Mercruiser 4.3 Coolant Reservoir Location

[AndyFL]

Hi! I am a new boat owner and have a couple of questions regarding my 2006 Mercruiser 4.3L (carburated) Alpha1 engine.

The Mercruiser Ops Manual explains how to check and refill the coolant reservoir, but is not clear as to where this reservoir is located. Can anyone tell me where can it be found?

Also, how can I tell if I have a Seawater Cooled model or a Closed Cooled one? Basically, what difference does it makes to have one versus the other? I apologize for my ignorance

My model #4211025TT.

Thanks, Andy

 

[Don S]

Re: Mercruiser 4.3 Coolant Reservoir Location

An engine with seawater cooling doesn't have a heat exchanger.
Can you post a picture of your engine. It's real easy to tell by looking.

 

[Bondo]

Re: Mercruiser 4.3 Coolant Reservoir Location

Ayuh,......

Basically,.....
If there's No Radiator Cap,...... It's Raw Water Cooled.........

 

[AndyFL]

Re: Mercruiser 4.3 Coolant Reservoir Location

Thanks to all for your replies. I don't see a heat exchanger nor a radiator cap so it seems mine is seawater cooled, please correct me if I am wrong. There is a blue color coded end cap just below the alternator, what is it for? An on-engine sticker has blue-coded parts listed as "Engine Cooling" related.

Here is a nice pic of my engine:

http://www.hitechmarine.com.au/aurora/assets/user_content/5cad3b87f19e12a3f5a6af9c4aa366eb.jpg


Thank you!

 

[Dryon]

Re: Mercruiser 4.3 Coolant Reservoir Location

If it's just below the large hose coming off the Circ Pump then it's a seawater drain plug. You should have five of these. They are color coded blue and are located as follows. One on each side of block just below exhaust manifold, one on each exhaust manifold at low point, and the one I believe you're seeing off the large hose.
Use these to drain the seawater to avoid a cracked block or manifold during winter storage.
Stick a small wire in each hole to unclog any rust or scale that may build up so it will completely drain.

 

[AndyFL]

Re: Mercruiser 4.3 Coolant Reservoir Location

Excellent advice Dryon, I do appreciate the good info. Here in sunny Florida we don't really have to worry much about winterizing, but is always good to know where these plugs are and what's their purpose.

Again, thanks for your post/ Andy