Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Cooling System

Reply
 
Thread Tools Display Modes
  #1   IP: 108.45.83.193
Old 04-20-2015, 09:12 PM
edwardc's Avatar
edwardc edwardc is offline
Afourian MVP
 
Join Date: Aug 2009
Location: Laurel, MD
Posts: 2,509
Thanks: 153
Thanked 595 Times in 388 Posts
Another Impeller Mismatch?

Well, I finally started de-winterizing this weekend. Was out of town for the last two, so I was chomping at the bit to get going. And the weather cooperated beautifully.

At first, it was smooth sailing. Engine started up on the second try. Ran great. Replaced the pencil zinc in the HX and ran again to test for leaks. None!
Tons of raw water out the back (as usual). Idle temp between 150 & 160; in gear tied to the dock at 2000 rpm it came up to 180 and stayed there, rock solid as usual. I should have stopped there and left well enough alone.

Instead, I checked my engine log, and realized that it had been 4 years on the same impellers in both the raw water and antifreeze pumps! I hadn't changed them since I put in a Moyer rebuild and a brand new Moyer FWC in 2011.

So I got out my spares, which I purchased in 2012 and kept sealed in a Ziploc bag to protect them. Since I have a V-drive engine, the coolant pump on the accessory drive is easily accessible, and the thumbscrew back on the Moyer pump makes it a breeze to remove. The raw water pump, however, is another matter. It's a Moyer pedestal pump, mounted up high at the flywheel end, which is the farthest from the cabin in my V-drive configuration. Squirming into the opening, lying on top of the engine, I was just able to reach it. The thumbscrew back came off easily, but the impeller didn't want to come off. With a lot of coaxing (and cursing), a pair of needle-nose pliers, a sharp hook tool, and the loss of some skin, I was finally able to get it out, but not without damaging it. It was intact, with all the lobes, but was definitely tired looking, with creases showing at the base of the lobes. I replaced it with one of my new spares (from 2012), cleaned & re-greased the o-ring, and reinstalled the back.

Engine started right up, and I quickly checked for leaks on both pumps. None! Success? No, not quite. A glance over the stern showed a bare trickle of water coming out, with an occasional anemic "bloop". A far cry from what I had just an hour ago!

At idle, the temp quickly climbed to 180 and stayed there, with a tiny bit of steam in the exhaust. Increasing the rpm to 2000 caused the temp to start climbing above 180, with more steam. More water out, but still not near enough. Its clear I can't run this way without overheating. And the water's still pretty cold here.

So, what went wrong? Am I another victim of the "Impeller size mismatch" problem that was noted a while back? Or is the pump so worn that a new impeller won't seal properly, but an old, swollen one will? If so, I don't see how, as this was a brand new pedestal pump installed in 2011 with the impeller it was shipped with. I did note that there was a perceptable wear pattern on the backplate where the impeller had been rubbing it. Is this normal, or should it be perfectly flat? I do have a spare unused thumbscrew backplate, and could try installing that.

Unfortunately, I destroyed the old impeller getting it out, so there's no going back. I have two new impellers arriving from MMI tomorrow to replenish my spares.

Other deas? Suggestions?
__________________
@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4


Last edited by edwardc; 04-21-2015 at 09:04 AM. Reason: fix typo
Reply With Quote
  #2   IP: 71.59.69.172
Old 04-20-2015, 09:29 PM
BadaBing's Avatar
BadaBing BadaBing is offline
Senior Member
 
Join Date: Jul 2007
Location: Little Egg Harbor NJ
Posts: 503
Thanks: 28
Thanked 16 Times in 15 Posts
I am hesitant to ask and suggest, knowing that you are a man of letters, BUT, are you positive th a the print on the cover didn't slip out of place? If a portion was out of the grove on the suction side you would suck.air, vs. Water, and have little flow and an occasional burp. Plus probably no leaks.
__________________
Bill
1974, Tartan 30, Unchained Melody
www.CanvasWorks.US
Reply With Quote
  #3   IP: 74.78.114.78
Old 04-20-2015, 10:00 PM
BunnyPlanet169's Avatar
BunnyPlanet169 BunnyPlanet169 is offline
Afourian MVP, Professor Emeritus
 
Join Date: May 2010
Location: York, ME
Posts: 952
Thanks: 25
Thanked 94 Times in 67 Posts
One semi-random thought - do you ever have to prime your water pump? Even though mine is below the waterline, if I go into the back, or introduce air in the intake, it will often not prime itself. Not always, but enough to think about.
__________________
Jeff


S/V Bunny Planet
1971 Bristol 29 #169
Reply With Quote
  #4   IP: 72.194.217.121
Old 04-21-2015, 01:56 AM
JOHN COOKSON JOHN COOKSON is offline
Afourian MVP, Professor Emeritus
 
Join Date: Nov 2008
Posts: 3,500
Thanks: 54
Thanked 855 Times in 629 Posts
One thing I would for sure do: Compare the new impellers with the ones that are in the pumps now. Let us know what you find.

