Overheating, thermostat replacement

GHARRIS1982

MEMBER
1999 VOLKSWAGEN BEETLE
2.0L
4 CYL
2WD
MANUAL
155,000 MILES

Overheated a few months ago and I replaced the water pump, thermostat and radiator due to a cracked housing around the upper hose. Ran fine for a few weeks and it overheated again. There was a crack around the brand new thermostat housing on the upper hose. Fixed it and it ran fine. Two days ago the upper hose on the radiator blew off and I had to tow the car 48 miles back home. Looking at it today and everything seems to be fine. Seeing how all of the issues seem to stem from the upper radiator hose could it be a problem with the new thermostat not opening? I just let the car run for about 20 minutes and the engine did warm up but there was no hot air coming out of the heater. Both the hose to the radiator from the thermostat and the upper radiator hose were hot to the touch but didn't feel like there was any fluid inside.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

This sounds like you have an air pocket. If the thermostat was remaining closed then you would not have heat in that hose as nothing would be coming through and that include the heat.

So I would suggest topping off the coolant and jacking the front corner of the vehicle closest to the fill cap so that it is higher then the rest of the system. This will help work the air to the highest point.

Here is a video on a similar video that shows how to service the system:

https://www.youtube.com/watch?v=pcfSTCPHLxA

Also, here are some other guides that help with these issues:

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

Lastly we need to pressure test the system to make sure there are no leaks and that it can hold pressure. Here is a guide for that:

https://www.2carpros.com/articles/radiator-pressure-test

I suspect if anything that you got a faulty thermostat you may end up replacing it again. I attached the process if you need it. Thanks

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