Mercruiser 3.0 water by-pass theory

[pfcmooney]

Good Afternoon Gents,

I have a 2006 Sea Ray 175 with the mercruiser Alpha one Gen II.

I bought the boat from a fella in Florida, boat ran but would not idle. So I got the boat, taking a chance that was the only issue. I took the TKS off the boat due to how expensive a replacement would be and put an electric choke carburetor on. So far so good, idles and runs great. I then experienced overheating issues. I inspected the impeller which was still in great shape, replaced the thermostat and the water pump. Still overheating. After watching some video on YouTube I decided to "by-pass" the intake/exhaust manifold by using the winterize blue drain hoses. I unplugged the manifold drain and let it dump out the bottom, allowing the water to still enter and cool the manifold but instead of routing through and dumping out the exhaust, it dumps into the hull and out the drain....I did that to test the theory. So, now I am contemplating bypassing the manifold using the drain and drilling a hole on the exhaust side to dump into the exhaust rather than getting stuck in what I'm guessing is rust within the manifold. That will give me a few more years before the manifold rusts out and needing a complete replacement. At that time, I will do it right and replace the manifold and riser. Thoughts?

 

[Rick Stephens]

Good plan to end up walking back from wherever you boat to. There is a reason things work the way they do. Bypassing will become overheating somewhere in your system.

Pull and inspect your manifolds and do the proper maintenance. Cutting corners costs lots more in even the short run.

 

[Scott Danforth]

Replace the impeller, never worth it to not do it.

Overheating is lack of flow

 

[dubs283]

That will give me a few more years before the manifold rusts out and needing a complete replacement. At that time, I will do it right and replace the manifold and riser. Thoughts?

Sounds like you're already at the point of needing a manifold and riser replacement. Can't imagine anyone here who regularly gives sound advice approving your "bypass theory".

All I can say is that it is your boat/engine and you can do what you like but if I saw this setup you're considering irl it would garner a head shake and some choice words....

 

[Lou C]

No.

 

[achris]

Now pull the exhaust elbow (and replace it as that's probably why it's overheating) and you'll also need to now replace all the rubber parts in the exhaust system (shutter, tubes etc)... I would strongly suggest you pull the drive again and replace the exhaust bellows and the seal on top of the water pump housing. They will all be burnt because they require the exhaust water (that you dumped into your bilge) to keep them cool and not burn up.

Chris....