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Discussion Starter · #1 ·
We are prepping the boat for launch on Monday and noticed on Wednesday that on on Westerbeke W-52 diesel, the coolant expansion tank for the heat exchanger was empty of its customary green diesel coolant. I filled it and returned to the boat yesterday. The coolant was down below the "max" line about 1/2" (1 cm.) I started the engine on the cradle (I have the ability to fill the sink and to run water into the raw water circuit) and it started quite well.

I ran it for about 45 seconds, which drained the sink and sent the pink winterizing antifreeze out of the boat.

I then examined the expansion tank. No change.

We examined the dipstick. It is blissfully free of water or coolant, although a problem with the anti-syphon loop spring plunger last year caused many oil changes. I am doubtful that the two issues are related, as I didn't note any loss of coolant in the closed circuit last year.

We eventually found the missing green coolant in the bilge under the engine...about a litre and a half (just over a quart).

So now I have an obvious leak that occurred over the winter, but which I can't replicate now. Is it possible I have a gasket or a seal failure in the heat exchanger, the hoses or...and I hope this isn't the case...the block itself that has "healed itself" with the arrival of warmer weather?

We have to get our boat back to our club on Monday, about a six-mile motor and/or sail. It has been suggested to me that after I am dropped into the marina basin that I borrow a dock for a few minutes and fire up the engine and watch the coolant levels and the temperature closely. I will also purchase a few jugs of coolant in case I have to replenish en route. When we get to our home dock, I will take off the heat exchanger and have it examined and pressure-tested. At this point, I just want to get back to that home dock. Monday will be a light-air day, so I will rig all sail. If necessary, I can likely just run the motor for a couple of minutes at either end of the trip.

Any suggestions on how a coolant leak in winter can just "go away" are welcome. I would like to eliminate some possible causes before I call in a mechanic.
 

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Valiente said:
We are prepping the boat for launch on Monday and noticed on Wednesday that on on Westerbeke W-52 diesel, the coolant expansion tank for the heat exchanger was empty of its customary green diesel coolant.
Are you refering to the coolant expansion tank for the closed cooling system?
Valiente said:
I filled it and returned to the boat yesterday. The coolant was down below the "max" line about 1/2" (1 cm.) I started the engine on the cradle (I have the ability to fill the sink and to run water into the raw water circuit) and it started quite well.
Was this the same amount of coolant that you left it with from the previous day?
Valiente said:
I ran it for about 45 seconds, which drained the sink and sent the pink winterizing antifreeze out of the boat.
I then examined the expansion tank. No change.
I understand that the coolant overflow container was low and I am curious if the coolant fluid full in the engine itself was low when you remove the pressure cap? Has that part of the cooling system ever been low?

Valiente said:
We eventually found the missing green coolant in the bilge under the engine...about a litre and a half (just over a quart).

So now I have an obvious leak that occurred over the winter, but which I can't replicate now. Is it possible I have a gasket or a seal failure in the heat exchanger, the hoses or...and I hope this isn't the case...the block itself that has "healed itself" with the arrival of warmer weather?
Healing itself is unlikely in an inantimate object, right? I have seen leaky coolant overflow containers. Is yours like most, plastic? There is a pressure pump that can be used to search for engine coolant leaks that attaches to where the engine pressure cap is located and is manually pumped up. They normally have a pressure gage attached and then the engne can be looked at for leaks whilst under pressure but not operating.
 

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Discussion Starter · #4 ·
Are you refering to the coolant expansion tank for the closed cooling system?

Yes. It's about a litre in capacity, more or less square and translucent, and sits high on the engine room bulkhead. A single 1/4" hose leads from this container to the forward end of the heat exchanger.

Was this the same amount of coolant that you left it with from the previous day?

It was down slightly. I had filled it to "max" and it was about a baby finger's width down from there.

I understand that the coolant overflow container was low

It was actually completely empty.

and I am curious if the coolant fluid full in the engine itself was low when you remove the pressure cap? Has that part of the cooling system ever been low?

Interesting you should mention that. When I opened the pressure cap (on a cold engine that hadn't run since November), about a spoonful of coolant came out. It's possible the hose clamp at the expansion tank alone failed (or the hose is cracked) and just the contents of that tank (500-1000 ml) are what we found in the bilge.

Healing itself is unlikely in an inantimate object, right? I have seen leaky coolant overflow containers. Is yours like most, plastic?

