Hi - I have only joined a few days ago, if someone could help I'd be very grateful indeed. I have an ( old faithful) AudiA4 Avant 1.9 tdi 1999 - 210k miles I believe it is a B5?
I have had it for fourteen years. Normally the temp gauge sits in the middle at 90C - seldom moves. A few weeks ago on a 50 mile round trip I noticed that after about 20 miles it crept to 100C plus. At destination I was there for about 1 hr, and on return trip it crept to 100 after about 6 miles - then 110 then a bit more then I got home. I did a similar trip but on the way back I stopped a few times and the engine was on tick over - and on the last mile home the temp went into 110 plus and bell and red alarm went off - just got home. No gunk in the oil / no white smoke / no loss of coolant. I had a new thermostat - similar problem persisted. I had new water pump - similar - by now I did the out trip and the return with fan and heaters blowing hot - seemed just a bit better. I had a new radiator - similar problem. It seems ok (as before) for the first 20 miles or so - then slight temp increase - then on the return - a quicker temp increase - not got to over 110 and no alarm (at 115C) as I drive now with heater blowing - cannot do more than 40 mile round trip. I am 76 - tried everything I can think of - any suggestions would be much appreciated. I am unsure how to post this to the wider community - would appreciate a bit of guidance here also pse. All the best and fingers crossed. Mike my personal email is.
info@ceramist-technologist.com

 

Prior to this, had you done anything to the cooling system? Have you scanned for codes with a scanner or VCDS? The Check Engine Light can be off but a code can still be stored in the computer. Also North America did not get the A4 with a TDI so we won’t have much experience with them. You may want to try your local forums who have this engine.

Doug

 

Thanks Doug - done nothing to the cooling system - my son has an OBD2 - checked - no stored codes - I am in UK - not sure how to acess 'Local' forums - will see if I can. Thanks for the reply though. Mike

 

I’m sure there are UK forums that will have more knowledge with the TDI. Good luck.

Doug

 

Just off the top of my head, I'm thinking you may have a blockage in your cooling system somewhere. Flush the entire cooling system (proper) three times, with plain water and the heater on full blast. If you want to use a cooling system flush product, go for it, but flush it three times and then refill with coolant and Distilled water. Let me know what happens.

Note: It may be a good idea to flush your heater core by itself first (it probably needs it anyway). If you choose to do that, use vacuum (on the outlet) instead of water pressure (on the inlet) to suck the junk out of the heater core. You will have less chance of damaging the core with vacuum coming out than you will with too much water pressure going in.

G/L

 

Hi, if you have not yet solved this insidious overheating, I have a suggestion based on experience with my A6 2.0 L turbo.

The coolant bleed hoses from the radiator and engine block are connected to the coolant reservoir to release air and automatically bleed the system. These tiny hoses are fitted with tiny air release valves at the radiator and engine block respectively. The valves preserve system pressure while allowing only bleed air to pass.

The valves can fail, which allows the system pressure to drop to atmospheric pressure. When you are on a long trip, the excess heat allows the temp to rise and you might also boil off coolant. For short trips the coolant just recirculates through the bleed hoses and reservoir and you do not generate enough heat to overcome the radiator cooling capability or boil your coolant.