chiod1

I still can't ID the source of my coolant leak. I have some coolant coming from the top of the engine underneath the air intake, on the passenger side. I also find small pools of coolant on the ground, but nothing in between!! the car runs cool, and it doesn't leak while running. It leaks in the middle of the night.Its been happening after the top end of the engine was done...any thoughts? thanks

Bill Ball

Passenger side under the air box? Not sure what you have checked, since you started a new thread rather than just add to the earlier one, but the bolt that holds the fuel pressure regulator to the block penetrates into the water jacket. If loose, it would leak in that area.

AO

Heater hose, and heater valve are suspect too.

SharkSkin

Could also be that coolant burps out of the tank during the initial post-shutdown heatsoak. You can try disconnecting the overflow hose and placing a paper towel under the nipple on top of the coolant tank just before shutdown to check this.

Not saying this is more or less likely than Bill or Andrew's suggestions -- just something else to check.

Nicole

...and you are sure it's coolant, not condensed water from the AC, right?

Is the level in your coolant reservoir dropping?

King James

Does the coolant pool in the area under the thermostat housing? If so, I had the same problem (didn't leak when car was running, pass side drip + coolant pooling in depression under thermostat housing) It is probably the seal under the coolant crossover housing. cheap part but a real pain in the *** to fix. I ran into a world of hurt trying to simply practice due diligence and fix the leak (instead of letting a bunch of little things pile up as we know can happen with these...) 4 allen bolts are diagonally holding the crossover housing to the block. one came out ok, the other 3 snapped...ended up dissolving the the bolts to get the crossover off, then had to drill / helicoil to get everything lined up again, incredibly lousy situation to chase a minor leak. put it all back together, filled w/water to test, and WP started pissing everywhere...phase II - TB/WP replacement.
Bad News - my Weissach has been out of commission for 2 years as a result
Good News - I really know the front/top of this engine like the back of my hand now!

I am literally getting ready to test it for the first time in 2 years this weekend, just need to get my fluids to top her off / charge battery / cross my fingers

Beware!

chiod1

wow, 2 years, good luck, I hope the best for you.

That oring underneath the thermostate housing was replaced and it dry. Its actually pooling under the upper radiator hose, but the hoses are dry as well. Looks like its coming from behind the crossover and streaming to the front.

Bill Ball's suggestion seems to be closest to the situation, Im gonna check that out. Let us know how your testing goes!

Gretch

There is a short hose that goes from the metal y to the coolant reservoir. It is very hard to get at...... if it leaks it can shoot coolant right at the top of the block in the back.

The other suspects have already been mentioned. The water jacket bolt and metal lid, and the shortie hose between the heater valve and the heater core line.

chiod1

where does it attach? on the back of the metal Y? I am assuming you mean the crossover when you say "metal Y", right? thank you!

chiod1

does anyone have pictures of the coolant setup? Thanks

marton

Did you check the clamp on the motor end of this hose? They seem prone to leaking.
slacken the clamp then make sure the hose is well pushed onto the metal tube & tighten again

marton

chiod1

problem solved!! just replaced the coolant bypass hose and clamps. leak free. gaskets 100%. im very happy!

TAREK

Glad your problem was solved. By the way the best way that worked for me to troubleshoot in the past was by revving up the engine and therefore whatever was leaking starts squirting out. Just wear eye protection

blitz928

Bill, so this is true, the bolt that holds the bracket for the damper and regulator(both sides) on the back of the motor penetrates the into the water jacket? I've managed to get a coolant leak after replacing the damper and regulator. I'll be pulling the airbox off tonight to see if this is where it's from but I did have those bolts out when I did the job so I suspect it might be from there.

StratfordShark

When i did intake job on previous S4 I put some kind of sealant (forget which) on threads of bolt which attaches the rear damper bracket. It does penetrate water jacket.