A3 8L overheating problems

Mqsas

Mqsas

Registered User
Joined
Nov 24, 2019
Messages
10
Reaction score
1
Points
1
Location
Europe
Hi, this is my first post, so bear with me.

I bought a 2002 A3 1.8T (150HP) recently. The coolant temperature gauge says it's overheating. If I start the car in the morning when it's cold, I always get the "coolant low" warning beep on the dashboard. But when it's warmer in the afternoon, the low coolant warning doesn't show often.

A week ago I drove 200 miles in one day. It started cold, the temperature gauge went up to 90 degrees in a few miles and then after about 10 miles it started overheating up to 110 degrees. There was a notable lack of boost during that time (only tried reving it up once or twice). After 50 miles, the temperature went back down to 90 degrees and in the final 150 miles everything was as normal as it should be. In the last 10 miles, I heavily abused the car and it didn't overheat. When I arrived at the destination, I checked the upper and the bottom hose and everything was normal.

When the temperature gauge is showing 110 degrees and I stop the engine, I can easily open the coolant bottle cap. There is some pressure, but not much.

The coolant isn't leaking because the level is the same. I changed the temperature sensor about a week ago, the problem wasn't solved. The thermostat was replaced this year and the water pump has 30kkm on it.

I'm taking it to the mechanic next week, but it would be great to get some suggestions before I get there.
 
Sounds like a water circulation problem if you are not loosing any coolant. My initial thoughts would be a pipe blockage, thermostat or water pump. A bad head gasket can also cause overheating and power loss but as you’re not loosing any coolant, you’re potentially ok on this front. You haven’t used any Radweld or similar in the past to fix a water leak have you?
 
BrummieLad said:
You haven’t used any Radweld or similar in the past to fix a water leak have you?
Click to expand...

Not to my knowlege. I just bought the car a month ago, went to the other side of the country to buy it. And since I'm an idiot and I always buy the first car that I see, it could end a lot worse. Need to replace shitload of things, but the engine has 100k miles on it and when I'm done in 2020, the car will stay in the family for the next 10 years.

I was told that the problems will be solved if I change the coolant TS. I bought it, replaced it with the new one, and I have a feeling that everything became a little bit better. Though I bought a black one and the one already inside was green. Could that be another issue?
 
I thought straight away coolant temperature sensor but if you have replaced that (with the correct part) then I would have a look at your water pump
 
Mqsas said:
Not to my knowlege. I just bought the car a month ago, went to the other side of the country to buy it. And since I'm an idiot and I always buy the first car that I see, it could end a lot worse. Need to replace shitload of things, but the engine has 100k miles on it and when I'm done in 2020, the car will stay in the family for the next 10 years.

I was told that the problems will be solved if I change the coolant TS. I bought it, replaced it with the new one, and I have a feeling that everything became a little bit better. Though I bought a black one and the one already inside was green. Could that be another issue?
Click to expand...

If it’s the right part number for your car, then the colour of the sensor should make no difference, it’s most likely just a different brand that’s all.
 
Update: I was at the mechanic a few days ago. I told him that I replaced the coolant TC, he instantly asked me if it was the same color. I said no, so he said this might be the issue.

I went to Audi dealership, bought an OEM coolant TC, replaced it, made an ECU reset and the problem is the same.

I took off the pipe that's returning the coolant to the bottle, started the engine, and the water is flowing back into the coolant bottle the way it should. I get the hot air inside the car, does this mean that the water pump is alright and it has to be a faulty thermostat? Could it be an airlock or something easy enough for me to repair?

Today I took a drive of 20km. The coolant temp went up to 110 - 120°C after 5 kilometers of easy drive. When the temp was at 110°C, I stopped the car, turned off the engine, went into the store for 2 minutes, came back, started the engine and the temperature was 90°C for about a minute, then it went up to 110°C again. The "low coolant" light on the dashboard started flashing when the temp went up to 110°C.

I took the car to mechanic. He's quite busy, but he checked the pipes and said that the car is not overheating and that it might be a faulty cluster.

I'm getting the car back to the mechanic on Tuesday when he'll have more time to check the car, but tomorrow I have a 200km ride in front of me and I can't skip it.

What do you think about the situation? Any input appreciated.
 
Don't know if this helps but there is a hidden menu in the climate control unit...

http://mr-fix.info/audi-single-zone-climatronic-hidden-menu-a2-a3-a4/

I've never tried it but there is a function to read the coolant temperature (channel 51) so could cross check to make sure the gauge is reading correct.

If it was my car and the thermostat hasn't been changed recently,that would be my first job to eliminate that,it could be sticking open/shut.

hth
 
tcg said:
Don't know if this helps but there is a hidden menu in the climate control unit...

http://mr-fix.info/audi-single-zone-climatronic-hidden-menu-a2-a3-a4/

I've never tried it but there is a function to read the coolant temperature (channel 51) so could cross check to make sure the gauge is reading correct.

If it was my car and the thermostat hasn't been changed recently,that would be my first job to eliminate that,it could be sticking open/shut.

hth
Click to expand...

Thanks mate. Went through the procedure, drove 20 kilometers again and monitored the temperature. It gradually went up slowly from the moment I turned the car on, and when it reached 75°C it stopped going up. I floored it for a minute or two after that and the temperature stayed stuck at 75°C.

