Audi A4 t'stat stuck open. Any quick fix?

Wife's 2000 Audi A4 2.8 30v. She informs me there's no heat. I finally drive it today - Baltimore back to DC - temp gauge sits just above the bottom mark all the way home, radiator hoses are not too hot to hold, coolant in the expansion tank feels about 150 deg. I suspect a t'stat stuck open.

It was replaced about 2-1/2 years ago by a shop that did the t'belts and a bunch of other stuff, some not particularly well.

T'stat on one of these is same labor as doing timing belts:

• Remove front 1/2 of car, all accessory drive components, all covers, timing belts, water pump.

• Replace thermostat.

• Reassembly is reverse of disassembly.

The car only has 97k miles, and the entire suspension is new 2 years ago. HD Bilsteins, 1" Vogtland springs, every control arm and bushing. It drives like new. But the clutch is engaging about 1/4" below the very top of the pedal, so I suspect it'll be due soon, and it needs rear wheel bearings. What I mean is: It's a nice car, but she's had it a long time and we're on the fence as to how much work we're willing to keep doing. I am NOT doing a clutch on an AWD A4. Period. I'd rather catheterize myself w/ a length of hot welding rod.

I just drained and flushed the coolant 'til it ran clean then let the car idle 'til the temp gauge was above the middle - but it got there very gradually - it didn't seemas though there was no heat until the t'stat opened then quickly come up. Then I turned the heater temp and fan to max and got heat for a minute or 2 but it cooled until it was blowing cold. So it looks like the t'stat is stuck open.

I've disconnected the heater hoses, attached 2 lengths of vinyl tube and filled the heater core w/ CLR. I'll agitate/pump it back and forth periodically and see if I can get better flow through the core.

I'll refill w/ Pentosin G12 and distilled water - hopefully whatever gack is hanging up the t'stat will go away.

• Should I run a commercial flush product first?

• Any tips for unsticking a stuck-open t'stat? (that's inaccessible)

• Remove the main hoses from the radiator and power flush w/ a hose?

Car isn't overheating, what's the problem? Springtime is just around the corner!

In the meantime, a nice electric seat warmer will warm the tooshie for the rest of the winter. http://www.thewarmingstore.com/heated-car-seat-cushion.html?productid=heated-car-seat-cushion&channelid=SHOPP&#.UtMmuqEVY0g

Block off the radiator.

In reply to 1988RedT2:

Cold car runs rich, dilutes the oil with fuel, doesn't heat the oil enough to drive moisture off, and the engine consequently doesn't last long at that point.

Kenny_McCormic wrote: In reply to 1988RedT2: Cold car runs rich, dilutes the oil with fuel, doesn't heat the oil enough to drive moisture off, and the engine consequently doesn't last long at that point.

Yes, I know. I was merely jesting. As a former Audi owner, I feel his pain.

In defense of Audi, ours was a wonderful car for the first 100k miles. Right after that, not so much.

Can't you get to the T-stat from below? I had a 99 Passat and I thought there was room there.

I know at some point the changed to a water pump driven off the timing belt. Mine was external. Maybe 2000 was the year?

You have my sympathies. I had a similar problem with my E39 a few weeks ago. Your description reminds me once again why I have stuck with BMW over the years - while BMWs are far from trouble-free, when they do break they tend to be a lot easier to fix than VAG products. My t-stat took a couple hours, but only because I replaced a couple other things while I was in there, did a full drain of the system, and it was 22F the day I was working in the driveway. Probably would have been 45 minutes to an hour in best-case conditions.

FWIW, the t'stat on mine was a Wahler unit with about 60k miles/6 years on it. The cooling system was spotless when I opened it up, so whatever failed is internal to the unit, not an external blockage. Don't know if VAG uses them, but the BMW unit has a DME-controlled heating element in the t'stat used to finely regulate temperature. If Audi does have this, you might find a code to confirm that's your problem.

Inline thermostat. Stuff it in the radiator hose, add a clamp and call it done. I have one in my diesel Liberty as the factory thermostat is a piece of garbage that can fail at 40k miles (fails open then never shuts again). The one I used was out of a Peugeot and Napa had it next day for all of about $8. Been in for 25k trouble free miles now.

What diameter is your rad hose? I'll get you the part number if your rad hose is the same as mine.

airwerks wrote: Inline thermostat. Stuff it in the radiator hose, add a clamp and call it done. I have one in my diesel Liberty as the factory thermostat is a piece of garbage that can fail at 40k miles (fails open then never shuts again). The one I used was out of a Peugeot and Napa had it next day for all of about $8. Been in for 25k trouble free miles now. What diameter is your rad hose? I'll get you the part number if your rad hose is the same as mine.

This is berkeleying genius! I'll google one up. It'll work 'til the stock one closes and sticks closed.

02Pilot wrote: You have my sympathies. I had a similar problem with my E39 a few weeks ago. Your description reminds me once again why I have stuck with BMW over the years - while BMWs are far from trouble-free, when they do break they tend to be a lot easier to fix than VAG products. My t-stat took a couple hours, but only because I replaced a couple other things while I was in there, did a full drain of the system, and it was 22F the day I was working in the driveway. Probably would have been 45 minutes to an hour in best-case conditions. FWIW, the t'stat on mine was a Wahler unit with about 60k miles/6 years on it. The cooling system was spotless when I opened it up, so whatever failed is internal to the unit, not an external blockage. Don't know if VAG uses them, but the BMW unit has a DME-controlled heating element in the t'stat used to finely regulate temperature. If Audi does have this, you might find a code to confirm that's your problem.

I love my e39 525iT manual and e36 M3. So predictable.

