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Coolant Light Flashing

712 Views 4 Replies 3 Participants Last post by  fat biker
I have a 1990 Jetta 1.8L Yesterday the coolant adapter on the side of the block cracked and I had it replaced, no problem. I went to the car this morning and the coolant light is flashing, it had only been warming up for about 2 mintues and according to the temperature gauge was nowhere near hot. The owner's manual says this light will flash if the coolant is too hot (it wasn't) or it is low on coolant (again, oit wasn't). Could the sensor that also attaches to that adapter be broken or not connected properly? Or is it something else? After having the work done yesterday I drove the car home (over 60 miles) with no lights flashing or heat problems. Hmmmmmm. Any ideas?
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Re: Coolant Light Flashing (jman73)

The coolant level sensor in the top of the coolant resevoir tends to fall apart with regular frequency. Could be the added pressure in your system after fixing the leak has shown it's fallablity. So pull it out and check and see if the probe end is split badly. Also, make sure it's snugged down in the tank. If it's bad, it can send some wierd data through the system. The problem is probably with the resevoir level sensor, because I think if the sensor in the outlet gives off a bad reading, the needle pegs.
Still though, since you were messing in that area, you should check the connections, and possibly replace the temperature sensor in the outlet as well, since the increased pressure can mess with that old sensor too. Both sensors are easy to replace yourself, but if you're replacing the one on the outlet, you will leak some coolant when you pull it out.
Re: Coolant Light Flashing (BookerDog)

Thanks for the info. I was not aware of the sensor in the resivoir. Any idea how much the sensors cost?
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Re: Coolant Light Flashing (jman73)

I think I got mine for about $20-25 at a dub parts place but I'm not exactly sure. I had to call around a bit. If your coolant resevoir is showing signs of some pressure cracking around the top, this is a good time to replace this too. Might check online with Impex(vwparts.com) or any of the other numerous online good parts places mentioned around here (parts4vws.com or germanautoparts.com)
Re: Coolant Light Flashing (jman73)

How did you fill the cooling system? It is easy to leave air trapped in the system.
I find the easiest way to fill is remove the top hose from the radiator and fill the system there.
Good luck,
fat biker
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