Loosing coolant

[lawrence_craig]

Hey guys,

I’m loosing coolant from my Volvo D2-55D. About 3 pints per 5 hours run.

The exhaust water looks ok. Any recommendations on where to check or what to look at/for?

Thanks.

[sailormed]

Look at water heater connections. cooling water">Engine cooling water circulates here as well. Often overlooked.

[lawrence_craig]

Thanks, good idea!

Two things I forgot to mention:

- I am getting an increase in water in the engine bilge. Not sure if sea water or coolant. Tried tasting and only got oil taste haha. The only sources in this part of the bilge is the salt water pump or the coolant pressure release overflow

- I am going to get the engine fully serviced over the winter period. Just hoping I can identify now so I can sort sooner than later. I am just topping up the coolant daily as needed.

[DougR]

There are several areas that you can check, the hot water heater connections being one of them. Other areas could be:

- Coolant circulation pump on the front of the engine. If the seal here is going bad you should be able to see some sort of antifreeze leak track on the front of the engine. Coolant leaking from the weep hole on the underside of the pump.
- Possible head gasket leaking coolant. Check for rising oil level in the engine and also leak tracks down the outside of the block below the head gasket.
- Loose hose clamps on the coolant hose which returns from the heat exchanger to the circulation pump, or a pin hole in this hose.
- A leak from the expansion plug on the back of the cylinder head, or any other expansion plug. There was a thread here on CF recently about a leaky expansion plug on the head that had developed a pin hole leak.
- Defective coolant fill cap, and the coolant going out the overflow, but it seems like too much loss for that to be the case.


All of these above possibilities will result in coolant collecting in the engine bilge.
It's also possible that there is a pin hole in the heat exchanger element and the coolant is leaking out into the sea water side and going out the exhaust. There was also a thread about a rusted thru exhaust elbow allowing hot saltwater to get into the exhaust and onto the aluminum expansion tank. This caused corrosion on the tank and a coolant leak into the exhaust.

Hope this gives you some ideas.

DougR

[lawrence_craig]

Originally Posted by DougR

There are several areas that you can check, the hot water heater connections being one of them. Other areas could be:



- Coolant circulation pump on the front of the engine. If the seal here is going bad you should be able to see some sort of antifreeze leak track on the front of the engine. Coolant leaking from the weep hole on the underside of the pump.

- Possible head gasket leaking coolant. Check for rising oil level in the engine and also leak tracks down the outside of the block below the head gasket.

- Loose hose clamps on the coolant hose which returns from the heat exchanger to the circulation pump, or a pin hole in this hose.

- A leak from the expansion plug on the back of the cylinder head, or any other expansion plug. There was a thread here on CF recently about a leaky expansion plug on the head that had developed a pin hole leak.

- Defective coolant fill cap, and the coolant going out the overflow, but it seems like too much loss for that to be the case.





All of these above possibilities will result in coolant collecting in the engine bilge.

It's also possible that there is a pin hole in the heat exchanger element and the coolant is leaking out into the sea water side and going out the exhaust. There was also a thread about a rusted thru exhaust elbow allowing hot saltwater to get into the exhaust and onto the aluminum expansion tank. This caused corrosion on the tank and a coolant leak into the exhaust.



Hope this gives you some ideas.



DougR

Thanks Doug. Really Helpful! Will have a look at each of those!

[lawrence_craig]

So after some further investigation, I don’t believe the loss in coolant is due to an external engine leak.

I have found something odd however:

The coolant is being lost even when the engine is idle and cold.

From this I would suspect the head gasket to be gone however the engine oil is fine (I.e. not milky) so not sure that’s the case.

Any other thoughts?

Thanks!

[Iaangus]

Originally Posted by lawrence_craig

So after some further investigation, I don’t believe the loss in coolant is due to an external engine leak.

I have found something odd however:

The coolant is being lost even when the engine is idle and cold.

From this I would suspect the head gasket to be gone however the engine oil is fine (I.e. not milky) so not sure that’s the case.

Any other thoughts?

Thanks!

Is there any condensation on the underside of the oil fill cap or on the dipstick after the engine cools down? This symptom will sometimes appear before milky oil. The water will evaporate but antifreeze remains in the oil and can damage or ruin bearings. When the engine has sat for several hours without to much motion you could loosen the drain plug if accessible and see what comes out first, antifreeze or oil. Also check the end of blow by tube for condensation, if there is grey sludge there you have water in your oil but the antifreeze left behind can ruin your engine. Good luck.

[dougweibel]

I'm not familiar with the volvo d2-55 but it seems if there were a head gasket leak it would be either from from a coolant passage to the cylinder or to an oil passage. So where is the coolant going? If your oil is not getting milky it must be the cylinder, but if you had any volume leaking into a cylinder I'd suspect you would get hydrolocked. Why do you suspect the head gasket?

[Iaangus]

Originally Posted by lawrence_craig

So after some further investigation, I don’t believe the loss in coolant is due to an external engine leak.

I have found something odd however:

The coolant is being lost even when the engine is idle and cold.

From this I would suspect the head gasket to be gone however the engine oil is fine (I.e. not milky) so not sure that’s the case.

Any other thoughts?

Thanks!

Coolant can also be lost through a bad o ring on the cylinder liners in which case it leaks directly into the oil pan. has your oil level gone up even a tiny bit? Thats a bad sign.

[lawrence_craig]

Originally Posted by dougweibel

I'm not familiar with the volvo d2-55 but it seems if there were a head gasket leak it would be either from from a coolant passage to the cylinder or to an oil passage. So where is the coolant going? If your oil is not getting milky it must be the cylinder, but if you had any volume leaking into a cylinder I'd suspect you would get hydrolocked. Why do you suspect the head gasket?

I suspect head gasket as I am not sure where else the coolant could be going.

This has been happening for about a month though (I’m a liveaboard). One thing that might suggest leak to cylinder is in the last 2 days, I have had a rough start from cold engine so may be that?

[dougweibel]

Have you noticed a change in your exhaust? If you have a cylinder head leak into the cylinder then it should be exiting as steam in the exhaust.

[Shrew]

Don't 'taste' bilge water. You could get very sick. There are testing kits out there.

Oil doesn't circulate through the dipstick tube, so if you are checking the color of the oil on the stick to determine if there is water is in the oil, it will not show that way. Plus water goes to the bottom of the pan, so you might not notice a small bit of water on the tip of
the diptstick. You would need to do one of the following:

1) Check to see if oil levels have increased
2) Do an oil change
3) Pull the oil filter

It is common for coolant to escape through the heat exchanger. The closed cooling side is a higher pressure than the raw water side. This can cause cooling to leak into raw water and be discharged with the exhaust.

I would be looking very hard at the heat exchanger.

[sailah]

You can add a tiny bit of UV dye to your coolant and it will then show up with a UV light. There are tons of videos on youtube and cheap stuff to get on Amazon.

It will help you see where it's leaking from.

Doesnt sound like a head gasket to me. Check the obvious first.

[barnakiel]

A powerful torch and a roll of toilet paper help find most leaks in no time.


Start at the heat exchanger as these leak quite often.


b.

[broken pete]

have you checked the heat exchanger?
On my Yanmar the exhaust outlet from the cylinder head also goes through the heat exchanger and then the exhaust elbow where the sea water in injected. the exhaust gasses do not meet the coolant of course.

There could be corrosion inside the heat exchanger through to that exhaust channel. This would allow coolant to drop into that exhaust channel and be blown out with the exhaust gasses.
This has actually happened to me this week.