Radiator Flush - Is This The Right Or Wrong Way?

[harks]

hey guys,

i had been experiencing higher then expected temps in my 32 GTR (although that was reading stock temp guage so how accurate that is... is anyone guess!) it was frustrating as the clutch fan was pretty well alway atleast 30% on even in <12c weather. and i hated the sound of it blowing all that air and the feel of the drain on the engine.

So, i decided i would first of all flush the coolant and see if that did anything, if not i would replace the thermostat, if that didnt work i was gonna get serious and buy a Koyo triple pass full alluminium rad (see the steps increasing in price exponentially!)

Anyway i got under the car, opened the radiator cap, coolant recovery bottle undid the air draig plug and then emptied the coolant.. the crap that came out was like murky brown... yuk, anyhow, i rinsed water through it, this is where the GTR service manual didnt really work for me.

i tightened the drain plug at the bottom and filled (expecting it to fill untill coolant would escape the air drain plug (as per GTR Service manual: Pg. EN-249/250) where i would then fill to full no dramas. HOWEVER, the radiator just filled. period. nothing out of the air drain plug (i had turned the car power on to put the heater on too, as directed) anyhow, im like, 4L in... its not full.... FML, so started her up, let her run, turned her off and filled some more, (like 100ml) so i scrolled through the forums and figured fk it, opened the radiator and started her up.. and then just poored in with it running and the coolant flowing, this proved very effective as there must have been BULK air in the cooling system becasue it was just bubbling like.. something that needs to bubble alot! and not boiling, as it was only 50-65c to the touch (probably not smart?) anyway i was able to get about 5.5L into her in the end.

TL:DR - my question is: when refilling the radiator, is there any harm in filling her till the radiator says no (just ignore the air drain plug) and then start her up cold, wait for the thermostat to open and start flowing coolant and then just poor and monitor untill all the tiny little bubbles escape and the system is completely full?

Cheers

Dan

Ohh and looks like the coolant was the problem, cause took it for a 20 min cruise, and clutch fan wasnt really coming on at all!!

[harks]

this probably should have been in the maintenance and servicing category. Sorry!

[GTSBoy]

Yes. That is the way to do it.

If you really want to flush the system you need to get it hot so that the thermostat is already open. Then you remove one hose from the heater connection at the firewall and jame the garden hose in there and run fresh water into it while the engine is running. There is also a block drain on the passenger's side. This is a necessary step to get it all swished out inside when the system is really gunky. Not so necessary for a simple coolant change.

The "coolant" wasn't your problem. Coolant is mostly water regardless of how dirty it is, so it still cools. It just doesn't protect against corrosion and so on when it's gone old, brown and acidic. You must have had a partial blockage in the radiator that you freed by cleaning it out, or you might have had a poorly bled system (and assuming it is now properly bled) and it is now wet in areas inside that weren't properly wetted before.

[XGTRX]

Great post mate. Thanks for the info.