6CTA Coolant Question

[Keith Giller]

Question, I have 6CTA’s. I’ve noticed that after some trips my coolant expansion/overflow tanks are normal level. A week or two later when I come back they are almost empty and always have to put a cup or two in them before I head out again. Boat runs great, put in 160 thermostats, No leaks as far as I can see in the diapers, don’t see anything in the exhaust, and coolant checks are always full. Plan on doing a pressure test in the coming weeks. Just curious if anyone has had this happen. Thanks.

Topic

[Keith Giller]

Thanks

I have diapers everywhere and nothing. My guess is the HXR’s.

[Richard Dodson]

I had a similar issue, wound up being a small leak coming out of the coolant drain on the turbo. There is a large banjo fitting on the bottom of the turbo, coolant at some time was leaking out. Found it by putting pads under all the possible places a leak could happen. Tony has a suggestion how to seal up the fitting, it took a couple of try’s to seal it up.

[Keith Giller]

Thanks…

Pressure test came back good on engines. I’m having the AC’s and HXR’s pulled for my two year maintenance on them. Hopefully the HXR service will solve the problem. Someone also mentioned the overflow caps or the tubes leading to the overflow tank may be the culprit?

[Steven Danaher]

I would purchase a cooling system pressure tester. Pump up the system with the engine cold and look for leaks. Also the gauge should stay steady for a long time.

[Keith Giller]

Thanks Gene

It’s just so odd it’s to both engines. zero overheating issues, or any other issues for that matter. Always do an annual service and pull the exchangers and AC’s per Tony’s recommendations. I wasn’t aware it could possibly be an internal engine issue with coolant. Thanks again. Gonna do a pressure test and see what happens.

[Gene Fuller]

If the overflow tank never gets completely empty the engine expansion tank will usually stay full.

Again, if you keep adding coolant it is going somewhere. It does not just get beamed up to the USS Enterprise.

There could be an external leak in the piping or an internal engine problem, but one way or another something is not right. If you do not smell or see anything in the exhaust my guess would be the heat exchanger.

[Keith Giller]

Thanks…

If it’s being lost somewhere I would think that when I do my coolant check in the engines they would be low as well but always full, like to the cap.

[Gene Fuller]

If you “always have to put in a cup or two” then the coolant is being lost somewhere. The level will rise and fall with temperature changes, but it will cycle back to the same level for the same temperature conditions.

[Keith Giller]

Thanks…

That’s what I am hoping. My buddy’s boat (he has Cat C-18’s) expansion tanks always seem to maintain the same level when he’s at the dock. Thanks again.

[Harry Karaoglanian]

I may be wrong here but isn’t this exactly how it should operate? It’s an expansion tank, so when the coolant expands its emptied into the expansion tank then re-circulated in the engine, so when you are at dock for extended periods of time, the tank would appear low?

Not sure what overfilling would do.

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