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Discussion Starter · #1 ·
I just launched my boat for the season. On my way across the bay in clean deep water my engine alarm sounded. I immediately shut the engine off and checked the intake for obstructions and also the oil level. Every thing seemed OK so I restarted the engine and since the alarm was no longer sounding I continued on my way slowly. I have a 150 hp Mercury OB. I installed a new water pump at the beginning of last year and put less than 50 hours on it. I guess my question is was the alarm just a fluke or do I have a problem. I have never had the alarm go off since I purchased the boat new in 2000. When I shut the engine off and let the water drain out it takes about 20 seconds before I can see the water coming out of the indicator on restarting. I do not know if this is normal since I never really paid that much attention to how long it takes to see water coming out. The water temperature coming out is approximately 130* F. Any suggestions on how to tell whether the water pump is working properly would be appreciated. Also if I need to have it checked out by a proffesional can anyone recommend one in the Ocean City area?
Thanks in advance!
 

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You should be able to touch the cylinder heads if not overheating ... if the tstats are the same as my '95 150's, they're set for 143°F. Water temperature at the telltale doesn't reveal much. One of my motors has pretty hot discharge water, the other just warm, but both run about the same temperature (I have gauges).

Was the alarm steady or intermittant (i.e. beep pause beep pause ...etc)? Intermittant is an oiling system alarm. What did the alarm and motor do on restart (any more alarms)?

Jim
 

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Discussion Starter · #3 ·
I took the boat over to the Bahia Marina this morning and Eric their mechanic was nice enough to take a quick look at it. He said it was deffinately running hot and pulled both tstats and ran the engine without them. Running without the thermostats didn't seem to help so it looks like he will be putting a new pump and thermostats in for me. Bummer!!! Well at least the problem didn't happen 10 miles off shore. I like to make the simple repairs myself but when you live 300 miles away the last thing you want to do when you come down for the weekend is fix your boat when you should be out fishing.
 

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Same thing happened to me last year.
Just curious what your mech. charged for that if you don' mind sharing .
Cost me $320 last year to have the thermostats replaced on a 115 Johnson.Tought that was kinda high on my part.
 

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Water pumps can typically last several years, although I change mine every just to be sure. I would take a look at the poppet valve. If it's stuck shut you'll overheat since excess water can't be dumped fast enough through the thermostat. Installing a pressure gage is an easy way to monitor pump performance. Depending on the engine the tell-tale is not always a good indication of water pump performance. Water can be shooting out but if the poppet is failing the upper cylinders won't get water. Some tell-tales come right off the pump tube before water gets to the head. Even at low pressure the water stream will look good but the poppet is bypassing. 130deg is not hot. Mercs run a 143deg T-stat. If it's stuck open you can overheat because the water doesn't hang around the cylinders long enough to transfer heat. The springs that Merc uses for the poppet are junk and know for corroding. Poppets are the most frequently overlooked part, everyone blames problems on t-stats and water pump. Poppet parts are very cheap and easy to replace. It sounds like you run in heavy salt water. Try flushing with something like Salt-Away to remove salt deposits. This stuff makes the inside of water passages spotless.
 

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Discussion Starter · #6 ·
[excited] The engine has been repaired!! The Bahia Marina was very reasonable I thought. The total bill to replace the pump and thermostats was $229.00. I can live with that!! The mechanic told me that it looked like the engine had been run without water because the rubber impeller was melted to the plastic housing. I then recalled having run the engine for about one minute last fall so I could fog the engine. Whoops, my bad. Hope to get out on the water next weekend and do some fishing finally.[smile]
 
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