Head Replacement

[mjmatos]

Hi all,
Tomorrow i will be starting the tear-down of my beloved girl to replace what i believe is either my HG or the cylinder head. A little background on the car, I purchased it in Feb of 2014 completely stock, now... not so much
without the spacers!
. recently I've been experiencing extremely rough idle. After I started noticing the rough running and misfiring i brought it to my mechanic to have him take a look. He gives me a call and tells me that my TB is so loose it can be moved and i confirmed before having him do the TB, after he told me this i assumed maybe my tensioner had failed causing the symptoms as this seems to be a common failure point. After having a full TB service to make sure all timing components were operating as they should, i thought i would have been fine.. NOPE misfires started occurring again and it actually started running WORSE than before, white sweet smelling exhaust, misfires on all four. After a bit of troubleshooting i decided to check the oil as i read on the forums to check, low and behold oil and coolant were mixing. Being that i have already spent major bucks on replacing the head last year (4 cracks along some intake runners) this time around I decided it’s time i DIY it.

So far I think i have read all of the DIYs on AZ, AW very informative stuff, i also found Pelican Parts has some step by step procedures with pictures as well, i will link them below in case anybody needs them. I received the parts a few days ago and moved the car to a buddys house to start the project! Although i have read all the threads and such i would like to ask if there's anything i should be looking out for when performing the job to make it easier and less stressful. here's what i ordered so far, all from europaparts

Vlave Cover/Head Gasket Set on sale $70
10 OEM head bolts $18.95
Oil Change Kit $47.90
head bolt tool $20.00
cam chain tool $25
TB Kit - $69.04 Serp belts,coolant locktite cam&crank seals, crankshaft bolts x 4, TB sticker
Rear coolant flange kit $37
Shipping UPS Ground - $19.95
Total: $308.45

I ended up not ordering a new WP, tensioners,and TB since it was just replaced less than 100miles ago.

[diagnosticator]

I do not know of any confirmed occurrences of 1.8T cylinder heads cracking such that coolant can leak into the cylinders. 1.8T cylinder heads just don't fail that way. There are lots of alleged but unconfirmed cracked and leaking cylinder heads, but I don't know any actual heads cracked that caused coolant to leak in to the cylinders. This is because of the design of the 1.8T head casting and the locations of the cooling jackets in the head.

[tHatOne guY]

After the cyl head R&R how do plan on getting the sludge out of the rest of the engine?

[mjmatos]

I do not know of any confirmed occurrences of 1.8T cylinder heads cracking such that coolant can leak into the cylinders. 1.8T cylinder heads just don't fail that way. There are lots of alleged but unconfirmed cracked and leaking cylinder heads, but I don't know any actual heads cracked that caused coolant to leak in to the cylinders. This is because of the design of the 1.8T head casting and the locations of the cooling jackets in the head.

What do you think could have cause the issue? Last time around the car had overheating issues, this time no overheating

[Seerlah]

Oil cooler. Doesn't account for the misfires, though. Do a compression test.

[mjmatos]

After the cyl head R&R how do plan on getting the sludge out of the rest of the engine?

Well for the cylinder head I'm contemplating purchasing a remanufactured head once installed I will be performing a sea foam treatment at the appropriate time, I'm sure with the new head there's a break in period before I can perform the sea foam not to sure on the tho

[mjmatos]

Oil cooler. Doesn't account for the misfires, though. Do a compression test.

Once I start the tear down I'll be performing a leak down test this should suffice I believe

[diagnosticator]

What do you think could have cause the issue? Last time around the car had overheating issues, this time no overheating

Defective head gasket.

[mjmatos]

heres a video on how it was running, I was reading up on the oil cooler as well may be something to look into if the leak down test comes back fine

[walky_talky20]

You can loop the oil cooler lines (ie: bypass the cooler) for a while to be sure. But the cooler won't explain coolant-smelling smoke from the exhaust, of course.

