Overheating

[2004Trophy2352wa]

I have a 2003 mercruiser 5.0 carborated. It started with my port riser getting warmer then the starboard and the alarm went off then i had replaced the impeller the water circulation pump and the thermostat and the risers were cool again. But the thermostat was hot and still sending an alarm. The risers and manifold's were replaced last year and I am still slightly overheating at the thermostat. The alarm starts to beap around above 2000 rpm then stops beaping once on plain. Manifolds and risers feel cool to touch thermostat housing is hot to touch. Doesn't seem to be a head gasket no water in oil and engine doesn't miss. After I turn it off I let it sit to see if risers are leaking down into cylinders to check if it gets hydro locked but it starts right up. It runs about 175 to 190 when getting ready to plain. At idle 175 on plain 180 185 wich is still to high. Please help I hope you have enough information?

 

[dubs283]

Possible failing engine circulating pump?

Are the hoses attached/routed correctly to/from the t stat housing?

Would like to guess blockage somewhere but with manifolds/elbows being cool it seems like not enough water supply/exit from the block. Pretty sure your 2003 setup does not have check balls for the elbow water supply

 

[2004Trophy2352wa]

Possible failing engine circulating pump?

Are the hoses attached/routed correctly to/from the t stat housing?

Would like to guess blockage somewhere but with manifolds/elbows being cool it seems like not enough water supply/exit from the block. Pretty sure your 2003 setup does not have check balls for the elbow water supply

Yes it has check balls they are clean and are working properly.

 

[2004Trophy2352wa]

Yes it has check balls they are clean and are working properly.

Also all hoses are routed correctly.

 

[2004Trophy2352wa]

Yes it has check balls they are clean and are working properly.

Pump is new

 

[dubs283]

Yes it has check balls they are clean and are working properly.

They are not

The check balls are allowing too much water past at lower rpm. There's not enough supply to the circ pump due to water exiting the exhaust before the circuit pump hose at the t stat housing

Remove the balls, turn them around and re tension the springs. Pretty sure it'll aid in blocking enough water so the circ pump doesn't starve

 

[2004Trophy2352wa]

They are not

The check balls are allowing too much water past at lower rpm. There's not enough supply to the circ pump due to water exiting the exhaust before the circuit pump hose at the t stat housing

Remove the balls, turn them around and re tension the springs. Pretty sure it'll aid in blocking enough water so the circ pump doesn't starve

I will try that. Make sense. How tight do the balls need to be they feel pretty free.

 

[dubs283]

The balls need to be seated in the barbs at rest

Shouldn't take much effort to move them off the seats but it's important that they seat with little/no gap

 

[2004Trophy2352wa]

I will try that. Make sense. How tight do the balls need to be they feel pretty free.

The balls need to be seated in the barbs at rest

Shouldn't take much effort to move them off the seats but it's important that they seat with little/no gap

Ok I have a gap with no seating. It definitely sounds like that is my issue. Thank you very much.

 

[2004Trophy2352wa]

Ok I have a gap with no seating. It definitely sounds like that is my issue. Thank you very much.

Well that didn't work. I'm lost I've been reading mercruiser repair manuals and all. That's why I came to this form. Thank you for your help.

 

[dubs283]

What is the condition of the drive? Where the sea water pump is located

Corrosion on the gear case housing can cause overheat at certain rpm

 

[2004Trophy2352wa]

What is the condition of the drive? Where the sea water pump is located

Corrosion on the gear case housing can cause overheat at certain rpm

I just had the sea water pump replaced 2 weeks ago after it started this temp issue. The outdrive is in amazing shape. I flush the engine every trip. For almost 20 years old the outdrive still looks brand new. I keep it on a trailer.

 

[2004Trophy2352wa]

The engine has about 6 or 700 hrs on it.

 

[2004Trophy2352wa]

The engine has about 6 or 700 hrs on it.

Gimble bearing and all the boots were replaced last year.

 

[2004Trophy2352wa]

I'm going to check all my block plugs when it cools down. it might be pulling air and not leaking

 

[dubs283]

I just had the sea water pump replaced 2 weeks ago after it started this temp issue.

Did you replace the sea water pump/impeller or did someone else? Were the parts installed oem?

 

[2004Trophy2352wa]

I had a marine shop do it. But it had this problem before they replaced the impeller. They use nothing but OEM parts.

 

[dubs283]

With vintage posted by you of roughly 20 years ago I'm assuming alpha gen 2

A few gen 2's that have passed my way have suffered from corrosion at the casted dam aft of the water pump assy between the sea water pickup and exhaust cavity. This is including fresh water operated raw water cooled.


With no eyes on this area I can only speculate based on my experience. You may need to remove the drive, split the halves and inspect

 

[2004Trophy2352wa]

With vintage posted by you of roughly 20 years ago I'm assuming alpha gen 2

A few gen 2's that have passed my way have suffered from corrosion at the casted dam aft of the water pump assy between the sea water pickup and exhaust cavity. This is including fresh water operated raw water cooled.


With no eyes on this area I can only speculate based on my experience. You may need to remove the drive, split the halves and inspect

 

[2004Trophy2352wa]

It looks practical new I still have original zines on it