Cooling system problem - please help!

[AMcC]

Details: Cape Dory 25D, Yanmar 1GM (not 1GM10)

OK - when I I put the boat away in the fall of 2019, all was well - pumped antifreeze into the system on the hard from a bucket, changed the impeller, drained the block, everything worked fine. Went to get ready to launch this spring - new batteries, so I brought a bucket of water onto the boat and tried starting. Started great! Pumped out only a bit of anti-freeze, and then no water coming out... so, I've checked every external hose from the bucket to the exhaust elbow - no blockages. I changed the thermostat (which was frozen shut), checked the impeller - no problems there... impeller hub does not run freely from impeller outer body... turning fan belt turns impeller... changed the engine zinc - no apparent problems there... tried 'priming' the impeller - no apparent issues, though with the boat on the hard, there's no natural water pressure pushing water halfway up the engine through the tubes/impeller, etc...

Starts fine, but no water comes out... ??? could it be the raw water pump? I don't see any leaks... engine block drain is closed... other suggestions? Supposed to head for Hudson river and points north in two weeks...
-Alec

[Frenchy]

Try investigating for air leaks. If your intake hose leads to the water strainer, look for air leaks at the lid gasket, hose connections.
It's possible there's a crack in the plastic bowl. If the intake hose runs directly to the raw water pump, look at the connection and pinhole leak in the hose itself.
Put a garden hose up into the intake and look for water leaks. Possibly the raw water pump gasket is not sealing.
It seems you checked every thing else I could think of. Good luck.

[Jim Evans]

I might suggest checking the mixing elbow for an internal blockage. They are certainly susceptible to internal corrosion.

[Chrisa006]

Maybe too simple but rev the engine a couple times. I changed an impeller once that was fine.

[AMcC]

I talked to a service manager and sales guy (two people) at Niemec Marine (dieselmarineparts.com) who were very helpful. I ordered a new seawater pump ($230?), plus new oil lines (the ones under the pump are heavily rusted). The service manager said a failed seal on the pump can also allow air to be sucked into the system, preventing water from pumping.

Will give an update after installing later this week.

May hold off on the oil lines and exhaust elbow - have both on boat in case something goes during my upcoming trip, but I'm reluctant to take more things apart in fear of breaking something in that process and delaying my departure...

I do have CLR on hand for a brief buildup rinse before I leave the dock, assuming the new pump does its job.

-Alec

[Kailua Kid]

Did you prime the sea strainer? Try running water via a hose up into the raw-water through-hull, with the sea strainer primed.

[gonesail]

In my experience a failed seal on a yanmar raw water pump would result in water dripping from the weep hole .. but the pump would still function. but I could be wrong and look forward to your solution.

[gates_cliff]

I have a westerner. Ran into similar problem a few years ago and eventually had to have a mechanic check it out. Turned out heat exchanger needed to be cleaned out.

[RC James]

You've checked all the obvious stuff.

How about 'farther downstream'?
I'm asking about the Muffler and exhaust hose to stern?

Birds nest? Wasp nests? Critter's winter quarters?

Just prognosticating while anticipating how to change a stuffing box in water.
RJ

[mgphl52]

Does your mixing elbow have the input line on a 90° nipple? If so, I highly suspect that's your culprit!
Try disconnecting the other end of the hose and see if you can blow thru it. If not, it's clogged...
After dealing with this once, I switched to a longer input hose and a straight nipple. With that, I can disconnect the hose and and use a piece of coat hanger to clean the build up.

[AMcC]

Well, I've isolated the problem to between the bucket and the output from the pump. However, I could only get one of the three bolts off the seawater pump - the others are rounded but good. Being afraid to do more damage than good, I'm waiting for the yard mechanic to get the old pump off.

Question: the oil lines below the pump are pretty rusted... I have replacements in hand, but am a little reluctant to get into even more repairs prior to my upcoming 2 week cruise... any guidance on how much I should be worrying about the rusted oil lines? I'd like to wait until after the current season if I can in case I run into other problems...
-Alec

[RC James]

The Oil-Line replacement is no big deal. Unbolt/Remove/Replace/Rebolt.

You can do it yourself, but if you've decided to have a Wrencher do the WaterPump, have him do the Oil Lines at the same time.

RC

[AMcC]

Update: after waiting four weeks for a mechanic, I had two (2!) booked for a two day period... the first was a 'friend of a friend' who found that he didn't have bolt remover nuts small enough for the bolts (I had told him that an 8mm turbo nut spun on the bolt head, but he didn't come prepared - didn't even bring a ladder...). The second was Breakwater Marine Services, out of New London. Well, their mechanic showed up, also didn't have any tools to remove stuck bolts, took a look at the engine and said "I'll be back tomorrow"... I got a call about an hour later from the head office saying "the job is more involved than we thought - we thought it would just be flushing the system or something like that - so we're not going to take on the job"... I was incredulous... seriously? I waited four weeks and drove down to CT from VT to meet your mechanic and you bail?

So - don't ever use Breakwater Marine Services. As I asked around the yard about them after this experience, I heard multiple other horror stories about the business...

Anyway - this got me upset enough to resolve to get out my dremel and grinder and dig into it myself to try to salvage my summer... and I got the bolts off! Broke a screwdriver tip and broke one of the bolts in half in the process, but got them off. New pump went on, cranked her up and she started spitting water again! Boat goes in the water today, I leave the dock tomorrow morning on the tide (yes, there's tide all the way up the CT river to Hartford and a bit further!).

-Alec

[S/V Ethan Grey]

Good on you, AMcC.

I am very hesitant to have any mechanic work on my boat or cars, I always feel like I’m going to get swindled or the quality of work will be subpar. I don’t know what happened to pride in doing one’s job well. Maybe it never existed. Anyway, rant off. Great job fixing it yourself and pressing on.