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Another question with regards to working on my wiring diagram. I'm thinking the simplest way to determine if the alternator has been run directly to the battery rather than the 1,2,B switch would be to put a DMM between the AO wire and engine ground, turn the switch off and check again? If it's run to the switch I should see similar voltage as at the switch selected battery bank, and with it off no voltage. If it's run straight to the house bank, I'll see no change with use of the switch. Is this correct and safe? I'm assuming the DMM provides sufficient resistance to do this. Currently with the alternator removed from the boat, I've got many wraps of 3M electrical tape around each cable terminal, but the thought of a dead short to the engine with these wires sitting loose as they are now is horrifying. I keep telling myself the electrical tape will do its job, but would feel better knowing the wires are either switched, or if direct to the battery, fused.

Thanks guys. I'm going to bring the alternator over to a local shop today, but I have strong suspicion it is beyond a rebuild. But, it would be nice, as Breakin said, to avoid all those potential downstream issues that always crop up when changing out any part.

You should be able to successfully run up to a 105A small case alternator with a 3/8 in. V-belt. I would recommend using an external regulator with temp sense snd set the alternator output derated downward approx. 10-25% for cooling efficiency.

I had seen in one of Main Sail's articles that the industry recommended maximum for 3/8 belts was 80A, but a more realistic recommendation accounting for imperfections in installation was 70A. Is it the derating done in the external regulator that allows the extra amperage with a smaller belt? I guess my biggest concern right now is trying to figure out a wiring diagram, to determine how all the various charging sources, and controllers interact on the boat. A lot was done by the PO, and I need to figure it out, to determine where I need to run larger whites for a larger alternator.

Out for a pleasant sail back from our weekend anchorage on Sunday, when the wind shut down and we had to fire up the Iron Genny. Over the course of a couple hours of motoring the intermittent hissing that I'd been attributing for the past two seasons to a slight leak at a fuel injector (a stitch in time...) gradually grew louder and more constant. Slowly the hiss started to sound less like a hiss, and more like grinding. Kristina went below deck to grab a beverage, and yelled up "It smells really weird down here". I went to check things out, and it sure smelt like burning rubber. I opened up the engine cover and just at that moment, the engine let out the most horrible squeal. Kristina quickly pulled the kill switch and we unfurled the headsail. Once back at the dock (thanks to a tow in from our slip neighbours) I pulled off the belt to try giving things a spin. The alternator is so frozen I couldn't even turn it with a wrench. Anyway, time for a new alternator, but I've got a few questions I want to run by you knowledgeable folks.

I'll give some info regarding usage and power needs, because I know it's important:
Our typical sailing is 3 weekends (Friday night to Monday morning) per month mid May to early Oct, with one 10 day trip during August. We have a house bank of 4 Trojan batteries wired for 12 volts and 460ish amp hours, installed by PO 2015. Solar = 123w rigid solar panel and 2 50w flexible solar panels, all over 10 years old, and the flexibles are questionable at best. We sail as much as we can, and keep motoring to a minimum. With North Western Ontario's long days, we're typically down 5-10 amp hours when we go to bed, and 30-50 when we wake up, depending how full the fridge is I guess. The alternator that failed is a 50 amp Mando, which seems likely to be original. The engine has 1360 hours on it.

Given the age of our batteries and panels, as well as our plans for longer cruising in a few years, I suspect a major electrical overhaul is in our future. That is not something I want to do now, in the middle of our short sailing season. So, while I know a large output, externally regulated alternator is the way to go, I'm thinking for now I'll go with a more simple swap, to get through the next season or two before everything else gets changed. So, I'm thinking an internally regulated unit with more amperage to run cooler, but still small enough that I don't need to start changing all my pullies. If I understand correctly, I should be able to get away with the current belt size on something up to about 75amps? Or, if I were to go for something around 100 amps, how much of a job is it to go up in belt size? I suspect I'd need to start changing wiring as well, to handle the increased current. Would that be the case with a 75ish amp alternator as well, and am I correct in thinking it is only the B+ cable that would need to be upgraded, or would all of the wires be carrying additional current? If so, it may make sense to stick with 50amps for now, though I suspect the undersized alternator relative to battery bank may have expedited this unit's demise.

Before installing the new alternator, are there any red flags I should look for in the rest of the system that may have caused the failure? I suppose I should check the batteries in case an issue with one of them could be to blame. Perhaps the belt has been too tight, in which case is there a way to determine if damage has been done to the water pump bearing? Anything thing else to check before I fry a new alternator?

Lastly, my understanding is that the B series engines have a bit of odd wiring, related to the oil pressure and ignition switch (if I recall). What do I need to look for in selecting a replacement alternator that will work here. The wiring on the old alternator includes two wires going to the exciter post, a wire going to an "S" post which I gather is battery voltage sense, but appears to be spliced to the (unmarked but I'm guessing) B+ post, and another wire going to the "P" post which seems to have something to do with the tach, though I don't understand what an alternator has to do with the tach, or what changing alternators will mean for my tach accuracy.

