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Courtney the Dancer
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If you are going to the trouble of inspecting it (or even if you don't inspect and you just worry about it), why not just replace it, it's easy and cheap? An ounce of prevention...
 

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If you are going to the trouble of inspecting it (or even if you don't inspect and you just worry about it), why not just replace it, it's easy and cheap? An ounce of prevention...
Agree 100%. Your can't really inspect it properly without pulling it out of the pump. Makes no sense t o me to risk the damage of overheating the engine for the cost of an impeler once a year.
 

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Mike, if you had a Westerbeke W-27 V drive, then we have/had the same engine. The PO of my boat installed a speedseal and it makes it much easier to access the impeller.

I hope I get to see your electric drive in person some day. Sounds like quite a set up.
Yep it was a W-27. That reminds me. I actually did install a speed seal cover too. But, it was during the period when I was try to get repair the engine. I converted to electric propulsion before I ever really got to use it. It certainly would have made changing the impeller much easier. But, I pulled the engine and sold it and never really got to put it to use.
 

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Tartan 37
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My Beta 38 Manual says "Every Year or 250 Hours, whichever comes first", so l change it yearly. I do not come close to 250 hours a year, even this past year with a trip to LIS through the East River ;) In fact the engine doesn't even have 250 on it yet :)
 

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I have a Perkins 4236M with a heat exchanger which is very difficult to get if impeller blades enter the stack, so I have fitted a Vetus water strainer between the salt water pump and the heat exchanger

The strainer catches the blade tips BEFORE they block the heat exchanger. It also allows you to visually check the strainer when you do your engine checks and spot if any blade tips have gone missing.

With this in place, the last impeller lasted just under 3 years. I do about 600 hours per year.

I also have a Speedseal with the lastest cover and it will be interesting to see it makes the impeller lasts longer
 

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A second strainer, after the impeller is a pretty neat idea. I can't believe it's been all these years and I've never thought of or heard of this idea. Do I just have my head under a rock or is someone aware of why this isn't more common?

On my boat, the hose that departs the raw water pump is a factor OEM molded hose, so I presume I would just replace it all with flexible tubing to a strainer first.

Very interesting thought.
 

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Every year.

About Over the years, about 1 in 3 had one or more vanes broken off when I changed it. No idea why.

Incidentally, I always check for water flow; even with one or two vanes broken, there was a healthy flow of water. I also got a speedseal, but it doesn't fit :-(. A real pain as I have a V-drive, so the engine is mounted backwards, and it's a bear to reach in to replace the impeller - a 10 minute job takes me an hour (dropped screws, swearing, etc) :-(
 

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On my boat, the hose that departs the raw water pump is a factor OEM molded hose, so I presume I would just replace it all with flexible tubing to a strainer first.

Very interesting thought.
I removed the rubber connecting piece and Copper pipe from the raw water pump outlet and used new flexible wire reinforced pipe from the pump to the strainer and then from the strainer back to the heater exchanger pipe.

This set up has been working for a few years now and does not seem to impede the water flow at all
 

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Simple. It needs to be inspected at least once a year. So if you have gone that far, replace for $30 or $40. Cheap for peace of mind. Remember it only takes a few minutes of overheating to ruin one. Example if your raw water strainer clogs and one keeps running. Crispy impeller very soon. As mentioned in other comments it is very easy to change. Especially after the first time. Why Risk Your Engine
 

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I've always made a practice of replacing my impellers in the spring of each year since I had one the came apart and distributed pieces of the vane throughout the cooling system. They are cheap, easy to replace, and the process gives me a chance to look the raw water pump a look.....
 

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Glad I found Sailnet
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Does everyone have a puller tool, or are they making do with other tools like me?

Regards,
Brad
 

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I have a puller tool. Only necessary, if I get to the impeller, before all the vanes disappear. :)
 

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Should depend on how many hours you run. If you winterize, pull the impellor out for the winter, inspect, and put back in in the spring if its still in good shape. Sitting in the pump with the vanes bent over all winter is probably worse than running it for many hours. With our short seasons up here, it's hard to put enough hours on to wear one out in one or even two seasons. Always keep a spare or two handy.
 

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I would think the unmentioned factor in this discussion is the quality of the water going through the pump. If your boat is in murky water with a lot of suspended solids I would think the impeller would have a shorter life than one operated in clean water. I think salt water vs fresh water would also have an impact on the lifespan.
 

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One reason experience may vary is that...

Neoprene impellers are NOT COMPATIBLE WITH PG ANTIFREEZE. Funny that this is not mentioned on the container.... Certain plastic strainers are also not compatible.

After one season in PG. A sample in EG was unaffected.


Yes, I've done testing. They get stiff. Nitrile impellers are not affected, and EG antifreeze does not affect neoprene parts (on of many reasons NO OEM USES PG ANTIFREEZE.

