3.0 running hot 200F

[ronaldreagan]

I have 2005 Mercruiser 3.0 that's running at 190 - 200 degrees with a 160 degree thermostat which seems high.

A couple weeks back it overheated and I replaced the sea water impellor, water tube, water circulation pump, thermostat (160 degree), manifold, and riser. The only thing that needed replacement was the riser since it had rusted shut but figured I would take care of everything else as a form of insurance.

Is this temperature okay or should I look for anything else to fix?

 

[Scott06]

I have 2005 Mercruiser 3.0 that's running at 190 - 200 degrees with a 160 degree thermostat which seems high.

A couple weeks back it overheated and I replaced the sea water impellor, water tube, water circulation pump, thermostat (160 degree), manifold, and riser. The only thing that needed replacement was the riser since it had rusted shut but figured I would take care of everything else as a form of insurance.

Is this temperature okay or should I look for anything else to fix?

no its not ok- should be running around 175 at most. Do you know if your gauge is accuurate ?
Was the impeller you removed intact or missing pieces. I assume you got hte water tube in the drive back in correctly, may have some pieces of the old impeller in the powers teering cooler or in the thermostat housing. You can take the water supply hose off the thermostat housing and see how much water comes out, This si the cold water supply so should fill a bucket in a minute or so ( somehware there is a merc spec for this bucket test)

 

[ronaldreagan]

no its not ok- should be running around 175 at most. Do you know if your gauge is accuurate ?
Was the impeller you removed intact or missing pieces. I assume you got hte water tube in the drive back in correctly, may have some pieces of the old impeller in the powers teering cooler or in the thermostat housing. You can take the water supply hose off the thermostat housing and see how much water comes out, This si the cold water supply so should fill a bucket in a minute or so ( somehware there is a merc spec for this bucket test)

Thanks for the reply. The old impellor was intact. The drive went on okay and the water was in the guide sleeve, it seemed okay.

 

[Scott Danforth]

did you only replace the impeller, or did you replace the whole pump assembly?

at 1000 RPM, you should be able to fill a 5-gallon bucket from the line coming off the transom shield in about 15-30 seconds

 

[ronaldreagan]

If I was to clean out the exhaust downstream of the riser since there may be a burnt flapper piece somewhere, what would be the best way to do this?

 

[Scott Danforth]

If I was to clean out the exhaust downstream of the riser since there may be a burnt flapper piece somewhere, what would be the best way to do this?

pull the drive and reach up

 

[ronaldreagan]

did you only replace the impeller, or did you replace the whole pump assembly?

at 1000 RPM, you should be able to fill a 5-gallon bucket from the line coming off the transom shield in about 15-30 seconds

Just the impeller and it was still good, show little to no wear compared to the new. The housing looked clean with no scaring. Replaced the impeller in the same direction as the old one. Will try the bucket test before removing the drive to check for debris since I hate the idea of having to drain the drive again.

How often are thermostats bad from the factory? The replacement was quicksilver.

 

[Scott Danforth]

Just the impeller and it was still good, show little to no wear compared to the new. The housing looked clean with no scaring. Replaced the impeller in the same direction as the old one. Will try the bucket test before removing the drive to check for debris since I hate the idea of having to drain the drive again.

How often are thermostats bad from the factory? The replacement was quicksilver.

I have never had luck just replacing an impeller on a new to me boat.

 

[ronaldreagan]

I have never had luck just replacing an impeller on a new to me boat.

I just disassembled the impeller, checked for anything in the exhaust path again (half the flapper was there from the over heat), and reinstalled very meticulously with proper torque specs. The temp reading on the gauge is 190F but 145F at the engine using a meat thermometer.

Any thoughts?

It might be the gauge or sending unit.....

 

[Scott Danforth]

probably the sending unit or corrosion on the wire