gundog123 Posted December 18, 2010 Report Share Posted December 18, 2010 Hi Guys, a bit embarrassed about this, i am a mechanic/tech and got this 55 plate Audi A4 2.0TDI in the shop last week, customer already had the car at a local garage (where he’s cheap) to have a water pump fitted due to poor/no coolant circulation as the guys blower would not produce hot air. When this didn’t work the car was brought to me. I check heater matrix for possible blockage issues and removed both pipes. Both were hot but i only got a trickle of water from the feed pipe and only when engine was revved quite high. I checked pipe work over at the EGR assembly where it is also indicating poor circulation in a similar manner when under higher revs. I checked the metal pipe which leads back towards coolant tank and feeds bottom of radiator and the coolant just sits on the elbow as there’s not enough pressure to force it up. Needless to say there is virtually no return to the header tank. There is no coolant loss that is noticeable and i have been keeping an eye out for that. The car does not overheat at all under any driving conditions. There is no warm air being produced inside the cabin. There are no diagnostic faults codes. There just appears to be no pressure in coolant system and if I didn’t know better i would say that impeller has probably become detached from water pump, but with water pump being replaced the day before i got it i know this is not the case (the guy that done it is genuine) I have been trying to get a hold of a coolant directional flow diagram just to see a definite direction in which way the coolant should flow so I can home in step by step. One thing that did catch my eye is the coolant (at least in my opinion) appeared to be coming out of the wrong hose to the heater matrix, i though that should have been the return hose but i may be wrong. if anyone has a directional flow for the coolant system please get in touch and i will forward my email address to you. Or if anyone has experienced this issue or something similar then let me know as I’m a bit pickled. As a rule of thumb the radiator should not come into the equation as it should still produce good circulation and heat when thermostat is shut. I monitored the coolant temp from diagnostic machine while running it up and thermostat can be seen opening in any case. HELP HELP HELP! :rolleyes::eek: Link to comment Share on other sites More sharing options...
cruiser647 Posted December 18, 2010 Report Share Posted December 18, 2010 Hi! The coolant cap is good I presume? Do you hear the cap 'pssstt' when you open it? Has any other work been done to the coolant system before you got it? Has it been flushed through to remove any crud? Incase someone mixed red and blue coolants? Link to comment Share on other sites More sharing options...
TIDYDUBS Posted December 19, 2010 Report Share Posted December 19, 2010 Is the pump a genuine VAG pump? Has it got an additional coolant circulation pump? what other work has been done? Link to comment Share on other sites More sharing options...
stuartxrv Posted January 30, 2011 Report Share Posted January 30, 2011 Hi Guys,a bit embarrassed about this, i am a mechanic/tech and got this 55 plate Audi A4 2.0TDI in the shop last week, customer already had the car at a local garage (where he’s cheap) to have a water pump fitted due to poor/no coolant circulation as the guys blower would not produce hot air. When this didn’t work the car was brought to me. I check heater matrix for possible blockage issues and removed both pipes. Both were hot but i only got a trickle of water from the feed pipe and only when engine was revved quite high. I checked pipe work over at the EGR assembly where it is also indicating poor circulation in a similar manner when under higher revs. I checked the metal pipe which leads back towards coolant tank and feeds bottom of radiator and the coolant just sits on the elbow as there’s not enough pressure to force it up. Needless to say there is virtually no return to the header tank. There is no coolant loss that is noticeable and i have been keeping an eye out for that. The car does not overheat at all under any driving conditions. There is no warm air being produced inside the cabin. There are no diagnostic faults codes. There just appears to be no pressure in coolant system and if I didn’t know better i would say that impeller has probably become detached from water pump, but with water pump being replaced the day before i got it i know this is not the case (the guy that done it is genuine) I have been trying to get a hold of a coolant directional flow diagram just to see a definite direction in which way the coolant should flow so I can home in step by step. One thing that did catch my eye is the coolant (at least in my opinion) appeared to be coming out of the wrong hose to the heater matrix, i though that should have been the return hose but i may be wrong. if anyone has a directional flow for the coolant system please get in touch and i will forward my email address to you. Or if anyone has experienced this issue or something similar then let me know as I’m a bit pickled. As a rule of thumb the radiator should not come into the equation as it should still produce good circulation and heat when thermostat is shut. I monitored the coolant temp from diagnostic machine while running it up and thermostat can be seen opening in any case. HELP HELP HELP! :rolleyes::eek: Hi Mate. Did you manage to solve the problem. I'm experiancing exactly the same symptoms on my A4 1.9 tdi. I've just had cylinder head gasket changed along with water pump, EGR cooler, thermostat and belts due to coolant loss. Now the leak has been repaired i've no heat what so ever (when i was loosing coolant, through the EGR cooler, the heater would be warm enough to warm my hands)! Link to comment Share on other sites More sharing options...
billygunn111 Posted January 16, 2012 Report Share Posted January 16, 2012 Stuart did you find a solution to your problem? Same issue here, mechanic puzzled!! Replaced thermo, water pump and matrix is fine! Top pipe hot, bottom cold and sblowing cold air when car static. Flushed out system and still no heating??? Let me know if you go it working! Thanks Link to comment Share on other sites More sharing options...
power bronze Posted January 31, 2012 Report Share Posted January 31, 2012 Hi Billygun...Same problem here,I have a A4 tdi convertible on a 06 plate..changed water pump and thermostat,had new core on rad,flushed heater matrix loads of times good flow with hose pipe both ways,put holts radflush through the system and bled from the top pipe but still no heat.any help would be really apreciated I have spent close on a grand already and at my witts end HELP!! Link to comment Share on other sites More sharing options...
Jmholdsworth Posted September 28, 2013 Report Share Posted September 28, 2013 Hi, Has anyone had a fix for this? Same problem on my 2008 A4 Cab 2.0tdi. This is what I've changed so far: Started with EGR cooler going. This was replaced. Water pump replaced Thermostat replaced Head gasket replaced EGR cooler replaced AGAIN Now we've coolant flushing around the pipes / cooling system but still the problem exists. It comes hot for a minute then gets much cooler, sometime cold sometimes just cooler. Please please please, can someone help. It's costing me a fortune so far!! Thanking you in advance. Link to comment Share on other sites More sharing options...
Mechcanico Lee Posted September 20, 2015 Report Share Posted September 20, 2015 How does the heater control the temp ?? By water shut off valve or by matrix flap bypass . Do they have one matrix or twin matrix one for each side with a diverter valve ? In jag x type diesels I have had similar symptoms , in one of the pipes that goes to the bulkhead there is a tiny thermostat , you would never know it was there .... in fact I stumbled on it doing another job .... could the Audi have one ??? In alot of engines the feed to the matrix will come from the cylinder head because that is the hottest area , but if the return from the matrix is flow restricted you will not get hot blower air If you turn blower speed off and Rev the car up for 30 seconds or something then turn blower on do you get hot air for a bit then it goes cold again ... if so that typical bad flow through matrix . I found if it's water pump impeller spinning on the shaft under load they will overheat so if no overheat symptoms probably not that Link to comment Share on other sites More sharing options...
Mechcanico Lee Posted September 20, 2015 Report Share Posted September 20, 2015 Just realised how old this post is DOH 1 Link to comment Share on other sites More sharing options...
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