1994 Mercrusier 350 Mag ECT bravo closed cooling system

[lazy grady]

Ocock ain't Cristal clear. I try harder. They say, never aground, always a lier!

 

[DennisG01]

6/27/24 Mechanic says, based on what I conveyed that Water Pump needs replacing.

Ummmm... yeah, I think we already talked about that?

 

[JeffN]

I didn't have the option my pickup was in the drive, and no fresh water connection. Just flush cuffs at the end of the season. A heat exchanger flush would still be a good addition to your maintenance program, you might be surprized at what's in there. Good luck with the new water pump, hope that does the trick. W hen I chasged my instrumtation to smart craft I added a water pressure gauge and that I found quite helpful. When it began to climb I knew it was time for a flush.

 

[JeffN]

Ummmm... yeah, I think we already talked about that?

Always good to narrow problems down before throwing parts at it.

 

[lazy grady]

6/29/23 over time Given my lack of mechanical skills, I have spent a load on unnecessary parts. A little cocerned now as to replacing the water pump? Thinking I will ask Mechanic to check all water cooling system flow for blockages before replacing pump? Inlet and outlets to heat exchanger is concern. I am sure there are other places that could be blocked up or need cleaning.

Thoughts?

 

[Hookup1]

You have a sandy bottom there. I would have the mechanic back flush the saltwater side of the heat exchanger. Some heat exchanges can be opened up and "rod-ed" out. They should be cleaned periodically anyway - they load up on deposits and need to be acid cleaned. Change the raw water pump impeller (probably due anyway). Flush saltwater hoses.

Other than checking coolant level I wouldn't touch the fresh water side of the system. I would be a little concerned about your overheating and blowing coolant out. Get the heat exchanger working and test. Don't let it overheat again though!

Hopefully you have a engine coolant temperature gauge that you can monitor. You should be able to see the engine warm up to around 185 degrees at which point the thermostat opens and allows the heat exchanger to cool and hold temperature. Check the thermostat opening temperature with the mechanic.

 

[lazy grady]

You have a sandy bottom there. I would have the mechanic back flush the saltwater side of the heat exchanger. Some heat exchanges can be opened up and "rod-ed" out. They should be cleaned periodically anyway - they load up on deposits and need to be acid cleaned. Change the raw water pump impeller (probably due anyway). Flush saltwater hoses.

Other than checking coolant level I wouldn't touch the fresh water side of the system. I would be a little concerned about your overheating and blowing coolant out. Get the heat exchanger working and test. Don't let it overheat again though!

Hopefully you have a engine coolant temperature gauge that you can monitor. You should be able to see the engine warm up to around 185 degrees at which point the thermostat opens and allows the heat exchanger to cool and hold temperature. Check the thermostat opening temperature with the mechanic.

You have a sandy bottom there. I would have the mechanic back flush the saltwater side of the heat exchanger. Some heat exchanges can be opened up and "rod-ed" out. They should be cleaned periodically anyway - they load up on deposits and need to be acid cleaned. Change the raw water pump impeller (probably due anyway). Flush saltwater hoses.

Other than checking coolant level I wouldn't touch the fresh water side of the system. I would be a little concerned about your overheating and blowing coolant out. Get the heat exchanger working and test. Don't let it overheat again though!

Hopefully you have an engine coolant temperature gauge that you can monitor. You should be able to see the engine warm up to around 185 degrees at which point the thermostat opens and allows the heat exchanger to cool and hold temperature. Check the thermostat opening temperature with the mechanic.

6/29/24 thanks so much for your comments:

1. As to "not touching the fresh water side of the system", please elaborate? My thoughts (probably wrong) are there is two water cooling accesses: sea water pick up through the stern drive and the quick connect hose used on the lift? The additional circulating system being the "self contained" antifreeze? What circulates the antifreeze thru the heat exchanger?

 

[Hookup1]

6/29/24 thanks so much for your comments:

1. As to "not touching the fresh water side of the system", please elaborate? My thoughts (probably wrong) are there is two water cooling accesses: sea water pick up through the stern drive and the quick connect hose used on the lift? The additional circulating system being the "self contained" antifreeze? What circulates the antifreeze thru the heat exchanger?

There is an automotive style centrifugal pump on the engine. No impeller to replace. These pumps usually leak at the bearing and should be fine. Assuming you got the thermostat in correctly and gasket is good you should have to do anything here either. Just make sure it has water and antifreeze and is "burped" to get the air out. Run it with the cap off and add water if needed. The antifreeze has corrosion inhibitors in it so even though it won't freeze by you it still needs to be in there.

 

[lazy grady]

There is an automotive style centrifugal pump on the engine. No impeller to replace. These pumps usually leak at the bearing and should be fine. Assuming you got the thermostat in correctly and gasket is good you should have to do anything here either. Just make sure it has water and antifreeze and is "burped" to get the air out. Run it with the cap off and add water if needed. The antifreeze has corrosion inhibitors in it so even though it won't freeze by you it still needs to be in there.

 

[lazy grady]

You indicate "Run it with the cap off and add water if needed.". Do u mean antifreeze water mix on top of heat exchanger?

 

[Hookup1]

You indicate "Run it with the cap off and add water if needed.". Do u mean antifreeze water mix on top of heat exchanger?

Yes. Have your mechanic check it.