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Sept 18, 2011 1:18:19 GMT
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Recently bought this tidy 728i for a reasonable price.  After a couple of days noticed the heater blowing stone cold  , a check for common causes on the net led to the heater valve under the bonnet, had a look at that but found it's been bypassed preventing water getting to the heater core, only one reason for someone to do this (IMO), the core is mince 98% sure this is the case, question is would it be worth connecting up the heater valve to see what happens ?, think I know the answer because to get to the core the whole centre console, half the friggin dash and possibly the steering column need to come out. don't want to risk flodding out the interior with coolant though. |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold  86 Mk4 Escort RWD V8, sold |
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Sept 18, 2011 18:58:42 GMT
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I keep a load of different sized bits of hose in my workshop to adapt blowers and suckers to fit heater matrix pipes and other pipes. I use this stuff mostly for extracting fluids. You could make something simlar and suck or blow through the matrix with the other end covered. If lots of air is leaking and it's not getting passed the hoses or the blocked end then you know it's the matrix letting air in or out somewhere inside the car.
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Sept 18, 2011 21:22:07 GMT
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or another explanation is the heater was stuck on full ie red hot and its been done to cool it
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ChasR
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Sept 18, 2011 22:57:16 GMT
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Depends. Many a car these days (Ford included (although Peugeot started it)) use the matrix as part of the cooling system. For cold air, they simply close a flap to the matrix.
Going with your theory though, the blender motors can fail in the heater boxes themselves (I have seen a car where all heater/blender motors seized solid).
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Sept 19, 2011 1:05:30 GMT
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What kind of cheapskate bypasses the heater on a 7-series! Yeah, the heater can fail, but isn't that much of a mission to remove. Your dash will have to come out, but you could do the job in a day, at a reasonably relaxed pace. Steering column can stay where it is. or another explanation is the heater was stuck on full ie red hot and its been done to cool it That's what the A/C is for! |
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Sept 19, 2011 5:32:20 GMT
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Cheers guys,
Ejenner, thats what i was thinking, some way of testing the core for leaks before i strip it out, may give that a go.
Tonka, yeah, the control panel is known to curse word up on these too.
Ches, what are blender motors ?, the blowers are fine, guessing they are not the same thing ?.
Skoda, yeah i probably could do it in a day, still looks like a big job though, as per usuall on a car like this all the screws and fixings seem well hidden.
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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ChasR
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Sept 19, 2011 11:31:22 GMT
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If your E38 has climate control with buttons to control the airflow the flaps for them will most likely be controlled by servo motors, which some people call blender motors. If you can direct airflow find then they should be ok.
As a whim, I'd be tempted to reconnect the heater valve and see what happens (a leak etc.) for testing purposes. Or try running water through a hose. Yes you could use air, but I am not convinced you would find the source of the leak with the . What colour is the coolant out of curiosity?
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Sept 19, 2011 20:23:09 GMT
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If your E38 has climate control with buttons to control the airflow the flaps for them will most likely be controlled by servo motors, which some people call blender motors. If you can direct airflow find then they should be ok. As a whim, I'd be tempted to reconnect the heater valve and see what happens (a leak etc.) for testing purposes. Or try running water through a hose. Yes you could use air, but I am not convinced you would find the source of the leak with the . What colour is the coolant out of curiosity? Ah, right, i think the air flow is ok but will check that later  Think i will try plumbing in the valve but i'll strip out some of the console to try and see the core. The coolant is water coloured  , the previous owner had the water pump replaced the day before i bought the car, probably skimped on the £20 or so for anti freeze as he was selling it |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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Sept 20, 2011 18:46:09 GMT
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I bought an e46 which had run for a while with water in place of coolant and I ended up chasing leaks all around the car - including the heater matrix.
If your matrix has actually been bypassed I would guess it's fubar.
On that car the matrix was as described by Mr Skoda - a long ish job that looked terrible but actually it all came apart (and back together) easily.
BTW I feel your pain. I bought a 740 e38 in spring and now the weathers getting a little cooler, surprise surprise no hot air. I'm yet to investigate but I bet it involves the heater valve, hopefully not a matrix change but it does loose a little coolant................
I've got some more imminent jobs to do first but I'd better hurry up and investigate before the screen gets too misty!
Rob
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Last Edit: Sept 20, 2011 18:46:34 GMT by rustempire
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ChasR
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Sept 21, 2011 8:23:22 GMT
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I asked as on my Old daily with no coolant I ended up changing the entire cooling system (gulp) it was leak ahoy . On my last car with a lack of coolant changes (it was black) the matrix also died). |
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Nov 13, 2011 21:29:07 GMT
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Turned out to be the heater valve  , i know i posted this thread in September, only just got around to fixing it the other week Anyhow, plumbed in the valve to see what would happen, remained stone cold, removed the valve to find it blocked.   Hoped to salvage it with a strip and clean out but it was a mess  A new valve from BMW is something like £240  , got a good used one off E-bay for £55 delivered. A bit tight to get at but not too bad, must be a nightmare on the V12.  Heater is working perfect now, no sign of any trouble at the core, dual climate/blenders etc working fine  |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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Nov 15, 2011 14:28:35 GMT
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A bit tight to get at but not too bad, must be a nightmare on the V12. |
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, a check for common causes on the net led to the heater valve under the bonnet, had a look at that but found it's been bypassed preventing water getting to the heater core, only one reason for someone to do this (IMO), the core is mince 
, i know i posted this thread in September, only just got around to fixing it the other week 
, got a good used one off E-bay for £55 delivered.