Loosing Coolant Somewhere causing overheating

[Tom Foolery]

Hi Smart folks,
~ I have already performed a search for my answer in this forum with no luck.

I am loosing coolant somewhere (Shrug)

I have none in my Bilge
I have none in the catch pain under my motor.

I am unable to make it out of my marina without overheating my motor and the alarm sounding.

I turn motor off, open floor, open the radiator cap (with glove and large towel) to find expansion tank empty!

I allow to cool down just a bit, open air bleed screw, refill with tap water from my sink, (generally takes three gallons to refill.) close air bleed screw when it starts weeping, restart motor with cap off.
top off as necessary, reinstall cap.

ALL of the fluid voids somewhere within less than 10 mins causing over heating again and I don't know where.

I idle just fine, generally about 20 mins prior to departure (No overheating)
Coolant Expansion Tank FULL.

Could I be losing it via a crack in my Exhaust Manifold and it voiding out of my exhaust?

I just don't know......

Any help or wisdom would be kindly appreciated.

36' Grand Banks
Twin 120 Ford Lehmans

 

[Southern Boater]

It would be going out with the exhaust water, but my guess is via a hole in the heat exchanger tube stack.
I’ve heard of cases where owners have soldered up, blocked off the offending damaged tube, once found by pressure testing, and still getting perfectly fine performance from the HE.

 

[O C Diver]

Yup, heat exchanger would be my first guess. If you're mechanically inclined remove the hoses from the heat exchanger. Put your hand over one coolant connection and blow into the other. Any flow indicates a leak.

Ted

 

[jgwinks]

One of my previous sailboats with a 20hp diesel had about a third of the tubes soldered off when I got it and it still cooled just fine. I did replace the tube stack though, figured the remaining tubes couldn't be much better than the ones that had already failed. Anyway it should be pretty easy to pull the stack out to inspect, they're made to be replaceable.

 

[SoWhat]

It would be going out with the exhaust water, but my guess is via a hole in the heat exchanger tube stack.

That would be the first place to start. Remove the zincs as a first check. No zinc left would be a solid indication of corrosion. When was the heat exchanger last replaced?

If one is bad the other will soon follow. Replace both along with all oil coolers. Heat exchangers are probably running about $600 each.

 

[Tom Foolery]

It would be going out with the exhaust water, but my guess is via a hole in the heat exchanger tube stack.
I’ve heard of cases where owners have soldered up, blocked off the offending damaged tube, once found by pressure testing, and still getting perfectly fine performance from the HE.

Thank you for your reply.
I have had the Heat Exchanger removed and "Boiled Out" and the person "SAID" he pressure tested it and that it "Passed"

I am going to try O C Diver's suggestion of removing both hoses off of the Heat Exchanger and blowing into one side and holding hand over other to see if air passes thru, if so there is a leak within......(Fingers crossed)

 

[Tom Foolery]

Yup, heat exchanger would be my first guess. If you're mechanically inclined remove the hoses from the heat exchanger. Put your hand over one coolant connection and blow into the other. Any flow indicates a leak.

Ted

I AM mechanically Inclined and I WILL attempt this Monday and report back. THANK YOU for your reply.!

 

[Tom Foolery]

That would be the first place to start. Remove the zincs as a first check. No zinc left would be a solid indication of corrosion. When was the heat exchanger last replaced?

If one is bad the other will soon follow. Replace both along with all oil coolers. Heat exchangers are probably running about $600 each.

Zincs replaced, they are NEW.
I do not know the date of Heat exchanger replacement.

 

[wkearney99]

Be sure to check your oil to make sure you're not getting coolant mixing into it. It'll have a milky appearance if it's been contaminated by water/coolant. That would be a sign of a head gasket or other more significant engine problem but most of those would show up as contaminated engine oil.

I've had a slew of 'exchangers' replaced on my EB47 C12 Cats (engine oil, fuel cooler, transmission cooler, turbo after cooler, etc). But none of those involve the circulating antifreeze.

