Technical Thermostat replacement procedure

[t0neloc]

This might be more appropriate for the tech talk forum but...

2014 Panda Pop 1.2 petrol

I have a slow weeping leak at the thermostat as evidenced by crystallised pink antifreeze on the pipe and a very slow drop in the header tank level.
The cam belt and water pump were replaced and new coolant added around 10 months ago.

Q. Do I really need to drain the entire system to replace the thermostat or can I just syphon out via the header tank to get the coolant to a level lower than the thermostat housing in order to swap it out? Any idea how much needs to come out to get to this level?

I'm sure I've done this many years ago on other vehicles. As long as it's properly purged of air after refilling I can't think why this shouldn't be OK.
The new thermostat has a metal pipe stub as opposed to the leaking plastic one on the OEM part.
Thanks.

 

[jrkitching]

The new thermostat has a metal pipe stub as opposed to the leaking plastic one on the OEM part

This is the type of thermostat that I always recommend using as a replacement. Those plastic spigots go brittle after a few years and always seem to end up leaking.

Do I really need to drain the entire system to replace the thermostat

No

can I just syphon out via the header tank to get the coolant to a level lower than the thermostat housing in order to swap it out

Yes; this is my preferred way of doing it.

You only need to drain to below the level of the thermostat housing.

But if you ever do need to drain the system completely, on models with an expansion tank integral with the radiator, you can get just as much coolant out by syphoning as you'll get out by disconnecting the bottom hose. It's worth doing it this way, because the bottom hose connection is fragile and if you disturb it, you may create another problem.

Work using clean equipment and you can put the coolant back in at the end. I generally leave the bleed screws alone; it's one less fragile thing to break. You may need to top it up a couple of times, but the system should self bleed just fine after a few engine cycles.

Keep a close eye on the level until it does stabilise; these engines are prone to HG failure if run seriously low on coolant. Once you've managed to get back in what you've syphoned out, it won't be far off (assuming it was at the correct level to start with, of course).

 

[Jazbee]

There is a pretty good youtube vid which covers this well, just watched it the other night and saved it for future reference......