Coolant Leak

[2000 Elisa's Ring SR 24]

I got the february blues this weekend and decided to go out to the boat and check on a couple of things. I took off the heat exchanger cap to find no coolant in the heat exchanger! There are no wet spots in the bilge and no signs of a leak anywhere. Where is it going?????<br /><br />I run 454 Mercruisers with a closed system.

 

[Don S]

Re: Coolant Leak

Could be nothing wrong. If the tubes in the heat exchanger are showing, it may be just slightly below the level of the tubes and you just can't see it. 1 or 2 cups of AF and it will probably be over full. If it takes more than that, then you need to do a pressure check of the system. Are your manifolds cooled with AF? Lots of possibilities for the leak. What year and model 454 do you have.

 

[2000 Elisa's Ring SR 24]

Re: Coolant Leak

1992 merc bluewater inboards....manifolds are cooled by AF. This has been a problem for me since last fall and I "think" i made sure the AF was full when I winterized. I found it odd that the coolant would leak without the engine being run. Is the AF falling into the cylinders from the manifolds??

 

[Don S]

Re: Coolant Leak

That is a possibility, you could drain down the antifreeze in the engine, and make sure the risers are empty. Then pull the risers and see if there is any antifreeze in the exhaust passage.

 

[Haut Medoc]

Re: Coolant Leak

Possible.....As Don says there are alot of places for it to leak....If the heat exchanger has an internal leak, the AF will disappear into the raw water side of the system.....A pressure test will answer your question on leaks....JK

 

[2000 Elisa's Ring SR 24]

Re: Coolant Leak

I checked the oil and the oil is clean, it was clean when winterized as well. Would you say that is a good sign that it isn't making it into the cylinders and maybe just the exhuast system or raw water system?

 

[Don S]

Re: Coolant Leak

Just the fact that the level is low after sitting during winterization means very little. You wouldn't be able to even tell if there was a cup or two of antifreeze in your oil just by checking the dipstick. It wouldn't show enough level change to be noticable, and the oil will not get milky unless it's being run. Going out the heat exchanger is a possibility (and a very strong possibility if the zincs weren't changed in it). But, if you put AF in the raw water side during winterization, you wouldn't be able to tell. The ONLY way you have is to drain the complete system and pressure check it. If it looses pressure, start isolate the heat exchanger and retest both till you find the problem. It may take a cylinder leakdown test and other tests to determine what exactly is leaking.