Cooling System pressure tester

Joined
Mar 21, 2004
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Near the beach in Delaware
I bought the cooling system test kit on Amazon (link below) to test my Volvo Penta boat engine closed cooling. It dropped by 2 lbs in 30 min.

Brought it home and decided to test my F250 pickup to see if could be a problem with the cooling system test kit. Pickup was cold but still unscrewing the expansion tank cap I could hear a hiss. So tight system there with no leaks. Pumped it to 10 lbs (got tired) and awhile later (30 maybe 60 min) it had lost almost 2 lbs.

So what to think? Cheap or defective cooling system test kit? How to test a cooling system test kit.

Return it?

 
It sounds like a minor leak in the pump, return it as defect. The ones with metal caps are okay but the pumps can be a bit sketchy, you can fit the hose to a old metal pump. The caps alone make it worth it, brand names can be over $30ea
 
It was interesting to see that it's more than just size and thread with respect to the adapter proper cap. Many seal like a normal bottle cap with a gasket on the inside top of the cap like you would expect. But several have a section of the cap that protrudes a little into the expansion tank and they seal with an o-ring that around the little piece of the cap that protrudes into the expansion tank.
 
There has to be more than a dozen cap styles so that makes buying a set with most of them makes sense if you own/work on many different years and makes.
 
There seem to be many of very similar cooling system pressure tester kits on Amazon. Same adapter caps, same pump, thing arranged in the case a little differently. The reviews I read did not mention any leaks doing a cooling system pressure test.
 
You did wet any rubber sealing surfaces, yes? Can't really expect a good seal dry.
 
There seem to be many of very similar cooling system pressure tester kits on Amazon. Same adapter caps, same pump, thing arranged in the case a little differently. The reviews I read did not mention any leaks doing a cooling system pressure test.
Its possible you just got a defective pump, just exchange it.
 
Its possible you just got a defective pump, just exchange it.
The pump is probably the problem. I think the plastic ones are cheaply made. There are similar looking ones with aluminum pumps that are probably better. I read instructions on one of the cooling pressure kits on Amazon and it said to make sure you always push the pump handle and plunger straight down the barrel with no sideways movement or it might leak. When you have to pump 20 or 30 times you are bound to not be perfect in how you push the handle each time.
 
Well I removed the radiator cap from the 2022 Subaru and put it in the radiator cap tester and pumped if to 12 lbs and the pump help pressure for several hours. Finally my wife asked me end the test so she could have the radiator cap back and use her car. The nerve!

So it looks like the pump has no leaks at least to 12 lbs.

I was hoping it was a leak in the pump. Now I have to consider there is a leak in the cooling system.
 
I bought an air powered cooling system tester on Amazon. No cap adapters just the hose, regulator and a valve. It has a 1/4" NPT female for pressurized air. I fitted a brass tire valve to 1/4" NPT female adapter to I can connect a cordless tire inflator to provide the pressurized air. One good thing is once the gauge reads the pressure you want to test with you turn off the valve and now the pressurized air can be disconnected. Any leak beyond the valve does not effect the cooling system pressure test.

In this case I bought a Stant 18 psi radiator cap to test my setup.

See pictures:
 

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I really like the air powered hose, regulator and gauge. The valve is the key as it isolates the air supply from the adapter cap and gauge.

Unfortunately it does not looks like you can find a lot of adapter caps like the ones that came in the cooling system pressure test kit individually. So I will keep the kit mainly for all the adapter caps it includes.
 
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