Cooling system mystery

[paulrfrancisco]

Ok.... I have twin 1990 454/Bravos FWC... and I have 2 seperate problems that are plagueing me. This happens more or less on both engines. I really cannot be 100% certain if one is with one problem and the other is the other problem, but problem # 2 below is definately on both moters... one to a greater degree that the other...

1. I get sea water with soot in my bilge.

2. I periodoccally have to add antifreeze to my FWC loop.

I have looked around and there is no antifreeze leaking into the bilge, so it must be going out the exhaust... and I dont see anything dripping when I start the moters up to see if seawater is leaking out the exhaust manifolds unless it happens once it gets hot and under higher rpms like while under way.

Anyone have any suggestions?

Please advise.

 

[Haut Medoc]

Re: Cooling system mystery

Ok.... I have twin 1990 454/Bravos FWC... and I have 2 seperate problems that are plagueing me. This happens more or less on both engines. I really cannot be 100% certain if one is with one problem and the other is the other problem, but problem # 2 below is definately on both moters... one to a greater degree that the other...

1. I get sea water with soot in my bilge.
I would look for a leak in the exhaust past the risers....
Ie , the hose claps on the exhaust boots are loose or one of the y pipes has a small leak.....
The downside of that is you will need to pull the motor to get a good look at the entire Y pipe....

2. I periodoccally have to add antifreeze to my FWC loop.
The most common spot would be a leak at the man/riser joint......

I have looked around and there is no antifreeze leaking into the bilge, so it must be going out the exhaust... and I dont see anything dripping when I start the moters up to see if seawater is leaking out the exhaust manifolds unless it happens once it gets hot and under higher rpms like while under way.

Anyone have any suggestions?

Please advise.

A small pinhole in the heat exchanger could do that.....
Pressure test it.....

 

[coastalcruiser]

Re: Cooling system mystery

you need to sikaflex the bottom of the Y or it leaks. It has o rings but there is lots of pressure. after a day of cruising there should be no water in the bilge

 

[180shabah]

Re: Cooling system mystery

If possible, get someone else to drive and stick your head in there and look while it is up and running.

Just stay clear of those belts!!!

 

[Don S]

Re: Cooling system mystery

you need to sikaflex the bottom of the Y or it leaks. It has o rings but there is lots of pressure.

If that Y pipe is leaking, it's probably cracked or corroded and no amount of sikaflex or any other sealer is going to be suitable for fixing a "BELOW THE WATER LINE" leak.
There is not "LOTS of pressure" in the exhaust, at least there shouldn't be. If there is, it's probably from a broken flapper laying in the exhuast somewhere.

Anti freeze could also be leaking out the heat exchanger and going out with the cooling water. Empty the coolant side of the heat exchanger, block them off and pressure check it.
If you don't have antifreeze in your exhaust manifolds for cooling, they won't be your problem.

 

[coastalcruiser]

Re: Cooling system mystery

I meant use sikaflex before installing the Y makes a huge difference!