Coolant Question

[par55347]

Over the weekend I had an overheating code pop up (SPN 110 FMI 15) and noticed the coolant tank was empty. That was the third time I used the boat this year and didn't have any issues the first two times. Last fall I had the same thing happen to me and had the dealer look at it.

I'm not very familiar with how the cooling system works since this is my first inboard that uses coolant, but I would think if the tank is empty vs just being low there would have to be a leak somewhere? Is it worth refilling and keeping an eye on it, or should I bring it back to the shop? Not sure I want to dump in $150 of propylene glycol just to have it leak out.

If this were a car with an empty coolant tank I'd be nervous the engine block is cracked. I'm hoping boat cooling systems work different!

2017 R21 with 160 hours

[freeheel4life]

Sounds like a leak. Sometimes theres an air bubble that works its way out but doubt that's your case. The code is indeed an overheat 1st level code. Do you have a heater?? If so I'd verify the pump is working and also not leaking. That's been the common place I've seen issues.

[par55347]

It does have a heater, and I actually ran it the last time I was out. Probably a dumb question, but the heater uses coolant?

[freeheel4life]

Yessir. Has its own inline pump that Ive seen leak. You would see a puddle of pink on your stbd rear ballast bag if its the culprit

[Jhfury]

I'm dealing with the same issue so I'm curious to see if it was fixed and how?

[freeheel4life]

Leaking coolant or overheating??

[Jhfury]

Both - I keep filling up the coolant and when I drive slow out of the marina it heats up after about 10 mins. I can make the temp go down with more speed.

I've looked all over for leaks and haven't found any but we do notice a new smell. Can tell if there's coolant in the bilge area cause it doesn't have enough color to tint the water enough.

My friend thinks it's the heat exchange, but the boat only has 65 hours on it - guess it's possible. From what I can tell, you don't just buy a new heat exchange...

[freeheel4life]

https://www.oreillyauto.com/detail/b.../375cs/4384812

^^put this in with the coolant and get a UV flashlight (cheap as well). Will let you know real quick if you have a coolant leak in the bilge and help find it. Will help if you go back down to the boat as dusk/dark.

All the coolant leaks I've had on Tiges were from the heater pump. About the only other places you could get it from are the inlet and outlet hoses to the exchanger. The exchanger itself. Or the head gaskets. Other outsider is a puncture/leak im the lines running to the heater core. They go thru the stringer so there's always a chance they rubbed thru.

[Jhfury]

Thank you! We changed the impeller out today and filled up the radiator. She ran great at 160 degrees until the coolant ran out. Went back to the slip and filled it, let the engine idle till the fluid was gone and repeated that process a couple times. My fingers are crossed that it is leaking from the heat pump. I called the dealership and that's what they said to look at too. There is definitely water in the rear compartments where the ballast sacks are, but it's hard to see what color. I did notice that one of the bags was slimy, so hopefully that is indicative of coolant. I have not even looked at the heater pump so I'm going to look at that tonight.

[freeheel4life]

If bag was slimy that was it. Dip you fingers in and BRIEFLY touch them to your tongue. If its sweet its coolant. You should have been adding pink Propylene Glycol which is non-toxic. Don't drink it but a quick taste won't hurt. If you go for the UV dye heater pump will look like this and bags will look like second pic

[Jhfury]

Ok thanks - I'm going to go and look for this tonight or tomorrow. I only added Propylene Glycol coolant to it. I read that mixing that with regular coolant will cause it to gel up, so hopefully the "slimy" feel that I had is still coolant.
How do you fix that photo above? Looks like the gasket or seal is broken in the actual pump. I'm hoping for a loose hose or something simple.
Seems like a lot of fluid for me to lose after having the boat on for 5-10 mins doesn't it? But the floor on both sides is wet. Don't these boats hold like 3 gallons of coolant?

[sandm]

free,
IF the heater pump is leaking is there a way to bypass it? we have a heater and here in vegas will NEVER use it. just thinking out loud if not ever going to use it should it be bypassed.

[freeheel4life]

You can get the dye at pretty much any autoparts store. Fun fact...if you just shine a black light at it in the bottle it won't light up. Something about once it mixes with the glycol makes it phosphorescent.

Sounds like a pretty good leak....but....once there's an airbubble at the top of the engine coolant quits circulating thru the heat exchanger quite quickly in my experience. Have had boats overheat that only need about a 1/2 gallon of coolant to top off the block thru the tstat and back in business.

If its the pump its just a replace whole unit. Ive only bothered taking one of those diaphragm pumps apart before....dont know where you would get individual parts for them or if they are even available.

[freeheel4life]

sandm yes. Port side near front of the engine you will see "From Heater" and "To Heater" in blue stickers. Cut a loop of 5/8" heater hose and just run the "From" and "to" outlets to each other.

You can either pull the added on relay that will be at the back of the engine to stop the pump from running(relay is tied to the fuel pump so pump always runs when engine runs) or just clip either the positive or ground at the pump itself.

Only replace 1 or 2 pumps on Tiges and a couple Skiers Choice boats. Feel like they were all 2-3 years ago and havent seen it since so guessing a bad production run....

[Jhfury]

Thanks man! You've been very helpful! I'm excited to hopefully find and fix my issue tomorrow so we can surf this weekend for my son's 14th birthday!