For what it's worth, I've just solved a mystery related to disappearing coolant. My 34MKii engine was losing small amounts of coolant every time I checked, even though I only ever use the engine for getting to and from the marina, raising and lowering sails, and anchoring.
There were no signs of leaks on any of the engine hoses. To check to see if perhaps it was evaporating, I put pieces of cardboard down at the bottom of the engine compartment, on both sides and under the belts, then ran the engine. Again, no sign of leaks. I also ran the engine with the coolant cap off to see whether there were bubbles, an indication of a blown gasket. Nothing there, either. And no, there was no spillage coming from the overflow in the lazarette.
I cleaned the bilge completely, and then ran the engine again. This time I noticed coolant in the aft bilge compartment, but at that point there wasn't enough to leak through the passage hole to the middle part of the bilge. I couldn't see any signs of the coolant on the curved hull leading down to the bilge, so I put my hand through to feel for any coolant. When I did that I was very surprised (to say the least) that the whole top of my arm became coated with the coolant. I then looked under the galley sink and found where the coolant hose runs through to the water heater. But again, there wasn't any sign of coolant, that is until I felt around to the back of the hose.
It turned out that the hose had developed a very small hole at the edge of the tube running from the water heater. It had been seeping from that hole around the back of the hose and down to where the hose goes through the bottom of the galley sink cabinet. It then ran along the whole length of that piece of laminate until it came to the edge, and then dripped directly down into the bilge.
Needless to say, I was quite relieved, particularly since the worst case option would probably have been a leaking heat exchanger, which would have required a rebuild. All that was required was cutting a larger hole in the back of the cabinet to make it easy to get at the hose, the cutting off of the damaged part of the hose, and resetting with a hose clamp.
Drh: You are correct that the "worst case" was to have an internal leak in side the HX.
However, You are lucky, because a "VERY worst case leak" might have been an internal leak inside the Water Heater !!
OR a SUPER worst case might have been inside the the engine itself!!!! You are lucky that you FOUND IT!!! :D :D :D :D
"Old Chinese Proverb" -- When that coolant recovery bottle level goes down - that coolant is going somewhere?????? :shock: :shock:
A few "Happy" thoughts :thumb:
Congratulations for playing detectiove work and finding the culprit! :D
It appears now that the Critical Upgrades topic is applicable to Mark II boats, too. IIRC another Mark II skipper had earlier reported replacing his heater hoses.
Point of information for everyone (actually two POIs.)
A leaking Hx is basically a throwaway item. Yes it can *sometimes* be fixed but is typically not worth the cost. OEMs were typically not copper-nickle (more expensive) and more prone to pin-holing (between the seawater and engine coolant sides) esp in saltwater. Coolant doesn't end up in the bilge (it goes out the exhaust) so it's hard to diagnose w/o pressure testing the Hx.
A leaking WH (again, typically a pinhole between the potable water vessel and coolant tube) typically does NOT lose engine coolant - it GAINS engine coolant. Why? The closed engine-coolant loop maxs out about 15 psi, and the hot water vessel is nominally at whatever pressure your potable water pump is set at (much higher than the engine pressure.) So coolant can't push against that high pressure and get into the potable water side (good thing cuz it's toxic, so BEWARE if your potable water is unpressurized.) The WH pressure can actually go much higher than the engine block*** (why the WH tank has a temp/pressure relief valve) so potable water can move in the opposite direction, sometimes with coolant ending up in the bilge or wherever the coolant reservoir bottle can overflow to (potable water pushes into the WH hoses, to the engine block, out the exhaust manifold pressure cap, to the coolant reservoir overflow.)
*** Why the check valve on the WH must be rated for WH use, and not the plastic ShurFlo CVs that are typically used on potable water lines. They can blow up (and ruin your day.)
Quote from: KWKloeber on January 14, 2022, 07:06:05 PM
.....................
.....................
A leaking WH (again, typically a pinhole between the potable water vessel and coolant tube) typically does NOT lose engine coolant - it GAINS engine coolant. Why? The closed engine-coolant loop maxs out about 15 psi, and the hot water vessel is nominally at whatever pressure your potable water pump is set at (much higher than the engine pressure.) So coolant can't push against that high pressure and get into the potable water side (good thing cuz it's toxic, so BEWARE if your potable water is unpressurized.) The WH pressure can actually go much higher than the engine block*** (why the WH tank has a temp/pressure relief valve) so potable water can move in the opposite direction, sometimes with coolant ending up in the bilge or wherever the coolant reservoir bottle can overflow to (potable water pushes into the WH hoses, to the engine block, out the exhaust manifold pressure cap, to the coolant reservoir overflow.)
