Overheating Problem

ok heres what happens...i have

ok heres what happens...i have a mercruiser 170..the engine overheats very fast...when i take apart the hoses and all to check them i see that my heat exchanger is full of anti-freeze..even after adding straight water in the reservoir..so this tells me that the fluid in the exchanger is never being circulated...thermostat? water pump? anything else?

I do not feel that you underst

I do not feel that you understand how a heat exchanger works.

The coolant in the engine is cooled by passing through tubes inside the heat exchanger that have cold water from the lake / river whatever pumped by the tubes from the pump in the lower unit.
This heated water is then dumped out the exhaust manifold.
The engine coolant never leaves the cooling system.

Check the impeller in the lower unit water pump.
If the impeller or pump housing is bad the engine will run hot because there is no water being pumped for cooling the exchanger.

Also check for the proper mixture of coolant when you are done. Now that you have added water to the engine coolant it could be weak.

ok picture this though...i add

ok picture this though...i added plain water directly to the engine when it overheated....the coolant in the heat exchanger was all coolant with no water...i realize it was wrong to pu in %100 collant in the first place but when i did add straight water shouldnt the contents of the heat exchanger be diluted?

I'm not following you. How

I'm not following you. How can you tell what is in the heat exchanger it's sealed and you can not see in it.
Are you sure you are looking at the heat exchanger? This is a cylinder about 3 or 4 " round depending on the model & what about 20" long again depending on the model.
Each end has a cap with one bolt in the center holding the cap on.
There should be 4 hose fittings 2 on each end.
That is the heat exchanger.
I can't see how you could tell what was in it.
I'm glad to help if I can but I think you must be looking at the wrong part. If the water you added is not going down any then the sealed part of the engine side of the cooling system is ok.
It would take a lot of water before you would see a change in the color of the coolant and the end would need to be removed from the heat exchanger to see this in the exchanger.
Then the coolant would just run out. Are you following me?
If the exchanger is closed & holding coolant you can not see in it.
If the boat is runnng hot it may need the impeller.

when i take the hose off that

when i take the hose off that runs from the engine to the heat exchanger...the exchanger is filled to the top so i can see in the hole...i will check the impeller today....hopefully thats my only problem

Now that make sense as to how

Now that make sense as to how you can see what is in the heat exchanger.
If you had removed the hose from the rear of the boat there would be nothing until the engine was started.
Do you see what I mean about the need for the water from the out drive impeller in the heat exchanger to keep the engine cool?
Best of luck.

ok charli here may be the prob

ok charli here may be the problem....i neglected to tell you that i also blew the belt on the alternator....from what i understand..that belt also turns the circulation pump in some way.(im not too sure how)...hhhhmmmm no circulation...no cool fluids....im an idiot...hope i didnt do any pemanent damage

Well the circulation pump is j

Well the circulation pump is just like the type used in a car. One pulley that is driven by the alternator belt is turning this pump.
I doubt you did any real damage so long as the engine didn't get too hot and had some coolant left in the block.
If it still runs and you have no leaks in the engine part of the cooling system & it isn't smoking or knocking I'd say it will be fine.

The marine engines are very well built.

It would be a good idea to change the oil just to be safe.

Nice if it is nothing more than a bad belt. Makes life a little easier.

Other way around on what's

Other way around on what's inside the tubes of the Hx... that's the raw water side. The coolant side is on outside of the tubes.