Check if you have a coolant loop that heats your domestic water using coolant. I *had* one coming off my starboard engine. A fitting broke and it puked 20 gallons of antifreeze all over the bilge (at $20/gallon). I've since capped it off. "Free" heat from the engine seems like a good idea until you have an engine get destroyed from coolant loss. I managed to catch the sudden temp increase immediately and shut down the engine before it caused any trouble.

A leak in the water heater loop could cause coolant loss, but it'd have to go somewhere. Likely causing the water heater over-pressure valve to release, which would likely dump to the bilge. Best CHECK how the water heater is plumbed.

 

[Tom Foolery]

Replies in RED

Be sure to check your oil to make sure you're not getting coolant mixing into it. It'll have a milky appearance if it's been contaminated by water/coolant. That would be a sign of a head gasket or other more significant engine problem but most of those would show up as contaminated engine oil.
I HAVE check the oil and it is Black like it should look (Diesel Black

I've had a slew of 'exchangers' replaced on my EB47 C12 Cats (engine oil, fuel cooler, transmission cooler, turbo after cooler, etc). But none of those involve the circulating antifreeze.

Check if you have a coolant loop that heats your domestic water using coolant. I *had* one coming off my starboard engine. A fitting broke and it puked 20 gallons of antifreeze all over the bilge (at $20/gallon). I've since capped it off. "Free" heat from the engine seems like a good idea until you have an engine get destroyed from coolant loss. I managed to catch the sudden temp increase immediately and shut down the engine before it caused any trouble.
I will check that although, on this boat, I have never had hot water.

A leak in the water heater loop could cause coolant loss, but it'd have to go somewhere. Likely causing the water heater over-pressure valve to release, which would likely dump to the bilge. Best CHECK how the water heater is plumbed.
I have removed and capped off the Water Heater

 

[Tom Foolery]

Replies in RED

Be sure to check your oil to make sure you're not getting coolant mixing into it. It'll have a milky appearance if it's been contaminated by water/coolant. That would be a sign of a head gasket or other more significant engine problem but most of those would show up as contaminated engine oil.
I HAVE checked the oil and it is Black like it should look (Diesel Black)

I've had a slew of 'exchangers' replaced on my EB47 C12 Cats (engine oil, fuel cooler, transmission cooler, turbo after cooler, etc). But none of those involve the circulating antifreeze.

Check if you have a coolant loop that heats your domestic water using coolant. I *had* one coming off my starboard engine. A fitting broke and it puked 20 gallons of antifreeze all over the bilge (at $20/gallon). I've since capped it off. "Free" heat from the engine seems like a good idea until you have an engine get destroyed from coolant loss. I managed to catch the sudden temp increase immediately and shut down the engine before it caused any trouble.
I will check that although, on this boat, I have never had hot water.

A leak in the water heater loop could cause coolant loss, but it'd have to go somewhere. Likely causing the water heater over-pressure valve to release, which would likely dump to the bilge. Best CHECK how the water heater is plumbed.
I have removed and capped off the Water Heater

 

[Lepke]

It's usually the heat exchanger because the coolant is usually under pressure and the sea water isn't. If your coolant system is tight and you have a cap on your overflow tank then the coolant is probably pressurized 7-15 psi. So as pressure builds, coolant is forced thru the exchanger and out the exhaust.

 

[Tom Foolery]

Reply in RED

It's usually the heat exchanger because the coolant is usually under pressure and the sea water isn't. If your coolant system is tight and you have a cap on your overflow tank then the coolant is probably pressurized 7-15 psi. So as pressure builds, coolant is forced thru the exchanger and out the exhaust.

Thanks Lepke, This is what it is looking like, (ie. the likely culprit)
I have removed the Heat Exchanger and had it "Boiled out" and supposedly pressure tested.

