
went to idle and then turned the engine off since this happened once
before
where I probably picked up a plastic bag wrapped around the water intake
on
the i/o. I raised the drive and felt around the intake holes searching for
blockages. None found at the holes, but a healthy crop of barnacles were
populating the surrounding areas of the drive. Started it up again and
revved it a couple of times and the temp subsided to normal. Then a few
minutes later the temp was up there again. I stopped. Turned off the
engine.
Restarted. And again, back to normal. This happened once or twice more
during my time out but on these later occasions all I did was put the
drive
in neutral, rev the engine a couple of times, put it back in drive and the
temp went back to normal saving me from having to get back up to plane
from
a dead stop.

The question is, did I cause come damage, say, to the impellor from the
impact on that large wave (this was a wake from a large ship that had
passed
about a 1/4 mile away in an otherwise flat and calm sea) or was it just
coincidental that I may have picked up something that would cause random
blocking/malfunctioning of the cooling system (would have to be pretty
small
to fit in the intake holes)?

Thanks for your help.

-Mike
1987 Sea Ray Sundancer 250
Repowered with a rebuild last year with 160 new hours on it.