Water pump failure

[waterdog]

Somewhere on the way to Barra de Navidad my high output alternator packed it in.   The heat at the output was so high it melted down the insulation and started arcing and sparking.   Of course I had wired it directly to the battery bank to avoid the "brother in law fries the alternator diodes by turning off the switch" problem.   The only downside of direct to bank wiring is that if you have a failure at the alternator you can't turn off the switch and stop the arcing.   So there I was with a wrench undoing the connection at the fuse.    Nothing ever goes wrong with the engine in port. I always end up doing repairs at sea.  

Such was case coming from Barra to Yelapa.   I heard a slight tick.   To me it sounded like a problem with a water pump.   So I tore apart the raw water pump.  Couldn't find any problem.   Started up the engine and we decided to run at 2000 rpm until we got into Yelapa.   After a while there was a crunch and a screech and a lot of shouting to turn the engine off.   The fresh water pump had packed it in.  The shaft completely failed.  

Fortunately, back in the planning stages, somebody on this board convinced me to bring a spare.  Installation did not go that smoothly.   The hose fitting on the top of the pump did not come with the new one.   Just a threaded hole in the pump.  The old pump had a pressed in fitting.  I ended up removing the old fitting with vice grips clamped onto the fitting with a screwdriver in the middle so the tube wouldn't get crushed.  Then I had to drill out the nice threads on the new pump and tap the old fitting in.  

Thankfully the wind had picked up so we were still making five knots while repairs were underway.  Unfortunately it meant doing the work while we were heeled over.   But at least it was done before nightfall and we arrived in Yelapa at dawn after motoring all night.  

Moral of the story:   if you buy the water pump from the tractor store, make sure you order the little fitting that the hose goes onto so you don't have to drill your new water pump out to make it work.

[Craig Illman]

Steve - Thanks for sharing that. I'm going to try to remember to check next time I'm down at the boat. The new pump is in a plastic bag with a gasket in the V-berth drawer.

Was your wiring from the alternator to the battery bank fused?

Craig

[waterdog]

Was your wiring from the alternator to the battery bank fused?

Craig

Yes.  Yes.  Yes!  The bank absolutely must be fused if wired in this way.   

It didn't stop the arcing however.   This is the downside of the "brother-in-law can't fry my diodes" alternator wiring scheme.

[Craig Illman]

Steve - I also have a circuit breaker at the house bank, nominally to isolate the house bank from the panel during equalization. I don't recall which side of the breaker I ran the direct line from the alternator. It would be easy to replace the current fuse, under the head sink, with another breaker that could be quickly tripped manually.

Craig

[Ron Hill]

Steve : What was/is the size of the fuse/s that you have/had at the batteries?  Just curious

[waterdog]

Ron

I know it is at least 200A it might be as high as 300A.  I don't recall what the criteria was for sizing, but it made sense at the time.  I run from battery bank through a fuse to a positive distribution post where I draw loads and feed from the alternator.   So in theory my alternator could feed a short on the load side, but I am much more concerned about the energy in a 440 Ah bank.   All the loads are individually protected in any case.   

Battery banks never used to be fused, but I think fusing of the bank has found its way into the standards now.   Ever since I wired an illuminated switch into an unfused dead short I have the utmost respect for the power of the batteries.   It's only 12 Volts, but it will happily burn your boat to the waterline... 

[karista]

Somewhere on the way to Barra de Navidad my high output alternator packed it in.   The heat at the output was so high it melted down the insulation
Moral of the story:   if you buy the water pump from the tractor store, make sure you order the little fitting that the hose goes onto so you don't have to drill your new water pump out to make it work.

It makes no difference whether you buy the pump at a Universal Dealer (over $300), or Kuboto Tractor store (about $100), you still have to buy the hose nipple, Universal P/N 301519 separately, for $18.70. Or you can go to Advanced Autoparts (P/N 323314) and buy it for $1.89.
The hose Nipple size is 1/8MPTx3/8 Hose.

