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!

Click to view attachment

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.

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

Red Devil makes a good product for crack heads .

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.

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!

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

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

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

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

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!

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.

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

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

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.

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

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.
Click to view attachment

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

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

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

There is no way that water could have gotten into the hole from the outside, right?

That was kinda my first mental reaction. VW cooling systems like to ventilate themselves. For the life of me though, I can't think of any hoses near the #4 plug.

I'm just finishing up the same kind of thing on my son's 2002 A6 2.7t. Might be the same deal. We had the same low pressure leak that lost about a pint a month. I was thinking it was a leaking heater hose because it had no liquid hitting the ground. He's about ready to head back to Eugene so I wanted to get it fixed.

Spent a whole day looking. Finally bought a dye pack. Drove it for a couple days. Again I spent hours on the lift digging around. Nothing.

Then for some reason I look under the big Y-pipe of the air intake. There's my yellow dye. Come to find out the 2.7 has an auxiliary electric water pump. I assume either for the heater or the turbo cooling.
The pump casing was leaking. Kind of a cheesy looking little pump.

Had to tear the entire intake system off. 29 electrical connectors to unhook to get it off. Changed the thermostat while was in there. Kind of in there. You have to literally take the entire front of the car off to do that.

Don't know if the A4 has the same thing? Just a thought.

Bad news this is keeping me from finishing up my engine rebuild and getting one of my 914's on the road.
I'm moving from the Audi to my daughters Escort that just dropped a valve seat. That is one horrible noise. I'm just glad it dropped after being parked. Hopefully the cylinder walls are still good. Will probably be doing a rebuilt head and one new piston and connecting rod.
Then hopefully dad can get back to playing with his toys.

I don't think so. The plug bore, coil, etc is dry. There are no hoses anywhere in the area. And those threads are wet below the gasket. That would have been nice...

I think that auxiliary pump is 2.7 turbo only, and it's to keep the coolant circulating after you turn the engine off hot. I also have an A6 4.2 and it has no aux pump.

Jim

I agree 100%! They make a real mess in the coolant system. Aside from what it does to the radiator and heater core if the head is cracked the crap makes it way harder to weld the head.

Plus, do you really want to send your daughter off with the car knowing that a major problem exist and you've dealt with it by simply pouring something into the system? It's a temporary fix at best designed best for a desperate situation like nursing a car home from middle of nowhere, or out of a dangerous neighborhood.

wanna see if its still leaking...its simple.
Pull the plug and remove the wire or coil on plug.
Start the motor.
If coolant sprays out...its leaking and needs to come off.

its a stupid simple test, but it will confirm the problem is not external.
If its leaking...it will shoot out coolant, so have some towels ready.

Rich

go to EMS..tell Michael that Rich Towle sent you...he is an old and dear family friend.

He can hook up a pressure test to the coolant system with the plug out....pump it up without the motor running and spray coolant out if there is a leak...
That is the simple and quick test if you have the proper tools, which he does.

He loves audis, so he knows his stuff.

Rich

WOW!! What a great lead!! I'm stopping by this morning on my way to work. I go right down I-495 on my way to Lexington, and he's right off 495 on 28.

I'll report back. Thanks again guys (especially Rich)!

Jim

one other thing to check.... The heater core. Unfortunately that is not a fun deal as it is really buried in the dash.

Fix it right. The stop leak crap is pure bullshit and WILL lead to other issues within the engine when it finds a capillary and blocks it off. Spend money now or spend more later, its up to you.

Yep. The fix for this problem is not in a bottle.

Fortunately it sounds like Jim got the message. Hope it isn't going to cost you too much.

If he went to Mike he should be fine.
He has been fixing european cars for over 30 years...and he sells them.
Damn we are getting old.
His family (brothers, sisters and parents) all drive audis...
He does like them and knows all the quirks.

I remember his first cool car...an early 60's diamond back split window corvette with a motor that was just amazing.

Here is a guy who rebuilt a lamborgini countach (the classic hard edged one) because he did not like how the heads flowed and knew he could do better...lol
I always laugh about that one...and he still has the car...and a few ferraris.


Rich

I'm heading over to EMS in the next hour or so. They don't open until 8:30, and that was too late for me yesterday- I needed to get to work. Took today off.

Meanwhile, there's a new observation. My wife and I drove it for 3 days (my daughter has her sister's car while we sort through this.) and didn't lose any coolant. Then yesterday, I left work late, so there was no traffic, and proceeded up 128 and 95 at "a high rate of speed". After cruising fast for a while, I smelled coolant. When I checked it this morning after it cooled down, it was low by about a pint and maybe a half. This doesn't connect to the wet threads at all, unless I'm dealing with multiple problems.

Looking forward to meeting your friend Mike.

And yes, we are getting old!

Jim

Have you looked at the water fitting on the back of the head? The plastic one. It's been an issue on VAG cars since they switched to plastic 25 years ago. I sell a TON of 'em.

