Gradual loss of coolant

[Breakin Away]

A couple of months ago I topped off the coolant in my reservoir up the the max fill line. I checked it today after returning from a weekend outing and noticed that it is about 1/4 up from the minimum line, so I topped it off again. Engine usage since I topped it up is about 15 hours. I see no clear sign of any leakage from the bottle into the locker or anywhere else, but I may not know all the places to look. Total engine hours is a about 495.

I am just wondering if this rate of loss is unusually high, and what it might indicate? (Leak in HX? Bad rings? Normal loss?)

FYI, I have never checked the zinc pencil in the HX - I have not yet even figured out exactly where the HX it is. (Wanted to look for it today after returning, but engine was still hot and I had to leave.) But surveyor checked it 3 months ago and said it was brand new, and HX had been recently acid washed, and water pump was brand new with pristine impeller. With engine running reliably at 165F, I have not had reason to be overly concerned about HX integrity or any other cooling issues. The lower level that I saw today was the first reason to have some concern.

Obviously I am going to check zinc pencil next time I go to the boat, but prior to that I would appreciate advice on what else to look for, or whether this consumption is normal.

[KWKloeber]

What engine - (put it in your data?)   The age of the Hx?

One of the best things you can do is learn as much as you can about the vessel (even before sailing it.)  There's tons of photos and info on the C34 site on the Hx and pics of the anode.  If you are in salt, it should be zinc - brackish, alum; fresh, magnesium.

Theoretically, the loss should be "~zero."  It might be a weak pressure cap, lowering the boiling point; a head or other gasket leak (any coolant odor in the exhaust?); or a pinhole leak between the two sides of the Hx (coolant being pushed into the sea water/muffler.)  If you have the leak in the Hx, running with the pressure cap loose will reduce the loss.

Pressure test the Hx (tee, pressure gauge, pressure source - like sm compressor, bike pump, etc - need only 10 psi test) and the block (can use an auto radiator pressure tester.) Pressure cap should be about 13 psi or so, depending on the cap.

-kk

[Ed Shankle]

Before you start diving deep into what might be happening, be sure you are comparing levels at the same temperature. Assuming you mean the level in the external overflow reservoir, it will increase when the engine is hot, due to expansion, and decrease when the engine is cold, due to contraction of the coolant. so always compare either when it is hot or when it is cold. But one against the other is apples to oranges.
regards,
Ed

[britinusa]

Rick,
as you know, I have recently done a lot of work on our Engine system, including replacing all of the coolant hoses.

After replacing them, I burped the system as per and then topped up the coolant reservoir. We ran the engine for about 2 hours and then checked the coolant again. It was down by about 1/2" inside the pressure cap, which is what I had expected as bubble work their way out (my theory). We ran it again last weekend and the coolant level was fine.

So I wonder if your situation is similar.

Paul

[Stu Jackson]

We ran our engine for almost 164 hours coming up the coast.  We topped off the coolant somewhere in Oregon with two cups of coolant and distilled water.  It happens.

[Breakin Away]

Thanks all for the suggestions. Please keep them coming.

It is entirely possible that my situation is similar to Paul's. I need to dig further into the service history to construct a full timeline, but I spoke to PO's engine shop, who told me that HX was acid washed and zinc pencil replaced in March 2015. Previous owner had to move out of the area suddenly and boat was immediately listed with the broker and placed on the hard. I believe that it was not in the water again until June 2016 when I launched it for sea trial. The antifreeze 50/50 mix is dated June 2015, so I suspect it was refilled by the broker after reinstall of the HX, and never used until my sea trial. In other words, lots of opportunity for air pockets to work their way out of the system after I purchased it.

I will check things out thoroughly per your suggestions, but it sounds like this may may be the explanation.

While on the phone with the mechanic's office staff, I asked whether they use zinc or aluminum for anodes. She wasn't very technical and I could hear her passing on questions to someone else, but they basically said they always use zinc. I asked why, since Deale, MD is definitely brackish water (mean salinity about 10 ppt), and they didn't have an answer. I suspect that they do it because powerboats could travel further down the Bay into salt water, and since they're in the habit of doing it for powerboats, they do it for everything. That's just a guess, though.

Since I've moved the boat about 30 miles up the bay to Rock Hall (mean salinity about 5ppt), I'll have to check local shops to see what they use. But I shouldn't switch the pencil to aluminum until I switch over all the anodes, so won't do it until offseason. In the meantime I will check the pencil (to be 100% sure) and replace with zinc if needed.

For when the time comes, does anyone know where I can find aluminum pencils? Catalina Direct only has zinc listed on their website.

It looks like the pencil screws in on the bottom of HX. Any special precautions I should use to avoid the whole thing emptying out onto the transmission?

Regarding KWKloeber's question, Engine is M35BC. Heat exchanger age unknown, possibly original.

[KWKloeber]

Honestly you probably won't find an Alum pencil, and Magnesium is hard to find as well.  You might try calling these folks to see if they can source them   http://boatzincs.com/   Shaft anodes are fairly available, but not pencils.

Pull the sea water pump to Hx hose and drain the Hx before unscrewing the anode (close the sea cock, but the pump doesn't let much dribble through anyway.)  You may find a replacement requires cutting a bit off a longer one.  (See anodes below, although it doesn't necessarily mean you have the OE Hx.) Hang your key on the sea cock handle so you remember to open it again.

