Is my Audi A4 head cracked? What to do?, Last update. 10/13. Spewing coolant. Options

[jk76.914]

I may be in a pickle. My daughter's 2004 Audi A4 1.8T, 105,000 miles, was using some coolant. I looked and looked and looked, there was no evidence of a leak. It used about a pint every 500-1000 miles, so I thought there should be some visible sign, but no. There's no symptom at all. Nothing wet, driveway dry, no smoke, starts good, runs fine....

But then yesterday, after topping it off again, I changed the plugs. The threads on the #4 plug were wet. The other three not. I'm guessing a crack from the plug to the water jacket somehow, and it probably opens up at temperature, seeping coolant into the combustion chamber.

What do you guy's think? The wet threads seem to confirm the diagnosis... Any other ideas? Anybody know if these things are prone to cracking?

Any danger in trying a Bars Leaks sealant? They're pretty well regarded, I think, and they have four products for cracks, head gaskets, etc... I'm thinking of trying the mildest first.

She commutes from Boston to Rhode Island daily, putting about 400 miles on the car every week.

Here's a picture of the 5 valve combustion chamber I found on line. Lots of opportunities here for cracks... Help!

[r_towle]

could be the gasket blew right between the water jacket and the plug.
Where are you specifically located?

Randolf Racing in Randolf
Shine Racing in Attleboro
European Motorsports in Lawrence.

All very good Audi specialty shops...all know the common issues with the motor...all of these guys will treat you right.

At the end of the day you need to pull the head and get it pressure tested to guarantee its not cracked.
Then re-assemble...and that is a new timing belt etc...and a good idea is a new waterpump at that time.
Flushing the coolant and radiator (or replacing the radiator) may also be good insurance...they last about 100k before becoming less than efficient.

I did all of this on my BMW...the radiator was last...and after I did everything else and drove it another 15k miles.
New radiator cooled it way down...so they do need to be replaced...it was not leaking, just no longer up to the task.
It had something to do with aluminum, coolant, chemistry etc...
Its kinda like a clogged artery...a new one does wonders.

Rich

[jk76.914]

Thanks Rich. I'm in Newburyport, so European Motorsports in Lawrence sounds like the place. I'll take it over Friday morning.

Here's what's puzzling me- there isn't any head gasket anywheres near the plug! For those threads to be wet, it's gotta be seeping through a crack, I think.

#4 is on the left in the picture.


Thinking back, the "low coolant" light first came on a few weeks after I had the timing belt changed. My daughter called from I-91 south of Hartford, on her way to New Jersey. It was about 11:00 p.m. in early January. I told her to keep going, but to monitor the temp gauge. If it got hot, she was to get off and get coolant or at least top it off with water (copious warnings about letting it cool off first). I speculated that the coolant hadn't been topped off by the shop. My own fault probably- I should have checked it the next day myself.

She made it in to Jersey, and topped it off the next morning. We've had to watch it ever since, which is about the past 25,000 miles.

Now I'm wondering if the low coolant level left the back of the head (around #4 cylinder) exposed to air inside, which over heated it locally, opening up a hair line crack after a few thermal cycles.

Just guessing until it comes off. I'll let everyone know the answer when I get it. I'm hoping it IS the gasket, because them my head may be serviceable....

Thanks again.
Jim

could be the gasket blew right between the water jacket and the plug.
Where are you specifically located?

Randolf Racing in Randolf
Shine Racing in Attleboro
European Motorsports in Lawrence.

All very good Audi specialty shops...all know the common issues with the motor...all of these guys will treat you right.

At the end of the day you need to pull the head and get it pressure tested to guarantee its not cracked.
Then re-assemble...and that is a new timing belt etc...and a good idea is a new waterpump at that time.
Flushing the coolant and radiator (or replacing the radiator) may also be good insurance...they last about 100k before becoming less than efficient.

I did all of this on my BMW...the radiator was last...and after I did everything else and drove it another 15k miles.
New radiator cooled it way down...so they do need to be replaced...it was not leaking, just no longer up to the task.
It had something to do with aluminum, coolant, chemistry etc...
Its kinda like a clogged artery...a new one does wonders.

Rich