I'm curious about the cylinder heads you've had. Were they both AMB heads (from B6 chassis)? Did either cylinder head say "Germany" on it? Or were they COSCAST heads?

[mjmatos]

You can loop the oil cooler lines (ie: bypass the cooler) for a while to be sure. But the cooler won't explain coolant-smelling smoke from the exhaust, of course.

I'm curious about the cylinder heads you've had. Were they both AMB heads (from B6 chassis)? Did either cylinder head say "Germany" on it? Or were they COSCAST heads?

Walky the first time around I was replacing the original cylinder head AMB code, the second head was a rebuild junkyard head also AMB, maybe the replacement head wasn't in the best condition who knows, and the coolant smelling exhaust is what leads me back to the head gasket here's a video of the exhaust

[diagnosticator]

I was reading up on the oil cooler as well may be something to look into if the leak down test comes back fine

A leak down test or a compression test cannot reveal a failed head gasket that is leaking coolant into the crankcase and cylinders. When the head was installed last time, were new head bolts used?

[diagnosticator]

Well for the cylinder head I'm contemplating purchasing a remanufactured head once installed I will be performing a sea foam treatment at the appropriate time, I'm sure with the new head there's a break in period before I can perform the sea foam not to sure on the tho

It is unlikely that Sea Foam will be effective. Instead, buy a gallon of BG Products engine flush, the same flushing solvent used by the Audi dealerships for removing sludge from engines. Audi won't sell this product over the counter, you need to buy it from the local BG Products rep. About $70 for a gallon jug. There is an Audi TSB with instructions on how to perform the sludge flush. The BG sludge flush is a unique mix of chemicals and motor oil. It contains ammonia and other strong detergents. I have used this product on sludged engines with low oil pressure with good results restoring oil pressure.

[Dame1009]

You can buy BG products from any Napa auto store or you could also use Liqui Moly engine flush as well. You should be able to get that at Autozone.


Sent from my iPhone using Tapatalk

[mjmatos]

A leak down test or a compression test cannot reveal a failed head gasket that is leaking coolant into the crankcase and cylinders. When the head was installed last time, were new head bolts used?

As mentioned before I think looping the oil cooler should help in this diagnosis. Last time new head bolts were used to my knowledge this was a very reputable engine builder I called them back recently, now they do not work on VAG cars anymore because they are to difficult! I just hope through the rebuild they didn't skip any corners.

[mjmatos]

It is unlikely that Sea Foam will be effective. Instead, buy a gallon of BG Products engine flush, the same flushing solvent used by the Audi dealerships for removing sludge from engines. Audi won't sell this product over the counter, you need to buy it from the local BG Products rep. About $70 for a gallon jug. There is an Audi TSB with instructions on how to perform the sludge flush. The BG sludge flush is a unique mix of chemicals and motor oil. It contains ammonia and other strong detergents. I have used this product on sludged engines with low oil pressure with good results restoring oil pressure.

Thanks diagnosticator glad I didn't move forward with sea foam, do you think this would harm a remanufactured head if the head ends up being replaced?

[mjmatos]

You can buy BG products from any Napa auto store or you could also use Liqui Moly engine flush as well. You should be able to get that at Autozone.


Sent from my iPhone using Tapatalk

Hey dame thanks for chiming in, I will for sure take a trip to go grab some, if they are out I'll just look for the closest dealer as diagnosticator mentioned.

[diagnosticator]

You can buy BG products from any Napa auto store or you could also use Liqui Moly engine flush as well. You should be able to get that at Autozone.


Sent from my iPhone using Tapatalk

The BG Products engine flush used by Audi is only available from a BG Products rep. It is proprietary for Audi, developed by BG Products exclusively for use by Audi dealers and not sold through the retail channel. The BG Products engine flush used by Audi dealers is intended for professional use only and requires following the application instructions described in the Audi TSB. The BG Products engine flush is far to complicated to apply and is to toxic for use by the general public or typical Audi owner. The Liqui Moly product is not comparable to the BG Products engine flush.