The temperature on the dashboard was (like always) another story. Fast to 90°C, and then up to 120°C (+/- 5C) and back to 90°C. So faulty gauge might be a thing. Does this sound logical? Are the gauge and the hidden menu in the climate control unit using a different sensor to measure the coolant temperature?
 
I've read somewhere that the channel 49 is the right one for coolant temp. Just tested it out and it is in line with the coolant temperature on the gauge instrument.

Left the car running for 40 minutes, turned on the heating, squeezed the hoses a few times, the temp started going up to about 100. When I increased the RPMs to 3000, the temp went up to 121 on the climate control unit. The top hose was warm. Not hot to the point I couldn't touch it, but it was nicely warm without a lot of pressure in it. The bottom hose however stayed cold. I measured the temp of the coolant in the coolant bottle and it was at about 80°C. The coolant is returning to the coolant bottle without any issues.

I cancelled the 200km trip today, will only do 30 and wait for the mechanic to fix the car next week.
 
Local engine shop, told me , when I first picked mine up , [ water loss that turned out to be the heater bulk-head feed-troughs] that the radiators have a habit of silting up , might be a good place to start , thermostat stuck closed ?
 
Last edited:
So about the 30km drive today, it was 60km drive, 30km in each direction. For the first 30km part, the coolant temperature was steadily rising. It went to 121°C on the climate control menu and it stood there for the entire time. It dropped to 90°C along the way for about 2 minutes, but it went back up to 121°C. The car was otherwise running smoothly. I didn't floor it and came to the destination. Turned the engine off, touched the hoses. The top hose was hot AF without much pressure in it. The bottom hose was stone cold.

Went into the mall, came back to the car after 30 minutes. Checked the temperature, still 121°C. Went back into the mall, came back after 1 hour, the temperature was 60°C. Started the car, drove 30km back home, the temperature never got above 95°C. Once I noticed that it stopped increasing, I floored it like hell, mostly highway pulls from 100 to 180km/h and didn't have a single issue. Stopped the car for 1 hour of lunch, went back, and it keept running smoothly. Did a few pulls and not a single issue. When I got home, I checked the pipes again. The top one was not as warm as when I arrived at the mall, and the bottom hose wasn't cold as it was when I arrived at the mall.

Any new suggestions? :)
 
audi upgrades
Sounds like Blocked rad , stuck thermostat
and or the water pump has lost it impeller

The other thing the engine shop , mentioned, these engines tend to warp heads ,121 c ?
... may be idea not to use the car, till its sorted -(
 
If there is no pressure in the system and ur losing coolant it could be down to the coolant caps not sealing good enough. The rubber on the cap over time stops it sealing right. Could try that there only a few quid on flebay.
 
Its going to end up with a warped head, get the hoses off the rad and see if any water flows through it , take the thermostat out , boil it in a pan of water , see if it moves , etc ..
 
Went through the entire internet looking for a solution and I found someone having exactly the same issue. Don't know if I'm allowed to post link, so I'll just post the screenshot:

a3overheat.jpg


As said, the water pump was replaced 30kkm ago, the thermostat is brand new, I came to the mechanic when the temp was showing 121°C and he said that it isn't overheated.

I want to eliminate as much of the possibilities before I get to the mechanic in 24 hours. It's Sunday and I have a little bit of free time, so I could try what the guy did, but I don't get the procedure.

Garden hose, connect to the drain valve. "Force in water" - how? Just fill the hose with the coolant and it will go up into the coolant reservoir? Help me out please. :)

Another thing that bothers me is why did the car stopped overheating (or showing the max temp) after 30km of drive? I don't know how water pump or thermostat would randomly decide to work or not.
 
Just drove 40km. When the car goes into "overheating mode", the temp goes up quite quickly. Today it went up slowly up to 96°C and it stayed there (+/- 5°C). I started flooring it after 10km and everything was the way it should be. No overheating and no warning light on the dashboard.

Stopped the car, turned the engine off. Went back into the car after 30 minutes and it continued to work like a charm. Tomorrow I'll wake up early, go for a 30km drive and if the problem comes back, I'll take it to the mechanic. But I'll hope that the problem solved by itself. Maybe it was just a persistant airlock, who knows.
 
FYI to all who care... It's the cluster issue. Everything was normal for 2 weeks and then the temp went on 121C (max) on the climatronic menu and the gauge the other day. I was ****** off and slapped the area on the top of the gauge. The temp instantly went back to where it should have been. Repeated the process about 5 times afterwards, the result is the same, a hard slap fixes the issue.

I have a OBD reader connected to my phone and it always shows normal temp fluctuations. 0 to 90+, then back to 90 and up and down for about 5 degrees as it should. When the dash temp goes to max, I slap the top of the cluster area and the temp comes down on the normal level in a second.

So, it's a faulty cluster
 
  • Like
Reactions: JOSE8LT
You must log in or register to reply here.

Similar threads

A
Overheating problems
Replies
2
Views
618
aledenro0803
A
DaveMK^
A3 1.8T 2003 overheating problems
Replies
12
Views
1K
abdus
abdus
D
S3 8L Overheating
Replies
10
Views
3K
s3mad_dude
s3mad_dude
Hanly
A3 8L speaker problems
Replies
3
Views
868
A3_130
A3_130
N4THW
Lowering Audi A3 8L - Problems
Replies
13
Views
15K
stu_b
S
Top
Back