Here's the engine (OEM Hx) "zinc" sizes:

If your anode plug takes the following wrench, get the corresponding anode (#1, #2, #3)**:
** caveat - this is for the correct OEM Hx, if PO installed a different Hx, then your mileage may vary.

     7/16" wrench - (#1)
     11/16" wrench - (#2)
     9/16" wrench - (#3)

If the anode tip hits the bolt for the cleanout cap -- don't cut your anode, just, 'er,     use a shorter bolt!! 

*****
(#1)
M-25
2" Hx anode Length: 2", Dia 1/4" / 1/8" NPT - plug 1/4" UNC; 7/16" hex head

Zinc anode w/ plug:
     Universal p/n 301069
     Canada Metal p/n CME00 / UPC: 10628309103191 / Substitute for Universal p/n 301069
     West Marine sku 519017 / mfgr p/n CME00 / $6.99
     Zinc anode only WM sku 524611 / mfgr p/n CMEZ00 / $2.99

****
(#2)
M3-20
M-25/XP/35/35A w/ 3" Hx; anode Length: 1-1/4", Dia 1/2"; NPT: 3/8" - Plug 3/8" UNC / 11/16" hex head

Zinc anode w/ plug
     Universal p/n 301068
     Canada Metal p/n CME1F / Substitute for Universal p/n 301068
     West Marine sku 6670863 / mfgr p/n CME1F / $5.79
     Zinc anode only, WM sku 6670905 / mfr p/n CMEZ1F / $1.79

****
(#3)
M-25XPB, 35B - w/ 3" Hx; anode length: 1 3/4" Dia 3/8" 1/4" NPT - Plug 5/16" UNC / 9/16" hex head

Zinc anode w/ plug
     Westerbeke p/n 11885
     Canada Metal p/n CME0 / Substitute for Westerbeke # 11885
     West Marine sku 332155 / mfgr p/n CME0 / $6.99
     Zinc anode only, WM sku 307314 / CMEZ0 / $2.99

PS: you can use the Hx anode port for a reverse pressure test.  Screw in an NPT tee w/gauge and a schrader valve, put stubby hoses with plugs in them on the seawater inlet/outlet; loosen the pressure cap.  Or if you don't have an air pump. just adapt to and apply a little dock water or water pump pressure to the sea water hose (just crack a valve to get 5-10 psi max.)

-ken

[Breakin Away]

Thanks for the info. I need to study some more to get familiar with the cleanout bolt. I assume that this is used for some sort of anti-scaling oparation?

FYI, I close all seacocks when away from the boat. I store the motor key attached to the water intake seacock with a detachable valet key ring:

[KWKloeber]

Yah talking about the end cap?  To clean out weeds etc that WILL get thru the pump and whatnot if you don't have a strainer.  Oh and to pick out pieces of broken off anode for those who don't change it when necessary and post the group wanting to know why they are overheating. 

-kk

[Breakin Away]

Yah talking about the end cap?  To clean out weeds etc that WILL get thru the pump and whatnot if you don't have a strainer.  Oh and to pick out pieces of broken off anode for those who don't change it when necessary and post the group wanting to know why they are overheating. 

-kk

Oh, I was envisioning a vertical bolt that was directly above the pencil. This sounds like a horizontal bolt that might interfere with the pencil. Just shows that I really need to get in there and look it over, since words can be difficult to envision.

FYI, I do have a good (large) raw water strainer, and just cleaned it out when I was working on the transmission. It actually looked quite clean, as did my primary Racor filter.

[KWKloeber]

Ugly end cap - note tiny tubes to catch junk. 

I've seen end caps opposite the anode, same end, offset from the end cap bolt, etc. 

One thing you may quickly learn as an owner, is no boat manufacturers has the word "standard" in its vocabulary.

-kk

[Jon W]

What is used as a gasket?

[KWKloeber]

What is used as a gasket?

Jon,  You can buy an OE gasket for 4 bucks (darn, there's that "$4" popping up again.) Or unabashedly cheapo me just got a sheet of red stuff (thick gasket material) from an auto parts, and cut a circle and punched a hole in the middle.  I have enough left over for the life of the boat.  Or mine.

-kk

[Breakin Away]

Over the weekend I moved the boat 75 miles to our winter storage location on the hard. After we were underway I noticed that the coolant reservoir was down from the top line by about 1/4" so I topped it off to the maximum line while underway. A couple hours after we were stopped for the evening (after about 6 hours of motoring) I checked in the bilge and found a surprise (and perhaps a hint) -- a few ounces of green coolant in the bilge! I looked at the reservoir, and it was still topped off. I opened the motor from top, front, starboard side, and under the aft berth and could find no trace of a leak or path of coolant flow along the bilge. At this point the motor was warm, not hot, so I cracked the coolant cap, heard a little hissing, so immediately closed it again with out opening it. (Could this have just been an air pocket leaking out under the pressure head from the elevated reservoir?)

We decided to proceed to our final destination the next morning. I checked the motor while underway and saw no leakage or any other signs of issues. Coolant reservoir maintained its level throughout, and no coolant in the bilge or anywhere in the engine compartment.

Does anyone have any hints of what could have caused a few ounces of coolant in the bilge?

(By the way, I did replace the zinc pencil as mentioned in an earlier post. Thanks for the help with that.)

[Jack Hutteball]

All of the coolant leaks from our boat have been the connections at the back of the hot water tank.  Very hard to get at!!!

Jack