..............
..............
Quite true, Ken.
But the water heater isn't always hot, is it?
Unless I need hot water, the electric side on my boat is off. Indeed, I only turn the electricity to it on for about half an hour before I need it, and, when hot enough, I turn the power off.
Likewise, when I go off sailing, the water is cold when I get on the boat and only warms up when I motor.
Once you pressurize the water system with the fresh water pump, you are likely moving water into the engine side of the circuit. I believe that is what Ken is saying.
[Edit] assuming you have a pinhole leak in the engine coolant leak in the heat exchanger loop within the hot water tank.
Quote from: waughoo on January 16, 2022, 11:27:01 AM
Once you pressurize the water system with the fresh water pump, you are likely moving water into the engine side of the circuit. I believe that is what Ken is saying.
[Edit] assuming you have a pinhole leak in the engine coolant leak in the heat exchanger loop within the hot water tank.
Could be, Alex. But I also open the hot water faucet if I'm not going to use the water to relieve the pressure on the (being unused) system.
Quote from: Stu Jackson on January 16, 2022, 10:58:05 AM
[
Quite true, Ken.
But the water heater isn't always hot, is it?
Unless I need hot water, the electric side on my boat is off. Indeed, I only turn the electricity to it on for about half an hour before I need it, and, when hot enough, I turn the power off.
Likewise, when I go off sailing, the water is cold when I get on the boat and only warms up when I motor.
I wasn't clear. The WH being on or off, water hot or cold, is irrelevant - the pressure pump raises the water vessel pressure to above the engine coolant pressure. Heating the water can raise it even further, but that's also irrelevant- so long as potable system pressure is greater than 15 psi, engine coolant can't move into the WH.
BUT as I said, if the potable pump is off, then toxic engine coolant COULD move into the potable water but it'll co-mingle/linger there until the pump is on and a tap or shower is opened up. i.e., you won't noticeably "lose" coolant, at least not a significant continuous volime because the potable system is a closed loop and there's nowhere for the coolant to go to - unlike the engine side which is not closed and has a low-pressure relief valve.
Is there a way to tell if the heat exchanger is failing? I have disappearing coolant also. I have a new water heater (2021) with new hoses. I don't see any leaks anywhere. If I pressurize the cooling system to 14 psi it steadily drops to about 5 psi and stays there. No signs of leakage anywhere on or near the engine. I'm thinking it must be HE but before I plunk down almost 700.00 for a new on I'm trying to confirm thats the culprit. Engine starts and runs fine so no signs of coolant getting into cylinders resulting in hydrolock. Any thoughts?
Thanks,
John
Quote from: Oldlaxer1 on May 04, 2022, 07:27:29 AM
Is there a way to tell if the heat exchanger is failing? I have disappearing coolant also. I have a new water heater (2021) with new hoses. I don't see any leaks anywhere. If I pressurize the cooling system to 14 psi it steadily drops to about 5 psi and stays there. No signs of leakage anywhere on or near the engine. I'm thinking it must be HE but before I plunk down almost 700.00 for a new on I'm trying to confirm thats the culprit. Engine starts and runs fine so no signs of coolant getting into cylinders resulting in hydrolock. Any thoughts?
Thanks,
John
Could be a leaking pressure cap. Cheaper to replace it first.
The 101 Topics has sources for new HXs.
Cap was purchased new in 2021 also.
I'll check the 101s. Thanks Stu
John
You're pressurizing the closed system w/ a radiator tester? If so the condition of the pressure cap doesn't factor in while testing.
Do you have a water heater hooked up? If so that (which is also a heat exchanger) could be leaking coolant into the potable hot water tank. It depends whether the water system is pressurized when you test the coolant system. One way to verify is to remove the pressure cap and pressurize the potable water system. If the WH Hx has failed pressure will drop as water is pushed into the engine coolant side.
You can test the engine Hx this way:
- Close the seawater pump supply thru hull.
