RW impeller

[Seas the Moment]

I am currently anchored at Murphy Islands up the St Johns. On my first day, while underway, during a routine engine inspection I discovered a small leak between the cover, gasket and RW pump. Not a big deal, I contained the leak until I reached day 1 anchorage. I then opened the cover, replaced the gasket (impeller still looked good) and was on my way for day 2. No more leak. Shortly while underway,the temperature on that engine quickly rose above what I was used to, and comfortable with, so I shut her down, locked the drive shaft (BTW, a large pipe wrench works well for this) ran on the other engine. So, I suspect I have an air lock and I am not pulling up the water from the strainer. Strainer is clear. Any suggestions on how to eliminate the air lock?

My thought was to remove the RW zinc plug (removed this zinc a long time ago!) and introduce water into the impeller cavity through this port to promote a prime for the pump.

Am I missing the mark? Any suggestions?

Thanks,
Loran

 

[jim rosenthal]

I think you might have burned the impeller by restarting the engine with the pump chamber empty, perhaps. You might need to fit a new impeller. I'd look in there again.

 

[MikeP]

"My thought was to remove the RW zinc plug (removed this zinc a long time ago!) and introduce water into the impeller cavity through this port to promote a prime for the pump. "

Before doing that, did you check the actual water flow from the exhaust at the rear of the boat to see if: 1 - water is flowing and, 2 - is it flowing the same from that exhaust as the other?

If no water or reduced water is flowing then perhaps something is obstructing the intake. Close the RW seacock, open the top of the strainer, open the seacock to see if water gushes out of the strainer. IF so, then it it's probably the impeller.

RW pumps don't usually require any priming. Have your's always needed priming when changing impellers?

 

[ohiohatteras]

My $.02.......everytime I replace an impeller, I pack the housing full of Vaseline after I put the new impeller in. Helps create initial suction and prevent air lock. Don't remember when or what old sea dog told me....... but I've been doing it for years and never an issue.

 

[workingonadream]

I have had this problem twice on two gas job boats. one I was able to correct with pumping water thru it and the second using Vaseline. I have never lost the prime on my hatteras pumps, but if I did, I would bleed it thru the zinc fitting and hook a hose fitting up to it to pump water thru to try and catch the prime. that of course would be after I checked everything before the pump. also how old is the impeller, how many hours on it, maybe its getting weak due to age and wear and tear. hope it all works out for you

 

[Finalee]

I always squirt dishwashing soap into the zinc fitting. That way there is a quick visual out the exhaust in the form of bubbles.

 

[Seas the Moment]

No Mike, they haven't needed a prime in past... but I guess there is always a first time. The fact is, I ran for 4 +hours on the impeller/pump with a slight leak at gasket/cover. (Hence the reason for the repair to the gasket) I ran at about 178 degrees. No problem, no restrictions. I anchored in 25' of water, so I know I didn't pick something up from bottom in strainer. That evening, all I did was take cover off, clean up the two mating surfaces, checked the impeller for all the vanes and cracks, looked good. Reassembled with new gasket/seal. During the task I could hear the air gurgling inside of the passageways. No, there was not the normal water coming out of exhaust.

BTW, I left the impeller puller at the slip dock box. I know, brilliant! If I need to change the impeller, has anyone been able to remove the "splined" impellers without the puller? I heard from a fellow boater that a couple of screwdirvers works, never tried this, but curious if others have.

So, I am about to tackle the job. I will let all know what I find.

 

[workingonadream]

you can do it with two screwdrivers just don't go too far into the pump when prying it out , but it can be done. good luck

 

[Andy B]

How thick was the gasket? And did you get all the old gasket material off the pump and cover ,I have had several small pumps not prime properly due to a thicker gasket on the cover ,never had this problem with a DD pump though.

 

[Seas the Moment]

As promised, here is my follow-up. The leak at the RW pump gasket caught my attention while underway. As I said, temperature was fine all the way to the anchorage, day 1. Before going underway, I checked all fluid levels, coolant, oil, etc. After I arrived at the anchorage and settled in a bit, I visited the ER and noted a strong coolant smell, but it was still to hot to open the coolant cap. My engine bilge had quite a bit of coolant in there. I figured the heat might have caused for some to go down the overflow tube.

As Mike suggested, I checked to be sure I had no obstruction from the sea strainer...plenty of water and as a matter of fact the pressure was so good with the cover off and seacock opened, I quickly dismissed my concern that I was not pulling enough water with the impeller, additionally, sufficient water was exiting the exhausts.

