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-   -   Heat at speed, cool air at idle (http://www.318ti.org/forum/showthread.php?t=7784)

Severian 12-02-2005 01:04 PM

Heat at speed, cool air at idle
 
Hello again everyone, I endeavored to fix the heat in my car last night, and it worked! See this thread for details if you want. But now that the Bowden cable properly operates the heater flap (so it shouldn't cause any problems), I notice that even though the car is up to temp the air is cool at idle. Only when I hit the revs does the heat kick in. So, hot air at speed, cool air at idle.

Any ideas? This was unexpected. It may be unrelated, but I noticed that I couldn't burp my cooling system without revving the engine last night, either.

Thanks in advance guys.

1996 328ti 12-02-2005 01:20 PM

Could also be the heater bypass valve located on the firewall.

Severian 12-02-2005 01:40 PM

When you say "on the firewall" does that mean under the hood up against the wall between the engine and the cab? Or do you mean inside the cab up against the wall in between the engine and the cab? Thanks cali.

I found a heater valve for $74.95 at bavauto.com, but is this something I could replace on my own? Do those hoses all have antifreeze in them?

1996 328ti 12-02-2005 01:58 PM

It is on the engine side. Don't replace it unless it's bad.
Turn on your heat and be sure the engine is at operating temperture.
I think there are two hoses going to the valve. Both hoses should be warm.

Those hoses would have antifreeze in them. Then the system would need to be bleed again for air. I've never done it, just watched a mechanic do it.

Severian 12-02-2005 02:04 PM

Thanks Cali, I found the precise diagram for this part (it's item 5, but you knew that), and I see where it should be in relation to the heater radiator. Now that I'm becoming more comfortable with how these "cars" work I think I can test to see if the two tubes are warm at idle. As you suspect, I suspect they will not be until I rev the engine, and even then the valve will only push hot water for as long as I throttle. But these are only guesses.

To bleed the entire system there's a valve on the bottom of the radiator, no? If I catch all of the coolant/antifreeze, can I reuse it after I perform the operation if I use a clean container to catch the coolant mixture?

1996 328ti 12-02-2005 02:06 PM

There is a bleed valve or screw on the top of the raditor.
You should have water flowing through the valve at idle.
And STOP calling me Cali. ;)

Severian 12-02-2005 02:22 PM

****! SO sorry about that, man. I feel like a jerk for getting you confused with another member.

I know the plastic bleeder screw you're talking about next to the coolant fill cap. Perhaps I can just lift the pump up and out of there (if the tubes are flexible enough) and use a vise to clamp them while I change out the part. Is that what you're thinking?

Thanks 1996 328ti
:)

cali-ti 12-02-2005 03:16 PM

Quote:

Originally Posted by Severian
****! SO sorry about that, man. I feel like a jerk for getting you confused with another member.

I know the plastic bleeder screw you're talking about next to the coolant fill cap. Perhaps I can just lift the pump up and out of there (if the tubes are flexible enough) and use a vise to clamp them while I change out the part. Is that what you're thinking?

Thanks 1996 328ti
:)

LOL ... i'm so good, i answer questions when i'm not even on! :biggrin:

cali-ti = eric, 1996 328ti = steven :)

aceyx 12-02-2005 08:08 PM

Quote:

Originally Posted by 1996 328ti
And STOP calling me Cali. ;)

At least he didn't call you Shirley. :biggrin:

1996 328ti 12-03-2005 01:20 AM

Quote:

Originally Posted by Severian
I know the plastic bleeder screw you're talking about next to the coolant fill cap. Perhaps I can just lift the pump up and out of there (if the tubes are flexible enough) and use a vise to clamp them while I change out the part. Is that what you're thinking?

It's not difficult to open the bleed screw. But be sure it's a bad valve first. Don't change perfectly working parts for another perfectly working part.

Severian 02-16-2006 12:33 PM

An update (and solution) to our quirky problem; a new Water Pump.

Recently our engine started making a slightly alarming metal-on-metal style noise...it was running louder than it should have. Our mechanic said the water pump was on the verge of going bad, and it was making the loud noise. With the new water pump we have heat all the time (even at idle).

WoOt!

