Time For a New Head

[old guy]

Mine is leaking. Rather than pull it off and possibly have to deal with cracks or warping I think I will just look for a rebuilt OEM head. That will require the least amount of downtime. Does anyone have a rebuilder that they recommend? I have found several on ebay in the $550 range. There are also new Chinese heads complete out there for the same price but I think I will stick with a rebuilt OEM.

Suggestions?

[EuroxS4]

Mine is leaking. Rather than pull it off and possibly have to deal with cracks or warping I think I will just look for a rebuilt OEM head. That will require the least amount of downtime. Does anyone have a rebuilder that they recommend? I have found several on ebay in the $550 range. There are also new Chinese heads complete out there for the same price but I think I will stick with a rebuilt OEM.

Suggestions?

New Chinese heads aren't even worthy of the box they come in.What exactly is leaking on the head??Or coolant leaking into combustion chamber??Personally rebuilt heads are hit or miss.Depends who did the rebuild and how well it was done.Maybe a used head is a better options possibly cheaper also.

Depending on what the issue with the current cylinder head is.It may be worth just decking the head and replacing the head gasket and bolts.

[themadscientist]

Ah, good ol' AMB heads. I replaced mine with one from a Turbo Beetle. $75 junkyard head. Resurfaced it and replaced valve seals. That was 60k miles ago.

[old guy]

The engine runs flawlessly. The only thing I noted was that after a 30 minute drive the upper radiator hose felt like it was under a lot of pressure and I have had to add about a cup of coolant every three or four days. I used my block tester to check for combustion gasses in the coolant reservoir and it tested positive. Also, if I let it idle with the cap off the coolant level will continue to rise to the point where it pushes it out of the top of the reservoir.

No indication of coolant in the exhaust, no white smoke, plugs look fine and no issues with a cold start.

[EuroxS4]

The engine runs flawlessly. The only thing I noted was that after a 30 minute drive the upper radiator hose felt like it was under a lot of pressure and I have had to add about a cup of coolant every three or four days. I used my block tester to check for combustion gasses in the coolant reservoir and it tested positive. Also, if I let it idle with the cap off the coolant level will continue to rise to the point where it pushes it out of the top of the reservoir.

No indication of coolant in the exhaust, no white smoke, plugs look fine and no issues with a cold start.

If the engine is hot and up to operating temp the coolant will get pushed out of the bottle when not pressurized.This is normal.But the fact that there are combustion gasses in the coolant does sound a bit odd.any chance of oil cooler leaking internally.It is a common issue on 1.8T. Fuel in the oil could give you a positive for combustion gases but then again I would assume a chocolate milkshake in the resevoir would also be present.It is possible you have a small crack in the head.1.8T head likes to crack between the valves.

However I would assume it would have cold start misfires or over heating when cold.But you have neither ones of those symptoms.It is possible the head gasket fire ring has sprung a leak and is not sealing properly.That the only other thing I've personally seen.



This normal happens after the vehicle has been over heated or has alot of miles on it.Long story short,its worth a shot.I always hope for the best fearing the worst.

[old guy]

No indication of coolant in the oil. When the coolant pushes out of the reservoir it is accompanied with many small air bubbles. Definitely combustion gasses. That's why I suspect it is a defect in the head and would rather be prepared to slap a new one on when I pull the old one off. I have no desire to putz around dragging the old head to a shop and having the car down for several days. I would prefer to gather up all the parts and be done with it in one day.

Edit: Although I guess I could pick up a rental and first pull and examine the head and go from there.

[EuroxS4]

Very possible but I would imagine if you have bubble in the coolant and you have a leak.Technically there shouldnt be any pressure in the system due to the leak.So it should be pissing under pressure under high load.Alot of time you can tell.The coolant normally leaves stains on cylinder walls.You can probably see it if you have a inspection camera or borescope down into the combustion chambers.

[old guy]

Very possible but I would imagine if you have bubble in the coolant and you have a leak.Technically there shouldnt be any pressure in the system due to the leak.So it should be pissing under pressure under high load.Alot of time you can tell.The coolant normally leaves stains on cylinder walls.You can probably see it if you have a inspection camera or borescope down into the combustion chambers.

I have several different borescopes at work. I'll take a look at lunch time after the engine has cooled down. However, I have never seen any indication of coolant in the cylinders. Cold starts are always flawless and I have never seen any white smoke coming from the exhaust.

[EuroxS4]

I agree but its worth a shot.It may just be starting at this point.

