Lemon Juice

Having problems with a slow leak in the coolant system. Audi technician pressure tested the system and said it was good. I replaced the expansion tank as it was poo brown. Seems to have helped a bit but... still have this feeling like this car is going to cost me another bundle of money.

I'm thinking I should've replaced the cap with the new tank. Go figure Audi doesn't give you a new cap when you buy the tank.

Has anybody had any issues with a faulty expansion tank cap?

2002 A4 Q 1.8t
145,000kms

pcasso87

Thats sucks bro!! sad to hear about that

Espritman99

the liquid was brown in the expansion tank? Like milky looking? If so that doesn't sound very good at all . Sounds like oil mixing with coolant. If thats the case, could be something like a head gasket or the better alternative, an oil cooler if your car is equipped with one. My bosses '00 Passat with the 1.8T has the same milky colored coolant which means oil is getting in somewhere, but been like that for awhile without any noticeable issues in regards to overheating and power. His car has 275k km's on it and he just plans to drive it until it stops.

Lemon Juice

Thanks guys.

What I meant when I said the tank was brown was that the actual plastic was a brown colour (the new one is white). When I took the old tank out I did see some small cracks along the bottom and back side closest to the firewall. I'm always checking the oil for coolant and can't smell any coolant burning so I'm thinking gaskets, etc are good.

What I think is happening is the cap on the expansion tank isn't forming a good seal around the tank and when the coolant condenses it's pooling under the cap and dripping down through the overflow and onto my driveway. I only notice a small pool under the car when it's been parked for a few days in a row.

Make sense to anybody else?

K04-S4

Shine a light straight down between the middle intake runners and see if there are two small puddles of coolant on the lower block lip. If so, could be the $7 plastic coolant plug in the block common to leak... held on with one screw.

Lemon Juice

Thank You. That was it. Finally got around to it today. Problem solved... I hope.

Thanks again for your help.

K04-S4

That's the one... bit of a PITA!

thealla

what is that called?

banana plug?

Lemon Juice

J Plug

Part # 06B-103-033-A $12.54 CAD at the dealership.

CaRtharsis

Hey, this sounds like what i've been told is my problem. I've had this plug replaced twice in the past 6 months and it is leaking again. I broke my ankle a week ago so I am unable to confirm is this time but there is coolant leaking in the driveway again.

Is there a more permenant fix for this issue? Its become quite a nuissance.