steve_c
Grumpy OAP & A2OC Donor
Unfortunately, you appear to have been supplied with testing solution for petrol rather than diesel engines, since the diesel solution is normally red. Can only suggest you take it up with the eBay seller.
Overheating TDI 90 (ATL)
- Thread starter andrewparkeruk
- Start date
Unfortunately, you appear to have been supplied with testing solution for petrol rather than diesel engines, since the diesel solution is normally red. Can only suggest you take it up with the eBay seller.
andrewparkeruk
A2OC Donor
@steve_c the listing clearly states petrol and diesel. It tests for CO2. Is that the wrong test?
Combustion Leak Tester Kit Detector Head Gasket Tester Fluid 30ml Petrol Diesel 5904816013320 | eBay
Combustion Leak Tester Kit. Car Combustion Leak Tester Kit. ✅ Leakage tester. If after a few minutes the fluid turns YELLOW or GREEN, combustion leak is present. Insert the tester in the radiator's inlet or expansion's tank.
rover.ebay.com
Pinkythelabrat
A2OC Donor
I’m sure I got blue to yellow liquid for my diesel too. 
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Sent from my iPhone using Tapatalk
@steve_c the listing clearly states petrol and diesel. It tests for CO2. Is that the wrong test?
Combustion Leak Tester Kit Detector Head Gasket Tester Fluid 30ml Petrol Diesel 5904816013320 | eBay
Combustion Leak Tester Kit. Car Combustion Leak Tester Kit. ✅ Leakage tester. If after a few minutes the fluid turns YELLOW or GREEN, combustion leak is present. Insert the tester in the radiator's inlet or expansion's tank.rover.ebay.com
To confirm if the kit is suitable, any way you could couple it up to the exhaust pipe and check for colour change. Tricky bit is to get just enough gas flow to bubble through the airlock without blowing the liquid out
Cheers Spike
andrewparkeruk
A2OC Donor
Thank you @Special edition Dave, that is extremely kind. As I had the coolant loss issue with the old expansion tank (Sep-2018), and the first items to be replaced trying to troubleshoot the issue were the expansion tank and cap (Feb-2019), I don’t think the issue lies there.
I need to try to understand why the pressure in the system is sufficient to push coolant out of the expansion tank pressure-relief valve, and yet the radiator fan has not kicked-in. As I have said several times, I don’t understand the mechanics of cars, but I am using the analogy of what is going on when I use my pressure cooker.
Using the pressure cooker I use maximum heat to get the contents up to pressure, indicated by the weight, then I reduce the heat to maintain temperature and pressure at an optimal level. If I turned-up the heat, the pressure-relief valve would open, there would be a big mess on the stove, but there wouldn’t be an explosion. This is a process in which I need to participate by managing the application of heat.
Back to the car. When I drive the car, and the temperature of the coolant increases to certain level, I would expect the radiator fan to spin to reduce the coolant temperature. This should be an automatic process requiring no input from me. If this doesn’t happen, temperature and pressure increases, and the expansion tank pressure-relief valve will spray coolant around the engine bay. I suspect this is what I am seeing, and I may have come to the limit of what I can observe.
I probably need to take it to a garage with VCDS and repeat what I did on Saturday. The question I need to answer is do I remain loyal to the local, excellent, VAG specialist, but with a new, and younger Audi Master Tech who may not have seen too many A2s; or do I travel to WOM who I know have an excellent reputation and a growing band of loyal A2 customers, and so really know their way around these cars.
Cheers, Andrew
If it's a head gasket problem the gasket tends to fail between the combustion chamber and a coolant gallery. Combustion gas then leaks into the cooling system and pressurises the expansion tank. In the early stages this tends to occur when the engine approaches operating temperature but does not get hot enough to activate the radiator fan. Over time the gasket leak progressively worsens and the system can pressurise even when the engine is cold.
The big watchout is that if you loose a lot of coolant the water temp sender in the cyl head is no longer in the coolant flow and reacts very slowly to the rapidly increasing cylinder temperature. Another sign is the heater running cold, again due to low coolant levels and lack of flow through the heater core
I don't think the test kits are foolproof so the liquid may not change colour with small gasket leaks.
Cheers Spike
The big watchout is that if you loose a lot of coolant the water temp sender in the cyl head is no longer in the coolant flow and reacts very slowly to the rapidly increasing cylinder temperature. Another sign is the heater running cold, again due to low coolant levels and lack of flow through the heater core
I don't think the test kits are foolproof so the liquid may not change colour with small gasket leaks.
Cheers Spike
andrewparkeruk
A2OC Donor
Thank you for that explanation @spike
When I had the car idling for an hour following the 40 minute motorway trip, I was surprised that I could grip the rubber coolant pipes. Based on no previous experience, I had expected them to be uncomfortably hot. The air temperature was quite low, the bonnet was off, this might explain it.
When I had the car idling for an hour following the 40 minute motorway trip, I was surprised that I could grip the rubber coolant pipes. Based on no previous experience, I had expected them to be uncomfortably hot. The air temperature was quite low, the bonnet was off, this might explain it.
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Traditional thermostats are designed to 'fail safe' with a big spring trying to keep it open and the wax capsule holding it shut when cold. As it heats up the wax expands and controls the degree of opening. If the capsule fails and the wax leaks out there is nothing to hold it shut so the spring takes over and opens it.
If for some reason it did stick shut the engine would overheat.
Cheers Spike
If for some reason it did stick shut the engine would overheat.
Cheers Spike
andrewparkeruk
A2OC Donor
Not cold, but bearably hot, rather than unbearably.
Thermostat was replaced 27-Sep-2018 as I had noticed the dashboard temp gauge become slow to 90°C when using climate control.
G
Guest 4123
Guest
Not sure if it's possible, but could the thermostat be installed the wrong way round?
RAB
RAB