[diagnosticator]

Thanks diagnosticator glad I didn't move forward with sea foam, do you think this would harm a remanufactured head if the head ends up being replaced?

The special Audi BG Products engine flush cannot harm any engine parts.

[diagnosticator]

As mentioned before I think looping the oil cooler should help in this diagnosis. Last time new head bolts were used to my knowledge this was a very reputable engine builder I called them back recently, now they do not work on VAG cars anymore because they are to difficult! I just hope through the rebuild they didn't skip any corners.

Worrying about the oil cooler is irrelevant in this situation. A failed oil cooler cannot cause the white sweet smelling smoke that is occuring, since a failed oil cooler cannot cause coolant to get into the cylinders to be burned at the volume needed to cause the smoking, and is inconsistent with all of the symptoms evident.

[mjmatos]

The special Audi BG Products engine flush cannot harm any engine parts.

Ok great thank you

[Militant-Grunt]

Make sure cylinder #2 valve seat on the head isn't cracked, extremely common on AMB heads. They leak coolant through there, and it will behave like a bad head gasket. Its as if AMB generation motors all had a bad casting in the head and only on that cylinder.

[mjmatos]

Make sure cylinder #2 valve seat on the head isn't cracked, extremely common on AMB heads. They leak coolant through there, and it will behave like a bad head gasket. Its as if AMB generation motors all had a bad casting in the head and only on that cylinder.

This was my issue with the previous head and I have a feeling this is what is causing the issues or a defective HG once I start working on it today I'll check a few things and report back my findings

[diagnosticator]

Make sure cylinder #2 valve seat on the head isn't cracked, extremely common on AMB heads. They leak coolant through there, and it will behave like a bad head gasket. Its as if AMB generation motors all had a bad casting in the head and only on that cylinder.

It is absolutely impossible for coolant to leak from crack/s between the valve seats like shown in the pic. This is because there are no coolant jackets near the bridges between the valve seats. In fact, if there was coolant jackets near the valve seat bridges capable of leaking coolant from cracks in the valve seat bridges, the cracks that develop there would not occur because the cracks are thermal stress cracks that result from less than optimum cooling of the bridge between the valve seats. Audi approves reusing heads with cracks between the valve seats provided the cracks are not more than ~0.8 mm wide. These common cracks do not effect the head gasket in any way.

[mjmatos]

Plugs from 1-4 L-R

[diagnosticator]

Plugs from 1-4 L-R

Looks like the coolant leak is at cylinder #3.

[customa4]

It is unlikely that Sea Foam will be effective. Instead, buy a gallon of BG Products engine flush, the same flushing solvent used by the Audi dealerships for removing sludge from engines. Audi won't sell this product over the counter, you need to buy it from the local BG Products rep. About $70 for a gallon jug. There is an Audi TSB with instructions on how to perform the sludge flush. The BG sludge flush is a unique mix of chemicals and motor oil. It contains ammonia and other strong detergents. I have used this product on sludged engines with low oil pressure with good results restoring oil pressure.

Agree with diagnosticator 100%. I've had nothing but positive experiences with BG and was gonna chime in with the same response. I went to a local VW and they said that's exactly how they deal with sludge without dropping the oil pan. I think it may take 1 or 2 oil changes to get through the BG flush though so pay attention to the instructions.

I've also had good experiences with BG MOA(prevent sludge), BG 44K(fuel system cleaner)and BG EPR(Engine Performance Restoration, good to clean piston rings and help compression).

Also wanted to mention I've had no problem buying these products over the counter at numerous dealerships. Only one I was not able to find a dealer to stock it was the EPR. The MOA and 44K were readily available at most dealerships, even Nissan and Toyota dealers. The sludge product can most likely be purchased from an Audi/VW dealer.

[Seerlah]

Take off head, have machine shop inspect and pressure test it, and go from there. But if you are replacing the head anyways, no need for the old head inspected. But you must be sure the replacement head has a proper decking prior to putting on to the short block. An absolute must!

