Water cooled pump losing prime

[emericksmaple]

This is our 3rd season with a sihi water cooled. In the past 2 years we have had no problem with them starting on there own. ( we have them on thermostats) This year we have come home 3 different times to find the pump running but no Vaccum. we stop them put water in them and the start pulling right away??? We have checked everything and we don't have any big leaks or ice keeping the releasers from coming shut. Any Ideas????

[WMF]

Hi Matthew, How are you getting the service liquid into the pump? Are you using the factory port on the side or are you teeing it in with the large inlet on top of the pump.

I have found the factory service liquid port will not reliably pull in liquid unless it is pressurized. It is best to simply tee it into the inlet.

Another possible problem could be if the pump has a small leak on one of the castings and the service liquid slowly drains out and then when it starts it does not have enough residual liquid to make any vacuum and get its prime.

[emericksmaple]

WE are using the factory port on the side.
so tee it into the vaccum side of the pump?

[WMF]

They will pull a lot more liquid when you tee it into the inlet, you may need a valve to cut the flow down a bit depending upon what size tubing you use.

The factory inlet is at a neutral part of the pump and will just barely pull in liquid on its own. Put a 1/2 plug in it and forget it. I have a couple of pumps that will not pull at all at the factory inlet. Most pumps are installed in an industrial setting and they pipe pressurized municipal water to the factory port.

[802maple]

What I do is pull the plug that is on the vacuum inlet side of the pump. It is a 1/4 inch NPT fitting and I put in a barbed fitting and run a 5/16th piece of tubing into your coolant tank. That will be sufficient to cool your pump.

[Teuchtar]

I like this idea. I have a new SIHI vacuum pump and was wondering the best way to pump the service water.
I don't have a separator tank on this pump yet. Whats involved in this tank ? If I run the 1" discharge line into a 15gal barrel , will that adequately separate out the water and antifreeze ? I'm thinking to install a bulkhead port in the bottom of the barrel, and run that back to pump suction.
If the tank was raised a couple feet off the ground, gravity would help the suction drawback to the pump. Is that the right thing to do ? Or maybe gravity feed is the wrong idea if it floods the pump after shutdown.
I'd appreciate any guidance you can share.

[emericksmaple]

would a check valve on the intake line help it to keep from loosing it's prime?