Carver Owners Forum

Do a pressure test. What are these, Mercs? Are they closed cooled exhaust manifolds or raw water cooled?

BTW, tranny coolers is raw water cooled, no coolant present.

+1 = Perhaps the "best" place for there to be a problem would be the block-off plates between the manifold and riser. This would be the easiest fix. A pressure test would tell you.

+1 - Perhaps the "best" place for there to be a problem would be the block-off plates between the manifold and riser. This would be the easiest fix. A pressure test would tell you though

Here's a link to a manual that has coolant flow diagrams. I believe it should be for your application. HTH
www.crusaderengines.com/wp-content/uplo ... 001-09.pdf

I have a 2005 Mariner with 6.0 Crusaders. The boat is new to me and I am learning.
I 'thought' that I was losing coolant as well. I would fill up the reservoir and cruise around at 3200RPM for a couple of hours. There is a noticeable amount of 'steam' coming out of the exhaust at cruise speed.
The next day I would check the reservoir and it would seem empty. I would proceed to fill. I am thinking that the coolant is leaking somewhere and burning off. Same symptoms and possible remedies as outlined by the folks on this string.
I was ready to do a pressure test.
Then I noticed that the coolant reservoir has 3 'compartments' in them. (this is my first experience with this style reservoir...my previous boat was 1989 carb stye engines).
The 'aft' compartment has the flow line leading down to the engine. The 'forward' compartment has the overflow line.
I realized that I would keep filling all the compartments viewing the coolant through the translucent tank. I would stop filling when it was completely dark with fluid.
I then realized that the aft compartment already had coolant. I was simply overfilling each time and it was exiting out the forward overflow line. Simple answer for my inexperience with the engines.

nautiyachti wrote:Qr Bbpost .....what does engine coolant loss have to do with my transmissions. they aren't part of the same system are they?...

Nothing to do with transmissions, no coolant through the cooler, not part of the closed cooling system.

Doesn't tell you much. Could be a cracked heat exchanger, a problem with a manifold or even a head gasket issue.

Unless you diengage the raw water pump, you don't want to run the engine very long out of the water. If you disengage the raw water pump, you don't want to run it too long or your exhaust is going to get way too hot. If you are feeding it with cooling water, then you're not going to notice much difference coming out the exhaust.

I think you need to just get the engine/ exchanger pressure tested properly to tell you anything definite.....you would have to run the engine on a hose for a while for it to heat up enough to create any pressure in the engine coolant.....or just remove the exchanger and take to a rad shop to be tested and or repaired, much easier in my opinion, if you suspect the exchanger only.To test the entire cooling system ,it has to be together....perhaps with the pressure on and it shows a leak somewhere, just remove the raw water hoses from the exchanger and see what comes out.....its a start.

nautiyachti wrote:Qr Bbpost...if I top up the coolant, run the engine and can see coolant coming out of the exhaust, does that tell me if this issue is from a cracked heat exchanger or ??

It can but as mentioned above, it could be from other sources as well so all it will do is confirm that you're losing coolant out the exhaust which you already know or it would be in your bilge or oil pan. You'd likely also need to run it for a while as mentioned which I wouldn't want to do for very long nor would I need to since doing a simple test by pressurizing the system in place would likely reveal the source of the leak. Get them to do it when it's on land, it affords a couple of more options for leak detection that you can't see while in the water such as out the exhaust port or dripless shaft logs without the engine running.

Make sure you test the coolant in your block come winterizing time! Don't add coolant after haul out then simply test the coolant at winterizing time in your heat exchanger, all you'd be doing is testing the coolant you just poured in the exchanger.

Thanks for posting the resolution, so many don't .....it will be a big help to someone with the same sort of issues....... ..