With your exhaust being the way it is and plugs showing confirmatiin it is from the combustion chamber, head has to come off regardless.

[mjmatos]

Agree with diagnosticator 100%. I've had nothing but positive experiences with BG and was gonna chime in with the same response. I went to a local VW and they said that's exactly how they deal with sludge without dropping the oil pan. I think it may take 1 or 2 oil changes to get through the BG flush though so pay attention to the instructions.

I've also had good experiences with BG MOA(prevent sludge), BG 44K(fuel system cleaner)and BG EPR(Engine Performance Restoration, good to clean piston rings and help compression).

Also wanted to mention I've had no problem buying these products over the counter at numerous dealerships. Only one I was not able to find a dealer to stock it was the EPR. The MOA and 44K were readily available at most dealerships, even Nissan and Toyota dealers. The sludge product can most likely be purchased from an Audi/VW dealer.

I was doing some research on the BG Products, they will for sure be making their way into my hands i cant believe i didn't know about this before! I will look up some dealers tonight and get the ball rolling i think i have found the instructions on the cleaner I will post later to confirm.

[customa4]

I've been posting to the forums for a while now about BG products and how amazing they've been. I kinda swear by it so much, one would think I'm a paid advertiser. I just know from my experience the stuff has worked wonders for every single thing I've used it for.

[thetikm]

You say it is impossible, but it happened to me. I had a similar crack to the one in the picture and would have misfires on cold starts. Once the engine warmed up the crack would close and run perfectly. Left the car sit for a week and the cylinder was full of water.

[diagnosticator]

You say it is impossible, but it happened to me. I had a similar crack to the one in the picture and would have misfires on cold starts. Once the engine warmed up the crack would close and run perfectly. Left the car sit for a week and the cylinder was full of water.

Then the coolant leaked into the cylinder from some place else. It is physically and technically impossible for coolant to leak from a crack between the valve seats simply because there is no coolant anywhere near the bridge between the valve seats, there is only solid metal. Coolant cannot leak from solid metal. It is as absolutely impossible for coolant to leak from a crack between valve seats to actually happen as it is absolutely impossible that an imaginary situation that defies the laws of physics will happen, as would be required for coolant to leak from a crack between the valve seats. Regardless, if you believe physically impossible events and conditions occur then you can believe what you want, but your belief does not change the reality of the technical facts involved.

The definition and meaning of the words, "Absolutely impossible" is not open to interpretation, there is no debatable alternative meanings of the terms here.

[thetikm]

Then the coolant leaked into the cylinder from some place else. It is physically and technically impossible for coolant to leak from a crack between the valve seats simply because there is no coolant anywhere near the bridge between the valve seats, there is only solid metal. Coolant cannot leak from solid metal. It is as absolutely impossible for coolant to leak from a crack between valve seats to actually happen as it is absolutely impossible that an imaginary situation that defies the laws of physics will happen, as would be required for coolant to leak from a crack between the valve seats. Regardless, if you believe physically impossible events and conditions occur then you can believe what you want, but your belief does not change the reality of the technical facts involved.

Do you have a picture of the coolant route through the head? Just by looking at my and quite a few others experience and the machine shops pressure test it just seemed like that was the answer. It would be nice to figure why amb heads have these problems.

[diagnosticator]

Do you have a picture of the coolant route through the head? Just by looking at my and quite a few others experience and the machine shops pressure test it just seemed like that was the answer. It would be nice to figure why amb heads have these problems.

The situation with cracks between the valve seats, is not limited to just the AMB head. Other VW/Audi group engines with similarly designed head castings experience the same cracks between the valve seats. This situation has existed for many years now, since the water cooled Audi engine was first integrated into the VW family of engines back in the early '70's.