[jfssail]

Bernd,

In some cases, the nipple comes attached to the pump. I purchased a spare from my Kubota dealer in 2004 and it came with the nipple in place, exact copy of the one from Universal. Purchased the spare after the original pump shaft froze in the middle of the Detroit River under the Ambassador Bridge. Got a tow and pump replacement in Detroit and completed my initial trip with the boat the next day to Port Clinton.

Jack F Stewart
1993 C36 #1233 "Windancer"
Port Clinton, OH

[Ron Hill]

Guys : The 2 nipples that Steve's talking about have to thread into the raw water pump and also have a barb to fit the raw water hoses.  Don't recall the nipple size thread (3/8" or 1/2" NPT?), but your raw water hoses are 5/8"!  I change my water pump at least a dozen times in 22 years and never had any problem taking the nipples off the old pump and threading them on to the new pump.  However, I always coated the threads with grease or Vaseline - that was BL (Before Lanacoat)!
My fresh water (internal 50/50% Prestone) pump came with both nipples - when I had to change out mine.

Steve : I'm not an electrical whiz, but I'll suggest that you had too large a fuse in 200 amps or +. My fuses at the battery are 100 amp(duel output) and I'd guess that you've never seen your alternator put out 100 amps and you might think about 125 or no more than 150amp fuse.  
I'm sure some of our electrical Oracles will SURELY correct me if I'm wrong.  A few thoughts

[waterdog]

Actually the fitting I'm referring to is on the fresh water pump.

[karista]

Bernd,

In some cases, the nipple comes attached to the pump. I purchased a spare from my Kubota dealer in 2004 and it came with the nipple in place, exact copy of the one from Universal. Purchased the spare after the original pump shaft froze in the middle of the Detroit River under the Ambassador Bridge. Got a tow and pump replacement in Detroit and completed my initial trip with the boat the next day to Port Clinton.

Jack F Stewart
1993 C36 #1233 "Windancer"
Port Clinton, OH

Jack
That was 6 years ago when you purchased your pump, now when you buy this pump you will need to buy the nipple seperately. Check out Torrenson  Universal Marine order site, it specifies the following note when ordering the pump: "A new by-pass nipple is required with this pump. Please add Universal Part Number 301519 to your pump order".
I guess, the earlier models may have had the nipple installed but the newer model does not, so its worth checking your spare pump to make sure it has the hose fitting, if not buy it at your Auto Parts store.

[SeaFever]

Steve,

I am in process of completing my wiring of the new Engine Panel tomorrow. So this is just in time, thanks!

Quick clarification questions: The fuse you are talking about is in line of the wire connecting the output of the alternator to the house battery, correct? Could you confirm, did you use 200A or 300A? Also what size wire did you use for this connection? This is a good size fuse, what kind of a inline fuse holder did you use?

And question which is slightly off-topic: How is the Fuel pump connected? Directly from the big stud of the starter solenoid (which means the fuel pump will be on when the Battery Switch is on) or is it connected through the engine panel (which means the fuel pump is on only when the key is turned on the engine panel)?

Thanks.

[Ron Hill]

Mah : Let me interrupt.  Look at my post above, as I believe that Steve used TOOlarge a amperage fuse.  Fuse size all depends on the size of your alternator and it's output. 
Yes, the fuse should be in line at the battery end of the wire if you go direct from the alternator to the battery (which I recommend).

The fuel pump should be connected to the post that is "hot" when the key switch is ON. 

[SeaFever]

Hi Ron,

Thanks for the quick reply. I understand on the size of the fuse. I had not read all of your post, now I did. I have the old Motorola Alt and will put a 50+ Amp fuse accordingly. Based on that a size 10 AWG wire should suffice for me. You probably used a 6AWG for the 125A

Understood on the wiring of the fuel pump. Hence the fuel pump is always on even while sailing (motor off). That is the way I have my wiring diagram now, however, doesn't make sense to wire it such that the pump is On only when the switch on the engine panel is on?

Thanks.

[Stu Jackson]

Yes, the fuel pump should only need to be on when the key switch is ON, i.e., preparing to start the engine, gauges energized, engine hour meter energized.