On Wed, 14 Mar 2007 11:50:49 -0400,
wrote:

Possibility of bits of rubber from failed old pump in the cooling
system....

Possible if the previous owner had an impeller give out, or this one
is getting ready to go. At this point I may go ahead and replace the
impeller on general principles. All of the other easy stuff has
already been checked as far as I can tell.

"Wayne.B" wrote in message
...
On Wed, 14 Mar 2007 11:50:49 -0400,
wrote:

Possibility of bits of rubber from failed old pump in the cooling
system....

Possible if the previous owner had an impeller give out, or this one
is getting ready to go. At this point I may go ahead and replace the
impeller on general principles. All of the other easy stuff has
already been checked as far as I can tell.


But if the engine checked out with a heat gun as you say, confirming a
normal reading on the helm temp gauge, it wouldn't seem to be an overheat
problem caused by impeller bits or any other cooling system malfunction.

On Wed, 14 Mar 2007 22:31:17 GMT, "RG" wrote:

But if the engine checked out with a heat gun as you say, confirming a
normal reading on the helm temp gauge, it wouldn't seem to be an overheat
problem caused by impeller bits or any other cooling system malfunction.

Yes. Changing the impeller is probably a good thing to do but I'm
going to be surprised if it actually fixes the problem. I had the
boat out for an hour at lunch time today, never running over 1400 RPM
or so since I was in the local canals. No alarms of course.

The closest Mercruiser mechanic has a new ECM cable on order, should
be in next week. Hopefully there is a record of the alarm trips in
there.

On Mar 14, 4:58 pm, Wayne.B wrote:
On Wed, 14 Mar 2007 11:50:49 -0400,

wrote:
Possibility of bits of rubber from failed old pump in the cooling
system....

Possible if the previous owner had an impeller give out, or this one
is getting ready to go. At this point I may go ahead and replace the
impeller on general principles. All of the other easy stuff has
already been checked as far as I can tell.


wayne, Here's a situation I was talking with a guy jsut today. And
even though a Mercury outboard it still makes sense. right after he
got his bass boat with the 200 hp outboard, the first thing he did was
pull the lower and inspect the impeller. Yeah, he said, " it was
starting to crack"
So he got an aftermarket impeller kit, and installed it. fine.

He took it out, and all was well till he nailed it, and in just a few
secondes an alarm was going off. he killed the engine, and looked
stuff over. didn't see any problems, and fired ti back up and took off
at slow speed all was well, till he nailed it again, in about the same
amount of time, the alarm went off. he idled it back down, the alarm
went silent and he cruised easy back to the dock.

He thought there might have been something really freaky, so he took
it to a Merc. dealer and told them the situation. The mechanic asked
him to repeat the story. about changing the impeller. Then the
mechanic said "Where'd you get the impeller?" the guy told him, and
the mechanic said, "thats your problem." They split the lower again
and took the impeller back out and it looked fine. just like new.
which it was.

BUT! the mechanic told him that the aftermarket impellers arn't the
same composite of rubber and are softer, so that at high RPM's, the
vanes were actually folding back and not brushing the pump housing,
thus the water flow dropped like a rock. The mechanic installed an OE
impeller, and told him to take it back out.

The guy took it back out and nailed it, and all was fine since.

I don't knwo if this is fit for your application, but I thought I'd
pass it along, seeing you just got the boat.