[old guy]

I agree but its worth a shot.It may just be starting at this point.

A pain in the ass for sure. I love my B6 but at some point I am going to have to put it out to pasture and pick up something a bit newer. As I get older wrenching is starting to lose its appeal...

[diagnosticator]

If the engine is hot and up to operating temp the coolant will get pushed out of the bottle when not pressurized.This is normal.But the fact that there are combustion gasses in the coolant does sound a bit odd.any chance of oil cooler leaking internally.It is a common issue on 1.8T. Fuel in the oil could give you a positive for combustion gases but then again I would assume a chocolate milkshake in the resevoir would also be present.It is possible you have a small crack in the head.1.8T head likes to crack between the valves.

However I would assume it would have cold start misfires or over heating when cold.But you have neither ones of those symptoms.It is possible the head gasket fire ring has sprung a leak and is not sealing properly.That the only other thing I've personally seen.



This normal happens after the vehicle has been over heated or has alot of miles on it.Long story short,its worth a shot.I always hope for the best fearing the worst.

Cracks like that cannot leak coolant into the cylinder or leak combustion gasses into the cooling system because there is no cooling jacket near that web between the valve seats. That is why those cracks develop there due to thermal stress from lack of nearby cooling. Audi allows reusing heads with cracks between the valve seats provided they are not more than about 1mm wide. Notice that the crack is dry, there is no evidence of coolant leaking through that crack.

In addition, if there are no head gasket leaks, the engine will run with the tank cap removed, and no coolant will be forced out of the tank, because there is no pressure to displace any coolant out of the tank.

[diagnosticator]

A pain in the ass for sure. I love my B6 but at some point I am going to have to put it out to pasture and pick up something a bit newer. As I get older wrenching is starting to lose its appeal...

Consider using ARP high strength head bolts for the reassembly. They also provide more clamping pressure on the head gasket to avoid future gasket failure. This is important considering the high cylinder firing pressures occurring with your turbo and tuning. ARP # 204-3902

[old guy]

Consider using ARP high strength head bolts for the reassembly. Those bolts do not stretch into the yield zone and can be reused. They also provide more clamping pressure on the head gasket to avoid future gasket failure. This is important considering the high cylinder firing pressures occurring with your turbo and tuning.

Yep. I was planning on using ARP bolts.

[cmiguel32]

Cracks like that cannot leak coolant into the cylinder or leak combustion gasses into the cooling system because there is no cooling jacket near that web between the valve seats. That is why those cracks develop there due to thermal stress from lack of nearby cooling. Audi allows reusing heads with cracks between the valve seats provided they are not more than about 1mm wide. Notice that the crack is dry, there is no evidence of coolant leaking through that crack.

In addition, if there are no head gasket leaks, the engine will run with the tank cap removed, and no coolant will be forced out of the tank, because there is no pressure to displace any coolant out of the tank.

I have pictures of an amb head with similar cracks that extended deep into the coolant jacket. Failed the pressure test at a local machine shop.

[Kevin C]

Cracks like that cannot leak coolant into the cylinder or leak combustion gasses into the cooling system because there is no cooling jacket near that web between the valve seats. That is why those cracks develop there due to thermal stress from lack of nearby cooling. Audi allows reusing heads with cracks between the valve seats provided they are not more than about 1mm wide. Notice that the crack is dry, there is no evidence of coolant leaking through that crack.

In addition, if there are no head gasket leaks, the engine will run with the tank cap removed, and no coolant will be forced out of the tank, because there is no pressure to displace any coolant out of the tank.

[Seerlah]

I don't know what Audi cheaped out on when they made the transition from AWM to AMB with quality control on the cylinder head metallurgy, but us AWM guys never have had this issue. Not one documented case that I have come across, and I currently run a completely stock head at butt dyno 350whp (more to come, and head that I bent valves in previously is currently being built...with story on how this happened at closing parenthesis. this head has also taken an incredible beating over the years, completely stock with no hairline fracture by cooling passages issue). Only issue I ever had was bending valves, which was caused by a piece of plastic that broke off TB cover getting caught in the crank gear and throwing off timing (having a little piece of plastic cause so much damage was quite frustrating, to say the least). Easiest route, source replacement AWM head (made sure to only get an AWM, though I am sure other small port 06A small port DBW compatible heads exist on the VW platform...like AWM).

