Changing thermostat 1.9 dg

[jake1953]

The Hanes manual says the coolant system has to be drained before changing the thermostat. Is it strictly necessary? How much water is lost when removing the pipe and thermostat cover.It is a 1987 and the thermostat is on the top of the engine. Any tips?

[ashman]

Personally I can't see why you would drain the whole system down, unless you wanted to give it a complete flush out. So, no it isn't a necessary thing to do.

I can't remember the exact layout of the pipe work, but if you can clamp the pipework either side of the thermostat without doing any damage then this will minimise coolant loss when you take the thermostat out.

You aren't going to lose a great deal of coolant anyway and remember to bleed it after you top it up. That's the point when you find out the bleed screw has been ravaged by a previous ham "interfered with" (sniggers!) owner and you have to replace it!

Ashman

[jake1953]

Thanks ashman. the bleed screw does turn 90 degrees but whether anything hapens inside remains to be seen!!Bled the system b4 and it seems to work.

[ashman]

The bleed screw is held on by a retainer and I'm not sure how much it should turn by, but if you have bled it before without any problems then it should be good again.

Ash

[jaylo264]

Quarter turn is all that's needed with the bleed screw on top of thermostat .
And if it were me , i think i would pull out a temp sensor to drain it a little , into a pail like , and check the sensor clip at same time .
One of my old metal ones had gone completely , how the thing held in i dunno, replaced em with plastic clips ex VW dealer and tied em on securely with cable ties.
jaylo