Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 11-07-2015, 21:57   #1
Registered User

Join Date: Jun 2013
Location: Idaho
Boat: Taswell 49
Posts: 11
Yanmar Raw Water Pump

I have a Yanmar 4LH-TE in my sailboat. A couple of months ago my exhaust started to steam with the water discharge. Research says partially clogged heat exchanger or impeller issue. Essentially, not enough flow through exchanger causing higher temps. Decided to look at impeller first. It is toast so I will replace it. What I do not understand is inside the pump housing it appears there is a build up of scale. See pic. The part I do not understand is the scale is so perfect, yet not symmetrical. See the different thickness in the tan/yellow layer. Is is actually part of the pump housing to create the offset for the impeller? Or do I have a real problem here? Beyond just a new impeller?
__________________

__________________
warmbluewater is offline   Reply With Quote
Old 11-07-2015, 22:25   #2
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
Re: Yanmar Raw Water Pump

Waiting for photo...
However there is a raised section in the pump body on the perimeter to compress impeller blades as they rotate.
__________________

__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 12-07-2015, 08:40   #3
Registered User

Join Date: Jun 2013
Location: Idaho
Boat: Taswell 49
Posts: 11
Re: Yanmar Raw Water Pump

Sorry my weak wifi would not let me upload a photo. Working on that. Sounds like what looks a bit like scale build up is part of the pump. Whew! Much cheaper than a new pump.


Sent from my iPhone using Cruisers Sailing Forum
__________________
warmbluewater is offline   Reply With Quote
Old 12-07-2015, 08:44   #4
Registered User

Join Date: Jun 2013
Location: Idaho
Boat: Taswell 49
Posts: 11
Re: Yanmar Raw Water Pump

Click image for larger version

Name:	ImageUploadedByCruisers Sailing Forum1436712259.824476.jpg
Views:	150
Size:	46.8 KB
ID:	105200


Sent from my iPhone using Cruisers Sailing Forum
__________________
warmbluewater is offline   Reply With Quote
Old 12-07-2015, 09:46   #5
Registered User

Join Date: Oct 2008
Posts: 218
Re: Yanmar Raw Water Pump

Quote:
Originally Posted by warmbluewater View Post
I have a Yanmar 4LH-TE in my sailboat. A couple of months ago my exhaust started to steam with the water discharge. Research says partially clogged heat exchanger or impeller issue. Essentially, not enough flow through exchanger causing higher temps. Decided to look at impeller first. It is toast so I will replace it. What I do not understand is inside the pump housing it appears there is a build up of scale. See pic. The part I do not understand is the scale is so perfect, yet not symmetrical. See the different thickness in the tan/yellow layer. Is is actually part of the pump housing to create the offset for the impeller? Or do I have a real problem here? Beyond just a new impeller?
If your are talking about the shallow "bump" on this inside of the housing, that is by design. The impeller vanes pass up and over the "bump" that is how it sucks water in from the intake side.
__________________
westsail42 is offline   Reply With Quote
Old 12-07-2015, 09:50   #6
Registered User

Join Date: Oct 2008
Posts: 218
Re: Yanmar Raw Water Pump

incidentally, I had a situation where a vane has broken off (like yours are about to), laid up against the inside the housing, and occasionally was spun around the inside. Sometimes it would get stuck over the intake port, nearly blocking it completely, then free it self and get stuck somewhere else.

Result: intermittent overheating. Caused a real head scratcher. Sometimes there would be water in the exhaust, sometimes not. From this experience, I install new impellers every 100 hours.
__________________
westsail42 is offline   Reply With Quote
Old 13-07-2015, 09:47   #7
Registered User

Join Date: Jul 2014
Posts: 16
Re: Yanmar Raw Water Pump

Hi
I rebuilt mine this winter because I was unsure of it condition I believe the bump is built in but from the picture the scale might be over doing gasket cement If there is only one spare to have it will be an impeller Way cheaper than a motor
JJ
__________________
jackj17 is offline   Reply With Quote
Old 13-07-2015, 12:28   #8
Cruiser

Cruisers Forum Supporter

Join Date: May 2014
Location: Houston, TX
Boat: Catalina 387
Posts: 40
Re: Yanmar Raw Water Pump

Quote:
Originally Posted by westsail42 View Post
If your are talking about the shallow "bump" on this inside of the housing, that is by design. The impeller vanes pass up and over the "bump" that is how it sucks water in from the intake side.
Yep, like Westsail42 says, that's how it's supposed to look. Once you get the impeller out, you'll see that there are two holes in the outer wall of the pump -- one on one side of that bump and one on the other side of the bump. Those are the pump inlet and pump discharge openings.

Here's a clearer photo in an online tutorial posted by Maine Sail...
Rebuilding A Raw Water Pump Photo Gallery by Compass Marine How To at pbase.com..
__________________

__________________
Jetx is offline   Reply With Quote
Reply

Tags
raw water, raw water pump, water, yanmar

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yanmar 3YM30 Raw Water Pump Failure hughfree Engines and Propulsion Systems 28 01-01-2017 16:59
Raw Water Pump vs Fresh Water Pump Cheechako Engines and Propulsion Systems 44 01-02-2012 15:31
Yanmar Raw Water Pump Rebuild in Ft. Lauderdale Dougfuller Construction, Maintenance & Refit 12 16-12-2010 17:00
yanmar raw water pump seacapture Engines and Propulsion Systems 1 17-07-2008 16:20
Yanmar 3QM30F Serial Number location? Raw Water Pump Problem... JohnnyB Engines and Propulsion Systems 14 27-06-2008 04:13



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 21:10.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.