cooling fans - not cutting in

grobbits · Unread post by **grobbits** » 27 Jul 2003, 01:15

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by alans

Dom,
I'm probably telling you something you already know, but always be sure to have the heater opened in the hottest setting when bleeding the coolant; air locks have a nasty habit of hiding in heater matrixs which is sometimes the reason the matrix fail due to the increased pressure more than corrosion.
Alan S
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grobbits · Unread post by **grobbits** » 27 Jul 2003, 01:17

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by alans

Dom,
I'm probably telling you something you already know, but always be sure to have the heater opened in the hottest setting when bleeding the coolant; air locks have a nasty habit of hiding in heater matrixs which is sometimes the reason the matrix fail due to the increased pressure more than corrosion.
Alan S
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Pardon my ignorance but how do you bleed the coolant, got exactly this problem on a ZX 1.9td after a rad change and don't have a manual and its to late to buy one

Dave Burns · Unread post by **Dave Burns** » 27 Jul 2003, 01:59

First you need to fashion a simple header tank from a drinks bottle with the bottom cut off and with a neck that will be a snug fit in the top of the rad, this is because the bleed screws are higher than the rad filler so you have to create a head of water that is higher.
When you have the tank in position and full, open the lowest bleed screw first, this is on the de-gassing pipe behind and to the right of the fuel filter and looks like a valve cap from a tyre, when coolant free from bubbles emerges replace the cap and open the next one, this is either on the heater matrix connector on later models or on early models at the end of a pipe connected to the matrix, you will find it near the brake master cylinder on a RHD car.
Give the top hose a good few fast squeezes as this causes surges through the system and can displace trapped air, be carefull with the bleed screws or caps as they are plastic with fine threads and can easily become cross threaded.
Dave

DLM · Unread post by **DLM** » 27 Jul 2003, 15:43

"did have a front end crunch with someone this week, but did'nt do any damaged to my car, but now i'm beinging to think otherwise"
Just a thought....
I've heard elsewhere (or maybe even here?) that a front end crunch can be the start of cooling problems - the impact may shake out any sediment or deposits in the radiator and restrict flow.
I'd check the radiator to see if it's hot both top and bottom as a rough guide to flow.
David

grobbits · Unread post by **grobbits** » 27 Jul 2003, 17:51

Thanks dave, did all that after replacing the fan sending switch thingy and found an extra bleed screw on the top rhs of rad which I recomed was 1st in line to bleed , Heater now works, all of the radiator gets hot so we're getting coolant circulating now but still no fan action. I ran it with the heater on up to 90c and then a bit longer with it off up to just belo 100c but still no fan action

I'm at a loss now, relays and things electrical are beyond me
Graeme

shaunthesheep · Unread post by **shaunthesheep** » 27 Jul 2003, 18:29

well,
bleed the coolant system again today, just to confirm what i had sad on an earlier post, no air to be found[:p][8D].
found the ideal header tank as well, a 1ltr rectangale bottle, eg a 1ltr castrol oil bottle, or in my case an empty dulux tinting machine colourant bottle[}:)].
well all is ok
heater works & no air again
now my mind can rest
dom[:D]

neil · Unread post by **neil** » 27 Jul 2003, 18:33

Had a small altercation with a roadside banking during the winter. Tow loop took the brunt of it resulting in the bottom subframe distorting and pushing the left hand fan upwards so that it now interferes with the plastic mount on the left side of the fan assembly. Dremels are wonderful things!

Dave Burns · Unread post by **Dave Burns** » 28 Jul 2003, 00:26

Bleeders on the rad are not really important, only those on the engine or its pipework need to be bled.
Have you fitted a new thermo switch, if so it ought to be OK but just to test the rest of the fan circuit, when the engine is at normal temp, pull the plug from the thermo switch and bridge the contacts.
One of the cantacts plus the feed should switch both fans on at low speed, the other cantact (this wont happen if the engine is cold)should switch the left hand fan on at high speed.
If the fans work, then either the temperature didn't get high enough to trigger them or the switch may be suspect.
If no fan activity takes place then look at the fuses in the engine compartment fuse box for both corrosion and blowing, if they are ok the relays may be in trouble, they are located in a plastic box in front of and between the two fans, pull them out and examine them and their sockets for corrosion.
Dave

grobbits · Unread post by **grobbits** » 28 Jul 2003, 17:33

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave Burns

Bleeders on the rad are not really important, only those on the engine or its pipework need to be bled.
Have you fitted a new thermo switch, if so it ought to be OK but just to test the rest of the fan circuit, when the engine is at normal temp, pull the plug from the thermo switch and bridge the contacts.
One of the cantacts plus the feed should switch both fans on at low speed, the other cantact (this wont happen if the engine is cold)should switch the left hand fan on at high speed.
If the fans work, then either the temperature didn't get high enough to trigger them or the switch may be suspect.
If no fan activity takes place then look at the fuses in the engine compartment fuse box for both corrosion and blowing, if they are ok the relays may be in trouble, they are located in a plastic box in front of and between the two fans, pull them out and examine them and their sockets for corrosion.
Dave
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Hi Dave,
Bridging the contacts works and I get slow(er) fan action and fast fan action so all I can do is presume the new thermo switch is faulty as when it's connected and the radiator is good and hot nothing happens, have a new one on order and my local friendly car electrical supplies shop is promising to test this one when it comes in later today.
Will keep you posted and thanks again
Graeme