Sorry if this is a repeat, I'm on my phone and having trouble with the new forum setup.
We don't seem to be able to get any water to flow to the aqualift and I was wondering what the group thinks.
The impeller is fine, and primed
The water intake is fine.
The heat exchanger is clear
A month ago we had a beautiful sail up the coast, with a decent following sea. When we started the engine up we couldn't get any water mixed into the exhaust, i played with the whole system and was able to get water flowing again. One of the last things I did was vent the aqualift. After doing that we had water in the exhaust, so I chalked it up to too much back pressure.
Fast fwd to today, no water coming out of the exhaust. Everything on the engine side is clear all the way up to the heat exchanger. My though is that it's the mixing elbow., but I'd love to get further input on this.
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Hi Alex. The thing that strikes me is that you were able to get the water flowing again the last time this happened. Have you tried to disconnect the inlet hose from the through hull and verify that the inlet strainer is not partially blocked? (Tom Sokoloski added a tee above the inlet valve to provide a straight path down to the strainer to make it easier to perform this check and clear a blockage without disconnecting the inlet hose). If you think it might be the mixing elbow, disconnect the hose coming from the heat exchanger and use something to probe the hole. If blocked or restricted with rust or salt deposits, try to start a small hole through the blockage, then use a coarse round file or piece of threaded rod to expand the opening. If that is clear however it pretty much points to a plugged heat exchanger. In that case remove the heat exchanger, remove the end cap and pencil zinc and flush it till everything runs clear.
Michael & Jayne O'Neill * Steadfast * 1985 C36 #372 * Salem, MA
Thanks Michael,
I took things apart last night, and your gut reaction was right, not the mixing elbow.
I think it's the heat exchanger, I'm able to get water to the impeller, and it runs out freely when the bleed screw is removed. I cleaned the strainer immediately last night, but I'll try poking something down there to be safe. When flushing the heat exchanger is that a "passive" flush (ie without the engine running) or an active flush? And would it be best to do one end at a time?
Alex
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Hi Alex:
I think you will have to remove the heat exchanger to accomplish this. Run water into the pipe that connects to the hose running between it and the mixing elbow. Let the water run out the hole for the pencil zinc carrying the debris with it. Use a drywall screw like an auger to help break up those pieces that will not come out through the zinc hole - the spent zinc is brittle and will crumble fairy easily. I think I have read some suggest that you can take it to a local radiator shop for a boil out but I have had good results using just the fresh water flush. After you put everything back together, watch the exhaust and temp gauge (that will let you know what is happening in both the raw and coolant circuits). Good luck!
Michael & Jayne O'Neill * Steadfast * 1985 C36 #372 * Salem, MA
Ahh, I see what you mean, thanks Michael. I'll give that a shot tonight, fingers crossed we'll still be able to go out for a nice long weekend next week.
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Alex-
If the heat exchanger work doesnt cure the problem, look again at the water pump. I believe you have an oberdorfer pump on your M25. Remove the face plate and run your fingernail over the inside face- if you feel a ridge where the impellor spins against it, that means you have some wear and may be loosing suction from the pump; the rubber vane edges are not making good contact with the plate. If you have wear, depending on the pump, you may be able to simply flip it over and use the other side.
Good luck
Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B
One thing you can try to narrow the problem, is to add a simple T connector just above the engine thru-hull inlet. Then attach a garden hose water source to this. With the engine thru-hull shut off, turn on the garden hose just enough to simulate the water pump flow. Then start opening the pipe fittings starting from the new water pressure source (the garden hose) until you find the blocked part or hose.
If it's flowing freely all the way through to the aqualift, then I would suspect the water pump is not working.
A side benefit of doing this is that you now have a great "fresh-water flush kit". I flush my engine after every saltwater sail, and my mechanic says he hates me for this (kidding) coz he says my engine will outlive me (not kidding).
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Be a bit careful of pressurizing your raw water system with a garden hose if the engine is not running. Depending on the design of the raw water pump, water might not even make it past the vanes. If it does make it past the pump and reaches the water lift and you let it go long enough, water will enter the exhaust manifold. You don't want that. If you're going to try this on a non-running engine, open the water lift petcock for the duration. As soon as you get fresh water out of the petcock, shut off the hose and close the petcock.
