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Old 01-10-2011, 09:24 PM
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Question Why does my car take forever to heat up? 1995 with 2.8L

Hey guys. It's winter and I'm cold. My car doesn't help me in that department. I have a 95 A6 with the 2.8L V6 with an autotragic.

My drive to work is 30 minutes long, back roads, going about 40 the whole time.

My car does NOT heat up enough for the heater to work. I'm freaking cold as heck.

By the time any other of our cars are fully heated up, my temp gauge has just left the bottom peg. It'll get up to about the first line and stop for a while. Then after about 20 minutes it'll move it's way up to the first bolded line, which I assume to be the bottom of the "normal operating range".

So then, it'll suddenly get cold again (and I mean fast too). It'll drop down to the first line or lower. I have no heat during any of this.

I have my ENTIRE radiator blocked off. The entire thing. I don't think the thermostat is stuck open because when it hits that second bolded line, it shoots back down which (I'm guessing) means the thermostat opened and the block gets cooled by the supercooled coolant that was sitting in the rad.

The only time I've felt heat from my car is when the temp was slightly above the first bolded line. When it's that warm, the heat works fine, great even. So it's not the heater core either. At least I don't think so.

It's not like it's even that cold. It does this anytime below 30 Degrees F!! Never mind the 8 degrees we had this morning. My oil temp is normally around... crap... the first line on the gauge past where it sits when it's off. I think it may be 60 Degrees C. Don't ask me why the engine temp is in degrees F and the oil temp is in degrees C... Don't get me wrong, the engine will EVENTUALLY heat up, but never above that first bolded line. Meaning I never have heat, because the heat doesn't work until the temp is ABOVE that line. It'll sit right below the line my whole drive home.

What can I do about this? Should I keep it in third the whole time on my way to work? Would that help? What else could be wrong? I bought this car for the sole reason of being a winter car. If it doesn't have heat, that may be a problem.

Please help guys, I hate driving when I'm cold.

EDIT: No, I do not have the heater on during any of this. I don't turn it on until the engine warms up. (Which is never) I even turned the temp down as I know in older cars the temperature gauge actually controlled the coolant going to the heater core, so by turning it down I stopped the flow. It didn't work.

Last edited by corrado33; 01-10-2011 at 09:26 PM.
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Old 01-11-2011, 12:50 AM
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When you have time, start the car and let it run 10-15 minutes.
Check both hoses going/coming from the heater core (you should be able to see them going through the firewall). If both are hot, then your heater core is ok and your problem may reside with either the exchange flap control or the climate unit itself.
If one of the hoses is cold (the return one, typically), either your heater core needs to be replaced, or your heater valve is bad (attached right on the "upstream" hose, before the plastic bleeder.)

Also, you may need a new Coolant Temp sensor (sender unit) since your gauge experiences what you described.
Good luck.
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Old 01-11-2011, 09:37 AM
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Try this too:

Let the car idle until the temp gauge gets to normal operating temp (gauge should point to the middle).
If you need to rev to around 1500 rpm's then do it.

When the car is at temp, check the heat.
If you have heat, drive the car preferably on a highway or interstate and see if the temp goes back down.
If it does, your thermostat is stuck open.

Otherwise, it could be a combination of the temp sender, flap control, and/or heater core like chefro said.
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Old 01-11-2011, 11:05 AM
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I agree either the heater core is plugged or it's possible your thermostat is stuck wide open.
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Old 01-11-2011, 04:28 PM
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Quote:
Originally Posted by soundguy View Post
Try this too:

Let the car idle until the temp gauge gets to normal operating temp (gauge should point to the middle).
If you need to rev to around 1500 rpm's then do it.
I've NEVER seen the temp gauge go above the second line. Even when letting it run for a while.

Thanks so much for all of the info guys.

Today as I was driving home, the temp gauge is smack dab on the second line. I try the heat on HI (digital climate control), and the heat was luke warm at best. I mean that air should be HOT like I can't hold my hand there hot.

And I was wrong, the oil temp goes to the line above 60 degrees C (whatever that line means...)

Alright, I will try everything you guys said, and get back to you. The heater core is pretty much (way) behind the glovebox (buried under the dash) like in a Corrado right?

EDIT: Nevermind, found your write up on it...

Last edited by corrado33; 01-11-2011 at 04:58 PM.
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Old 01-11-2011, 06:17 PM
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Quote:
Originally Posted by corrado33 View Post
I've NEVER seen the temp gauge go above the second line. Even when letting it run for a while.
In that case check the thermostat it is either stuck wide open or completely missing or just the wrong one all together.
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Old 01-11-2011, 07:36 PM
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I would imagine that the easiest way to tell if the T-stat is stuck open is by "feeling" the hoses temperature. 10-15 minutes is more than suffice to feel the hoses HOT.
If they're not, then probably you do need a new T-stat.