TRUE GRIT
Reply With Quote
  #5   IP: 216.115.121.240
Old 04-21-2015, 02:05 AM
lat 64's Avatar
lat 64 lat 64 is offline
Afourian MVP
 
Join Date: Oct 2008
Location: Fairbanks, Alaska
Posts: 1,964
Thanks: 39
Thanked 240 Times in 157 Posts
I often "fix" things before they break. It's a calling.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1

"Since when is napping doing nothing?"
Reply With Quote
  #6   IP: 12.219.49.130
Old 04-21-2015, 08:44 AM
marthur's Avatar
marthur marthur is offline
Afourian MVP
 
Join Date: Dec 2004
Location: Grand Rapids, Michigan
Posts: 831
Thanks: 25
Thanked 33 Times in 28 Posts
Quote:
I often "fix" things before they break. It's a calling
I hear you brother. And I want to do it myself even at twice the cost!
__________________
Mike
Reply With Quote
  #7   IP: 108.45.83.193
Old 04-21-2015, 09:24 AM
edwardc's Avatar
edwardc edwardc is offline
Afourian MVP
 
Join Date: Aug 2009
Location: Laurel, MD
Posts: 2,509
Thanks: 153
Thanked 595 Times in 388 Posts
Quote:
Originally Posted by BadaBing View Post
... are you positive th a the print on the cover didn't slip out of place? If a portion was out of the grove on the suction side you would suck.air, vs. Water, and have little flow and an occasional burp. Plus probably no leaks.
It's a good theory. I like it a lot better than the alternatives! I stuck the o-ring in the groove pretty good with enough grease to hold it there, but given the poor access and visibility I have, if it did slip I wouldn't have been able to see. One of the things I'll have to check somehow. Thanks!

Quote:
Originally Posted by BunnyPlanet169 View Post
One semi-random thought - do you ever have to prime your water pump? Even though mine is below the waterline, if I go into the back, or introduce air in the intake, it will often not prime itself. Not always, but enough to think about.
No, I've never had to prime the pump. And it always had LOT of flow in the past. If I don't tie off my dinghy to the side when I'm backing, the exhaust will quickly fill it (DAMHIKT)!

Quote:
Originally Posted by JOHN COOKSON View Post
One thing I would for sure do: Compare the new impellers with the ones that are in the pumps now. Let us know what you find.
TRUE GRIT
Will do. I may get to the boat on Thursday. Otherwise, it'll have to wait for the weekend.
__________________
@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4

Reply With Quote
  #8   IP: 198.11.8.218
Old 04-21-2015, 10:06 AM
BunnyPlanet169's Avatar
BunnyPlanet169 BunnyPlanet169 is offline
Afourian MVP, Professor Emeritus
 
Join Date: May 2010
Location: York, ME
Posts: 952
Thanks: 25
Thanked 94 Times in 67 Posts
Quote:
Originally Posted by lat 64 View Post
I often "fix" things before they break. It's a calling.
This process is often simultaneous for me....
__________________
Jeff


S/V Bunny Planet
1971 Bristol 29 #169
Reply With Quote
  #9   IP: 108.45.83.193
Old 04-25-2015, 10:01 AM
edwardc's Avatar
edwardc edwardc is offline
Afourian MVP
 
Join Date: Aug 2009
Location: Laurel, MD
Posts: 2,509
Thanks: 153
Thanked 595 Times in 388 Posts
Update

Quote:
Originally Posted by JOHN COOKSON View Post
One thing I would for sure do: Compare the new impellers with the ones that are in the pumps now. Let us know what you find.

TRUE GRIT
Well, I got back to the boat yesterday. I pulled the replacement impeller from the raw water pedestal pump, and compared it to the new ones that just arrived from MMI. NO difference in any dimensions. I even compared it to the used 4-year old impeller I took out of the coolant pump (I didn't destroy that one). Again no difference. So I put the replacement back in.

The o-ring was still fully seated in the backplate groove, so that's not the cause.

Next, I tried replacing the slightly worn backplate with a new unused one with a new o-ring. Again, this made no difference. I put a bucket under the exhaust and collected exactly 1 gallon while at idle in neutral. This took 76 seconds, giving a flow rate of only 0.79 gallons/minute. Way too low.

So, then I started to wonder if it's just a coincidence that the reduced flow began after changing the impeller. So I started looking for other causes.

