Coolant Leak (with pics)

[Denio24]

This is my sister's car. I haven't really noticed any major coolant leaking on this vehicle, but now says she has no heat. I topped off the coolant res. and now the engine stays on the cold side of the temp gauge; we may be looking at two separate issues here but who knows, it may be somehow related. What do we think? I'm placing my bets on coolant flange.

photo slideshow: LINK

[APR_Fast]

Looks like coolant flange on the rear of the engine with possibly a bad coolant temp sensor(does the coolant temp gauge bounce around?) the sensor is cheap enough so replace it with the assembly. the other one looks like the thermostat went hence why the no heat possibly the j plug too started to leak.

Unfortunately, common problems but well documented on how to fix them.

[Menyahs]

Based on your pictures I would second T-Stat & J plug. I just replaced mine again with a refresh kit from ECS. Thermostat was sticking open sometimes and car would take along time to get up to temps, or just stay around the 1/4 mark on the gauge. I had small leak in the same location. When I started tearing it down I found the old plastic J plug was cracked in half and leaking.

Coolant flange is located on the rear of the engine so that doesn't look like the source in your pics. Could also have air in the system if you have no heat, but my money is on a sticking T-stat.

If you really want to nail down the source of the leak before spending money on parts I would recommend getting a cheap UV dye kit. I added it to the coolant, drove for a few days then inspected with a UV flashlight. Made it easy to confirm where the leak was coming from.

as APR_Fast said there are a lot of treads on the subject to help you figure it out.

Just make sure it doesn't get too hot. . . . if the gauge creeps up above noraml tell your sister to pull over and stop driving immediately. First time I had this same issue it was fine until I got 400 miles from home then t-stat got stuck in the closed position, over heated my engine and resulted in $2200 with of repairs.

[ECS Tuning-Audi]

I'd say from the looks of those pics you have a leaky rear flange and possible leaking thermostat or j-plug.

How many miles are on the vehicle? Do you know when the last time the water pump/timing belt were serviced? I only ask because the coolant towards the front of the engine around the front of the oil pan most of the time means the o-ring for the water pump is failing. You can squeak by by just replacing the o-ring but you'll need to tear it down pretty much the same way you'd do a water pump/timing service so you might as well do everything while you're their to avoid future issues that could arise down the road.

Jason