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**Wotname** · 19-04-2017, 19:23

Re the lubes:

AFAIK, silicone grease (like DC4) is OK with most common Nitrile rubber compounds but not so compatible Silicone rubber compounds (sorta counter intuitive). Petroleum based grease (like Vaseline) is the opposite.

The "special" lube supplied is glycerine is kind to all "rubber" impellers and great for your hands as well.

Disclaimer: I'm not a chemist so this may be bull dust but it matches my experience.

rajsach · 19-04-2017, 23:29

Quote:

Originally Posted by OrangeCrush

Ah ok that makes sense, thanks for the explanation. Yes mine is luckily quite easy to get to. There isn't any gasket stuck to my surface plate, I think I will be fine simply cleaning it with soap and water before putting it back on.

Your engine is similar to mine. The impeller orientation looks fine. The CAM at the bottom of the housing makes the arms turn that way so the pump works properly. YouTube it and you'll understand. You don't have a gasket but you do have an O-ring that needs to be inspected and replaced if needed. The impeller kit comes with it.
I apologize for the sparse explanation but the best thing to do is to go to YouTube and research it. Lots of good info there, just search "impeller change" and watch multiple videos and narrow your search and you'll quickly see a common theme
Hope this helps
Raj

rwidman · 20-04-2017, 06:21

Quote:

Originally Posted by Wotname

..........The "special" lube supplied is glycerine is kind to all "rubber" impellers and great for your hands as well. .............
.

And you can buy it at any drug store.

**a64pilot** · 20-04-2017, 06:42

Quote:

Originally Posted by Jim Cate

A64,I've been under the impression that silicone grease was not harmful to rubber products, and that petroleum based greases were. Silicone grease is often recommended for lubing o-rings, and i have used it thus for many years besides using it on water pump impellers. NEver found identifiable harm from this practice.

Further, why do you want the lubricant to dissolve? What harm will it do to the impeller as it runs? It will wear off pretty quickly at any rate, i suspect.

Jim

Jim it would probably be fine and cause no harm, without knowing what kind of "rubber" the impeller is made of, you can't know, and most all of us have dishwashing liquid, which works well.
I just go back to my mechanics training that had us using either "surgical lube" or of all things vegetable shortening.
Surgical lube is I think pretty much KY jelly and of course dissolves in water, the vegetable shortening goes on anything fuel like O rings, fuel dissolves it almost instantly.
Then I have a special lube for hydraulic O-rings, stickier than honey, I have no idea what it is.

If it doesn't dissolve, then it of course gets washed downstream, and while I doubt it would hurt at all, I don't want grease in my heat exchanger.
I put rubber in parenthesis, cause its about as descriptive a word as plastic.
I use Globe dry run impellers myself, and I have no idea what they are made from, it may not be anything different just the color?

**John_Trusty** · 20-04-2017, 06:57

I was told by an old salt at the docks that the best lube for impellers was KY Jelly (or the equivalent)! It's readily available, cheap, safe for all plastics, and it's completely water soluble, so doesn't hang around or gunk up the impeller after it's full of water. Going to try it this spring, although there may be some questions about why I keep a tube in the tool box!

30West · 20-04-2017, 11:47

Quote:

Originally Posted by a64pilot

I use Globe dry run impellers myself, and I have no idea what they are made from, it may not be anything different just the color?

Had to look those up, thanks! I'm paranoid about running my impellers dry, after burning a couple just after buying my boat and driving it 500 miles home. I'll be priming my raw water pumps before launch in a couple weeks.

Dielectric silicone grease is particularly well suited for a wide variety of rubbers and plastics.

Quote:

Silicone grease is commonly used for lubricating and preserving rubber parts, such as O-rings. Additionally, silicone grease does not swell or soften the rubber, which can be a problem with hydrocarbon based greases. It functions well as a corrosion-inhibitor and lubricant for purposes that require a thicker lubricant.

It makes sense that silicone grease must contain something that keeps silicone dissolved, so I don't use it on silicone products, but don't really need to lubricate silicone parts.

I'm quite sure silicone grease does no harm to heat exchangers. If it did create a lasting silicone coating in flowing water, it would be a miracle product and used everywhere. Soap and KY dry out, and contain quite a few chemicals that haven't been tested with rubber. Short term I'm sure they are fine, but if you want hoses to come off quickly in an emergency after a couple years of heat and drying, you need to lube them with silicone.

Mike OReilly · 20-04-2017, 12:15

I just checked my impeller prior to our launch (Sunday). As usual, it was wet with anti-freeze from winter layup. I’ve never greased my impeller, and have never (to my knowledge) lost one due to it becoming dry.

And yes, some of my spines are bent the opposite way.

OrangeCrush · 22-04-2017, 11:18

Hey obvious question here but I just started to second guess myself based on some diagrams. Looking at my original picture, can you guys verify that my impeller will spin counter-clockwise? The raw water intake hose is on the right and the hose to the heat exchanger is on the bottom, so I presume it will spin counterclockwise to push water from ocean to motor.

Sent from my iPhone using Cruisers Sailing Forum

LLizzard · 22-04-2017, 11:26

I cannot answer your question, but can say that even if they are the wrong way, they will flip around, likely in the first couple of revolutions. Lube as previously discussed and should be no problem.

**Wotname** · 22-04-2017, 15:48

Quote:

Originally Posted by OrangeCrush

Hey obvious question here but I just started to second guess myself based on some diagrams. Looking at my original picture, can you guys verify that my impeller will spin counter-clockwise? The raw water intake hose is on the right and the hose to the heat exchanger is on the bottom, so I presume it will spin counterclockwise to push water from ocean to motor.

Sent from my iPhone using Cruisers Sailing Forum

Yes