Picked one up for like $150, diesel shop machine shop decked it (info people should know, thanks to you Fletch: answer to your question about sourcing a machinist: diesel shops usually have a machinist with his own shop on site that works on diesel truck parts. much cheaper to machine parts than order brand new ones, with the things they work on. large percentage of the time any diesel machine shop is credible as far as reliability and credibility goes because truck parts are the only thing they really machine. and if they don't have a machinist on site with his own shop for that shop, they will point you in the direction of the one they use. take their advice because a deck for a machinist that works on diesel truck parts strictly with the occasional passenger vehicle walk in request is something kind of difficult to mess up, quite frankly. for more involved tasks, inquire with that particular machinist and research credibility locally in the matter because that is when real machining that can make or break an engine build resulting in a loss of a lot of money comes into play, like displacement increasing to more involved process like short block building. my machinist is also a diesel shop machinist and one of the best in the area. was lead to him by same advice I'm giving right now and wasn't the first person I met looking for a local machinist. told me how he built a few VWs in his younger years, first time I met him and follow that guy where he goes like your stalker ex-girlfriend...without the craziness. old shop caught fire which in turn burned down his shop. I know where he currently has a new shop which is of course another diesel repair shop, where he was purchased all new equipment by company simply off reputation, company location, company hours, etc) and been running it till this day. Swapped over all components, including cams and hope it stays problem free (kept old lifters that came with head, but seeing no scoring is what told me to go ahead with it. added crap ton of assembly lube regardless, no problem yet and current engine has seen the speedo just shy of tapping out...before throttle let off).

My suggestion is to source a used AWM head, have it decked, slap it in and call it a day. Or Keith (walkytalky20) can tell you which replacement ones are safe and unsafe to buy. Something about a particular stamp to look for, even when no stamping of an engine code on tab.

[diagnosticator]

I have pictures of an amb head with similar cracks that extended deep into the coolant jacket. Failed the pressure test at a local machine shop.

Please post the pictures you have. Again, there is no coolant jacket within at least an inch from the web between the valves. This is because the web is the wall between the port walls.

[diagnosticator]

I can't tell for sure if those picts are of a 1.8T cylinder head. Regardless, the cracks shown are definitely cracked down into the port wall below the valve seats, not the typical case. However it is still a fact that there is no cooling jacket where those cracks are located and cannot leak coolant or combustion gasses into the cooling system.

[diagnosticator]

I have never heard before that the AWM does not develop cracks between the valve seats. I know that cracks between the valve seats is common with Audi/VW engines in general. For example, Audi and VW diesels have been cracking between the valve seats for 30 years. It's not just an AMB problem. Turbocharged 5 cylinder Audi engines commonly develop cracks between the valve seats also.

[diagnosticator]

Mine is leaking. Rather than pull it off and possibly have to deal with cracks or warping I think I will just look for a rebuilt OEM head. That will require the least amount of downtime. Does anyone have a rebuilder that they recommend? I have found several on ebay in the $550 range. There are also new Chinese heads complete out there for the same price but I think I will stick with a rebuilt OEM.

Suggestions?

Here is a good looking head, appears to be no cracks, very clean. AWD $350 Recent rebuild?

http://www.ebay.com/itm/2000-GTi-VW-...RXeW-P&vxp=mtr

[a4darkness]

Hope you get this sorted Fletcher.

x2 on ARP head studs. They're also not one-time-use so if the head needs to come back off or be adjusted that's fine.
If you do use them keep in mind after a short period of break-in time you'll need to pull the VC and retighten.

If you're gonna buy a used head, drop the coin and rebuild with all Supertech internals.
After rebuilding mine with those the top end was vastly improved, really made a nice difference.

Really glad to see you're keeping the B6 alive!

[evo_ski]

Go Old Guy!

My biggest issue is that any head that had cracks in it was a leper to all the local machine shops. They don't care if the manual says it is fine, they won't touch it. So you either get a new head or slap your current one back on and hope for the best. Hopefully they will be able to get your setup dialed how you want it.

[seanf86]

mine had cracks between all the valve seats, close to or larger than 1mm, I got a used AWM head with no cracks for $60 and had it pressure tested and machined and have been running it ever since.

[cmiguel32]

Please post the pictures you have. Again, there is no coolant jacket within at least an inch from the web between the valves. This is because the web is the wall between the port walls.

The machine shop pressure tested it and fluid was bubbling from one of those 2 cracks (Cylinder 2). I purchased this AMB head used from a forum member. It was fully built. Had to have the parts swapped over to a rebuilt AWM head because it wouldn't hold pressure.