Thoughts and wisdom appreciated!

Set the bucket on the floor by the engine, that's where the return goes (old liquid) and put the hose with fresh water/coolant on the upper step above the engine, that way it's fed by gravity. I've also used a funnel on the upper hose and just poured it in instead of relying on the engine creating a vacuum.

It sounds to me like this method would avoid any air bubbles, and the need to burp the system. Did you find that to be the case?

Just be careful with the compounding. Our first time doing it, we had some of the blue migrate into the white. It was easily resolved with additional careful compounding, but who wants extra work?

I've never dealt with EG/PG issues and know only what I'd do when there's something questionable - overkill it LOL!

Make sure it's all out of the block and coolant pump as it's going to be by gravity. 

I tend to agree. I normally start by overthinking, and then proceed to overkilling!

Without using the engine drain plug, does anyone have any idea how much is left in the block after draining the wh loop and proprietary hose as described in the "burping method" post? I began with a low coolant situation, so measuring what came out was meaningless.

Aaron, what I've done worked like a charm. Unhook the return side hose from the water heater, and stick that in a empty bucket, then attach a hose to where the return connected to the thermostat housing and stick it inside a jug or bucket of distilled water or whatever you wanna flush it with. Remove the thermostat, and put the housing back on. Fire up the engine and watch all the coolant be flushed. Then you can repeat the process with your choice of coolant. Half hour job.

Am I correct in thinking that this method requires starting with the system full of either AF or water? I'm thinking that doing this with a dry system wouldn't create a prime to draw the water/af from the bucket.

Aaron

It depends on what you want to accomplish!!  To me a "flush" is a  "flush" — remember the old Flush-and-Fill kits Prestone used to?? sell in every Kmart auto aisle where you cut in a garden hose fitting into a heater hose and flushed up and out the radiator cap?

If you want to drain and rinse/dilute that's to me a different thing.

Thanks Ken,
I guess really all I'm looking to accomplish is a drain and rinse, as you put it. Everything seemed reasonably clean, so I'm not too worried about a power flush, though it would probably be a good idea. However, with the short timeline to launch, and the club still not having running water for a hose, I'm really just trying for the simplest option. I can do a proper flush another season, perhaps in the fall to avoid the spring time issues with the club water supply. At this point I'm basically just trying to avoid AF compatibility issues. I've heard horror stories of mixing PG and EG, and I have no idea what was in there.
So given that, would it be reasonable to fill the manifold and heater loop with water from a jug, drain, and do again, and then fill with 50/50 and burp the system? Would that get the rinse water throughout, without the Tstat opening? From looking at your schematic, it seems to me that it would.

Thanks guys! So here's where we're at. When I removed the hx and all hoses, all the coolant drained from those areas. I also sucked out the wh loop with a little hand pump. I believe this should have removed most of the coolant from the system, but as I did not drain through the incredibly inaccessible drain plug as suggested in the manual, I assume there is still some coolant in the block itself? I mean surrounding the cylinders, hopefully not in them! Everyone here seems to use the hose to drain, as described in the burp method post, rather than that plug.

The coolant and all internals I could see looked pretty clean, no sludge,  but I don't know if the previous owner had EG or PG in the system (just that it was green). So I want to do my best to remove all traces before refilling with new stuff. Launch is this weekend, and while we could probably get from the launch ramp to a slip before overheating, and deal with this in the water, I'd feel a whole lot more comfortable having the boat ready to go. Breaking down on the ramp and delaying everyone else, is not how I hope to start the season.

Run the engine for a while.  Whether it comes up to running temp or not should not matter, since the coolant is circulating.

This is where I'm confused. If the engine is not up to temperature, is it still circulating on the hx side, or just on the wh side? Looking at Ken's schematic, I'm understanding that the coolant only circulates on the wh side until the Tstat opens? I suppose the hx side gets flushed in a sense as you fill from the manifold. Anyway, that side doesn't really need a flush as it was just refurbished.

The alternative is to remove the hose from the Tstat cap to the exh manifold and adapt your garden hose to there.  BUT as you flush the block you'll get leakage out the Tstat cap (the 1/8" hole in the Tstat flange) plus the flush water coming out the WH hose you removed from the coolant pump.

Thanks for the very detailed reply Ken. I guess this is the method I would have to use, as my Tstat housing does not have the petcock. Would I not get the same result from putting the garden hose right to the manifold, rather than removing that Tstat-manifold hose?

Now I just need the yard to turn the water on. They're really waiting until the last minute. I realise it wouldn't be as thorough a flush, but could I just fill and drain the system a couple times from the manifold using jugs of water, to sufficiently dilute whatever coolant is left in the block? Or does it require the pressure of a garden hose to circulate, since the engine isn't running?

