TDI Engine Temp

[tdi alastair]

Hi there, new here, have looked through past posts a bit but none seem to quite answer my problem....................

2003 TDI Passat when driven hard (I don't mean excessively, but not pootling) the temp climbs above its usual 90 degrees right up to the red if you let it, in fact the first time it did the light came on telling me to stop. If you ease off or stop the car cools down back to 90.
Other odd thing, which looking on here would indicate temperature sender is that a couple of times the temp has dropped right back to almost minimum, then for no reason will pick up and go to 90 again.
I have taken the thermostat out, but that was to no effect.

Should the electric fan come on or is that only ac related?

Might go and see if I can find the sender now

Any thoughts would be much appreciated

P.S top hose hot bottom cool as I would expect

Cheers

Al

[tdi alastair]

No One any ideas? I have taken the sender off, may replace it see what happens

[sergiup]

That doesn't sound right at all, all TDi's I've seen (well, I've lived with 2 so far) almost never go above/below 90C once warmed up; one of those stays solid on 90C even in hot weather (40C+ outside temp) while city-driving, so definitely get yours checked out.

I might be wrong, but I seem to recall there are two fans: one for the AC and one for the main radiator, and I'd say that the main one would usually come on unless it's cold enough outside. Maybe someone will correct me if I'm wrong (I can't look 'til I get home).

[tdi alastair]

No, well thanks anyway. I have ordered a temp sender so we will see what that brings!

[Col]

You've done the right thing. The temp senders are notorious. Hope it sorts it.

Don't forget to bleed the system as well after you have changed the sender.

[tdi alastair]

Didn't Work!! Made it boil yesterday, so now know there is something else underlying, I'm bowing out and its off to the garage! It's not my favourite car of the week!

[philnewman2002]

Sounds like the Water pump to me, had a similar problem with my A6, and on short journeys you were okay, but once out on the Motorway, temp gradually climed to over 120, and had to stop....

[sergiup]

Sounds like the Water pump to me, had a similar problem with my A6, and on short journeys you were okay, but once out on the Motorway, temp gradually climed to over 120, and had to stop....

Good point..
Alastair, did you change your water pump with the last cambelt (it should be changed I think)?

[JayB5UK]

I'd put money on Water pump!

Always change or ask the garage / mechanic to change it when cambelt is done. The belt has to come off to do this anyway so it makes sense to change it while the car is apart.

[passat 1 b5]

water pumps on these have a plastic impeller which can break up and thus not work correctly/well this is quite a job as i have just replaced it on my tdi its also worth replacing the thermostat as this is not an expensive part! if neither of these help it could be a blocked radiator coolant system:beerchug:

[ged8365]

i have a very similar problem with my a3 1.9 tdi,i have changed the thermostate,temp sensor and water pump and had the system flushed, still have the same problem, iam going to try and get my radiator tested i will post the results if i can

[Col]

Another check is to;

Feel the bottom hose, if it is cold or very cool despite the engine temp being high, would probably mean head gasket failure.