The Cap'n

Another thought. You're probably already there at the shop. But after all was said and done fixing the aux water pump on the 2.7T A6. I had a leak in a new spot.
So OK what did I screw up? After digging around I found it. On the back of the head is the coolant sensor. Kind of an odd arrangement. Its held in place with a U spring gadget. Somehow while I was digging around all the hoses back there I knocked it loose a bit and it was dripping.
Would have been more than a pint a month and its on the high pressure loop.

Sounds like a "marginal" head gasket to me. BTDT! I had a Triumph many years ago that would hold the coolant level for weeks of normal commuting. Some hard driving like a mountain pass would cause the engine to blow coolant out the overflow tank and eventually overheat. Combustion gasses leak into the coolant chamber, over pressurize, blow coolant, and then it would overheat from low coolant.

Try checking the coolant for hydrocarbons. The test is pretty simple (I think kind of like a special litmus paper test).

I was able to re-torque the head bolts on the Triumph as a short term solution until the engine was totally overhauled when the bearings needed replacement. The re-torque kludge lasted many many months.

Cheers,

Eddie

.....Trade it in on an R-8
(you'll be glad you did!!)
( you said your daughter...*Sorry* bro)

a pressure test properly done will show all leaks....who knows if you have more than one thing going on.

RIch

OK, I'm home

I made it to EMS and met Mike. First of all, he sends his regards, Rich. He's a very knowledgeable guy, and we went out to the A4 to have a look. We could smell coolant as we walked up to it, and that's the first good news, I guess- it's gotten worse, so it should be easier to diagnose. He looked around under the hood while I told him my tale. He also couldn't see anywhere it's obviously leaking, but he said he'd take it in and pull all the plugs and do a leak test and find the problem.

We walked around and looked at his used car inventory- very impressive! A friend of mine came along with me, and he may return and buy a 2006 A6-4.2 with 25,000 miles that Mike has...

So about then we walked back to the A4, and there was a small pool forming from the AC condensate, and Mike said, "wait a minute. Back the car up." So I did and there was a second puddle, about 6" across and centered under the back of the engine. It was coolant.

So neither of us can make a connection between the wet threads and the leak, but I got to thinking about my story, and I remembered that I was remembering it wrong. It wasn't after the timing belt change, in January, that my daughter was driving to New Jersey. It was July, and she was driving to New Jersey after the dash of the car had been torn down at the local Audi dealer to extract the carcass of either a chipmunk or a flying squirrel who had moved into the heating system through the cabin air filter, and then died there. Now I'm thinking they monged up the heater core, or didn't tighten a clamp or something. Now that I'm smelling coolant inside the car, and now that a puddle has seen fit to form under the car. Still can't connect to the plug threads, but I'm dropping the car off to Mike on Tuesday, and I'll report back.

Thanks everybody, for the interest, advice, and reference (Rich). Mike also does insurance appraisals, and I still need my 914 appraised for my new insurance company. So that'll be next.

Here's the car my buddy looked at-
Click to view attachment

Believe it or not, things are making more sense. The 1.8t (and most VAG engines) are very sensitive to cooling system leaks. With the advent of more and more plastic parts, this seems to be popping up more often but the problems go all the way back to the old 1.6l engines. If there's a minuscule leak, even so small only gasses escape, the system can't pressurize properly. Under pressure, the coolant cannot turn to a gas at higher temperatures. When the pressure is relieved, gasses can form almost anywhere in the system and create hot spots while the overall temperature of the coolant seems normal. Since the head is the highest point in the system, that's where the hot spots generally occur. This can cause cracking in the head but normally it's just warpage.

On a somewhat related note, I've run across any number of people who are pissed that VW switched to plastic water pump impellers as they tend to go out early and often. On every one I've come across, there was a leak somewhere else in the system. Most often, a worn overflow tank cap.

I'm overdue for an update...

Took the car in to EMS, and they had it for 2 days (2nd day mainly waiting for parts). Pressure test showed ROHAR was right about the plastic- there is a plastic outlet (or inlet?) flange on the back of the engine near the firewall that opened up under pressure. They replaced all of the plastic plumbing with new- both for coolant and for crankcase vents. Wasn't cheap, but I consider it high value because of the extent. I drove the car for a couple of days, and then delivered it back to my daughter. We're monitoring coolant level every couple of days, but so far so good. Still can't explain the wet plug threads.

Last post on this topic. Car is spewing coolant. Daughter was stranded on the interstate during rush hour. Called EMS. Turns out, he never did the pressure test. He said that 90% of the time, they just replace the plastic plumbing with new, and that fixes it, so that's what they did. $781. I limped it in to Autobahn Performance (Peabody) last night, stopping 4 times to top off water. Drove it with the cap off so I didn't have to wait for a cool down. Assuming the worst: shopping for a new head.

Too many chances for cracks- these 5 valve heads are like swiss cheese. Thinking they should have gone to 4 valves and made up for it by dialing in a bit more boost on the 1.8 turbo. They max out at 8.6 psi only. Five valves was probably too much of a marketing gee-whiz to give up.

Damn these water-cooled cars.