This is always hard to tell you what they did but it sounds like they had someone who was not sure what they were doing. First of all if they even told you that they would doing a vacuum test on a cooling system, they didn't know what they were talking about. It sounds like someone who has not been trained because cooling systems don't operate in a vacuum. They build pressure. You can vacuum test the cap but not the system. Think about it, if you pull a system that is full of fluid into a vacuum, you will need a system to recover all the coolant as you pull it into that vacuum. This is how you test an AC system. You recover all the freon into a storage bottle and then the vacuum pump pulls the system down into a vacuum to see if it can hold it or if there is a leak. The cooling system is tested by pressurizing it.
The only way I can really see they damaged the pump is if they put too much pressure on the system. The system operates around 15 PSI but the cap should have a PSI rating on it which should not be exceeded. So if they put too much on it there is a chance it pushed out the front seal of the water pump.
So this may take some convincing but I would watch this video so you are familiar with how to test the system and then ask to be shown how it was tested. Don't tell them on the phone that is what you want because that will give them time to prepare. Just tell them you want to come down and go over the vehicle so you are clear on what needs to be done. While going over it, ask them to show you how they tested it and found the leak so you can see the leak as well.
If the leak is coming from the front of the water pump then this is the seal and is the weakest link in the system after the pressure relief on the cap. The cap is designed to allow small amounts of pressure out so that the system does not over pressurize and leak. However, when they test it the cap is not on there and if they add too much pressure the front pump seal is the first to allow the pressure out. Once it fails it leaks.
Just make sure they are using a cooling system tester and ask what PSI they tested the system at. As you can see if they are using the proper tool, it is almost fool proof because there is a big red line on the gauge telling them it is too much pressure.
In my opinion, this may just be bad luck. It is unlikely that they did something wrong because as you can see it is not a hard test. More than likely your pump was starting to leak and pressure testing it just presented the issue. However, if they did this wrong then they could have caused it. It is just never easy proving that.
Hopefully this helps. Let us know what happens. Thanks
Wednesday, November 13th, 2019 AT 5:12 AM