Overheating TDI 90 (ATL)

A

andrewparkeruk

A2OC Donor
I have had my TDI 90 since 2009. It has always been superbly maintained by the same VAG specialist garage. I am not "mechanical": all I do is maintain a spreadsheet of what has been done and what needs to be done.

For the last 18 months I have had an issue with coolant loss. Whenever I check, there is spray on the coolant expansion tank.
IMG_9871.jpg


Background:
I bought the car Oct-2009 from someone who used to post on this forum, it had 47,000 miles on the clock, full main-dealer service history, and was 5 years old. My VAG specialist garage changed the camshaft drive belt / coolant pump. Since then that job has been done another two times: Aug-2013 (102,000 miles); Sep-2018 (153,000 miles).

My car has fully-functional OpenSky, version 2. During the winter months climate control is always on and set to around 20ºC

Ironically the day before the most recent cambelt change, I had a dashboard coolant level warning, a first for me. I added 300ml to the header tank.

Summary of relevant work:
26-Sep-2018: coolant level dashboard warning; added 300ml to header tank (ironically the day before the car booked in for …)

27 Sep 2018: coolant pump replaced; routine service item with camshaft drive belt
27 Sep 2018: thermostat replaced; dashboard temp gauge had become slow to 90ºC with aircon on

11-Feb-2019: coolant level dashboard warning
12-Feb-2019: coolant expansion tank and cap replaced

26-Feb-2019: coolant level dashboard warning; expansion tank had lost 500ml. Due to new header tank, easy to see sprayed pink coolant
(Unseasonal weather! A really warm, sunny day. After an hour on motorway with aircon off and OpenSky open; warning occurred waiting in traffic queue at traffic lights; classic overheating. Thankfully this happened a mile away from home)
27-Feb-2019: radiator hose fan sensor (at bottom of radiator) replaced

Because we have changed everything else, garage convinced that the fault must lie with the radiator fan control unit; the fan is working at low speed but could not be made to run at the second, higher speed. It is an expensive component so we have replaced cheaper items first.

02-Mar-2019: routine check; some pink coolant spray visible from expansion tank safety valve before 100 mile motorway trip. Cleaned tank
03-Mar-2019: check before 80 mile motorway trip, cleaned pink coolant spray from expansion tank. On returning home pink coolant spray visible

11-Oct-2019: coolant loss diagnosed caused by overheating. Garage has run the car (presumably minus climate control) for a prolonged period and the radiator fan will not run. Garage reckons the only component which can be causing the issue is the radiator fan control unit. It is on back order at Audi UK

14-Jan-2020: radiator fan control unit replaced
Garage ran car for 4 hours after fitting and no overheating issues; hopefully issue resolved

21-Jan-2020: topped-up coolant to halfway point cleaned reservoir of any pink spill. Monitor ...
22-Feb-2020: checked coolant level; added 300ml to header tank

You will see that the garage has been really responsive. Whenever I have had an issue they have had my car in the very next day. Because I usually have climate control running, the radiator cooling fan runs. As a non-mechanic resolving this needle-in-a-haystack could cots me a fortune: I have never prioritised fixing it, and that garage has always helped me by working on it as a background task.

The issue I have is two-fold. We have never got to the bottom of the overheating / coolant loss, and far, far worse the VAG specialist garage owner who has looked after my car for ten years was tragically killed in Oct-2019.

What should I do?
The other day @Dean opened a possibly related thread https://www.a2oc.net/community/index.php?threads/cooling-fan-not-kicking-on-fsi.42394/ but which was perhaps FSI-specific

I don't have VCDS

If you got this far, thank you
Andrew

PS I am not sure the mechanic who fitted the radiator fan control unit was able to run the car to confirm the radiator fan is now working at the second speed; it will have been parked-up and idling I presume. I haven't done it either as it is pretty antisocial (and illegal) to run an engine on the public highway with the car stationary: I don't have an off-road area in which to do this
 
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Its got to be going somewhere. Likely if its not boiling over then you've probably got a leak somewhere - radiator maybe? Could you check for wet patches with a torch?
 
RAB said:
Head gasket OK?
Click to expand...

I'm no expert on A2s, but coolant coming out round an expansion tank (especially one that has been replaced) looks like it's becoming over-pressurised. If it's not overheating (temp gauge high/steam under the bonnet), then something is pushing it out under pressure, which is a classic sign of head gasket failure. I hope I'm wrong and I don't think it's that common, but I'm sure others will be along to advise soon.
 
