2007 Mercury 150 Opti alarm problem

[jay's snake]

2007 Mercury 150 Optimax serial # 1B434225.
After running the boat for about 15 minutes, a buzzer went off. It was a single buzzer for a short time.
After checking it over, I found two problems.

1. First, I had a fuel leak at the end of a hose on the front of the engine. I cut-off the end of the hose and re-attached. Leak fixed.
   
2. The oil tank on the engine was about an inch low so I loosened the cap and started the engine, but it would not fill the engine oil tank. I found the inline oil line filter was plugged. I replaced this filter last December, so I was surprised to see it plugged- up so soon. I cleaned the pickup in the remote tank and changed the inline filter. I do not understand why that filter is getting plugged-up. I only use Mercury DFI oil and everything looks clean.
   

Both problems fixed, so I took the boat back out and once again the buzzer gave a single buzz after about 15 minutes. Dang, how many unrelated problems can one motor have all at once?

After reading thru this forum, I’m thinking the buzzer is caused by an overheating situation. Water is coming out the “pee hole” ok I guess. I replaced the water pump about 4 years ago and the gauge has always read kinda low, but I’m more used to Johnson motors. My understanding is at idle it should have maybe 1 to 4 pounds of pressure? I’m also wondering if it could be a thermostat problem? Any guidance in how to diagnose this is appreciated. Thanks!!

[jay's snake]

I took the boat out this afternoon to get some more information.
Soon after I started the motor, I took it out of gear and raised the RPM and the alarm sounded. It had barely run for a few minutes, so I don’t think it could have been overheating. However, I thought it could be a coolant flow issue. I turned the motor off and went fishing for a few hours with the trolling motor.
After a few hours, I then started the motor and drove it to get some pressure readings. At idle it is barely above zero and at WOT it is at 9 lbs according to the dash gauge. I know the spec is 12 lbs at WOT, but I don’t know if I can trust the gauge or not. The alarm did not come on any more.

Any ideas what to check next?

[SilverFox579]

Water pump should be replace annually or every 100hrs whichever comes first, so start there. Water pressure specs are 1 - 3psi at idle and at least 12psi WOT. Is your water pressure gauge analog or Smartcraft? When servicing the water pump, make certain you replace, at minimum, the impeller, the plate, and all 3 gaskets (one each either side of the plate PLUS one below the pump base). If you need a complete kit - If you want to order or price Mercury Engine Parts or Accessories...

You cleaned the remote tank pickup but did you drain, clean, and refill the remote with clean oil? You could have congealed "gunk" at the bottom of the tank.

NEVER rev an Optimax in neutral, only in gear and going somewhere.

Since you're at least 3yrs overdue on water pump service you might do your engine a favor and make sure all the other recommended annual maintenance items are up to date also, some helpful topics from the FAQ at the top of this forum.

Recommended Annual Maintenance or Winterization for Optimax Engines

Compressor STRAINER Cleaning

Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

Bleeding air from the Engine Mounted Oil Tank

WARNING HORN "BEEPED"

[jay's snake]

Thanks for your response Phil.
The water pressure gauge is a manual gauge using a water tube that runs back to the motor somewhere. I think I might hookup another gauge just to verify the gauge reads correctly.
Next I’ll get a water pump kit ordered and get busy on those maintenance items. These Mercury’s like to be pampered I guess.

[buster502]

no need to pamper just maintenance items,the very first thing i would do is the water pump kit (all 3 gaskets is a must) next i would find out where the problem with fuel filter getting dirty so much,tank cleaning might in order and lines,thermostats and poppet valve kit,do you know how this motor has been taken care ??? i would start from scratch and go thru it first with simple maintenance items

[EuropeanAM]

Water pump should be replace annually or every 100hrs whichever comes first, so start there. Water pressure specs are 1 - 3psi at idle and at least 12psi WOT. Is your water pressure gauge analog or Smartcraft? When servicing the water pump, make certain you replace, at minimum, the impeller, the plate, and all 3 gaskets (one each either side of the plate PLUS one below the pump base). If you need a complete kit - If you want to order or price Mercury Engine Parts or Accessories...

You cleaned the remote tank pickup but did you drain, clean, and refill the remote with clean oil? You could have congealed "gunk" at the bottom of the tank.

NEVER rev an Optimax in neutral, only in gear and going somewhere.

Since you're at least 3yrs overdue on water pump service you might do your engine a favor and make sure all the other recommended annual maintenance items are up to date also, some helpful topics from the FAQ at the top of this forum.

Recommended Annual Maintenance or Winterization for Optimax Engines

Compressor STRAINER Cleaning

Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

Bleeding air from the Engine Mounted Oil Tank

WARNING HORN "BEEPED"

^^^ Spot on

Do you use a Funnel when adding oil to your Remote Oil Tank?

[jay's snake]

Yes. I use a funnel.

[EuropeanAM]

Might need to check for a very thin layer of "goo" at the bottom of the remote tank (clean the entire tank out).

Over the years, a couple hairs here, a few grains of sand there, and 2-4 drops of water each time it's raining (conservatively) can build up into enough to cause problems with filters and screens.

One thing is for sure... anything plugging the filters is coming in through the oil cap, one way or another.

[jay's snake]

Yep, I will definitely spend a little more time cleaning out that oil tank and lines after I get the cooling issue resolved.

[jay's snake]

Ok, I pulled the lower unit down to get at the water pump and by the way, discovered that someone has been trying to steal my lower unit. The trim tab and bolt is missing and one other bolt and 2 nuts are missing as well. The lower unit was hanging on by the 3 nuts towards the front. I guess they didn't bring the correct wrench to get those removed. (some people suck!)

I didn't find anything unusual with the water pump or gaskets. I did notice that when I place the copper tube up into the engine, it does not feel like it pushes into a seal on the upper end. From the discoloration on the tube I would expect there to be a grommet that it would go into to seal. It sounds like it just rattles around up there. Can you tell me if this sounds like an issue?

Thanks!

[EuropeanAM]

The seal in the adapter plate is the exact same part as is used in the water pump (outlet seal to water tube). Should feel very similar at each end.

The tube will move around CONSIDERABLY when the gearcase is removed, but should not "fall" out of the grommet (grommet should be able to retain the copper water tube).

[jay's snake]

Is it possible that the upper seal could have fallen out? Do you have to pull the powerhead to check it?

[jay's snake]

OK, I see the grommet up inside there and I understand now after many, many attempts that you have to install the tube in the powerhead first and then connect it to the water pump housing second. I definitely beat my head up against the wall trying to stab it into the powerhead with it connected to the waterpump already.

Tomorrow, I'll test it and see if I made any improvement. I did not see anything obviously wrong with the pump components, but I replaced the upper and lower housings along with the impeller and gaskets so everything is new.

[jay's snake]

Just a final post to wrap things up. The water pump was the problem. Even though it had no visible damage, it was apparently old and not flexible enough to do the job anymore. WOT pressure is now 14-15 lbs. Thanks for everyone's help!

[SilverFox579]

[EuropeanAM]

Sometimes that preventative maintenance does indeed make a difference.