I do not have a coolant jacket layout diagram for the cylinder head. However visually inspecting the cylinder head bridges between the valve seats, will reveal the fact that there is a lot of metal between the valve seats and the regions in the head casting where cooling jackets can be located. I estimate without looking at a head that the thickness of solid metal between the valve seat bridges and the cooling system jacket nearest the valve seats is at least 1.5 to 2 inches.

The cracks are caused by thermal stresses near the combustion chamber surface that eventually cause the cracks to develop due to poor cooling of the valve seat bridges, more common on higher thermally stressed modified tuned engines. If there was coolant close enough to the bridges between the valve seats to leak from surface cracks between the valve seats, then the thermal stress surface cracks that occur would not develop in the first place.

[Kevin C]

Do you have a picture of the coolant route through the head? Just by looking at my and quite a few others experience and the machine shops pressure test it just seemed like that was the answer. It would be nice to figure why amb heads have these problems.

A snip from a picture taken be Integrated Engineering. This is a top view of the combustion chamber and shows where the water jackets are.


Opposite side of the head.


If you see a crack like this and have a clean combustion chamber (a good indicator of a leak) get the head pressure tested.

[diagnosticator]

Kevin,

If the structure of the head is examined without the valves installed, it will be seen that the height of the port walls that form the bridges between the valve seats, is at least an inch tall from the opposite side of the port walls to the combustion chamber surface of the bridge between the valve seats. The thermal stress cracks that develop at the combustion chamber surface of the bridge between the valve seats, does not extend more than an 1 or 2 mm at the deepest, and with at least an inch of metal from the surface of the valve seat/port wall bridges to the nearest coolant jacket, it is not possible for coolant to leak from the surface cracks that develop between the valve seats. The plane where IE cut the head casting is undefined in the pics, and only obscures the situation here, since cuts on different planes will reflect different cross sectional views of the head casting.

To confuse the situation further, many automotive machine shops are ignorant of the facts involved with the common surface cracks that develop between the valve seats and will often refuse to pressure test or rebuild a head with surface cracks evident, claiming that the head is faulty beyond usefulness, being uninformed of the technical facts associated with the surface cracks that are often visibly present at the surface between the valve seats.

With these facts in mind, and with Audi's official approval of reusing heads with cracks less that 1mm wide, there is nothing to be gained by pressure testing heads with these surface cracks existing. Recommending pressure testing in these situations only continues the pervasive misunderstanding of the actual factual situation regarding cracks between the valve seats, at least implying the possibility of coolant leaks from the surface cracks despite the actual impossibility of coolant leaks occuring, resulting in wrongly condemning many heads that are otherwise in reusable condition. This is the typical consequence of misunderstanding the facts involved, costing Audi owners a lot money that does not need to be spent attempting to fix an imaginary non- problem.

Finally, I believe a lot of guys think that the cracks are responsible for coolant leaks into the cylinders, misunderstood when the head is replaced with a head without the surface cracks, not recognizing subtle evidence of defects of sealing of the failed head gasket actually responsible for the coolant leaks into the cylinders. Since the leak is fixed after replacing the head and head gasket, being unaware of the head gasket failure not clearly evident visually, the incorrect conclusion that the cracks leaked coolant is assumed to be confirmation of of this misunderstood situation.

[Kevin C]

The manuals tries to predict crack depth based on crack width; and I agree there is a good correlation. That said, it's not perfect and that's why I recommend a leak test if you have cracks and signs of coolant on the same cylinder. To me it's a matter of risk management. The mechanism of the crack forming is the metal expands when hot, and with heating its strength is also diminished. At some point the metal compresses past its elastic limit and is permanently deformed in compression. When the motor cools down, that section is now in tension. If the tension is high enough a fracture starts and you have a crack.

If such a crack makes its way to coolant, it will tend to self seal when the motor comes back up to temperature. Head gaskets can do the same thing, but are typically more of dramatic failure (shorter time frame). The slow leak of a crack often shows up as a cold start misfire. You don't lose a lot of coolant. The tough part is knowing how far the crack has gone, one factor that is not taken into account is the number of thermal cycles.

