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car blows cold air when idling but hot when driving!?


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13 replies to this topic

#1 paulmk4snoopy

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Posted 06 February 2010 - 10:41 PM

any ideas what this might be or common problems?
...i know about the coolant valve i replaced that last yr i dont think its that it was fine before i put in the new engine!anyone had a similar problem?cheers paul

#2 paulmk4snoopy

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Posted 06 February 2010 - 10:58 PM

right jus done a bit of homework and iv narrowed it down to three things it might be ....an airlock in the system, a blockage or a dodgy thermostat (which came wi the other engine)!i got the old thermostat in the shed aswel as a spare waterpump so im good for spares! :lol: .
whats the best way to flush the system?how do u bleed the system get and get rid of airlocks?cheers paul

#3 mtbdean

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Posted 06 February 2010 - 11:32 PM

Sounds normal to me?

#4 Deano_365

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Posted 07 February 2010 - 10:55 AM

I had similar problem!

Does it blow cold air even if you have been driving for a while, then just say you stop at lights? If it does, I think that will definately a faulty thermostat.

An airlock normaly increases the temperature, so you guage will be reading higher then normal..But to remove an air lock, have your engine running for a while, then just loosen the cap but dont unscrew it fully and hopefully you will get some bubbles in the little tank.

Best way to flush the system..

First, unscrew the bleed valve on the bottom right hand corner of the radiator, then unscrew the cap off the coolant tank (to control how fast all of it comes out, just slightly loosen the cap)

Screw the valve back on, then fill your coolant up with water (you dont have to fill it completely) then release the valve again to flush it... I repeated this twice, until it was pretty much clear!

Once your done, you might aswel top your coolant up with some new stuff, then run engine so it gets into the system.

The level will go down, but just top it up with coolant or water.

#5 paulmk4snoopy

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Posted 07 February 2010 - 07:15 PM

hey deano thanks for the reply
iv been out messing about with it today, iv just put the antifreeze back in and run the engine til the fan kicked in while squeezing all the pipes!iv left the cap off now for about an hour jus waitin til its cold and then im gonna start it up and see if it has made any difference!

i only noticed it wa blowin cold while sat in a car park waiting for someone the car was warm when i parked up and had engine running for a good ten minutes when i noticed! i dunno what it could be other than an airlock!im hoping its sorted it.
earlier i had the engine cold and felt all the pipes the one coming off the thermostat stayed cold to begin with and then opened and get warm thats right isnt it?...il report back when iv been back out to it but do you really think it could be the thermostat?

what did urs turn out to be? cheers paul

#6 Deano_365

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Posted 07 February 2010 - 09:28 PM

Mmm tbh i dont know what my problem was, when i flushed all my system and put new coolant in, it just seemed to have gone.

When the car is just sitting with the engine running, the pipes do get hot.

Ill dig out some more info because im not sure if the heater matrix will have anything to do with it?, but funny stuff like that is normaly due to a faulty thermostat!

#7 paulmk4snoopy

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Posted 07 February 2010 - 09:45 PM

i just been out to start it up and its made no difference at all!the more i think about it the more im confused if it were a dodgy thermostat why would it blow hot when im driving.....because the waterpump is spinning faster and the extra pressure pushing it open?!?lol iv no idea really!haha
im gonna try flushing it all 2moro the matrix and all!
hmmm what are the chances it bein a sticky coolant valve?..or an electrical fault or sensor!?
il update again 2moro
cheers paul

#8 jonyb4

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Posted 08 February 2010 - 01:56 AM

if the car also runs cooler than normal, change the thermostat

#9 paulmk4snoopy

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Posted 11 February 2010 - 02:43 AM

:blub: i dunno what to say jony ive come to expect more from u!??usually a couple of paragraphs wi some technical data to back up ur theorys and a few photos!??....weres all that ey!?lmao

and for the rest of u.....the problem solvers ive come to rely on.......nath, tre, davedarave, olimk4 to name a few uve all let me down bigtime!haha :P ...except u deano ur the man!lol 8)

well anyway i havent done owt wi the car yet its been too cold!think i might change the thermostat while i got water dropped an the pipes off!wa gona have a look at it but decided not to cos u need a new gasket n sealing ring if u disturb it dont u?

its just bugging me to why its started doin this.....iv read all there is to read on it in the manual and have come up with nowt!

it would be nice for someone to tell me this has happened to them and what it was!
anyway when i get to the bottom of it i shall let u all know this will make a good reference if it happens to someone else.
thanks for all ur replies ppl 8)

#10 trecoll

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Posted 11 February 2010 - 09:40 AM

it would be nice for someone to tell me this has happened to them and what it was!


I would, but I haven't had this problem :whistle:

anyway when i get to the bottom of it i shall let u all know this will make a good reference if it happens to someone else.


Good stuff, help the community and all that Jazz.

thanks for all ur replies ppl 8)


Thats fine :nakkal: :lol:

#11 olliemk4ghia

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Posted 11 February 2010 - 09:40 PM

i havent been on! and dont u have my number should have txt me lol or is it i got your number im not sure eny ways have u checked your swictch for your hot and cold because sometime my car when the switch is round to hot it blows cold then i move it to cold n back to hot again and it blows warm ??? mayb that might b a faulty heat valve ( i forget what its called theres a guid on how 2 fit 1 just recently been posted) mine also blows constantly hot hmmmm ....

OOOOOOOH danm 4gt bowt them alloys u desperate for them tyres?????? sory pal

#12 paulmk4snoopy

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Posted 20 February 2010 - 05:31 PM

:lol: im jus kiddin!
right a little update the other day i replaced the thermostat and used a different coolant valve my mate had lyin around!
its not made any difference at all aswell as that i also flushed everything including the heater matrix!?
the only thing ive got left to try is to bypass the valve with some copper pipes!......im thinking maybe could be an electrical fault something that sends a variable current thats why it blows hot when im driving !?anyway who knows il get to the bottom of it eventually

#13 paulmk4snoopy

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Posted 24 February 2010 - 09:07 PM

well i was living with it because it at least it was blowing hot when i was diving but the other day stopped blowing hot at all so it forced me today, to due to being cold to try the copper pipes in place of the coolant valve....and now its blowing hot all the time so my guess is either the valves buggered or the facia control!......at least its hot now il leave it til the summer i think now :lol:

#14 jonyb4

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Posted 27 February 2010 - 04:28 AM

:o how dare you?!


lol checkt he thermo mate, bet you a fiver its past it ;)

do the boiled water in a mug test on it, or just replace it straight up, will only be a fiver at a breakers etc, mind it be £10 as you'd owe me hehe

aye id not bother with a seal/gasket, if it leaks after its refitted then go get one lol, will only be a lil trip to ford and a few bob anyway




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