Yes.

There is a pressure pump that can be used to search for engine coolant leaks that attaches to where the engine pressure cap is located and is manually pumped up. They normally have a pressure gage attached and then the engne can be looked at for leaks whilst under pressure but not operating.

Thanks for the methodical thinking. I'll check out the tank clamp when before we launch Monday.
:)
 

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I'd also suggest checking the clamps and hoses, and the fittings under them if possible. One way to check fittings for a very slow leak is to wrap some paper towel strips, or the non-adhesive bandage tape over them, and check back after running. You'll find an obvious soggy green stained one if there was a leak.

I don't think I'd worry about spare coolant at this point--if it is leaking, just add water, since you may very well have to drain the system to fix any major leak anyhow. Easier to throw out water.<G>
 

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Discussion Starter · #6 ·
Yeah, I was all ready to buy green stuff...and then the idiocy of that hit me. Even the lake is 5 C...I can just pour water in.

I'll check the clamps Sunday. Funny thing is that I was considering a rethink of the heat exchanger anyway, because I want to plumb it into a nearby Atlantic hot water tank.
 

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I second the use of a coolant system pressure tester. I bought one from an automotive store. Cost approximately $100, give or take.

The pressure tester makes finding leaks a snap. You can fix in a few minutes what could otherwise be a time-consuming mystery (particularly as some leaks will only appear at certain system pressures, or when the engine is cooling, etc.)

Just connect in place of your pressure cap, pump to appropriate pressure (at or below rated pressure for your pressure cap) and observe. I found a hose clamp leak and a leak at a petcock on the heat exchanger in less than a minute. It is very easy to see where the leak(s) exist.

Highly recommended piece of equipment...
 

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Rob, you caught me in a fully-caffienated moment ("Stand back folks, he's fully caffienated!") and I had a flash thought about hundred-dollar pressure testers.

What if you took a shrader valve ($3 from the tire store? For a good one with a metal stem) and installed it in a good radiator cap (ouch, yeah, $20?<G>) and then simply put that on the radiator, cold. Pump it up with a bicylce pump or whatever better you have, test it for 15(?) psi. Go away and come back in three or four hours, test it again. If there's a leak--it's going to show. No leak? OK, that should be good enough.

Will only work on whatever that cap fits on, but still...if you start with a suspect cap you're planning to replace anyway, and a shrader valve from a flat bicycle tire (free behind any bicycle shop<G>)....

Cheap kuldge that Valiente can try!
 

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hellosailor,
I suppose that an IED (Improvised expanding device) could fit the bill. I am not going to gang up on you with Hobo and I do enjoy alternative ideas to an already available hand pressure pump that isn't given away cheaply and may only have to be used one time and then stowed for a very long time. Heck I've got a chest overflowing with stuff. Good point.
 

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hellosailor,

An improvised solution could work. With my skills, however, I'd probably spend several hours getting the parts together and assembling them as you suggest - only to find that my improvised device leaks!

If one has the skills to construct a device that could withstand the pressure without leaking - then sure, I see no reason why your idea wouldn't work.

The main point I wanted to emphasize is that pressure testing is the only real way to find all of the leaks in a coolant system. It's fast too. After stressing about my leak problem and spending a lot of time trying to solve the "mystery", the pressure tester provided immediate results. I was so pleased with this approach that the expense seemed well worth it.
 

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Discussion Starter · #11 ·
While the expansion tank contents fluctuated yesterday during an hour-long run at cruise speed, it didn't go above "max" or below "add". I, on the other hand, added a hose clamp to the tank barb...a likely culprit, I think, for the original loss of coolant.

I will monitor this, however and will likely have the entire cooling system/heat exchanger pressure-tested just in case. I will also examine all petcocks/drains and hoses for tiny leaks.

I would've done this yesterday, but I was a tad preoccupied (see "gravity versus boat" thread...) in General Discussion.

Thanks for the responses!
 

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Valiente said:
I would've done this yesterday, but I was a tad preoccupied (see "gravity versus boat" thread...) in General Discussion.

Thanks for the responses!
Yes, running home to put on a pair of clean shorts will eat up a bit of time... so will stopping by the ER to get your heart restarted. ;)
 

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you may be able to get a loaner pressure tester from oreilly auto parts, they're real nice about loaning tools. (they have a program) :)
 
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