Changing thermostat - draining coolant neccesary?

[jaz3]

Hi All,

Yes I know there are plenty of threads on changing the thermostat but my question is - is it absolutely neccessary to drain all the coolant? Can it just be topped up afterwards?

Im not the most mechanically minded person but after reading the DIY threads, it looks quite easy - its just the coolant part im not quite sure on.

I am changing the thermo because the needle rarely moves off 'C' and vtec is not coming on sometimes.


Thanks

[Zilli]

nope.... most of the collant will be within your radiator, and unless your car is turned on, and your water pump is pumping water around, you wont get much coolant draining from the thermo housing.

You will get SOME leakage, but i wouldnt worry about that too much, just check your levels afterwards and replace. Remember, coolant is hot, so do this when your car is cold.

You CAN replace the cooolant if you want to do a coolant change at the same time though...

[dc2dc2dc2]

good boy zilli
im not racist
but i gave u a rep

[jaz3]

Thats what I was hoping to hear!!

[jaz3]

I read in a few threads that coolant needed to be drained to ensure there are no air locks?

[Zilli]

nah no need for that... when you are done, turn your car on and leave the radiator cap off, and when the thermo opens, the pump will circulate the coolant around, and any air bubbles will come out... in any case, the air will come out of the overflow hose...

[jaz3]

Sweet. Thanks heaps for your quick reply.

[Zilli]

sweet dude.... in the meantime try not to rev your car too hard!

[dc2dc2dc2]

*closed*

[DLO01]

Wrong. The thermostat housing is low height wise. Water wants to level out. If you don't pre drain some coolant, half of the coolant in your radiator and your engine will spill everywhere. Its like punching a hole in a bottle, anything above it is gonna come out.

If you pre drain in to a clean container, you can re-use it if it is not old. :thumbsup:

[Zilli]

i didnt get much come out of mine...

[bennjamin]

nah no need for that... when you are done, turn your car on and leave the radiator cap off, and when the thermo opens, the pump will circulate the coolant around, and any air bubbles will come out... in any case, the air will come out of the overflow hose...

exactly right.

but also remember to put the temp slide to HOT , leave the car idling until the thermo fan switches on TWICE and top up the coolant as it drops in level.
after twice most air would of worked its way out. replace cap and drive as normal , and check your overflow resevoir in the next few days , it may need a top up.

[OMG.JAI xD]

uhmm and if the new thermostat doesnt fit in one way.

it should have a little needle bit on the metal plate of the thermostat.
thats suppose to be the internal bleeder. i think.

but yeah make sure that faces up. or "top".

=] just my input

[jaz3]

Would it be ok to drive for the time being till I get time to do it on the weekend?

[nd55]

> I am changing the thermo because the needle rarely moves off 'C' and vtec is not coming on sometimes.

I'm not sure a colder thermo will achieve anything for you.

> but also remember to put the temp slide to HOT

Like Ben said, the water through the interior heater bypasses the thermostat, try driving with the heater ON (and the windows open if you must) to see if anything happens before you drop cash on the thermo.

I think you're better off blocking half the radiator and just being conscious to keep one eye on the temps.

I used to do this on a old Kingsood with more than a few faults and it worked a charm in winter.

Nick.

[jaz3]

Im not changing it to an aftermarket thermo..im buying a new replacement from honda this afternoon. Hopefully they have stock.

I had the heater on this morning and nothing changed...