[Kevin C]

Cracks like that cannot leak coolant into the cylinder or leak combustion gasses into the cooling system because there is no cooling jacket near that web between the valve seats. That is why those cracks develop there due to thermal stress from lack of nearby cooling. Audi allows reusing heads with cracks between the valve seats provided they are not more than about 1mm wide. Notice that the crack is dry, there is no evidence of coolant leaking through that crack.

In addition, if there are no head gasket leaks, the engine will run with the tank cap removed, and no coolant will be forced out of the tank, because there is no pressure to displace any coolant out of the tank.

Please post the pictures you have. Again, there is no coolant jacket within at least an inch from the web between the valves. This is because the web is the wall between the port walls.

I can't tell for sure if those picts are of a 1.8T cylinder head. Regardless, the cracks shown are definitely cracked down into the port wall below the valve seats, not the typical case. However it is still a fact that there is no cooling jacket where those cracks are located and cannot leak coolant or combustion gasses into the cooling system.

Link to page with bubbles / head crack: yes its a 1.8t http://forums.vwvortex.com/showthrea...acked-AEB-head




http://www.audizine.com/forum/showth...1#post11673141

The measured wall thickness between the seats is 12 to 14 mm, about 1/2 of what you are claiming (1"/ 24.5 mm). The cross section views show where the jackets are.



http://www.audizine.com/gallery/data...AEBvsAWP-1.jpg

[PreciseD]

Link to page with bubbles / head crack: yes its a 1.8t http://forums.vwvortex.com/showthrea...acked-AEB-head




http://www.audizine.com/forum/showth...1#post11673141

The measured wall thickness between the seats is 12 to 14 mm, about 1/2 of what you are claiming (1"/ 24.5 mm). The cross section views show where the jackets are.



http://www.audizine.com/gallery/data...AEBvsAWP-1.jpg

I have already shown those to John and he still refuses to accept the fact that coolant IS behind the webbing and that the small little crack WILL leak coolant into the combustion chamber....

[Steve Bassen]

I've got a complete longblock in my garage you can have for a steal of a price :p

Also got a stripped small port head, but it needs valvetrain swapped over from another head to make it complete.

[old guy]

Thanks for the offer Steve! However at this point I think I will just pick up a rebuilt AWM for a quick swap. Money really isn't an issue. Downtime and wrenching time is.

[themadscientist]

Cracks like that cannot leak coolant into the cylinder or leak combustion gasses into the cooling system because there is no cooling jacket near that web between the valve seats. That is why those cracks develop there due to thermal stress from lack of nearby cooling. Audi allows reusing heads with cracks between the valve seats provided they are not more than about 1mm wide. Notice that the crack is dry, there is no evidence of coolant leaking through that crack.

In addition, if there are no head gasket leaks, the engine will run with the tank cap removed, and no coolant will be forced out of the tank, because there is no pressure to displace any coolant out of the tank.

No, it won't get "pushed" out persay, but it expands and has to go somewhere.

[MurkyRivers_A4]

Link to page with bubbles / head crack: yes its a 1.8t http://forums.vwvortex.com/showthrea...acked-AEB-head




http://www.audizine.com/forum/showth...1#post11673141

The measured wall thickness between the seats is 12 to 14 mm, about 1/2 of what you are claiming (1"/ 24.5 mm). The cross section views show where the jackets are.



http://www.audizine.com/gallery/data...AEBvsAWP-1.jpg

Im getting deja vu

[themadscientist]

The engine runs flawlessly. The only thing I noted was that after a 30 minute drive the upper radiator hose felt like it was under a lot of pressure and I have had to add about a cup of coolant every three or four days. I used my block tester to check for combustion gasses in the coolant reservoir and it tested positive. Also, if I let it idle with the cap off the coolant level will continue to rise to the point where it pushes it out of the top of the reservoir.

No indication of coolant in the exhaust, no white smoke, plugs look fine and no issues with a cold start.

That's exactly how mine started. Mysterious coolant loss, weird behavior from the coolant temp gauge at times. After a while I started to get rough cold starts and the coolant consumption really kicked up. The failed hydrocarbon test is the real dead-to-rights giveaway. The hoses will all be pretty stiff after a 30 min drive. A seasoned tech can tell when they're "too hard" but a pressure tester gauge will tell a good story too.

I have already shown those to John and he still refuses to accept the fact that coolant IS behind the webbing and that the small little crack WILL leak coolant into the combustion chamber....

