Coolant Level Question

[MorningStar]

I had the same problem. Replaced the hose to the overfill tank. But still was finding antifreeze in the bilge. I put small pieces of paper towel stuffing in all areas of the engine and left for a week. I returned found the problem. When the temp dropped, a hose was allowing antifreeze to seep out. Tightened the hose clamp really tight and that fixed the problem. The leak did not appear in warm temps or while the engine was running under pressure. The pressure tester in cold conditions is a good test with the paper towel as an indicator.
Hope this helps.

Barry Dupuy
s/v Morning Star #35
Kemah, TX

[sailorbob]

Thanks for the info, Ken, about Auto Zone and pressure testers. Will the device come with instructions? I have never used such a thing, so if anyone knows how to use it, guidance would be much appreciated.

Has anyone else experienced air in the overflow tube as I described above? A solution would be great - the reservoir level SHOULD rise and fall with heating and cooling.

Thanks!

Bob
Second Wind #301

[wolfe10]

Bob,

The pressure tester merely replaces the radiator cap. Take the cap to the parts store so you know they have one on their pressure tester that will fit.

Install it just like the cap. Pump it up to the PSI rating of your original radiator cap.

And, if there is air in the cooling system itself, that air cushion can absorb the expansion/contraction of running and shutting off. No different then in any other vehicle with a pressure cap and overflow reservoir. The solution is to keep filling (of if air pocket at the water heater to bleed the system) until the closed part of the system contains ONLY coolant/no air.

Then, physics will dictate that the coolant level in the overflow reservoir rises when hot and lowers when cold.

Brett

[KenKrawford]

I finally borrowed a pressure tester and was able to hold 18 p.s.i. steady for over 2 hours. I also tested the cap and it began to leak at 8 p.s.i.
I couldn't find any specs for the pressure rating of the cap but I doubt it is the problem. If it was, I'd expect to see coolant leaking around the cap and down the engine. Not so in my case. The quest continues.

[sailorbob]

Ken, I just bought a new radiator cap - Universal Westerbeke part 298854. It reads "14 LBS" on the top, so I'm betting that's the pressure rating. If yours gives up at 8 LBS, that sounds like it isn't doing the job any more. I plan to rent a pressure tester from Auto Zone once the boat is in the water (soon) and see if the system holds pressure. If it doesn't hold, should I be able to see where the leak(s) is/are, or will it just leak air? Of course, it's been leaking all winter under no pressure at all, and I have more antifreeze under the engine after this winter (at least 8 oz.) than ever before (7 winters), and this has been about the mildest winter since we bought the boat! Does anyone believe that seals can shrink up in cold weather and leak? If that's the case, leaking antifreeze over the winter is "normal" and there's nothing to do about it. That doesn't seem right to me.

Posts from you and Brett Wolfe suggest I may have air in the system, to account for the failure of the expansion tank level to rise and fall as the engine warms up while running and cools down after shutting it down. I can top up at the manifold while the engine is running. Any other tricks to getting air out? How do you bleed air by the water heater?

Thanks.

Bob Fine
"Second Wind" - #301

[sailorbob]

Now that Second Wind is floating again, I started working on my coolant level issues. First, I mopped up a winter's accumulation of Dex-Cool in the engine bilge - it turned out to be about a pint, which is more than I have ever had in the 6 previous winters. I have not yet rented the pressure tester from Auto Zone to see where that might all be coming from over the winter, but I think that's a separate issue from the failure of the coolant recovery tank level to rise and fall.

Next, I topped off the manifold, which had gone quite low over the winter. Then I started the engine with the manifold cap off, ready to add more 50/50 Dex-Cool, but antifreeze was sputtering out of the open manifold, getting all over the place. I thought I had to top off with the engine running to force the air out, but with the cap off, wow, what a mess. I also opened the petcock on the thermostat housing, to bleed air, but antifreeze starting coming out right away. I shut the engine down, filled the coolant recovery tank, and went sailing. I had to run the engine quite a bit getting in and out, and the temp gauge on my instrument panel ran up to operating temp and stayed there - no overheating. But when I checked out the recovery tank back in my slip, still no change in level and still air in the hose from the manifold to the tank.

Brett believes I have air somewhere in the system, and that makes sense to me as an explanation of why the expanding antifreeze doesn't push into the expansion tank, but the solution is escaping me so far.
1) Would running the engine in the slip with the expansion tank cap off help? That cap appears to have a small hole in the top, so maybe not.
2) Could a faulty manifold pressure cap be responsible? Perhaps it's staying down and not allowing flow out of the manifold?
2) Do I have to run the engine with the manifold cap off and put up with the sputtering and the mess? Is the spattering caused by escaping air, which will stop once the air is gone, so I should just grit my teeth and mop up afterward?
3) How do I bleed air back by the water heater (assuming my other efforts don't fix the air issue)? Where is the bleed valve back there, and do I need to hire a mechanically adept 5 year old to fit back there and do the work? Does the bleed valve look like the one on the thermostat housing?