The 2nd path is up thru the Tstat, to the exhaust manifold, to the Hx, and back to the coolant pump. Until the Tstst opens that path is "essentially" closed off so the coolant in that circuit doesn't circulate.  (That's not exactly the case because there's a 1/8" hole in the Tstst to let a minimal flow thru the exhaust manifold

Thanks Ken, that answers my question. The flow through the hole is too minimal to be relevant. That said, I suppose the only option if a flush needs to be done on the hard is to remove the thermostat? Or could I essentially flush the two halves of the system as you described it, separately? Fill and drain from the hx, and from the hose below the pump plus wh loop?

Just curious how much flow there is through the thermostat bypass. I notice that Westerbeke indicates in the manual that the thermostat should be removed for coolant changes, but I've never seen that mentioned on this forum. Why would this be necessary given that there is, as I understand it, a bypass which allows continuous flow of the fresh water side? I assume this flow is fairly restricted to allow the engine to get to temperature in a cold body of water. Any ideas how long one would have to run the engine to fully circulate the system if trying to flush with distilled water? It seems to me that with the bypass, we shouldn't have to wait for the engine to come fully to temperature.

Regards,
Aaron

All my hoses have finally arrived, so time to try putting this thing back together. I purchased some cork gasket material to put between the hx and the bell housing. It looks like what was originally there was a synthetic black rubber of some kind, but I figure cork should do the job. Any suggestions regarding what to tack it to the bell housing with? I was thinking a couple dots of RVT. The original material seemed to have been stuck on pretty well. Also, the new Seakamp brackets came with little squares of gasket material for between the bracket and the hx. Should I also put something between the worm drive and the hx? Perhaps some inner tube? I've read that it may be better no to isolate the hx from the engine, from a corrosion perspective.

Thanks guys, I'm going to order the parts tomorrow. The bonding strap sounds like a good idea, though our pencil anode barely erodes at all over a season, so I don't think galvanic corrosion is too much of an issue here.
I managed to improvise a pressure tester, and the hx seems to be ok. I'm actually a little disappointed, as that would have been a relatively easy explanation for the missing coolant. I guess it will remain  a mystery until I can run the engine and do more testing. I'll open it up this weekend  and start the cleaning process, repainting etc as per Main Sail's instructions on his site. Hopefully I can get all the parts fairly quickly and get the cooling system back together for launch on May 14th.

I was able to get the hx off the boat this weekend, and will bring it into a radiator shop to be pressure tested this week. Would folks suggest cleaning it up on my own (external and internal) and then bringing it in, or having it pressure tested as is so I know if there was leak at baseline? I haven't opened it up yet, as I don't have gaskets at this point anyway. From photos, it looks like the end cap gaskets could just be cut out of a sheet of gasket material, or is it best to purchase them. I mean it's just a disc. Speaking of gasket material, the cork or whatever it was that was between the hx and the engine is completely rotten, any suggestions regarding what to replace that with?

While I'm doing all this work on the cooling system, are there any other projects I should tackle at the same time?

Ken, thanks for all the info!
I'll look into the new clamps, I take it they wrap around the hx like a worm clamp? I've seen photos of some like that.
With regards to shipping, if it changes anything, I have a place just across the border that I ship to regularly. Given Thunder Bay's location, it's often easier to get things shipped to Minnesota rather than from Canadian sources. We don't even have a local chandlery here, or I'd gladly support them.
The T-stat to manifold hose looks to be in good condition, so I suppose I could leave it as is, or order one, and if the wrong one arrives, it's not the end of the world.

Thanks Stu,
Never having worked with wire reinforced hose before I can't get over how stiff it is when you're dealing with minimal room to work, and can't approach it from a good angle. That's working on a boat though!
I'll definitely use Lanicote or an equivalent (Marelube?) when reassembling.
Thanks for the tip on the Toyota part, unfortunately it looks like the M35B has a more complicated hose with multiple bends in it. You can see some good photos of it here https://c34.org/wiki/index.php?title=Flow_directions_in_engine_cooling_hoses_(both_early_and_B-series_engines) It's the port side hose back to the coolant pump.
It seems like I should just replace all the hoses since I'm going to this much trouble anyway, so may as well remove them in whatever way is easiest, without concern for maintaining their integrity. I'm thinking that it is probably important to consider the order of reassembly to make the process as easy as possible.

So, I made it to the boat today, with the intention of removing the hx, cleaning it up, an getting it pressure tested. Loosening the bolts on the brackets revealed that the brackets are no longer welded to the hx, which seems to be a common issue. If only it was so easy to remove the hoses. I can't for the life of me get the port side hose (to the vented loop) free. It turns easily, but because it is such a stiff, wire reinforced hose, I can not for the life of me get it free. Also, due to positioning and obstructions, I can't get the upper port side hose ( to the coolant pump) free.That one doesn't budge at all. Any suggestions? Am I best to just disconnect them from the other ends, since they are likely due for replacement anyway? That upper port side hose appears to be a moulded item, I'm guessing that would need to be ordered through Catalina.