Severian 02-21-2008 01:18 PM

Update: We no longer have hot air at idle. On days when it's really cold I just turn off the blower since it starts blowing cold air. I'm going to have a new Water Valve put in.
http://www.realoem.com/bmw/showparts...02&hg=64&fg=18

teetime4one 02-21-2008 01:35 PM

so, your car worked fine for the past 2 years with the new water pump...then the heat went out recently?
i also have a problem like this...the heat problem i mean.
post again if the water valve works for ya.
thanks

Severian 02-21-2008 02:04 PM

I will indeed. The problem is not an overnight development...I've been dealing with it by revving the engine at stop lights. I am tired of this though, and I would like my car to blow hot air while at idle RPMs. My wife would also like it; she's ready to disown the car. Such animosity towards a car into which I've poured so much work cannot go unchecked!

So far I've performed (or had performed) the following on this car:
* Replaced Thermostat
* Burped
* Fixed bowden cable problem
* Replaced water pump

All fixes resulted in improvement of some kind. This is sort of the final frontier for heat issues I think.

teetime4one 02-21-2008 02:12 PM

good luck

elchicano 02-21-2008 02:15 PM

Yea i have the same problem, it just started like to two days ago i'm gonna check it out and see if i can fix it.

teetime4one 02-21-2008 02:16 PM

sounds good Dave.
let me know what you find.

elchicano 02-21-2008 02:22 PM

I gotta go to school in a bit but i 'll check it when i come back.

elchicano 02-21-2008 08:39 PM

Is the heater bypass valve and the heater control valve the same thing? I just checked my car the heater gauge is in the middle and its blowing out warm air. I'm gonna check the coolant it might need some. I checked the hose in the bottom of the radiator it is warm so it might be the bypass valve right? I'm starting to get confused with all this stuff.

Severian 03-26-2008 07:34 PM

Now, after some time has passed, I'm happy to report that I was probably just suffering from a shortage of coolant all along. Once I used the bleeder screw technique and added plenty of coolant I was good to go, the heat works MUCH better than it did before.

Again, this is also when the following things have been done already:

* Replaced Thermostat
* Fixed bowden cable problem
* Replaced water pump

Hey, at least we're warm now! That's what counts.

elchicano 10-01-2008 09:02 PM

Okay since winter is on its way. I need to fix my heater. So where is the bypass valve at. I tried looking for it and i couldn't find it. It's prolly somewhere under my nose but i don't see it. Can someone show me on the pic where i should be looking at.

http://i210.photobucket.com/albums/b...411/engine.jpg

aceyx 10-01-2008 11:48 PM

Wrong side of the firewall. Go in through the passenger side kick panel.

elchicano 10-02-2008 01:17 AM

Quote:

Originally Posted by 1996 328ti (Post 41537)
It is on the engine side. Don't replace it unless it's bad.
Turn on your heat and be sure the engine is at operating temperture.
I think there are two hoses going to the valve. Both hoses should be warm.

Those hoses would have antifreeze in them. Then the system would need to be bleed again for air. I've never done it, just watched a mechanic do it.


hmm i thought it was under the hood since thats what i got from steve's comment. I guess i read it wrong. Well if its true and thats where its at no wonder i couldn't find it. haha:biggrin: Thanks i will look for it then and see if i need to replace mine.

aceyx 10-02-2008 02:09 AM

I may be confusing this with some other part.

elchicano 10-02-2008 03:40 AM

I think you are talking about the heater cable with the yellow tab. I will check that as soon as i check this, i read in another thread where its located and have a general idea of where it's at. So i'll see if i can find it tomorrow.

RidingSimple 10-26-2008 07:43 AM

It's located on the back right of the motor from that angle, near the fusebox. Two heater hoses go from the back of the motor, and in through the firewall to the heater core behind the radio area. I have an extra heater core and switch if anyone needs them (building a track car in Hawaii, don't need heat).

Mr.Squeelerz 10-26-2008 02:39 PM

I'm having the same problem too. What good is my remote start if I only get heat at speeds?....boooo

I'm watching this thread for possible solutions.

nyle 10-27-2008 09:56 PM

hm. generally the lack of heat at idle is because the system has a little bit of air in it.

which is a b***h. there are a bunch of different ways to bleed your coolant (and verify that it is properly bled). search around and try a couple.