However, did you buy the car just before the "winter" started? One idea... have you tried to bleed the system? I'm just wondering that maybe you have an/some air pocket/s in the system and the coolant doesn't reach your heater core?
Is a little "work" involved (to find the rear main pipe's bleeder down in the wire jungle), but it is worth a try, along with checking your heater hoses.
Keep us posted, pls.
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Old 01-12-2011, 08:40 PM
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Quote:
Originally Posted by soundguy View Post
When the car is at temp, check the heat.
If you have heat, drive the car preferably on a highway or interstate and see if the temp goes back down.
If it does, your thermostat is stuck open.
.
Car was at the first bolded line today (highest I've ever seen it), and I got on the highway. Went about 65 for about 5 minutes, and it dropped down below the first line.

When I was having this problem in my rado, my brother (x VW/audi/Mercedes trained mechanic) told me to let my car sit there and warm up. The bottom hose should get hot before the top hose. If not, your thermostat is broken.

Quote:
However, did you buy the car just before the "winter" started? One idea... have you tried to bleed the system? I'm just wondering that maybe you have an/some air pocket/s in the system and the coolant doesn't reach your heater core?
Yep, right before winter. Could you provide me any more info on bleeding the system? I'll search, but I'm being lazy at the current moment.
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Old 01-12-2011, 09:44 PM
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It's actually pretty simple. Run the engine until hot and locate the heater core valve bleeder (you need to take the cowl off). Unscrew gently 2-3 turns. You should get a steady stream of coolant. You'll get steam escaping - which is ok. If you get fizzing, hissing, gurgling, it means you have air in the system. Screw back and then repeat several times until you get a steady flow.
Next step is to loosen the main rear pipe bleeder. You need to locate it first and leave in it a socket + extension + rathcet - is like a 5 or 6 Allen (metric).
You should be able to find it close by the coolant temp sensor - you see it on the coolant line in the photo.
I include a pic so you know what you're looking for.
(By the way, if you follow hose labeled number 1 (in the pic) through the firewall you should find the heater clore plastic bleeder.
Don't forget to top off with coolant after you get done.
Attached Thumbnails
Why does my car take forever to heat up?  1995 with 2.8L-heater-hoses.jpg  
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Last edited by chefro; 01-12-2011 at 09:48 PM.
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Old 01-13-2011, 09:29 AM
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Chefro where is the t-stat located on a 95 2.8???
Is it easy to get to?
My 3.0 is easy my 4.2 couldn't have been in a more concealed location.

I'm positive it's the t-stat with Low engine temp/no heat. What else could it be.
It probably broke on the last guy and they just pulled it out to get home.

The problem is your cooling too much. The t-stat at rest is closed so the coolant in the engine heats up. When the coolant gets hot enough(~190) the heat will cause the t-stat to open an allow the coolant to flow to the radiator where it gets colder and cycles back to the engine.

There is only one way the engine can stay cold like that. The T-stat is missing or stuck open. It is very common for them to stick half open when they fail. That happened in my car. In the summer you will see the opposite the half opened t-stat will prevent coolant from circulating and you will overheat.

For example you start the car and it's 15 degrees out.

The T-stat is closed and the cold coolant is trapped inside the engine and you will have no heat because the climate system uses the heat from the coolant to heat the car.

When the engine reaches approximately 190 degrees the spring in the t-stat assembly weakens and allows the valve to open releasing the pressurized colder coolant from the radiator into the engine.

When the spring cools off it strengthens and closes the valve blocking the flow of coolant and maintaining 190 degrees.

If it does not close or open properly it can not maintain ~the 190 temp.
In your case it is not closing.

THE QUESTION IS; Where is your T-stat located?

I would think Advance auto would have one.

here's a link.

http://www.ecstuning.com/Audi-C4_A6-...ng/Thermostat/
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Old 01-13-2011, 05:30 PM
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Quote:
Originally Posted by Jackmup View Post
Chefro where is the t-stat located on a 95 2.8???
Is it easy to get to?
My 3.0 is easy my 4.2 couldn't have been in a more concealed location.

I'm positive it's the t-stat with Low engine temp/no heat. What else could it be.
It probably broke on the last guy and they just pulled it out to get home.

The problem is your cooling too much. The t-stat at rest is closed so the coolant in the engine heats up. When the coolant gets hot enough(~190) the heat will cause the t-stat to open an allow the coolant to flow to the radiator where it gets colder and cycles back to the engine.

etc etc...

http://www.ecstuning.com/Audi-C4_A6-...ng/Thermostat/

Thanks. How a thermostat works is easy enough, hence why I blocked off the radiator. Yeah, I'll have to find it. Shouldn't it just be on the other side of the bottom radiator hose?

