Before you go and tear off the lower unit? What temperature the boat
running at? Does it overheat while idling or cruising on plane? How can
you tell water is comming out the exhaust if the boat is still in the
water? Or is the water intake of the lower unit in a tub of water when
you note a lack of water in the exhaust?

If water is only comming out of the exhaust only while the engine is being
flushed I would suspect your water impeller located in the lower unit. If
at any time you ran the engine without having the water intake submerged
or without muffs, I would bet a week salary you screwed your impeller.

To change the impeller, you will need to pull the boat out of the water,
pull the lower unit off, remove the impeller housing and replace the
impeller. Any parts person worth their weight in salt should be able to
give you exactly what you need to replace the impeller. JUST BE SURE YOU
GIVE THEM THE SERIAL NUMBER OFF OF THE ENGINE AND/OR DRIVE SO THEN CAN GET
YOU THE RIGHT PARTS.

If you still having problems some other places to look are the thermostat,
and if that don't work try backflushing the system.

Last but not least, please do youself a favor and get a mercruiser manual.

Hope this helps,

Bob Dimond


I have an Sea Ray 180 BR with a 135 MerCruiser and it is running hot.
While it looks like it flushes ok, it think it may be a restriction in
the water flow. It was kept in the water and had a large amount of
growths on the stern drive (now kept in dry storage). I got it all
cleared up and repainted but there may still be some clogging in the
water intake. How can I get in there and clean it out? It doesn't
have removable vents so I assume I have to take apart part of the
lower drive. If so, do I need to remove the prop to do so? Also,
water only comes out of one exause when flusing the engine. I can't
remember if that is correct or not, but it does flow pretty good when
flushing it.

I am a learner when it comes to boat maintenance, so your assistance
would be appreciated. Any tips would be appreciated as well.

Mike