| Author |
Message |
    
david_hense
New member
Username: david_hense
Post Number: 2
Registered: 03-2014
| | Posted on Wednesday, November 05, 2014 - 11:19 pm: | 
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I recently acquired a DuBrie, 5HP, 4 cycle inboard engine. I'm in the process of making a stationary stand for it. My question concerns the engine mounted water pump. Is it required to have the cooling water tank installed at a higher elevation than the pump to keep it primed by gravity? The brass pump has a built-in disc check valve. |
bruce
Senior Member
Username: bruce
Post Number: 457
Registered: 07-2002
| | Posted on Thursday, November 06, 2014 - 07:45 am: |
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The cooling tank when installed and running in a boat is always beneath the water pump. Should the cooling tank rise above the pump while under way- you have big problems.. |
johnoxley
Senior Member
Username: johnoxley
Post Number: 125
Registered: 04-2010
| | Posted on Thursday, November 06, 2014 - 08:08 am: |
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Hi - Not sure about this. Most old engines will have a pump suction beneath the water line, hence a drowned suction. There are always exceptions, but most are like this. That said, most plunger pumps will not have a problem lifting cooling water a few inches.
Then you have to make sure the water injection into the exhaust, if fitted, does not suck back raw water into the cylinder. Salt water in particular can do a lot of damage. Water injection into the exhaust, if fitted, needs to be a distance from the exhaust port or injected into a muffler. |
miro
Senior Member
Username: miro
Post Number: 778
Registered: 11-2001
| | Posted on Saturday, November 08, 2014 - 09:05 pm: |
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For most old marine engines that are run on land . i.e. not in a boat, the usual practice is to have a 5 gal bucket of water with hoses going to the pump intake and the water jacket water outlet.
Since the engines are not under a load, i.e. are in effect idling, there is not so much heat to dissipate, so the 5 gal bucket will allow the engine to run for a good long while.
And when the water starts steaming, you simply turn the engine off for a while, and go and have an adult beverage with a pal in the next display tent.
There is usually no issue for a restored pump to suck water into the system.
For engines that have the water outlet directly injected into the exhaust manifold, it a bit more messy and the engines are usually only run for a very short time, since the water used for cooling gets splashed all over the place by the exhaust which makes it difficult to capture and recirculate.
miro |
david_hense
New member
Username: david_hense
Post Number: 3
Registered: 03-2014
| | Posted on Sunday, November 09, 2014 - 09:31 pm: |
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Thanks to all for your helpful water pump information.
David |
bcm
Senior Member
Username: bcm
Post Number: 60
Registered: 11-2009
| | Posted on Monday, November 10, 2014 - 11:08 am: |
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David,
Here is an excerpt from the original www.goslowboat.com that explains operation of a typical reciprocating cooling water pump. Note use of a small tank located above the pump.
 |
ernie
Senior Member
Username: ernie
Post Number: 1903
Registered: 01-2002
| | Posted on Monday, November 10, 2014 - 07:53 pm: |
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Bruce is very correct! However I have never heard it put that way...
Miro is also correct about the 5 gallon bucket. Best and simplest
As to pump packing use Teflon string and let it drip a little the same as a prop shaft stuffing box.
Packing like this (even Teflon) will eventually burn with no water to lube it
Hope this helps
Ernie |
david_hense
Member
Username: david_hense
Post Number: 4
Registered: 03-2014
| | Posted on Monday, November 10, 2014 - 08:57 pm: |
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Ernie, I will change the black greasy graphite packing to Teflon string as you suggested.I will also loosen the packing nut. Thanks again to you guys, David |
bruce
Senior Member
Username: bruce
Post Number: 458
Registered: 07-2002
| | Posted on Monday, November 10, 2014 - 11:42 pm: |
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I've been known to use a little DOW silicone stopcock grease with the teflon packing string. |
david_hense
Member
Username: david_hense
Post Number: 5
Registered: 03-2014
| | Posted on Tuesday, November 11, 2014 - 10:37 am: |
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Bruce, Where can I find Dow silicon stopcock grease: Hardware, Marine store, Home Depot, Ace ?? The bronze plunger shows a little wear,is that a problem? Someone used a pipewrench on the packing nut. Thanks, David |
dick
Member
Username: dick
Post Number: 27
Registered: 07-2004
| | Posted on Tuesday, November 11, 2014 - 10:48 am: |
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"The cooling tank when installed and running in a boat is always beneath the water pump. Should the cooling tank rise above the pump while under way- you have big problems."
I'm not sure I understand why this needs to be set up this way. Can you explain it further? Thanks, Dick |
ernie
Senior Member
Username: ernie
Post Number: 1904
Registered: 01-2002
| | Posted on Tuesday, November 11, 2014 - 05:58 pm: |
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If the water rises above the boat
It sank
The cooling tank is the lake or whatever the boat is floating in
Sorry for the confusion but we do need a chuckle once in a while |
bruce
Senior Member
Username: bruce
Post Number: 459
Registered: 07-2002
| | Posted on Tuesday, November 11, 2014 - 09:47 pm: |
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David,DOW Silicone stop cock grease is available at your friendly plumbing supply wholesaler.Comes in a tooth paste style tube. Wear on the pump plunger can cause premature wear on the packing. Use a bit of sand cloth on the plunger stem when changing the packing to limit irregular wear points. |