If and when I do find it, I'll probably just buy one from advanced/auto zone. Are these cars pink coolant or green? (Guess I could just go look )

I'll probably try to look for it this weekend, and see what I can do. Thanks for the help everybody. The thermostat, and bleeder things seem the two most logical places to start. If they don't work, then I'll go for more drastic measures.
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Old 01-13-2011, 11:55 PM
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On the 95 2.8 the T-stat is located on the front (Bank 1 side).
I read that it can be replaced without taking the timing belt off, but unless I do it and know exactly how's it done, I wouldn't put my seal of "knowledge" (LOL) on it.
Anyway, I advanced the "bleeding" idea because is the first and foremost simple thing that it can be done.
(We still don't know how hot they get or how cool the hoses remain, though...)
Checking the heater hoses' would have been another simple thing.
Good luck and keep us posted.
Attached Thumbnails
Why does my car take forever to heat up?  1995 with 2.8L-hose4.jpg   Why does my car take forever to heat up?  1995 with 2.8L-095-reinstallheads.jpg  
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Last edited by chefro; 01-13-2011 at 11:59 PM.
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Old 01-16-2011, 09:30 AM
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Alrighty guys, did a little test this morning. Started the car, revved it to around 1500 till it was almost out of the initial "block" of temperature at the very bottom of the temp gauge (no where NEAR warmed up) and felt both rad hoses. Top one (that's in the top right (drivers) side corner of the rad) was HOT. Bottom left (passenger side) one was warm. That means that coolant was flowing through the rad even though the car wasn't even close to warmed up. Aka I have a bad thermostat. I'm going to go check the hoses going to the heater core now, but the first thing I'm going to do is replace the thermostat.
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Old 01-16-2011, 11:05 AM
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i did the stat on that motor and it is right behind the timing belt. It can be done without removing the belt but i did lossen mine. there is an aluminum housing that a hose ataches to that it sits behind. \huge pain in the *** but can be done.
FWIW i had a siimilar issue with my 95 Audi 90. after replacing the stat, water pump , akl heater hoses core and bleeding it to death i gave up and only use it as a summer car. Your issue does sound like the stat though.

Good luck.
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Old 01-16-2011, 12:15 PM
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I also felt both hoses coming from the heater core. They both felt warm with the heater on HI for about a minute or so. Although it was a PITA to get my hand down to them without taking stuff apart. (Which I didn't feel like doing.)
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Old 01-22-2011, 11:06 PM
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Alrighty well my lack of heat is NOT related to my car not heating up.

I changed my thermostat. Everything went well. Went to bleed the system, loostened both bleeders (rear main was a PITA, freaking hex was ALMOST stripped before I touched it, nothing an hour of WD-40 didn't fix). So as I poured more coolant in, it came out of the rear main bleeder. Awesome. None came out of the one behind the firewall, but I figured that was ok, since it was decently high up and the car wasn't running

I let the car heat up, and turned the heat on, knowing that coolant SHOULD be flowing through where the 2nd bleeder is. Nothing. I took the bleeder screw out... COMPLETELY. Nothing. Not a drop of coolant spilled out. I could SEE the coolant, but it wasn't coming out at all. I mean, shouldn't it be pressurized, shouldn't it be pretty much squirting out of there?

So, what's the verdict on the no heat situation. Clogged heater core perhaps? What's the thing that's right in front of the bleeder valve? I'm guessing it's a solenoid of some type to shut off the flow? Could that be broken, not letting new coolant in? Broken climate control thermometer, never telling the computer that the car is cold inside? Ideas?
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Old 01-23-2011, 12:06 AM
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Click the image to open in full size.

In front of the heater bleeder screw is the heater valve I was mentioning previously. That is responsible for allowing the coolant to flow through the heater core. It is vacuum actuated, so when you turn the heater on it opens up and lets the coolant flow toward the heater core. It has a white arm that opens/closes the inner flap, so you can actually see it moving when turning the heater on/off. Have someone turn the heater on/off and observe that little control arm. If it doesn't move, then you need to change the valve.
It is about $ 23-25.
Since you got into the thick of things, you can actually pull it off the hose (I know, is a bit of an effort - not much room in there) and try to blow it while moving the control arm; maybe is plugged with debris. Also, you need to make sure it receives vacuum while you have the engine running.

In any event, when you pour coolant have your heater bleeder opened first, as it is the highest point in the system. If you have both bleeders open at the same time, the coolant will not flow through the heater bleeder...guaranteed.
Makes sure it flows through that bleeder, then close it, and only after that open up the main pipe's bleeder (the little 5-6M hex). When you get flow there too, tighten that one too, and fill the overflow reservoir to max. Screw its cap and then start the car. As you start the car the system starts to pressurize itself. Turn the engine on and let it warm up for 10 mins or so. Then turn your heater on.
At this point you start opening up slowly (just a couple of turns suffice) the heater bleeder. As said before, steam will come out and is ok. However, if you get gurggling, fizzing, hissing, keep closing and reopening the bleeder several times until you get a steady stream of coolant, but no more fizzing/hissing (that's air escaping).
Do the same for the main pipe bleeder. When you have there a constant flow of coolant, close her up. Do a quick 5-10 min drive, return and park it. When it's cooled down you can check the coolant level and top it off.
If you replaced the T-stat, if your Water pump is good, if the heater valve is good, if your heater core isn't plugged, then by now you should definitely have heat.
If you still don't have heat after all these conditions are met, then you got a problem with the climate control unit, as it doesn't open up the flap inside the HVAC box.
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Last edited by chefro; 01-23-2011 at 12:09 AM.
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