1986 390 water flow

[Chasntail]

Happy holidays everyone, this past season I've been battling some warmer engine temps, also i am wondering about how much water flow i should have coming out of the exhaust, when I start the motors it takes 10 or more seconds until I get water out of the exhaust. Once pumping it is not a steady flow it pumps water than a pause than pumps again. I have crusader 454s fwc, I replaced the manifolds and risers and still run warmer than normal. I'm wondering what everyone else is getting for flow, is it supposed to be constant or does it seem to be normal for the flow to be intermittent? I replaced both impellers at the time of the new exhaust install. One last thing the flow was exactly the same before new exhaust? What's next oil cooler? Heat exchanger? Any help would be appreciated.

 

[hottoddie]

I have the exact same boat and engines. Mine take 5-10 seconds to get water flow as well. However the water flow out the exhaust is constant from idle and increases with rpm. Is this a new issue with you? How long have you owned the boat? What engine temps are you getting? On some boats the water flow does fluctuate but not mine. Could be design of the exhaust with the water lift style mufflers. If this a new issue and you are running higher than normal engine temps I would check your U coolers for restrictions and make sure the strainers and thru hulls are clear. Also get a infrared temperature thermometer to confirm the engine temps.

 

[Chasntail]

The water flow isnt a new issue I've owned the boat for 2 years. But I do run at 193 degrees at cruise. Once I come down it takes several seconds to begin to cool. As far as the flow it's one of those things that I see a boat doing something different than mine I try to get it fixed. I am flushing the freshwater side over the winter, and going to run barnacle buster through raw water side to see if anything abnormal comes out.

 

[Alvin Bruning]

Has anyone added a water feed heater core in a boat, like is installed in an automobile to get heat into the cabin? I have a 1987 Sea Ray with the Cruisair EBO 4 heat exchanger that does not work.

 

[sbw1]

The water flow you describe is due to the the design of your water lift mufflers. The canisters fill until they reach the overflow and that water gets dumped overboard. You may have extra exhaust noise at start up too, before the canisters fill with water.

 

[hottoddie]

View attachment 63659 The water flow you describe is due to the the design of your water lift mufflers. The canisters fill until they reach the overflow and that water gets dumped overboard. You may have extra exhaust noise at start up too, before the canisters fill with water.

The intermittent water flow may be due to the water lift mufflers but I have the same year 390 with same engines and water lift mufflers. I get a smooth constant water flow out the exhaust and both my Crusaders 454s run at 160-165 even at wot. There is a 1989 390 at my yacht club with Mercruiser 454s and it has smooth water flow also with no higher than 170 degree temps. I think the OP should be more concerned with the 193 degree engine temps than the water flow. They may or may not be related.

 

[sbw1]

The intermittent water flow may be due to the water lift mufflers but I have the same year 390 with same engines and water lift mufflers. I get a smooth constant water flow out the exhaust and both my Crusaders 454s run at 160-165 even at wot. There is a 1989 390 at my yacht club with Mercruiser 454s and it has smooth water flow also with no higher than 170 degree temps. I think the OP should be more concerned with the 193 degree engine temps than the water flow. They may or may not be related.

Yes. Temperatures do seem high, but who knows what is going on there given the little info provided. OP didn't say what type of cooling system the boat has, nor if it is a boat run in salt water prior to moving to fresh water. As you point out, it could be a number of things. I responded to the variable water flow because my two prior SeaRays had water lift mufflers and that was the way they functioned from the time they had 2 hours on them until I sold them years later. My present boat with water lift mufflers does the same thing, again since it was brand new. So, this is not something to worry about by itself.

 

[FINAL DRAW]

I have seen the inner lining of suction hose collapse between strainer and fresh water pump. On a '88 390 also. Over heat at cruise, ok at idle. FYI

 

[hottoddie]

It sounds like the OP is saying both engines run hot at the same temp. That is unusual and to me it's time for the infrared. BTW I've never seen raw water cooling Crusader 454s in a 390 so I assumed that is what they are.

 

[CaptRonn]

View attachment 63665
Yes. Temperatures do seem high, but who knows what is going on there given the little info provided. OP didn't say what type of cooling system the boat has, nor if it is a boat run in salt water prior to moving to fresh water. As you point out, it could be a number of things. I responded to the variable water flow because my two prior SeaRays had water lift mufflers and that was the way they functioned from the time they had 2 hours on them until I sold them years later. My present boat with water lift mufflers does the same thing, again since it was brand new. So, this is not something to worry about by itself.

It sounds like the OP is saying both engines run hot at the same temp. That is unusual and to me it's time for the infrared. BTW I've never seen raw water cooling Crusader 454s in a 390 so I assumed that is what they are.

From the OP:

I have crusader 454s fwc, I replaced the manifolds and risers and still run warmer than normal.

 

[Chasntail]

It is an odd scenario, because both motors began running warm at the same time. The motors are fwc. The manifolds have coolant running through them not raw water. The boat is on the Chesapeake. The mufflers make sense as to why the intermittent water flow, I was hoping that this was the issue of my motors running warm. But it seems that is not the case. I agree I should have IR the temps and not rely on the guages alone. But its winter lay up and I cant do that at the time. With all this being said the exhaust is new, so I'm assuming at this point being that I can't do a run with an IR temp gun should I move to the oil cooler next and have it checked or the heat exchanger?

 

[sbw1]

It is an odd scenario, because both motors began running warm at the same time. The motors are fwc. The manifolds have coolant running through them not raw water. The boat is on the Chesapeake. The mufflers make sense as to why the intermittent water flow, I was hoping that this was the issue of my motors running warm. But it seems that is not the case. I agree I should have IR the temps and not rely on the guages alone. But its winter lay up and I cant do that at the time. With all this being said the exhaust is new, so I'm assuming at this point being that I can't do a run with an IR temp gun should I move to the oil cooler next and have it checked or the heat exchanger?

Rather than throw money at it, I would be inclined to launch it in the spring and get some better info with IR and go from there. But, that is really easy to do where we live. Might be harder in your area. Has the boat lived in salt water before you owned it?

 

[Chasntail]

I may just wait till spring, in was hoping to get resolved before hand so I'm ready to go in the spring. But waiting might be a better idea. I have plenty other things to focus on. The boat has been in the Chesapeake the passed 12 years not sure before that.

 

[Saverio]

when was the last time the thermostats was changed they could be clogged ??? or the wrong temperature?
You can take a peak of your heat exchangers and remove the side covers and see how they look. you can pick up a wooden dowel at the depot to clear it out. they do sell new side tank gaskets also.

good luck
Saverio