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!

[Mike Bellis]

Might be a cracked head. Might be a head gasket. Either way you will need to fix it. The stop leak may work for a while. Or not at all. You could try it. Most of these typs of leak seal need a hot engine to work. Make sure you follow the directions exactly. Remember, these types of products all plug up radiators also while fixing a leak. Any pinch point in the cooling system will attract the stop leak.

[914.SBC]

Thats too bad. Sounds like a cracked head and hopefully like the other member said, it is a head gasket.

[vtursi60]

Red Devil makes a good product for crack heads .

[HAM Inc]

It is more likely that you have a head gasket failure than a cracked head.

In my 27years of cylinder head work the situation where a crack would open and leak coolant at operating temperature, but not leak at ambient temp has been so rare that I can't recall a specific incidence of it. When castings relieve themselves and crack, the crack will usually leak all of the time.

Your head may cracked, but it might be such a small crack that when the engine is cold and not running (with no coolant system pressure) that it is not detected.

It sounds like the head needs to come off. Have it pressure tested and resurface.

[rohar]

1.8ts are prone to head gasket leaks at over 100k. The head studs tend to stretch a little over that much time. I'm with HAM Inc. the head has to come off. On the up side, these heads come off pretty easy. I'd bet if there is a crack, a visual will find it, but a pressure test would be more convincing. When you put it back together, use a quality head gasket and NEW head studs. The factory studs are not intended to be reused as they're designed to plasticate on install. I'd suggest ARP studs for replacement and don't skimp on a cheap torque wrench.

GOOD LUCK!

[Valy]

I bet is just the gasket.
Pull the head and check. No other way to do it anyway.

[r_towle]

It is more likely that you have a head gasket failure than a cracked head.

In my 27years of cylinder head work the situation where a crack would open and leak coolant at operating temperature, but not leak at ambient temp has been so rare that I can't recall a specific incidence of it. When castings relieve themselves and crack, the crack will usually leak all of the time.

Your head may cracked, but it might be such a small crack that when the engine is cold and not running (with no coolant system pressure) that it is not detected.

It sounds like the head needs to come off. Have it pressure tested and resurface.

I guess BMW 6 cylinder heads are left out of this thought...they all leak once cracked, but only at hot temps...

I agree, pull it off and spend a few bucks to have it pressure tested.

I found that you can shop around and find a head that is ready to bolt on faster than getting yours fixed...and typically its cheaper.

There is a guy in Alabama that wll ship you a head and wait for your core head.
The classic BMW crack is between the water jacket channel and the exhaust port.
It opens up at high temps and all the coolant gets burned up...so there is almost no trace of the leak till you do a pressure test on the head.

Rich

[jk76.914]

Thanks for all the replies. Groan. Not sure if I'm up for pulling the head myself. Do you have to pull the front of the car off, like when you do a timing belt?

Any suggestions as to a shop in eastern Mass that would do a good job for a fair price?

What do you guys think about this deal?

http://cgi.ebay.com/ebaymotors/00-05-VW-PA...=item4cf99a9261

[r_towle]

Randolf Racing.
My buddy brings his audi there all the time.

To replace the head you replace the timing belt at the same time...its connected to the head.
So, yes....

Rich

[Bleyseng]

Says "Made in Taiwan" so I wouldn't buy it for my daughter as I hate those late night calls at 2AM "Daddy, the car broke down and I am all alone here".
Now if I was going to unload the car, sure!

[HAM Inc]

I guess BMW 6 cylinder heads are left out of this thought...they all leak once cracked, but only at hot temps...

Rich I've repaired many-a M20, M50,-M54 BMW head over the years. They do leak when not running, just notmuch. The cracks typically won't pass enough fluid when the engine isn't running to be noticed. But let the car sit for a long time and the coolant will slowly drain through the crack. Seen it plenty of times.

[Mikey914]

10:1 on the headgasket, especially if you are running a modified boot profile.

[jk76.914]

It sounds like the head has to come off either way, but why would the threads on the plug be wet if its a head gasket? They're wet all the way to the plug's gasket. And I don't mean damp- visible liquid water. The tip itself looks like normal usage- light brown/tan deposits. The bore in the head where the coil tube sits, and the coil itself are dry.

Thanks again for the help. I'll follow up when I know the final plan.

Jim

[HAM Inc]

Jim it's definitely possible that you have a cracked head. Statistically it's way more likely that a head gasket will fail than the head will crack, but as we both know, both can happen. And both can happen to the same engine.

[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

[Mike Bellis]

Your cooling system is blowing steam into the cumbustion chamber at 13-16psi. Your valves and entire cumbustion chamber are problably wet too.

[brant]

I HATE all "stop leak" or "head gasket in a can" type products
do not pour that crap in your engine please


if you do you will likely be soon replacing your heater core, all water lines, cleaning out the solid tubing water lines, new radiator, and then new head.

I recently did a head gasket job where the owner poured that crap in to fix a bad head gasket.

All of the passages between the block and the head were completely sealed. Guess what happens when NO water gets to the head on an water cooled engine. Its a fun way to warp everything!

don't use the late night TV products. They are a sham... snake oil... (and not the good kind of snake oil that Jake sells)


check the exhaust pipe while running. You might find the motor is burning the coolant off. That could foul out or cause a wet plug. Shine a flashlight into the spark plug hole. If all of the carbon build up is cleaned off of the piston and its shiny clean, that is a sure sign your burning coolant.


brant

[jk76.914]

I HATE all "stop leak" or "head gasket in a can" type products
do not pour that crap in your engine please


if you do you will likely be soon replacing your heater core, all water lines, cleaning out the solid tubing water lines, new radiator, and then new head.

I recently did a head gasket job where the owner poured that crap in to fix a bad head gasket.

All of the passages between the block and the head were completely sealed. Guess what happens when NO water gets to the head on an water cooled engine. Its a fun way to warp everything!

don't use the late night TV products. They are a sham... snake oil... (and not the good kind of snake oil that Jake sells)


check the exhaust pipe while running. You might find the motor is burning the coolant off. That could foul out or cause a wet plug. Shine a flashlight into the spark plug hole. If all of the carbon build up is cleaned off of the piston and its shiny clean, that is a sure sign your burning coolant.


brant

Piston crown looks about the same in #4 as in the rest. (I looked in with a flashlight.) Also, the business end of the plug looks the same as the rest- dry with light brown/tan deposits. It's the threads that are wet, and they're wet their whole length. If there's a crack between the water jacket and the plug bore, it's up the threads near the gasket seat. Coolant is being metered down the thread sprial into the combustion chamber. At least that's my current theory.

I'll see when I get into it. I'm not putting any sealant into the engine until I'm convinced there's nothing left to loose.

Jim