Default Should Both Manifolds on Mercruiser 8.1 Inboard Be Warming Up Equaly at Cold Start?

[Az9]

Hi,

I don't own a Searay, I own a Regal, but with a very similar setup as some of the Searay Mercruiser 8.1 Horizon Inboard twins. I hope I can get an opinion. I'm on salt water in southern CA.

When I turn on the engine, in about 5-10 mins. one manifold becomes warm to the touch. The other is cold.

After 15 mins. I turn the engine off. The cold manifold starts warming up and, eventually, reaches similar temp. as the one that's already warm.

Is this normal???

Heat exchanger seems to function normal. It warms up to the touch at about same time as the warm manifold, then cools off to the touch I'm guessing because it is working...

Manifolds are brand new.

I'm not currently driving the boat so I can't test engine under load, because the second engine is out of commision.

 

[hottoddie]

Sounds normal. The sea water flows thru one side of the engine across to other. The second side will warm up as it is being cooled by sea water that passed thru the other side. When you shut the engine down the cold side will then absorb heat from the engine block and reach the same temp as the other side and the engine block as well.

 

[Az9]

Sounds normal. The sea water flows thru one side of the engine across to other. The second side will warm up as it is being cooled by sea water that passed thru the other side. When you shut the engine down the cold side will then absorb heat from the engine block and reach the same temp as the other side and the engine block as well.

Thank you!

 

[LG111]

Normal. One side is slightly warmer than the other at idle.