Really, there is no reason to use PG for anything other than potable water. It is NOT better for the environment, more bidegradable, or less toxic to fish. Don't believe me, read the MSDSs and the EPA studies on glycol run-off. It's just urban legend perpetuated by marine centers and PG makers. Not too surprising, huh?

Do use PG in the potable system.
 

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Good point. I use the pink stuff (PG) in the potable water only. Engine gets regular automotive green stuff (EG), even the raw water circuit. I buy the cheapest I can find for the raw side, better quality for the fresh side. The head doesn't like PG either, use the cheap EG there. You'll do fewer rebuilds that way.
 

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My very recent tale (5 days ago) of impeller failure at a very inopportune time. I carried a spare but decided not to replace the old one because it didnt have many hours on it. Trip from Marsh Harbor Abaco back to Florida on my 28' S2 with Yanmar 2GMF engine. Going from Green Turtle west, we stopped at Hawksbille Cays for the night, a nice anchorage. Next morning planned to go on to Mangrove Cay for the next night. Got up and started out and engine ran for about 10 minutes before alarm came on.. We anchored again and I checked everything else first because I simply didn't think it could be the impeller. Finally, took the entire raw water pump off and sure enough, the impeller was just spinning on the shaft and it had vanes ready to break off. NO problem, I have a spare, or so I thought. Turns out I was sent an impeller for a Yanmar 1GM and had never bothered to look at it. OH SH&*! What to do? If we could maybe get into Foxtown, we might be able to get a ride to Marsh Harbor where they might have an impeller. Getting into Foxtown involves threading a rocky maze of very shallow water. Fortunately, "Ragtime" draws only 3'10" and we ran the engine for about 10 minutes at a time till the alarm came on and then put out the anchor and waited for 20 minutes. It took us over two hours to get within 300 yds of shore at Foxtown while very closely watching th4e depthsounder and stressing over whether the engine would overheat whilst threading between rocks.
Finally anchored and sent son-in-law ashore in dinghy to a bar we could see. He radioded back that he got in touch with Marsh harbor Boat Yard and they had the correct impeller and he had arranged a ride with some guy who was going to the airport in exchange for paying for gas. 4 hours later, right at dark, he got back with new impeller and gasket after riding in the typical bahamian truck that broke down every 5 minutes.
I put in the new impeller but the gasket was not as thick as the old one and the screws wouldnt tighten enough so I had to find some washers somewhwre to use but it worked.
While he was gone, I invented 4 ways to make an emergency water pump,
1. Route the bilge pump exhaust thru the heat exchanger, I didnt like this cuz it made the bilge pump run continuously.
2. Gravity feed water from a water jug and water hose connected to raw water pump outlet. This sorta worked but involved someone standing on the cabin top to get sufficient head pressure.
3. Water hose connected to water pump outlet and other end stuffed into a water jug using duct tape wrapped round it to get a seal. Squeezing the jug provided pressure feed. This required having several water jugs ready and filled with salt water and someone filling the empties.
4. Cut the almost broken vanes off the impeller. Drive a screw thru the rubber into the plastic part that fits on the housing shaft to keep it from spinning on the shaft. Running at low speed it could pump.
Fortunately, the impeller was available and we didnt have to try my methods.
Once we got it on, the next day, we ran the engine all out and got an average of 6 kts for 12 hours to go from Fox Town to West End, a distance of 75 miles in 12 hours, a record for Ragtime.
Even with the washers, the gasket was leaking and we had to pump the bilge every half hour. My NEW bilge pump suddenly failed WTF? Fortunately, I have a manual bilge pump that we used. Turns out the NEW bilge pump had been wired in with regular untinned wire that had turned to a corroded mess. I happed to have some good tinned wire I used to solve that problem the next day.
On leaving West End this past Thursday morning for West Palm, the engine ran for 3 hours at 6 kts but suddenly we got a new type of engine alarm I couldnt identify. It didn't seem to be cooling but the engine was definitely running slower, WTF? By the time we got into West Palm after 11 hours, we were going only 4 kts and NO WIND. NEW Batteries were DEAD. It was alternator failure. Engine was running on only the mechanical fuel pump instead of the electrical one that provides more fuel. Yes, it is the original 1981 alternator.
I had bought backups of every part I thought I would need. extra belts, filters, extra fuel but its always the thing you don't have.
Having a boat sit in the Bahamas for 4 years where you cannot work on it ages it very rapidly because you dont fix things one by one as they fail, consequently, we say 4 years worth of failure in our trip. It wasn't till the last day (the crossing) when I finally managed to get the auto-pilot working again. The old plugs had simply become too corroded in the salt air to allow ti to work and I just twisted the wires together. The autopilot kept my sanity intact.
 
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