I would do this before jumping to the assumption that the heater core valve is broken.

elchicano 10-28-2008 04:48 AM

Well i finally got around to check my heating issue. I check the yellow cable and the PO fixed it by getting it screwed on. I checked the hoses that go to the heater core valve and both of them are hot. I had the car at an incline on my drive way. I bled the radiator and waited until i got the bubbles out. What i noticed is that i was getting hotter air while the car was on my inclined driveway then when i was driving with the heater on. So i'm lost i don't know where to go from here. The radiator and thermostat where changed about two years ago. Any suggestions would be welcomed.

ngr5011 12-05-2008 04:43 PM

I had the same problem...
 
all that I had to do was let the car sit over night so its cold, then turn the key to on (no start) heat on high, fan on 3, turn your bleed screw until fluid comes out. There is air in your system. This solved it for me after replacing the thermostat.

labiel 12-06-2008 10:57 PM

Same problem here:/ Cold(warm) on idle hot at high(but not to hot). It all happend after swap so I hope it's not heater since it's very hard to remove. I've repleced water pump during swap. I don't have stream from upper hole in coolant tank - I've read that this happens when pump is bad or when there is air in system. Since I burped it for 1h twice, checked valve (ok), thermostat is opening ok, I'm left with water pump, but it's new:/ Anyone found solution?

stymes01 12-17-2008 02:54 PM

Hate to beat on this thread, I have a similar problem. I regrettably have to drive my 98 cali top in the winter in MN (hopefully for the last year). 2 winters ago I stored it but took it out occasionally. It did this blow cold at idle thing too, I flushed the coolant and that problem seemed to go away. New problem. My car struggles to stay at temp when not at highway speeds in cold weather. Another interesting problem is that every window on the car ices up from the inside and is terrible below 20 degree F. Its so bad I end up only being able to use my mirrors to see on either side of me and behind me. Even the Hatch ices up from the inside with the defrost on for an hour if its below zero. My ideal solution would be to not drive the car in the winter, but since I have to anyone else have this problem with icing up on the inside of the car. I'm not kidding its every window and I cant see a thing. The windshield defrost takes care of the windshield minus the top 6-8 inches . I'm not sure where all this moisture is coming from!

labiel 12-21-2008 01:17 AM

Solved, I've added additional electric pump from E34 and now it's warming fast plus I have hot air when engine is warm and stopped since electrical pump do the trick ;) I think you could have broken heater core, check if your're not loosing coolant. But if engine is not warming at all or slow check also thermostat.

zoner 12-21-2008 01:46 AM

Quote:

Originally Posted by 1996 328ti (Post 41539)
There is a bleed valve or screw on the top of the raditor.
You should have water flowing through the valve at idle.
And STOP calling me Cali. ;)


Ahh! So that's what that screw is. I've always just bled cooling systems through the radiator cap, and just did the same with my ti. Seems to have worked fine... :| ??

Severian 01-23-2009 06:58 PM

Quote:

Originally Posted by ngr5011 (Post 205751)
all that I had to do was let the car sit over night so its cold, then turn the key to on (no start) heat on high, fan on 3, turn your bleed screw until fluid comes out. There is air in your system. This solved it for me after replacing the thermostat.

This is a step I have not done...I'll try this. If you can't tell, this problem never permanently went away for me. It has plagued me for the entire life of the car. Heat at RPMs is better than no heat...I solved that in early '08. But as in my post above here are all the things I've done.

* Replaced Thermostat
* Bled air
* Replaced water pump
* Fixed bowden cable problem

Severian 01-23-2009 07:00 PM

Quote:

Originally Posted by stymes01 (Post 207508)
...I'm not kidding its every window and I cant see a thing.

Stymes, I'm no expert, but this symptom makes it sound like your cab recycle is on all the time Perhaps that flap is stuck? I don't know where it is though.

Zolf 12-20-2011 09:33 AM

Had the exact same problem. Heat at speed, cool/cold air at idle. Bowden cable did it for me.

http://www.318ti.org/forum/showthrea...010#post316010

volgapower 12-24-2011 03:28 PM

how should i check wether the bowden cable is not working?

Zolf 12-25-2011 02:24 AM

I played around with the temperature knob. Turning it to "cool" I could hear a clicking sound as it "clicked" into place. However, turning it the other way (towards heat) no such sound was produced. But this isn't the proper way of doing it. I was just lucky, I guess. Remove the radio panel + radio and check to see if the cable is securely attached. A couple of screws and ~30min later you should have your answer.


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