E21 (aka 320i) BMW used a inline t-stat IIRC

You do NOT need to remove the front of the car. You unclip the bumper cover and a couple bolts at the fender and top of the lock carrier, unbolt the bumper brackets, replace one bolt on each side with a long M8 bolt (such as a Miata transmission case bolt) and slide the assembly back four or five inches. You don't even need to disconnect any hoses since they all have giant S-curves in them just for this purpose. With practice it takes less than ten minutes.

Knurled wrote: You do NOT need to remove the front of the car. You unclip the bumper cover and a couple bolts at the fender and top of the lock carrier, unbolt the bumper brackets, replace one bolt on each side with a long M8 bolt (such as a Miata transmission case bolt) and slide the assembly back four or five inches. You don't even need to disconnect any hoses since they all have giant S-curves in them just for this purpose. With practice it takes less than ten minutes.

AKA - "Service position"

vdubinsd wrote: E21 (aka 320i) BMW used a inline t-stat IIRC

And Amazon had it - made by Stant - in stock for about $30 w/ prime shipping.

I'm about to drive the car to work - I soaked the heater core and expansion tank overnight w/ CLR and flushed the hell out of the rest of the system. Refilled w/ G12 and distilled h2o. Maybe I'll get lucky and whatever crap is holding the t'stat open washes away.

Thanks, VDUBSINSD!

I bought the 320i t'stat from amazon and finally had time to install. I capped off the unused port w/ a turned aluminum bung and a scrap of hose, cut the upper hose and installed. Car heated up to mid gauge and, having thoroughly cleaned the heater core w/ an overnight CLR soak, flushed the system, and refilled w/ fresh Audi coolant and distilled water, the heat blows wicked hot.

I'll do the noisy rear wheel bearing tomorrow and Mrs. Motomoron will have a non-ghetto hooptie 'til the clutch is used up. Then we're done w/ V.A.G. products for good.

airwerks wrote: Inline thermostat. Stuff it in the radiator hose, add a clamp and call it done. I have one in my diesel Liberty as the factory thermostat is a piece of garbage that can fail at 40k miles (fails open then never shuts again). The one I used was out of a Peugeot and Napa had it next day for all of about $8. Been in for 25k trouble free miles now. What diameter is your rad hose? I'll get you the part number if your rad hose is the same as mine.

Bingo.

I will say this nicely: As someone who ran auto repair shops for 7 years, I can honestly say we would have gone belly-up if it weren't for 98-04 VAG-COM cars. They were so full of crazy stuff (with parts that were only supplied by the dealer) that it was our gold mine.

One of our monthly reports showed that 58% of our profit came from Audi/VW cars.

My advice is to put an inline T-stat like Airwerks suggests and sell it FAST.

One more tidbit... In 2007, our shop filed a lien on a 2002 Golf with 80,000 miles to recover an $800 repair. I could have bought that car from the business for $800. After 5 years of watching VAG-COM cars cycle through our shop, I passed. Seriously.

We make a lot of money on them too, but that's primarily because they're by far the most common German car around here, and a lot of shops refuse to work on them because they are afraid of money or something. So we're maybe 40% GM, 30% VWAG, 30% everything else.

I'd buy an Allroad in a heartbeat. The cars really aren't that bad expense-wise. Regular maintenance items last just about forever, the chassis don't rust out while-u-watch. Sure they can be expensive if you let problems go, but that is an owner problem not a car problem.

Yes... a 6-speed Allroad, that's what I want. Rare as hens' teeth though, but they can be had really cheap. (Automatics would be okay if they were maintained but the VW service interval is "drive it until it stops moving then replace transmission". They last forever if you don't do that.)

I didn't know anyone actually made inline thermostats. I've always just used two universal housings and bolted them together with a thermostat in the middle.

That's my something new for the day.

I remember the first time I saw one, thinking "what the hell is that?"....glad it worked!

In reply to Knurled:

You may have missed the part about "B5 chassis 30 valve V6" The t'stat is under a long cast aluminum housing the runs essentially from the center of the motor to the left (viewed from the front) behind both sides of the t'belt for that cylinder bank. At absolute minimum you need to pull the under tray and bumper shell, rotate the core support out and long-bolt it, remove the accessory drive belt, t'belt covers, and it's theoretically possible to zip-tie the t'belts to the sprockets, loosen the tensioner and work the t'stat housing out from behind the belt.

But it's 75% of the labor of a t'belt service, which is ridiculous. I hate this car, and hate working on it. The first time the (disengages in the first 1/4" of pedal travel) clutch exhibits slippage, this thing leaves. Last V.A.G. car we own. Ever. Period. Full stop.

motomoron wrote: You may have missed the part about "B5 chassis 30 valve V6" *snip* But it's 75% of the labor of a t'belt service, which is ridiculous. I hate this car, and hate working on it. The first time the (disengages in the first 1/4" of pedal travel) clutch exhibits slippage, this thing leaves. Last V.A.G. car we own. Ever. Period. Full stop.

That's not so bad relative to some other newer cars I can think of. Certainly I'd rather do that than do, say, a water pump on a 2.7 Chrysler, or pretty much anything on a 3.6 GM.

Regarding the clutch travel, that seems to be the M.O. for VWAG clutches. They want the thing to barely disengage if you are compressing the carpet. That's not so much a problem with cable clutch cars because you can ignore the procedure and adjust it so that there's minimal play at the top of the stroke, but on hydraulic clutch cars, well they just suck.

In reply to motomoron:

Do you have the Part# of the inline thermostat that you have used?

oldopelguy wrote: I didn't know anyone actually made inline thermostats. I've always just used two universal housings and bolted them together with a thermostat in the middle. That's my something new for the day.

Fiat used them on the 124 as well

You just need a Water Pump and Timing Belt.

Stant 13578

Available from amazon