Over temp Under load.

LukeS

Member
Can any one help !!
1.4 TDI
2 symptoms, under high load (high speed for more than 5 mins) temp starts to climb to about 100 C. I slow down, start stop driving etc back to 90 C as normal. 2nd symptom no heating set air con to a toasty 25 C. No blower as normal untill engine has warmed up then blows freezing air. Can't tell if its cooled air as it so cold out side. The novilty of driving around seeing my own breath is wearing off.

Any idea's welcome.

LukeS
 
Hi Luke, welcome to the A2oc
If you are also loosing coolant from the expansion tank then its possibly the head gasket is on its way out. A low coolant level would also account for poor heater performance.

Cheers Spike
 
This was my first thought, used to have a mini that the heater stopped working when the coolant level got low, but coolant level was spot on.
I'm now thinking that the thermostat may be stuck closed such that when upto temp there is no flow to the radiator or the heater matrix.
Does any one know how the webasto fits in to the water system and how you test it?

Thanks LukeS
 
Right did some more investigation this morning. Webasto works !!! it's firing up and generating heat. I appears to provide heat to a seperate fluid circuit that just goes accross the back of the engine bay to a heater matix in the air con unit. The aluminium pipes that run to the air con unit are getting hot, but the air con doesn't seem to be using this heat the fans only come on when the engine is up to temp. I think I now need to plug in to a VAG COM is there a member out there with one in the south west.

Cheers

Luke.
 
Hi Luke
Hot airflow into the cabin is controlled by temp sensors which signal motorised flaps to direct the airflow the selected areas like the windscreen or cabin foorwells etc. It could be a sensor problem or the flaps, which are known to stick. VagCom should find the problem area.
Regarding the engine overheating at high speed/load, there are reports of waterpump impellers coming loose and slipping at high speeds on some Audi models. I don't think it has happened on an A2 yet but its worth keeping in mind, particularly if the pump has not been changed with the cambelt.

Cheers Spike

PS. Have a trawl through this thread for possible VagCom owners in your area - http://www.a2oc.net/forum/showthread.php?t=4251
 
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Thanks Spike, I have taken the plunge and ordered the Vagcom cable, it was about time. I'm probably well overdue on the cam belt so will probably do the too together what is the recommended interval on the cam belt ? I have done a lot of motorway driving and the symptoms would suggest something like this although both symptoms occured together so I'm still favouring a sensor some where. Do you know if the webasto circuit is seperate, if so does it have a seperate pump? or is it part of the main water system. if so a vane less or stalled impeller could explain.
Cheers Luke.
 
Hi Luke
I don't think the Webasto has its own circulating pump so coolant flow will be reliant on the engine water pump. Cambelt replacement recommendations have changed a few times but the latest info says 5 years or 75000 miles, whichever comes first

Cheers Spike
 
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Finally got to run the VAG-COM on the car. Car's been under a foot of snow for most of the last month!! So have been driving the 4x4 anyhow fed up with filling it up with fuel so really must get the A2 back on the road.

VAG-COM not showing much of interest other than;
16885 - Vehicle Speed Sensor: Implausible Signal - which ammused me, computer thinks A2 can't possibly be going that fast :)

and

Address 08: Auto HVAC
Controller: 8Z0 820 043 D
Note: Excessive Comm Errors

Any one any ideas what this means?

Any way off to GSF before they shut to get cam belt kit and water pump.
As the cam belt is well over due and may as well do the pump at the same time. Hopefully it is an issue with the water pump. and thermostat whilst I'm there.

I'll let you all know the out come.

LukeS
 
Well well what do you know.
Just took the water pump out and the impeller fell on the floor !!! :eek:
That'll be the problem then. :)

Thank goodness I didn't know what I was going to do if I didn't find a problem

Cheers

Luke.
 
Glad that's solved it! What's the age of your car and how many miles has it done?

Is your new water pump impeller plastic or metal?
 
Just finished getting it all back together.
Quick test drive no over heating and heater working!!
normal service is resumed.

Re mileage 99333 !! Cam belt was well overdue.
impeller is plastic and had clearly been slipping as was very loose on the drive shaft.

I will post some pictures and experiences etc of changing the cam belt and pump to help anyone else thinking of tackling the job.
At a more reasonable hour off to bed now, got to catch a train at 7am :mad:

Cheers

Luke.
 
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