One year I did not properly winterize my raw water system and my water pump housing distorted as it iced. It all looked good, but only pumped at high RPMs due to insufficient clearance between the vanes and the housing. Replacing the impeller did not help. Only replacing the pump restored normal water flow. Just something to consider if you live in a cold climate....
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Success (Well 90% at this point)! Took off the H/X last night, flushed it, reinstalled, and now we have water in the exhaust again!
Now the joy of clearing the airlock on the closed circuit side....
Update: which only took half an hour this time, we're getting better at this!
So we have now added the freshwater flush to our list of regular maintenance items. This is our third season with the boat, so we think we will do this every other year. Anyone think this is not regular enough?
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Glad to hear you are back in business! The semi-annual flush seems like a good idea, however I have no idea about the best frequency. See what comes out year after next and compare to what came out this weekend. You went 3 years and unless you see it noted in the boat's maintenance log there is no telling when the previous owner flushed it before you.
Michael & Jayne O'Neill * Steadfast * 1985 C36 #372 * Salem, MA
Good point about the pressurizing, Nick.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Well, halfway across the Georgia Straight (after a great sail 15-20 knots, beam reach) the wind shut off. Fire up the iron gonna, and low and behold no water in the exhaust!
Looks like this may be a water pump problem. I replaced the impeller, and took an "extra" hard look at the pitting on the cover plate of the raw water pump.
Anyways, new impeller didn't immediately resolve the issue, so I loosened the hose clamps on the "raw water out" on the heat exchanger. We started the engine, I moved the hose around a bit (to bleed it) and success!
So Peter's thought on it being a suction issue seems pretty accurate.
Thanks to everyone's input, i think it's time for me to write a guide on troubleshooting raw water cooling issues!
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Hi Apologies for resurrecting this thread but.....last week I started the engine and had that dry sound you guys have been referring above. and although I think that the information in this thread is great I am a bit lost with the technicalities.. any pictures on what I should check? please.....
I have already checked that there is a good flow of water flow from the seacock and the hose to the water pump is not blocked. also woth noticing that this is a brand new oberdorfer pump installed about ten engine hours ago. and when I removed the front of the pump to check the the impeller there was back water pressure. Thus I would assume it is a blockage on the water exchanger.
any thoughts? pics?
Regards
Andres
Andres & Arantzazu
S/V "Carpe Diem"
Hull: 1773
1999 C36 mkII
Hong Kong
http://www.abclubhk.com/
If it were me, I'd try to narrow down where the blockage is. Sort of the same principle as narrowing down an electrical fault.
Use the garden hose method I mentioned above and start removing hoses at critical points to see where the flow stops, i.e. remove the impeller and see if it gets that far. Remove the heat exchanger in-host, then the heat exchanger out-hose, then the exhaust elbow injector hose...and so on.
It's probably a simple blockage somewhere in the flow.
Just be careful about over-filling and/or over-pressurizing as Nick said above!
If everything is flowing ok, then have unpressurized fresh water flow while you run the engine (i.e. a fresh-water flush like you'd do with an outboard motor). If water flows out the exhaust then obviously the blockage is in the engine water intake strainer or thru-hull seacock.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Andres,
Is it possible that you may have crossed the hoses when you switched to the Oberdorfer pump so the suction hose is now on the outlet side? Just a guess.
Tom & Janis Grover
C36 #0949
SR/WK, M25XP
Midland, ON
NOTE 1. Avoid at all costs filling your muffler with water that is not being pumped out. It will back up into your engine via the exhaust manifold and this can do serious damage to your engine. Any time you think this is happening STOP and remove the drain plug from your muffler and drain it. Do this as often as you think the muffler might be filling with water and not being pumped out.
NOTE 2. You're working around a running engine and exposed rotating components. Be careful.
NOTE 3. You're working with salt water near the alternator. Avoid getting salt water in the alternator.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Hmmmm....to avoid water backing up in the muffler, why not just unclamp the hump hose to the muffler and let the water drain into the bilge? Wouldn't that guarantee (or at least help guarantee) that water won't back-fill into the exhaust manifold?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
hi guys
all fixed
The elbow on the heat exchanger was almost fully blocked of what it seemed barnacles. I guess that this was due for little use of the boat.
Anyway, thanks for the advise
Regards
Andres
Andres & Arantzazu
S/V "Carpe Diem"
Hull: 1773
1999 C36 mkII
Hong Kong
http://www.abclubhk.com/