Well, last night I checked the coolant levels again... the starboard took 8 gallons. Way too much to go down the overflow tube. I added fluid to the heat exchanger, started the engines and built up some pressure in the system, shut down the engine and started to look around. I heard/saw a small leak from lower exhaust coolant hose on the right of the engine. The culprit. I am changing out the hose this am and will be underway thereafter. About 4 years ago all the hoses, fuel and coolant were changed... guess which hoses they overlooked? Yep, 2 of the 4 lower short intake hoses to the exhaust manifolds. (the most difficult to change) So, lesson learned here... it isn't always what it seems to be and don't stop looking when I find the first issue. Seems coincidental that I had the gasket leak at the RW pump and I also had the exhaust coolant hose leak. But, then again things do seem to happen in pairs.

 

[MikeP]

Glad you found it! As you observed, sometimes things aren't what they seem and there are, occasionally, coincidences where issues that seems related symptom-wise ends up being two different problems.

 

[Seas the Moment]

Thanks everyone for your input and suggestions. Once again... this forum is amazing and certainly reassuring. I feel like I have a team of experts out with me every time I take her out.

All the best to everyone!

Loran

 

[Seas the Moment]

One last item: I have an engine bilge with several gallons of coolant. Where does one responsibly dispose of this?
BTW, after bending and contorting in ways I didn't think I still had in me to replace the 5" piece of hose, she ran great at 176 degrees for the 4hour trip to next anchorage.

 

[jim rosenthal]

Pump out what you can with a hand pump, and then soak up the rest with engine diapers. Bag them all up for your next port of call that has trash service, where they can accept that sort of thing, knowing what it is. Most communities can recycle liquid AF.

 

[MikeP]

Many marinas have a disposal tank for AF (and oil). I'm not sure if it's the case in all states but at least some states require that most stores that sell oil/AF to the public must accept waste oil/AF for recycling at no charge. But, as they say, "check your local regulations!"

 

[spartonboat1]

you can do it with two screwdrivers just don't go too far into the pump when prying it out , but it can be done. good luck

I have developed a non-screw-driver technique that works like a charm. This for the old 6-71N and similar pumps that do not have the built in threaded puller inside the impeller. If there is interest, I would be glad to post the tools and technique.

P.s., I am a little anal about impellers, as I pull them annually to avoid them taking a set, plus I have the peace of mind of knowing their condition when I splash.

 

[spartonboat1]

If I need to change the impeller, has anyone been able to remove the "splined" impellers without the puller? I heard from a fellow boater that a couple of screwdirvers works, never tried this, but curious if others have.

So, I am about to tackle the job. I will let all know what I find.

Yes, I have developed a set of tools from common stuff that works better than the "toothed tool" that tears at the impeller center section. (this is my second response about this - sorry). It backs out the impeller with no grief and maybe the slightest tool marks on on a fin.

This tool set also prevents damage to the edges of the impeller opening, always present when two screw drivers are used.

I will post pictures of the tools, and how they work.

P.s., this site often mentions Dawn dish detergent as an impeller lube. Also, after startup, a nice soapy froth shoots out, when water flow is present!

 

[bobk]

From a resident chemist: Suggest you not use Vaseline (petroleum based) on neoprene impellers. Dawn, silicone grease, antifreeze, KY jelly etc. will work and not harm the rubber. Vaseline would be fine on a nitrile impeller, but they are not suitable for RW use.

Bobk

 

[Hat52MY]

Agree with the Vaseline, it will harm rubber components significantly. The best thing I have discovered for rubber (impellers, Sea Strainer gaskets, etc..), I learned from the pool industry is Aladdin's Magic Lube. I was replacing certain rubber gaskets and seals every couple of months due to the chlorine & other chemicals in the pool. Started using the Magic lube and have not replaced any gaskets or seals in years. Started using on the boat and found the same holds true with sea strainer gaskets, impellers. Use on the inside lip of hoses and the hose will easily pull off next time you need to remove (this is helpful when cleaning/flushing raw water side of engine). Use on impeller gaskets and you can reuse gasket without issue. You can order on-line, most pool stores have in stock and some Home Depots. Costs about $10 for large tube and has paid for itself in saving gaskets alone and my impellers typically last 5 years (@ 100hrs a year). If you slather on the inside spline of the impeller it easily pulls out with little effort.

Aladdin's Magic Lube #631
http://www.aladdin1950.com/files/9713/7155/9899/Magic_Lube.pdf

 

[Mike36c]

Although the Admiral doesn't approve I have used spray Pam for years as an impeller lube. For easy impeller removal just shut down the RW, open the plate, spray some in the pump, bump the engine a couple of times and the impeller slides right out. I also use it for initial start-up for new impeller. Tef-gel on the splines is nice too. Just my $.02