The issue with this type of failure is it will damage the cylinder over time. On motors I have torn down with cold start roughness and small self sealing cracks, the upper ring land had significant wear (non 1.8T ). My advice is if you have a cold miss, pull your plugs and see if you have a odd deposits, plug coloring, and signs of less deposits in the chamber (steam cleaned).

This one is between the intake and the exhaust valve and extends into the water jacket.



http://forums.vwvortex.com/showthrea...acked-AEB-head

[Furly]

The amount of B6 head failure I've seen is enough for me to (with a background in manufacturing) say that I believe the AMB heads were sourced from a different manufacturer or produced with a different casting method thus resulting in a casting defect. The failure rate of B6 heads is far more than any B5 1.8T head I've ever seen. Which is a shame because the AMB was audi's last 1.8T and you'd think they learned from the previous .

That said, my cylinder head didn't have a crack but rather had a pinhole that the machine shop located and it was gushing out badly. The problem progressively got worse and it happened to a few of my local B6 friends as well. The head gasket showed no sign of failure and there was absolutely no warping of the head or block. The car never overheated. So I have to disagree with the people constantly defending the AMB heads saying they never crack or leak..because it's not a gasket problem, or at least wasn't for me and the 6 friends I've seen with the same issue locally. Usually it's cracks or pin holes.

Also it's not worth rebuilding a head with cracks so don't blame the machine shops for not wanting to rebuild a cracked head. I wouldn't either if I were them. It's a liability risk and why would you want to put a cracked head back on your car and waste all that time and money ?

That said also beware of aftermarket "reman" heads online. They won't have an AMB (or any other audi stamp) on them. They will be blank where the AMB is and those are usually Chinese castings. So you'll be taking a gamble there too. Just buy a used head from a B6 or B5 and call it a day. And make sure it's been pressure tested and resurfaced, if not make sure to have that done at a reputable machine shop.

[customa4]

Valve Cover
Timing Belt
Cylinder Head

[diagnosticator]

The amount of B6 head failure I've seen is enough for me to (with a background in manufacturing) say that I believe the AMB heads were sourced from a different manufacturer or produced with a different casting method thus resulting in a casting defect. The failure rate of B6 heads is far more than any B5 1.8T head I've ever seen. Which is a shame because the AMB was audi's last 1.8T and you'd think they learned from the previous .

That said, my cylinder head didn't have a crack but rather had a pinhole that the machine shop located and it was gushing out badly. The problem progressively got worse and it happened to a few of my local B6 friends as well. The head gasket showed no sign of failure and there was absolutely no warping of the head or block. The car never overheated. So I have to disagree with the people constantly defending the AMB heads saying they never crack or leak..because it's not a gasket problem, or at least wasn't for me and the 6 friends I've seen with the same issue locally. Usually it's cracks or pin holes.

Also it's not worth rebuilding a head with cracks so don't blame the machine shops for not wanting to rebuild a cracked head. I wouldn't either if I were them. It's a liability risk and why would you want to put a cracked head back on your car and waste all that time and money ?

That said also beware of aftermarket "reman" heads online. They won't have an AMB (or any other audi stamp) on them. They will be blank where the AMB is and those are usually Chinese castings. So you'll be taking a gamble there too. Just buy a used head from a B6 or B5 and call it a day. And make sure it's been pressure tested and resurfaced, if not make sure to have that done at a reputable machine shop.

I guess no one reads or understand my posts...there are of course differences in the types and locations of cracks as a general concept. From your comments above, and from others, it is becoming clear that the facts involved with cracks between the valve seats on our 1.8T heads cannot be understood as the unique situation they are being different from the general term "crack" in the head as a technically historical aspect. I guess some guys just can't understand the situation here so treat the cracks like any other crack that leaks coolant. F'it. As they say, "Ignorance is Bliss". My attempt to enlighten the everone is a failure. "You can lead a horse to water......"