1992 Passat cooling system/temp gauge | Technical matters | Back Room Forum

Fri 10 Dec 2004 16:42

1992 Passat cooling system/temp gauge - tamginelli

Hi,
Im having bother with the cooling system on my 92 passat 1.6 TD.
After idling for a while the temp goes up as expected, but at speed it just sits at 70 (lowest mark on the gauge). Also, the heater isnt blowing hot air at speed. The manual says it should be at about 90 degrees, normal running.
Does this mean it isnt getting round the engine since its not getting hot?
I drained, flushed and refilled the system with coolant a couple of weeks ago, but didnt remove the thermostat (realised this after reading grahamf1's post this month!). Could this be causing the problem....but it rises when stationery!!
Cheers,

T
--
Remember, fun is the key, but remain seated at all times or you may die. SHABBA!

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Fri 10 Dec 2004 18:55

1992 Passat cooling system/temp gauge - Roberson

It sounds like the thermostat to me. The chances are that its worn out, and not closing up when it should. When working properly, the thermostat is closed when the engine is cold, allowing the water to circulate only within the engine and not the radiator. This allows the engine to warm up quickly. When a set temperature is reached, it will open and allow cold water to flow from the radiator. But if the temp drops too low, it will close back up again and allow the temperature to rise.

With yours, it is jammed open, so the cold water (cooled by the airflow through the radiator when moving forward) is allowed to flow through both the engine and radiator, and thus it isn?t being allowed to warm up. When the engine is just idling, the lack of airflow through the radiator means it will gradually allow the coolant to warm, but as soon as you move off, the airflow cools it down.

Hope that made sense.

So, I suppose you could change the thermostat, cos they don?t cost much, and I can't think of what else it might be.

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Fri 10 Dec 2004 20:15

1992 Passat cooling system/temp gauge - Civic8

As Roberson said..It is the only temp control of the engine..
plus it wont do much for fuel consumption..
--
Steve

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Fri 10 Dec 2004 20:19

1992 Passat cooling system/temp gauge - tamginelli

Roberson, that sounds good to me! Give that a go tomorrow. Cheers!
as for fuel consumption, I hope it is giving me poor figures...Ive done 715 miles from a full tank with a fair bit left to go! Hopefuly fixing this gives me better consumption again.

Cheers chaps!

T
--
Remember, fun is the key, but remain seated at all times or you may die. SHABBA!

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Mon 13 Dec 2004 09:10

1992 Passat cooling system/temp gauge - GrahamF1

My girlfriend's Fiesta is also doing this (temp needle just getting into the 'normal' area but not rising to 90 degrees, and I've recently done the coolant on this (and did remove the 'stat this time!)

But she assures me that it never used to get any higher than this anyway...

Might just change the 'stat for peace of mind if it's quite cheap.

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Mon 13 Dec 2004 13:29

1992 Passat cooling system/temp gauge - Cliff Pope

Before reading too much into figures shown on a rather crude gauge, I think it's worth checking that the gauge is reading correctly.
Take the sender unit out, earth it with a jump lead, and hold it in a pan of just-boiled water. That should be the reading to aim for with the engine.

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