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Discussion Starter · #1 ·
Hi guys me again thanx for the help with me last post! I have now changed the thermostat and now have a good temparature, now i have another problem, i had this before the thermostat went, but as i get to higher revs the heating in the car gets hotter, but if im in traffic it goes cold? its ok when im going along probably not as good as it should be, any ideas guys?
 

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It could be a few things, But if it is just the heater is going hot or cold then my finger points at a blocked matrix, Though i seem to recall some years ago when i owned a e32 735, it had some heater valves (not sure on the correct name for these) near the matrix which failed on it, which cause the drivers side for example to be warm but the heat out of the passenger side vents to be cold, or the heat to come out of the windscreen vents, but not the cabin vents, so i cant discount them either, but i'm sure the bmw experts will clarify.

Couple of questions worth asking though,

-Are you losing coolant?
-does the temperate gauge move? (it should be in the middle of the dial, through most cases of driving).
 

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Discussion Starter · #4 ·
Thanks for the replys guys, the problem was there before i changed the thermostat, if i is a blocked heater matrix how to u unblock it?, also does the heating system have its own thermostat?
 

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Could well be air in the system still......

1.Jack the front of the vehicle up onto stands as high as possible,
2.Turn the ignition on,engine off,heater on fan setting 1 and temperature fully hot,
3.Remove the rad cap/expansion cap,remove the bleed screw from the rad and IF you have them the bleed screw(s) from the thermostat housing/top hose, return pipe or EGR thermostat.
4.Fill the radiator up and keep pouring till there are no more air bubbles coming out from the bleeds, when good then install bleeds and tighten down(don't snap them),ensure the rubber O-rings/seals are still on the screws/on the bleed holes.
5.Suck some water out so it's not full to the brim, replace the cap and then start the car. Run her up and check for heat from the vents when warm and check if over heating still persists.
6.If good then check the water level again in the morning when cool.
 

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Discussion Starter · #6 ·
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hi i tried this and everything seems to be ok no air bubbles, im am yet to check the heater matrix, where on these cars is the matrix? e34 2.5 petrol. And how would i check to see if its blocked, the weather is so cold at the minute and i have no heating, soo cold help me!
 

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1.If you turn the heater off for 30 seconds when the car is warm then turn it on again does it blow hot then cool down again?

2.Also if you remove the radiator cap and look in the top of the neck and have somebody hold the revs up does it shoot coolant out of the small hole in the inside of the rad neck?

3.Is the top and bottom rad hose getting hot?
 

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Discussion Starter · #8 ·
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Hi mate thanx for the reply. Here is the answer to your question:

1: The heating stayed cold after 30 seconds

2: I couldnt find the pipe you was on about around the neck of the bottle, it doesnt appear to have one, but when the car was revved up there was movement in the water, like putting a hose in a bucket full of water movement if u get me.

3: And yes the Rad hoses are hot, not too hot though, i can touch them without having to take my hand off!

Hope to hear from you soon mate ty!
 

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If you look inside the radiator neck there's a small hole in the side, when you hold the revs up there should be coolant flowing out the hole :thumbsup

Let me know.

It's why the rad cap has 2 O ring seals, one goes above the hole and the other below
 

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If there is NO water flowing into the expansion tank from the radiator neck with the rad cap off and the revs held up high then the water pump is toast IMO, most likely the impeller come off
 

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If the rad hoses are hot and you have no heat from the heater then check the pipes that come from the heater taps to the heater matrix, are they hot?

If no then use a multimeter on the heater tap plug and change the heat setting on the dash with the ignition on, the voltage should change on the meter when you change the temp
 

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Discussion Starter · #17 ·
Ok i will try testing this plug i know which one you mean, the pipes the the matrix are cold at the mo even the the car was at running temparature! Is this plug fused?
 

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Discussion Starter · #18 ·
What i done is i bled the cooling system, it had a few air bubbles in it and now seems to be free of them, i have heat on the inlet hose on the heater valves and the small pipe just above it, still no heat, this leads me to think the heater valves are stuck, as when my missus turned the temperature gauge in the car i could here no solenoid or any noise suggesting movement at all, could this be the problem?
 

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What i done is i bled the cooling system, it had a few air bubbles in it and now seems to be free of them, i have heat on the inlet hose on the heater valves and the small pipe just above it, still no heat, this leads me to think the heater valves are stuck, as when my missus turned the temperature gauge in the car i could here no solenoid or any noise suggesting movement at all, could this be the problem?
Yes, it will also hold air in there as the taps were not open when bleeding the system, if you have power at the plug and it changes when you switch temp then you need new taps, number 15 here http://www.realoem.com/bmw/showparts.do?model=HJ62&mospid=47393&btnr=64_0114&hg=64&fg=18
 

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Discussion Starter · #20 ·
Right , what i done is tapped the valves with a hammer gentle now i can here movement in the driving side valve but not in the passenger one. But still no heat in the cab. Sorry if im annoying u lol. Could this now be a blocked matrix?
 
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