Twin 60's on a Cat rib
Ran fine for 4 hours
Mostly at slow speeds while I was teaching My friend the basics of boat handling etc
Then we set off on a run at about 3500 rpm on both units
An audible alarm (continuos) sounded We were in a fast flowing narrow channel ( 6 kts of current against us) with rocks all around us so we slowed to 1500 revs on both and found a mooring
I thought seaweed or something had blocked the intake
There was little water from the starboard engine and none from the port
I poked at the outlets.Ran the motors agin and the water flow from both was 'reasonable' but not great
I limped to a marina and cleared the outlets again
Now loads of water from both.
However after about 4 mins of cruising again the alarm was back on the starboard engine
If ran at up to 2000 all is ok.
Water flow looks great .I have heard somewhere about a grommet in the powerhead causing probs
Any other ideas folks!?

The problem is now cured.
It seems that the range of four stroke Mariner/ Merc engines from 40 to 90 hp circa 1999 to 2004 have all had the same problem ref a 'gromett' type seal that needs replacing.
Under the power head.
If anyone else has difficulties like this I can talk them through it.
This seems to be e Great Forum
Not only outboard probs can be fixed but yer Golf Swing too