I am going to attempt to remove the radiator hoses and hold one end with hand and blow thru the other as OC Diver has suggested and report back. NOTE: Unknown age of the Heat Exchanger

 

[jgwinks]

I've never seen it happen but to my thinking a leak in the water heater loop would add to the coolant volume, if the water pump and heater were turned on. Domestic water's probably 20-30 psi and a little higher in the heater as it heats and expands. Coolant cap is only 7-10 psi. Even with the pump off, the coolant would have no where to go unless a faucet was open and you'd see that. Can't go into the water tank as there's two check valves in the pump.

 

[catalinajack]

I have never understood the thinking behind boiling out an "old" heat exchanger and reinstalling it cuz it held pressure. That pressure test is only as good as the day it was done. Reinstall it and the next day it could start leaking. The problem is we often do not know how old or well-cared-for (anode maintenance) the heat exchanger is. Yes, they are not inexpensive. My Lehman 120s came to me with 5,500 hours and no record of when they were replaced. I did find one spare aboard so, obviously, at least one side was replaced but no idea of when. Not liking the idea of being stuck in the northern remote reaches of the Canadian Great Loop route, I replaced both. How old is old? I do not know. I do know that with new oil coolers and new exchangers, I am good for a long time.

 

[Roger L]

I had the same issue was the heat exchanger but was a little more difficult to diagnose. Before the heat exchanger failed entirely I was gaining”coolant/salt water and it was overflowing from expansion tank,could have been blown head gasket. When it failed entirely it ran out the exhaust. I had pink water in my Racor raw water strainer which was a dead give away.

 

[Roger L]

Further explanation about prior reply. When I had a small leak in heat exchanger all was fine at low RPM because the pressure in the raw water and coolant water were in equilibrium. At higher rpms the raw water pressure exceeded the coolant water and pushed water out the expansion tank. I never had to refill tank.When the leak in the exchanger became worse I lost all my coolant out the exhaust , when I refilled and the engine sat is when I saw the coolant had migrated through the raw water system back into the Racor strainer

 

[High Wire]

If I read that right you are losing 3 gallons of coolant in less than an hour? That is a pretty big leak and should be able to be found with leak check as described. You can also take your tank cap to an auto parts store and borrow a radiator leak tester. I know my Perkins cap is too big for any car tester.

 

[diver dave]

Thats a fast leak.


This is what u use. If u have coolant recovery, just substitute hoses. No need to have a cap fitting.

My HE story includes running 400 miles out of harms way with an inbound hurricane. A race i lost. Leaky HE went to an island car rad shop while we waited tied to trees. [emoji30]

 

[Bmarler]

Thats a fast leak.
View attachment 122624

This is what u use. If u have coolant recovery, just substitute hoses. No need to have a cap fitting.

My HE story includes running 400 miles out of harms way with an inbound hurricane. A race i lost. Leaky HE went to an island car rad shop while we waited tied to trees. [emoji30]

i have the same tester only with a snap-on label. it's the best way to troubleshoot a cooling system. with a loss like the op is experiencing it should be easy enough to find.
i don't know what his pump configuration looks like, but i once had a double pocket pump that had a fresh and raw water pump on the same drive shaft. i had seals fail on that and send coolant through the raw side. i could see green water coming from the exhaust.

 

[Southern Boater]

With all these failed heat exchanger comments, and the issues we have with a commercially operated Cummins QSB powered work boat, for those taking on long passages, it may be worth while putting a bottle or two of a good radiator stop-leak in the engine spares box.

We use K-Seal, 8oz. or 236ml., and found it to be a good product to buy some time and keep the boat operating until a new HE can be fitted/repaired.

 

[diver dave]

The fix-it juices may require a more stable coolant/air interface, not sure tho.
Another idea is a few lead bullets, the calibre to match the id of the tube. As u pressurize the coolant with the handy tool above, u will see leaks visible with the end caps removed.

 

[Southern Boater]

The fix-it juices may require a more stable coolant/air interface, not sure tho……….

I’m not sure all “juices” are created equal, the K-Seal works for us, usually going through one HE per season, around 1500 hours, even with regular anode replacement with every 250 hour oil change.

I carry a couple aboard for my 3208’s, I consider it cheap insurance.