I had this problem on the first FSI I bought. I too thought it was head gasket, to test it i bought a gadget that plugged into the hole in the expansion tank when the cap is removed. essentially it had a u bend in it that was filled with a fluid that changed colour if CO2 was bubbled through it - i thought it was a simple head gasket tester. in my case it wasn't the head it was the filler cap gasket that was the issue - but you've already done that. the kits are cheap on ebay to test head. cheers
 
The head gasket test liquid is pretty reassuring and cheap. It just shows combustion gases in the coolant venting. Easy to do and no mechanical skills required.

I think idling for no good purpose on a public road is subject to spot fines but running a car up to operating temperature while performing a recognised diagnostic test is hardly the same thing.

Ps. I’d maybe also try another new cap on the expansion tank as well - maybe a known good cap. Cheap and I got a ‘new’ one from eBay which leaked and a second hand one which didn’t.


Sent from my iPhone using Tapatalk
 
Thank you all.

Each time I check, coolant is visible around the “waist” of the coolant expansion tank; I tried to show that in the photo.

The expansion tank cap seems to clamp really well, and opens with a bit of a pop. Obviously I would prefer a simple solution, like replacing the cap.

I don’t have VCDS so can’t activate the fan at higher speed by doing that.

I will start with trying the head gasket test by getting one of those kits.

I will report back
 
It could be worth doing a temporary bypass of the egr cooler.If no change then as @RAB suggested maybe head gasket.Its because you are running hot as well as losing coolant.
 
I would suspect the head gasket. Classic sign for me was coolent loss but only under heavy load and when the engine was up to temperature. Another simptom I had was the heater would not get and stay hot even when the temperature guage was reading 90 this was down to presure in the cooling system. A cylinder pressure test did not pick up my head gasket problem. Gasses in coolent should.
 
Go for the simple thing first... replace the expansion cap, the seals and internal relief valve age. Cheap to replace. Then if you still have issues look deeper.
 
andrewparkeruk said:
PS do I need a kit with a bung big enough to fit into the hole in the centre?
View attachment 61707
Click to expand...

Yes you do. The kit I linked to has a bung that will match any hole with a diameter between 35mm and 41mm. If this is not the right size, you can easily do an eBay search for a kit that will fit, although all the ones I saw appeared to be the same size.

If that's not a good fit, I'd be inclined to buy a cork stopper of the correct size and fit the U bend tube to that.
 
“... try bypassing the EGR”. I don’t know what an EGR is, where it is, et cetera.
What part of me not being “mechanical” do some fail to grasp? :)
I appreciate you may be trying to help but that sort of thing isn’t in my world.

I do know how to take-off the bonnet, I can clean things, top-up liquids, take photos of what I see, I’m pretty good at shopping, ... I can do: take it to a garage.

Using a head-gasket test kit looks straightforward (now that I understand where it fits, thank you @steve_c); similarly I could replace the lid of the expansion tank.

It is peeing-down here just now and my car lives on the road. When it stops raining I will measure the hole in the coolant expansion tank and buy a head-gasket test kit, and a cork stopper if needed. I will post the results as soon as I have them?

Andrew
 
andrewparkeruk said:
Using a head-gasket test kit looks straightforward (now that I understand where it fits, thank you @steve_c); similarly I could replace the lid of the expansion tank.

It is peeing-down here just now and my car lives on the road. When it stops raining I will measure the hole in the coolant expansion tank and buy a head-gasket test kit, and a cork stopper if needed. I will post the results as soon as I have them?
Click to expand...

Testing for head gasket failure with one of those kits is pretty straightforward, but it's important to warm up the car sufficiently before using it to ensure the coolant is actually circulating. This may take some time with your diesel engine.

Here's another eBay listing with rather more detailed instructions:
www.ebay.co.uk

Bt-1 2x50ml Combustion Leak Tester Kit Co2 Fluid Head Gasket Test Block Car 14e for sale online | eBay

Find many great new & used options and get the best deals for Bt-1 2x50ml Combustion Leak Tester Kit Co2 Fluid Head Gasket Test Block Car 14e at the best online prices at eBay! Free delivery for many products!
www.ebay.co.uk
 
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