{"id":49856,"date":"2023-03-07T10:03:00","date_gmt":"2023-03-07T15:03:00","guid":{"rendered":"https:\/\/www.cruisingworld.com\/?p=49856"},"modified":"2023-12-12T13:54:44","modified_gmt":"2023-12-12T18:54:44","slug":"replacing-impellers-raw-water-pumps-onboard","status":"publish","type":"post","link":"https:\/\/www.cruisingworld.com\/how-to\/replacing-impellers-raw-water-pumps-onboard\/","title":{"rendered":"Replacing Impellers and Raw-water Pumps Onboard"},"content":{"rendered":"\n
\n\n\t\t\t
\n\t\t\t\t\t\"Impeller <\/div>\n\t\t\t\n\t\t\t\n
\n Overheating damage caused by reduced raw-water flow.<\/span>\n Courtesy Steve D\u2019Antonio<\/span>\n\n\t\t\t\t <\/figcaption>\n <\/section>\n\t\t\n\n\n

One of the most attractive aspects of a cruising lifestyle is independence. However, with that independence comes self-reliance. If you have a fire, you can\u2019t call the fire department. If you get hungry, you can\u2019t call for a pizza delivery.<\/p>\n\n\n\n

While it helps with boating to be a mechanical and electrical expert, it is by no means a necessity to cruise safely<\/a> and enjoyably. However, you must be able to perform certain tasks, including the replacement of fan belts, fuel filters and impellers (and raw-water pumps). You must also be able to bleed air from the fuel system.<\/p>\n\n\n\n

Fan-belt service was covered in a recent column, so let\u2019s have a look at raw-water pumps. These pumps use a flexible rubber impeller to move seawater through the heat exchanger, where the seawater absorbs heat from the engine\u2019s coolant. From there, the water moves to the exhaust mixing elbow, where it cools the hot exhaust gases, and then goes overboard.  <\/p>\n\n\n\n

This is important: Without cooling water, the exhaust hose and muffler will overheat, often faster than the engine itself. If you suffer an overheat, be sure to inspect the exhaust hose and fiberglass or plastic mufflers for damage.<\/p>\n\n\n\n

I\u2019m a firm believer in \u00adpreventive maintenance, and it is my strong recommendation that impellers be replaced annually or every 600 hours, whichever comes first. In fact, because some of the blades are always compressed\u2014and because deformed, disused or lightly used impellers can suffer more-frequent failure than those in regular service\u2014this preventive maintenance is something that I consider a requirement. Impellers are relatively inexpensive, and replacing them virtually ensures that, short of a clogged intake, you will never have a \u00adpremature impeller failure.<\/p>\n\n\n\n

\n\n\t\t\t
\n\t\t\t\t\t\"Tools <\/div>\n\t\t\t\n\t\t\t\n
\n An impeller puller (left) or a plastic pry bar (right) are preferred tools for impeller removal.<\/span>\n Courtesy Steve D\u2019Antonio<\/span>\n\n\t\t\t\t <\/figcaption>\n <\/section>\n\t\t\n\n\n

When replacing impellers, resist the temptation to pry out the old impeller using a screwdriver. Most pump bodies are made from relatively soft brass and are easily damaged. Typically, you\u2019ll damage the \u00adcover-plate sealing surface, which in turn leads to air or water leaks. Instead, use an impeller puller or a plastic pry bar.  <\/p>\n\n\n\n

Once the impeller is removed, inspect it for lost blades. If any are missing, you\u2019ll have to go looking for them \u201cdownstream.\u201d In most cases, they\u2019ll be stuck at the inlet side of the heat exchanger. <\/p>\n\n\n\n

\n\n\t\t\t
\n\t\t\t\t\t\"Worn-out <\/div>\n\t\t\t\n\t\t\t\n
\n Worn-out impellers can shed blades, which are ingested by the raw-water cooling system. <\/span>\n Courtesy Steve D\u2019Antonio<\/span>\n\n\t\t\t\t <\/figcaption>\n <\/section>\n\t\t\n\n\n

Then, look carefully at the pump\u2019s cam. This is a crescent-\u00adshaped device over which the impeller blades ride and are deformed, which in turn creates the pumping action. The cam too is made from brass, so it will wear away (and \u00addezincify) over time. If it wears enough, pump capacity can be reduced or stopped altogether. Often, the wear is noticeable only when comparing the old cam with a new one, so it\u2019s a good idea to have a replacement on hand.  <\/p>\n\n\n\n

Use caution when replacing the cam. The securing screw is small and easy to drop into the bilge. Also be sure to retain and reuse, or replace, the sealing washer. <\/p>\n\n\n\n

\n\n\t\t\t
\n\t\t\t\t\t\"cover <\/div>\n\t\t\t\n\t\t\t\n
\n This ridged water-pump cover plate (left) and worn-out cam (right) will require replacement.<\/span>\n Courtesy Steve D\u2019Antonio<\/span>\n\n\t\t\t\t <\/figcaption>\n <\/section>\n\t\t\n\n\n

The cover plate should also be inspected at this time. While discoloration on the side that bears against the impeller is normal, any discernible wear, if you can feel a ridge, is too much. The plate should be replaced. <\/p>\n\n\n\n

Plates without embossed writing on the outside face can often be reversed to double their life. Like the cam, if the cover plate wears too much, the impeller seal will be compromised; it might lose suction and stop pumping. <\/p>\n\n\n\n

Steve D\u2019Antonio offers services for boat owners and buyers through Steve D\u2019Antonio Marine Consulting stevedmarineconsulting.com<\/a>.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Knowing how to change a raw-water pump is must-have knowledge, even for beginner boaters.<\/p>\n","protected":false},"author":11,"featured_media":49858,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"BS_author_type":"BS_author_is_guest","BS_guest_author_name":"Steve D'Antonio","BS_guest_author_url":"","hydra_display_date":"","hydra_display_updated":false,"_yoast_wpseo_primary_category":"164","_yoast_wpseo_metadesc":"Changing a raw-water pump on a sailboat, monthly maintenance by Steve D'Antonio","_yoast_wpseo_title":"","_yoast_wpseo_meta-robots-noindex":"","arc_story_id":"","arc_website_url":"","custom_permalink":"","arc_subtype":"","arc_exclude_from_feeds":false,"sponsored":false,"sponsored_label":"Sponsored Content","sponsored_display_label":false,"sponsored_image":false,"post_right_rail":true,"post_right_rail_ad_1":true,"post_right_rail_ad_2":true,"post_right_rail_ad_3":false,"post_right_rail_ad_4":false,"post_right_rail_recirc":true,"fixed_anchor_ad":true,"post_top_ad":true,"post_off_ramp":true,"post_taboola":false,"labels":true,"apple_news_api_created_at":"","apple_news_api_id":"","apple_news_api_modified_at":"","apple_news_api_revision":"","apple_news_api_share_url":"","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":"","ad_settings_ads_on_this_page":true,"ad_settings_automatic_ad_injection_into_the_content":true,"ad_targeting":"","sponsored_url":"","social_share":true},"categories":[164],"tags":[1225,183,319,1947],"acf":[],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/posts\/49856"}],"collection":[{"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/comments?post=49856"}],"version-history":[{"count":0,"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/posts\/49856\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/media\/49858"}],"wp:attachment":[{"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/media?parent=49856"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/categories?post=49856"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cruisingworld.com\/wp-json\/wp\/v2\/tags?post=49856"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}