Thanks to all our fellow 350 owners!

Bob Fine
"Second Wind" #301

[wolfe10]

Bob,

As long as you are not overheating or loosing coolant externally, I would give it a couple of sailing/motoring trips before drawing any conclusion.

It only takes a small amount of air in the system to "absorb" the volume increase due to running the engine (perhaps 100 degrees above the coolant temperature when the engine is off). Air IS compressible, liquid is not.

I would top off the heat exchanger (manifold) right to the top with the engine off and coolant cold).

Fill the reservoir to the cold full mark and either raise it up or remove the overflow hose from the heat exchanger (manifold) to allow the hose to fill with coolant.

GO SAILING/MOTORING. If, after 5 or so "heat cycles" the air is not purged, THEN go to plan B and bleed at the water heater. Yes, with any cooling system with an overflow reservoir, level should rise when hot and decrease when cold. Same in your boat, car, RV, tractor, etc. Physics is physics.

Brett

[saileagleswings]

If you take the cap off and coolant doesn't flow from the expansion tank to the coolant manifold on the engine, checkfor blockage in the very narrow passage in the neck of the manifold just below the radiator cap. Remove the elbow connected to the overflow line from the manifold. If you cannot poke a fine wire through the passageall the way into the neck of the manifold, the passage is blocked.
If blocked, there is no way for the antifreeze to expand and raise the level in the expansion tank. So it must be forced out somewhere else.

[Palmettomoon350]

I too am experiencing this coolant leak and it is driving me nuts. The burp tank is good, the hose is good the clamps are tight but I still loose coolant into the engine bilge. I placed an absorbant pad underneath the engine to determine the leak direction. I found spots all over the pad and yesterday it was soaked. My burp tank is almost empty. I watched very intently and saw a small drip appearing to come from the rear of the engine. Next week I will attempt to locate this leak.

Carl Beckmann
Palmetto Moon # 223

[wolfe10]

Carl,

Rear of the engine is the heat exchanger. Check hoses in and out.

Brett

[Palmettomoon350]

Brett,
Thanks much. I will check there first thing Thursday 31 May. I will let everyone know.

Carl
S/V Palmetto Moon # 223
Charleston SC

[Zephyrina]

Our first experience with an untraceable coolant leak came after 2 1/2 years of operation and 425 engine hours. We finally discovered the 5/16th ID vinyl hose to the coolant expansion tank had cracked and melted where it come in contact with the hot engine. The coolant was evaporating and leaving no trace as it passed over the engine. To prevent this from happening again we isolated the hose from direct contact with the engine (see photo). The hose is first wrapped in sliver duct tape at all contact points and further isolated by winding a galvanized wire around the tape and forming a small spring to elevate the hose. Duct tape was also applied to the hose where wire ties secure it to the larger hoses.

Another source of invisible but significant coolant leaks is the 10” hose that runs horizontally behind the engine connecting to the starboard side of the heat exchanger (see photo). Hundreds of hours of engine vibration can loosen the hose clamps at both ends, producing puddles of coolant under the forward part of the engine. Tightening the clamps stopped the leaks. Pinholes leaks in the heat exchanger can also be a source of coolant leak, with no outward evidence

[Zephyrina]

Here is a photo of the spring under the coolant hose

[Palmettomoon350]

Went to palmetto Moon last Thursday and ran the engine and checked for leaks. None that I could find except the wire hose from the manifold to the heat exchanger. This 11" hose, the wire is coming out on one end gave me the idea that a small gap has developed and it may be leaking. I tightened the hose clamps, either end about 1/2 turn so we shall see. I will check this week and run the engine and check the new pad.

Carl Beckmann
Palmetto Moon # 223

[wolfe10]

Here is a photo of the spring under the coolant hose

Perhaps I don't completely understand the photo, but it appears that your raw water hose going into the exhaust elbow is clear plastic hose. If so, that needs to be replaced immediately with approved marine cooling hose (black and much heavier construction).

Even if this is just the hose to the overflow bottle, it is better to use real coolant hose that is designed for the chemistry of coolant, operating temperatures and pressure.

Brett

[Triumph]

I had a similar problem, coolant showing up under the engine. Very difficult to detect, but it ended up being the hose that is about 11" long back where the heat exchanger is. It only leaked when it got hot. If you start the cold engine, and run it for a while in the slip, still nothing. But then take her away from the slip, run her for an hour, and the coolant shows up under the engine. I changed out the hose, which was 7 years old, and there is no more coolant under the engine. However, through evaporation, I do have to add water to the reservoir now and again.