- Open the muffler petcock and drain it. Leave it open. (I ASS/U/ME that the C34 Aqualift has a drain?)
- Pressurize the closed coolant system and keep it up to pressure.
- If the Hx has a pinhole the coolant that goes missing will eventually drip out the muffler petcock. It may take a while depending on the leak. This isn't my preferred way but perhaps the easiest/least invasive? Or pick one of these:
- remove the 5/8" hose from the Hx that goes to the vented loop and coolant will drip from that port of the Hx.
- pull the Hx anode and coolant will drip from there.
- at the seawater pump, remove the 5/8" hose to the Hx and let it drain. coolant drip will from that hose. (The Hx outlet [to the vented loop] goes higher so the coolant will take the lower path out inlet hose.
- remove the pump cover plate (if it's an Oberdorfer) and coolant will drip out the pump/impeller.)
- remove the Hx end cap, you know where the weed/junk accumulates and blocks the tubes. The coolant will drip out there.
Many ways to skin a Cat-alina Hx. The last three are my preferred/easiest on the C30 - I don't know what's easiest for you.
Your Hx mounts to this type single bracket that's bolted to the top of the bell housing (and blocks removing the transmission dipstick)?
-k
John : If you are worried about the HX - remove it and take it to a radiator shop. They'll boil it out (if needed) and pressure check it!!
That will eliminate one possible source of the leak !! It is probable the time of it's age that the HX needs to be cleaned out !!!
A few thoughts
John - There is a drain on the Aqualift muffler. Check the petcock drain valve before you try to open it. If it looks bad, have a new one on hand to replace it. Catalina Direct sells one. It's a little pricey, but it's a better quality valve. I think mine was the 1/4" valve. FYI - It needs to be able to be opened to drain the muffler if your engine doesn't start after a couple tries to avoid flooding your engine with water, and it needs to be able to close so no leaks.
If you haven't changed your HX anode in a while, checking for coolant by removing that plug is a good idea too. Then you can check for both.
John
PS: if you need to run the engine, to minimize coolant loss you can run with the pressure cap loosened so that pressure doesn't push coolant out the exhaust with the seawater. Especially while seawater temps are still low. Just watch your temp gauge and refill the manifold if needed (your recovery thank won't be functioning with the cap loose.)
John,
One thing that I don't think has been mentioned is the engine coolant pump. They are long lived and rarely do go bad but ## happens. Look for a spray or evidence of coolant on the back of the pully. Sometimes a smell of coolant while running. Because the leak may be small and becomes a very fine spray from the rotating pully it may not be very obvious.
I've never used it. There's UV dye that can be added to coolant to track leaks. Possibly light can be rented from auto supply. May be worth investigating. IMHO much better than changing parts that may or may not be bad.
Happy hunting,
Jim
Thanks everyone. I'll be working on the suggestions this weekend and will report back (or ask more questions...).
Check ALL coolant hose connections and hose condition if the Hx test is negative!! Especially hard-to-get-to hose clamps. There's a 50-50 chance that it will be 100% of the time that an impossible hose barb as on the stbd side of the exhaust manifold will be the culprit.
The exhaust flange gasket could leak which will send coolant out the exhaust.
John : If you remove the HX it might well be the time to replace all of the old hoses too!!
A few thoughts
Didn't get much of a chance to work on the leak over the weekend due to other commitments but I was able to get some UV dye and a UV Light. Put the dye in the system and ran the motor up to temperature and once the T-stat opened ran for about 5 more minutes. Checked with the UV light and lo-and behold there was a leak at the reducing fitting for the hot water heater. Naturally it was running down the back side of the hose so it wasn't easily seen without the UV light. Recovery tank also had a bit of a drippy leak. Got things all tightened on Sunday. Last night I pressurized the system up to 14 psi and it held. Whew! What a relief so I took her out for a spin. Thanks for all the help and insight guys. The autozone dye and UV light cost me a little over 22 bucks I think. Well worth it!
John : What A great "leak" chasing method!!! :thumb:
A thought
You have been hunting that for a while now. Congrats on finding it!
The proverbial eureka moment. Was great that after all that work the fix was so easy. If I understand it correctly, the UV stays in the system and the next leak can be found with out adding more.
Jim
Jim, it was your suggestion that helped solve the riddle. I hope others see this thread when similar issues crop up. Thanks for the help!