Oh man! I had that same talk with Diagnosticator years ago. I work on these cars for a living. I've seen so many cracked AMB heads using coolant that it isn't funny. I've even had a customer that got his hands on the Audi TSB about re-using cracked heads if the crack is "within spec" and he had me re-use the head. Not surprisingly, he had the exact same issue immediately after reassembly.

[ShogunR32]

Rebuilt AWM head for sure! I bought my avant from a dealer upstate and the bastards sold me the car with a cracked head. I bought a rebuilt AWM head from Ebay and had it installed. No CEL or coolant issues since.

[old guy]

That's exactly how mine started. Mysterious coolant loss, weird behavior from the coolant temp gauge at times. After a while I started to get rough cold starts and the coolant consumption really kicked up. The failed hydrocarbon test is the real dead-to-rights giveaway. The hoses will all be pretty stiff after a 30 min drive. A seasoned tech can tell when they're "too hard" but a pressure tester gauge will tell a good story too.

I did check my reservoir cap for the blow off pressure. According to the Bentley it should open at 1.5 bar. Mine opens around 23 psi (1.6 bar) so it’s pretty much doing what it is supposed to do. That does seem like an awful lot of pressure and explains why the hoses can get so hard.

[Toronto5.5]

Why don't you try a little stop leak to see if the issue goes away? Could fix it for a while. Unless you have the time & energy then give er a go.

I second an AWM head over an AMB one.

[diagnosticator]

I have already shown those to John and he still refuses to accept the fact that coolant IS behind the webbing and that the small little crack WILL leak coolant into the combustion chamber....

The problem with that cross section is that the cut is not at the port web. It does not accurately show the relationship between the web between the ports and the distance to the closest coolant jacket. Consequently, I don't believe it is useful for providing any relevant info about this controversy.

What I don't understand is how a lot of guys fail to understand the specific situation with the cracks between the valve seats and why they practically are not capable of leaking coolant into the cylinder, despite multiple attempts to explain the situation and Audi's technical allowance of reusing heads with cracks like shown here. Sure, no cracks is the preferred condition, but blaming all these gasket failures on these cracks is technically unjustified, even though replacing the head and gasket always fixes the alleged leaking cracks.

[diagnosticator]

The machine shop pressure tested it and fluid was bubbling from one of those 2 cracks (Cylinder 2). I purchased this AMB head used from a forum member. It was fully built. Had to have the parts swapped over to a rebuilt AWM head because it wouldn't hold pressure.

Those cracks are not capable of leaking coolant or combustion gasses. The condemnation of the head by the shop in your case is the typical case where shops automatically claim the head leaks through those cracks due to ignorance of the facts involved. Your experience with the shop saying the head leaks though one of those cracks cannot be proven unless you saw the evidence first hand during the pressure test that may not have actually happened. Not questioning your integrity, but I don't trust shops that usually automatically condemn any head with a crack. If you did not witness the pressure test, there is no way to confirm what the shop claimed.

The only reason I continue to argue this controversy is because guys continue to post misleading and incorrect information about these cracks.

[diagnosticator]

That's exactly how mine started. Mysterious coolant loss, weird behavior from the coolant temp gauge at times. After a while I started to get rough cold starts and the coolant consumption really kicked up. The failed hydrocarbon test is the real dead-to-rights giveaway. The hoses will all be pretty stiff after a 30 min drive. A seasoned tech can tell when they're "too hard" but a pressure tester gauge will tell a good story too.



Oh man! I had that same talk with Diagnosticator years ago. I work on these cars for a living. I've seen so many cracked AMB heads using coolant that it isn't funny. I've even had a customer that got his hands on the Audi TSB about re-using cracked heads if the crack is "within spec" and he had me re-use the head. Not surprisingly, he had the exact same issue immediately after reassembly.

Do you believe Audi techs working at dealerships ignore the TSB? Why don't you believe the factory knows something about these cracks? Sure if the cracks exceed allowed maximum width then the head should not be reused. It is amazing how many cracked heads are confirmed to leak despite the coincidence involved since the new head and gasket always fixes the alleged leaking cracks.

[diagnosticator]

I apolgize Fletcher, I did not intend to derail your thread. I regret arguing this controversy here.

[old guy]

I apolgize Fletcher, I did not intend to derail your thread. I regret arguing this controversy here.

No problems here :-) It's a learning process for all of us.

[diagnosticator]

No, it won't get "pushed" out persay, but it expands and has to go somewhere.

True, however when the coolant is already at operating temperature the bulk coolant is not expanding further, with no head gasket leaks, there are no gasses leaking into the cooling system so the engine will run with the cap removed and no coolant will come out of the tank.