Bill
s/v TRIUMPH

[sailorbob]

I read with interest Brett's comment about the hose running from the manifold to the expansion tank. Original equipment is a clear tube, and mine looked dubious, so I replaced it at the beginning of the 2011 season. The Westerbeke part #24637 I ordered and received is, like the original part, a clear polyurethane tube, so it seems like Westerbeke believes this material is adequate. But it doesn't seem to me like that material should be up to the heat and chemistry, as Brett suggests. Brett, is there a clear tubing material that is more suitable? Or do you give up on being able to see through it? What sort of tubing do you recommend?

To date, I have seen a number of suggestions to deal with the air in the expansion tube and the failure of the expansion tank level to rise and fall with engine heating and cooling. In no particular order --

1) One is to simply go through a number of heating and cooling cyles through normal operation, and top up (at the manifold?) each time after it cools down, suggesting that the air will eventually work itself out. The theory here is that air in the system will absorb pressure changes, so that rising pressure will not force the air up and out of the expansion tube into the expansion tank.

2) Instead of simply letting repeated cycles force the air out, another suggestion for getting air out of the system is to bleed air with the petcock at the thermostat and at the water heater. I don't know where to look at the water heater. Is the bleed valve there another petcock like at the thermostat? Where should I look? The theory here is the same as the first suggestion above - eliminate air in the cooling system, and then heating expansion will force the air up and out of the expansion tube.

3) Next idea is to lift up the expansion tank so that gravity helps run antifreeze down the tube into the manifold. Presumably I will have to remove the wire bale holding the tank in place, disconnect the wire ties holding the tube in place, and also remove the manifold pressure cap. This suggestion assumes that air in the system is not the problem, but that for whatever reason, heating expansion is not adequate to force the air out of the expansion tube, so let's help it out.

4) It has also been suggested to run a wire through the neck at the manifold to be sure it is not clogged somehow. The rationale here is that the problem is not air in the cooling system, but that blockage is keeping heating expansion from driving the air out of the expansion tube.

I will try #4 first, then #3, then probably #1 and/or #2.

I still believe that the failure of the expansion tank level to rise and fall is unrelated to the pool of antifreeze in my engine bilge during the winter. I cleaned up almost a pint of coolant this spring, but I have not yet checked to see if it continues to leak in warmer weather and whether it leaks when the engine heats up from operation. To address this issue, suggestions include renting a pressure tester from Auto Zone to see if the system holds pressure, checking for leaks using paper toweling, or preemptively tightening hose clamps throughout the sytem, particularly back at the heat exchanger. If the system is not pressure tight somewhere, will the pressure tester force antifreeze out somewhere I can see it? Of course, I could be wrong about these problems being unrelated - perhaps a system leak (instead of air in the system) is absorbing heating expansion pressure and so failing to change expansion tank level.

Bill (Triumph) - how did you tell which of the several hoses was leaking at the heat exchanger? It makes sense to me that it wouldn't leak from running at the slip - I believe the engine runs hotter under load, and I would think increased rpms increase system pressure as well.

Any other suggestions and ideas from fellow owners? I will be following up on the suggestions above in the next couple of weeks. Film at 11.

Bob Fine
Second Wind #301

[wolfe10]

Bob,

I use "regular" high end (black) heater hose. Gates, green stripe is a good one:

http://www.gates.com/index.cfm?location_id=1175

And, after bleeding at water heater and thermostat and then a couple of heat/cool down "burp" cycles, coolant has always "behaved properly" with level rising when the coolant is warm and falling when it cools off just like every other engine in car, RV, boat, etc.

Brett

[leigh weiss]

The coolant leak mystery might be solved!!!
The two bolts holding the alternator tension bracket to the block might be the culprit. In my case the lower ( longer bolt )
is threaded into the head all the way into the cooling water passageway. If the bolt is loose or not have it's threads sealed with silicone, or both....presto a slow leak that plagued me for some time. The fix was simple. The results after several weeks of run/stop (hot/cold) cycles, were stellar.
Hope this helps solve one more problem besides mine.


Leigh Weiss c-350 #155 "Brisa"

[nybor]

hello all. just bought a 2006 350 and love it. I want to baby it, so i changed the oil, filters, impeller, etc. the problem was it was running at 180 degrees - too hot? So i replaced the thermostat and radiator cap and perfect - 160 degrees.
However, i have just change the coolant and it is back to 180. i know it is air and i will do the cycling, but questions:
how can the heat exchanger petcock expel air since it is at the bottom of the unit? i used it to drain the old coolant.
i did get air bubbles out of the thermo housing and the reservior is moving down as the engine cools. but my main question is what does the exhaust elbow do? why does it have a 1/8 " npt plug on top of it? to do what?
thanks in advance.
dave bloomquist