Fsi coolant problems

freakyeke

freakyeke

A2OC Donor
I bought an fsi last week. I drove it 150 miles home without problems.

The next day, my wife took it to take the kids swimming and returned with the car steaming from under the bonnet and the coolant warning flashing on the DIS. I turned it off immediately and noticed the expansion tank coolant level was a couple of inches under the min mark. Not empty but nearly empty.

The following day, I topped up the coolant and bled the system, only for boiling coolant to shoot out of the top of the expansion tank. The cooling fan never came on but the temp gauge was at 90 degrees.

I also noticed that the lower radiator hose was cold so deduced that the thermostat was at fault.

I arranged for a mobile mechanic to fit a thermostat, £153 in total and £92.55 for the start. He bled the system and the bottom hose warmed up and cooling fan came on.
I was happy.

I drove to work that night. I had done maybe 20 miles and the coolant warning light came on. I immediately stopped and checked the coolant level. Low again? I topped it up and continued on my way to work. I did the same coming home.

I have changed the expansion tank cap and all seemed well, until I drove just 5 miles in heavy traffic. Steam coming from under the bonnet again.

I am going to get a new expansion tank tomorrow from TPS or Audi to see if that might help because there's either no pressure in the system or the coolant is just boiling? If not that, it sounds like a head gasket failure.

Does anyone have any ideas? There are no noticeable leaks and no signs of head gasket failure.
 
Hi a few things to check are the
1 water pump is not leaking
2 small plastic "y" pipe fittings on the small coolant pipes close to expansion bottle
3 small pipes where they go through the bulkhead for signs of leakage
4 the large long plastic pipe that is on the rear of the engine under the inlet assembly -it joins the water pump to the thermostat housing. it becomes brittle and can crack. its approx 45mm dia and 450mm long.

one last thing to check is to get your mechanic to sniff test the expansion bottle this shows if there is combustion gasses present. good luck mike
 
I wouldn't spend money on the coolant bottle it is unlikely (but not impossible) to be the cause.

If your coolant level is virtually at the bottom of the bottle, let alone a couple of inches below the "low" line, then there is enough in there to do the job and it would not have boiled just because of this.

I suspect that the thermostat WAS the main cause of your problems (the cold bottom hose being a clue) but I reckon what has happened now is that all of the pressure of the steam has caused a leak somewhere (probably on the Y piece that Mike mentioned, but it could be anywhere.)


Imagine all of that pressure, steam is very powerful, it drives (or used to drive) trains and traction engines remember. And in your sealed system there has to be something that will let the pressure out and even with the cap being able to vent a little, it cannot vent it ll when the car gets so hot that is steams.

So please check for leaks and get the head gasket tested, before you spend any more money.


Steve B
 
a2sumo said:
Hi a few things to check are the
1 water pump is not leaking
2 small plastic "y" pipe fittings on the small coolant pipes close to expansion bottle
3 small pipes where they go through the bulkhead for signs of leakage
4 the large long plastic pipe that is on the rear of the engine under the inlet assembly -it joins the water pump to the thermostat housing. it becomes brittle and can crack. its approx 45mm dia and 450mm long.

one last thing to check is to get your mechanic to sniff test the expansion bottle this shows if there is combustion gasses present. good luck mike
Click to expand...

Birchall said:
I wouldn't spend money on the coolant bottle it is unlikely (but not impossible) to be the cause.

If your coolant level is virtually at the bottom of the bottle, let alone a couple of inches below the "low" line, then there is enough in there to do the job and it would not have boiled just because of this.

I suspect that the thermostat WAS the main cause of your problems (the cold bottom hose being a clue) but I reckon what has happened now is that all of the pressure of the steam has caused a leak somewhere (probably on the Y piece that Mike mentioned, but it could be anywhere.)


Imagine all of that pressure, steam is very powerful, it drives (or used to drive) trains and traction engines remember. And in your sealed system there has to be something that will let the pressure out and even with the cap being able to vent a little, it cannot vent it ll when the car gets so hot that is steams.

So please check for leaks and get the head gasket tested, before you spend any more money.


Steve B
Click to expand...

Thanks guys. I'll get the car on axle stands today and check every area for leaks.
 
Good idea, but please be careful, slide a wheel under each sill just in case. Axle stands are ok but always use an extra safety measure (sorry if I am preaching to the converted)

And get the engine up to working temeorature first. Some leaks only appear when there is a bit of heat / pressure in the system.

I hope you find a leak that could be a much cheaper fix than a head gasket.
Steve B
 
So sorry to hear of the problems you have ,and only just purchased this A2, I'd agree with both comments from A2 sumo and birchall.
 
Birchall said:
Good idea, but please be careful, slide a wheel under each sill just in case. Axle stands are ok but always use an extra safety measure (sorry if I am preaching to the converted)

And get the engine up to working temeorature first. Some leaks only appear when there is a bit of heat / pressure in the system.

I hope you find a leak that could be a much cheaper fix than a head gasket.
Steve B
Click to expand...

I'll use my ramps instead and chock the rear wheels. Thanks for the help ;)
 
freakyeke said:
I'll use my ramps instead and chock the rear wheels. Thanks for the help ;)
Click to expand...

The reason that I mention the safety is that my niece came home one day (two months ago) and parked at the rear of her house as usual and saw a guy's legs under a car and realised that it had collapsed on him. He died! Just because he hadn't taken a few extra safety steps. That was tragic and I would hate for it to happen to anyone else. My niece was traumatised by the experience (understandably) so sad.

So no appologies from me for repeating the advice constantly, even for the safety conscious members.

Steve B
 
Update on the cooling system:

Car running on ramps and under tray removed. There looks to be a 2" horizontal crack in the big coolant hose at the back of the engine. I can only see a little of the pipe, but it's definitely dripping from there. So, at least I know where the leak is coming from. Now, to get it fixed. I don't think I fancy doing it as the space is very tight.
 
Be aware that this part can split wide open and then it's total fluid loss. That is what had happened to a repair a2 1.6 I bought to save but the engine is cooked. Glad you found it. Cheers Mike
 
Thanks Mike. I won't be driving the car again until it is fixed. But, I'm struggling to find someone to fix it. Oh the joys!
 
freakyeke said:
What a horrible thing for your niece to witness.
Click to expand...

Yes, and her husband had to rush out to try and lift the car off him as he was still just about breathing. But they were too late.
So you can see why I always comment when people talk about getting under cars.

Steve B
 
freakyeke said:
Update on the cooling system:

Car running on ramps and under tray removed. There looks to be a 2" horizontal crack in the big coolant hose at the back of the engine. I can only see a little of the pipe, but it's definitely dripping from there. So, at least I know where the leak is coming from. Now, to get it fixed. I don't think I fancy doing it as the space is very tight.
Click to expand...

Even though the labour charge will not be small, at least you are now spending money on a true fix rather than on things that are not broken. Plus the very good news is that it was not the head gasket (although the overheating MAY have affected that (but hopefully not).

Fingers crossed still for you

steve B
 
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Birchall said:
Even though the labour charge will not be small, at least you are now spending money on a true fix rather than on things that are not broken. Plus the very good news is that it was not the head gasket (although the overheating MAY have affected that (but hopefully not).

Fingers crossed still for you

steve B
Click to expand...

Thanks Steve. I have my fingers crossed too.
 
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