The raw water strainer was not clogged, although I did find about a half dozen of the tiny brine shrimp in there. After rinsing them out and replacing the strainer, the flow rate increased a little to 1.25 gallons/minute. Still too low. At Idle in neutral, the temp started off at 155. When I increased to 2000 rpm in neutral, the temp climbed to 180, the flow rate increased a little to 1.71 gallons/minute, and I got a lot of steam out too. Decreasing back to idle did NOT bring the temp back down to 155, it only settled in at 170.

My plan at this point is to buy some 5/8" hose and start isolating sections of the raw water circuit to prove or disprove a clog. Headed to the boat right now.
__________________
@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4

Reply With Quote
  #10   IP: 216.115.121.240
Old 04-25-2015, 10:50 PM
lat 64's Avatar
lat 64 lat 64 is offline
Afourian MVP
 
Join Date: Oct 2008
Location: Fairbanks, Alaska
Posts: 1,964
Thanks: 39
Thanked 240 Times in 157 Posts
I recommend Old Bay seasoning for the brine shrimp.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1

"Since when is napping doing nothing?"
Reply With Quote
  #11   IP: 108.45.83.193
Old 04-26-2015, 08:41 AM
edwardc's Avatar
edwardc edwardc is offline
Afourian MVP
 
Join Date: Aug 2009
Location: Laurel, MD
Posts: 2,509
Thanks: 153
Thanked 595 Times in 388 Posts
More updates

Yesterday, I disconnected the hose leading to the RWC pump intake, and led it to the galley sink. This removed the v-drive cooler, strainer, ball-valve, and through-hull from the circuit. With about 4 gallons of water in the sink, I started the engine and measured a flow rate of 1.6 gallons/min (38 sec/gal) at idle in neutral. Slightly better than before. I attribute the slight increase to the fact that the sink provides about an extra foot and a half of head.

So, it looks like things are OK on the intake side. Next time I get there, I'll try bypassing the raw-water side of the HX.
__________________
@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4

Reply With Quote
  #12   IP: 108.45.83.193
Old 04-30-2015, 07:30 PM
edwardc's Avatar
edwardc edwardc is offline
Afourian MVP
 
Join Date: Aug 2009
Location: Laurel, MD
Posts: 2,509
Thanks: 153
Thanked 595 Times in 388 Posts
Solved - it was NOT the impeller

Yesterday, I got to the boat and bypassed the raw water side of the heat exchanger. I figured this would give me a minute or two to make some flow measurements before it got too hot. And it worked.

What I found was that the raw water flow was up to 3 gal/minute at idle, and a prodigious 6 gal/minute at 2000 rpm! This exonerated the new impeller, and implicated the HX. Apparently it really WAS a coincidence that the flow reduced right after I changed the impeller.

Anyway, I pulled off the HX and opened the endcaps. I found two of the lower chambers almost filled with coarse grey-white crystals, probably a combination of salt and corroded zinc from the anode. The other two chambers, and all four of the top ones, were clear. A few minutes with a hose and a coat hanger wire and everything was good to go.

I replaced the endcaps with new seals and o-rings, remounted and reconnected the HX, and fired her up. Was quite happy to see the normal flow. It measured at 3 gal/min in idle, with the temp down at 135, and 6 gal/min @ 2000 rpm with the temp at 165. This is exactly what I expect at this time of the year.

So I'm now a happy camper! Boat's scheduled for haulout tomorrow so I can paint the bottom.
Attached Images
 
__________________
@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4

Reply With Quote
  #13   IP: 54.205.35.55
Old 04-30-2015, 09:47 PM
BadaBing's Avatar
BadaBing BadaBing is offline
Senior Member
 
Join Date: Jul 2007
Location: Little Egg Harbor NJ
Posts: 503
Thanks: 28
Thanked 16 Times in 15 Posts
Great analysis, thanks for the heads up.
Need to remember to open the HX at spring commissioning and clean my pipes.
__________________
Bill
1974, Tartan 30, Unchained Melody
www.CanvasWorks.US
Reply With Quote
Reply

Tags
impeller, overheating, pedestal.pump, raw water pump

Thread Tools
Display Modes

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Replacment impeller for Oberdorfer not making the grade Baltimore Sailor Cooling System 17 06-28-2013 11:57 AM
Oberdorfer water pump impeller replacement CalebD General Maintenance 0 04-05-2010 01:10 PM
Changing the impeller Unregistered Cooling System 10 12-03-2009 02:43 PM
Impeller Woes patsfan Cooling System 1 08-06-2006 06:59 AM


All times are GMT -4. The time now is 08:02 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved