prblue
Well-known member
I'm new on the forum so hello everyone. I have a 2005 Golf V 4x4 drive (4motion) with a 2.0 TDI BKD engine (PD). I bought it 2 years ago and I had no issues until a couple of months ago I noticed gradual coolant loss. Now that I think about it the loss may have been there from the start, just very slow. I normally do short trips. I noticed the coolant loss on those rare occasions when I drove for more than 10 minutes. I initially thought this is probably a head gasket seal, or warped/cracked head. I had a similar issue on another car so I was on the lookout for bubbles in the reservoir. Nope, there were no bubbles. I had to use the car so I continued to drive it until I also started having very strange starting issue.
The starting issue would only happen if the car was left off overnight or longer. Basically I would hear the starter turn the motor somewhat and then get to a sudden stop. Waiting a minute and trying again would eventually start the car. Sometimes I had to try few times. I would see lots smoke in the exhaust after starting. Once the engine got to the temperature the smoke was gone and it drove fine. I suspected the starter and replaced it. It didn't make any difference. The starting problem and coolant loss got progressively worse. Eventually once the starter stopped I would have to turn the engine manually a bit to get it going. To do that I would put the car in first gear and push it slightly until I felt engine give a bit of resistance. Then attempting to start would succeed (again sometimes after few tries).
I started researching the problem and I came to a conclusion that this may be an EGR cooler leak that sends coolant via the EGR valve into intake and cylinders. I thought that when the engine was hot the coolant would evaporate and don't cause much issues (I was always topping up with red coolant, never water), but once the engine was stopped it condensed in the inlet manifold and on startup whichever cylinder would try to get air first would get a gulp of coolant and get hydrolocked in the process.
So I replaced the EGR cooler, but in the process I found no sticky gunk in the old one, just what looked like dry soot. Same in the EGR valve and pipe connecting the two. If EGR cooler was the source of the leak I thought the pipe, the cooler and the valve would all be full of gunk.
However, when I removed the inlet manifold I poured half a liter of coolant from it, and the inside walls were covered in sticky black gunk I also removed the rocker cover and removed glow plugs in hope of sticking an endoscope camera into cylinders to assess their status. No luck the camera was about a millimetre too thick However, when I turned the engine by hand coolant shot from the first cylinder's glow plug hole. The remaining cylinders were dry. Also the ends of the glow plugs looked dry in cylinders 2,3 and 4, while number 1 was covered in something that looked like dense oil? Based on the above I started thinking I probably have a broken head gasket seal, a cracked head, or a cracked engine. I also drained oil from the engine and I found about a tablespoon of coolant in it.
Now, I think if I had a cracked engine block I would also have oil in coolant unless the crack was where there is no oil pressure. Also, I would expect a lot more coolant in oil if this was indeed a cracked engine block. On the other hand if this was a cracked head or a broken seal I would expect bubbles in the coolant tank.
I refilled the coolant to the brim, I pumped squeezing the hoses to remove air and I left the engine with glow plugs removed overnight and coolant cap open. The coolant level didn't go down. Also there was no coolant in the cylinder in the morning. I put everything back together with exception of replacing the coolant cap (I left the reservoir open), connecting the anti-shudder valve and EGR valve as I wanted to take the EGR out of the picture. And I run the engine until it heated to temperature. Some bubbles occurred which suggests my previous air draining attempts were not fully successful, but once air was pushed out there were no bubbles. I left the car overnight. No issue starting it in the morning, also coolant didn't go down.
I left the anti-shudder valve off because I believe the way it works closing in the moment the engine is switched off creates significant vacuum in the intake manifold and the cylinder that happens to be attempting to pull air so it might have contributed to sucking the coolant into the cylinder through some breakage in the seal.
So now, I'm a bit puzzled. I know that starting and coolant loss issues were caused by the coolant hydro locking the first cylinder (maybe others too - perhaps I just managed to look at when the coolant was in the 1st cylinder by chance). The valves are not sealing completely (I could hear the air squeezing past when I turned the engine by hand with glow plugs in place) so the coolant could slowly escape through them allowing me to eventually start the engine. This suggests a coolant leak into the cylinder somehow, but I can't understand how is it possible that high pressure gases do not leak the other way too causing bubbles? Surely no matter the coolant pressure the combustion gasses are under hundreds time more pressure. Does anyone have any ideas? Is there any coolant supply to the pump-injectors in the BKD engine? (I have bosh injectors). Can coolant be leaking through into the first cylinder from anywhere else?
Since I replaced the EGR cooler I failed to replicate the issue, but I still have the EGR valve, the anti shudder valve and the coolant tank cap disconnected/removed and the car's front is lifted up by half a meter so the car is angled (I don't know if this matters. I worked on the car through the weekend so all my testing was with the front wheels up in the air.).
Also, I'm reluctant to close the coolant tank cap to avoid pressure build up as perhaps this is what causes the leak to activate. Can anyone think of any issue driving without it? I need to use the car until I get a new head gasket and I have time to remove the head. Additionally, I was told by a garage a head has to be planned after it has been removed. Is this true? Can I simply remove the head and replace it without doing anything (possibly replace the gasket), or is the head likely to warp when I release the bolts making proper reassembly impossible?
Sorry about the length of this post and the number of questions, but I don't know where to turn to deal with this. Various mechanics have quoted me thousands for various repairs while it is uncertain what is broken while my fiancee tries to convince me it's time to buy a new (used) car, but I'm still hoping this can be repaired cost effectively. I ended up doing the investigation and EGR cooler replacement myself. I also have a surface grinder so I could probably plan the head if necessary, but I would prefer to avoid it if possible.
The starting issue would only happen if the car was left off overnight or longer. Basically I would hear the starter turn the motor somewhat and then get to a sudden stop. Waiting a minute and trying again would eventually start the car. Sometimes I had to try few times. I would see lots smoke in the exhaust after starting. Once the engine got to the temperature the smoke was gone and it drove fine. I suspected the starter and replaced it. It didn't make any difference. The starting problem and coolant loss got progressively worse. Eventually once the starter stopped I would have to turn the engine manually a bit to get it going. To do that I would put the car in first gear and push it slightly until I felt engine give a bit of resistance. Then attempting to start would succeed (again sometimes after few tries).
I started researching the problem and I came to a conclusion that this may be an EGR cooler leak that sends coolant via the EGR valve into intake and cylinders. I thought that when the engine was hot the coolant would evaporate and don't cause much issues (I was always topping up with red coolant, never water), but once the engine was stopped it condensed in the inlet manifold and on startup whichever cylinder would try to get air first would get a gulp of coolant and get hydrolocked in the process.
So I replaced the EGR cooler, but in the process I found no sticky gunk in the old one, just what looked like dry soot. Same in the EGR valve and pipe connecting the two. If EGR cooler was the source of the leak I thought the pipe, the cooler and the valve would all be full of gunk.
However, when I removed the inlet manifold I poured half a liter of coolant from it, and the inside walls were covered in sticky black gunk I also removed the rocker cover and removed glow plugs in hope of sticking an endoscope camera into cylinders to assess their status. No luck the camera was about a millimetre too thick However, when I turned the engine by hand coolant shot from the first cylinder's glow plug hole. The remaining cylinders were dry. Also the ends of the glow plugs looked dry in cylinders 2,3 and 4, while number 1 was covered in something that looked like dense oil? Based on the above I started thinking I probably have a broken head gasket seal, a cracked head, or a cracked engine. I also drained oil from the engine and I found about a tablespoon of coolant in it.
Now, I think if I had a cracked engine block I would also have oil in coolant unless the crack was where there is no oil pressure. Also, I would expect a lot more coolant in oil if this was indeed a cracked engine block. On the other hand if this was a cracked head or a broken seal I would expect bubbles in the coolant tank.
I refilled the coolant to the brim, I pumped squeezing the hoses to remove air and I left the engine with glow plugs removed overnight and coolant cap open. The coolant level didn't go down. Also there was no coolant in the cylinder in the morning. I put everything back together with exception of replacing the coolant cap (I left the reservoir open), connecting the anti-shudder valve and EGR valve as I wanted to take the EGR out of the picture. And I run the engine until it heated to temperature. Some bubbles occurred which suggests my previous air draining attempts were not fully successful, but once air was pushed out there were no bubbles. I left the car overnight. No issue starting it in the morning, also coolant didn't go down.
I left the anti-shudder valve off because I believe the way it works closing in the moment the engine is switched off creates significant vacuum in the intake manifold and the cylinder that happens to be attempting to pull air so it might have contributed to sucking the coolant into the cylinder through some breakage in the seal.
So now, I'm a bit puzzled. I know that starting and coolant loss issues were caused by the coolant hydro locking the first cylinder (maybe others too - perhaps I just managed to look at when the coolant was in the 1st cylinder by chance). The valves are not sealing completely (I could hear the air squeezing past when I turned the engine by hand with glow plugs in place) so the coolant could slowly escape through them allowing me to eventually start the engine. This suggests a coolant leak into the cylinder somehow, but I can't understand how is it possible that high pressure gases do not leak the other way too causing bubbles? Surely no matter the coolant pressure the combustion gasses are under hundreds time more pressure. Does anyone have any ideas? Is there any coolant supply to the pump-injectors in the BKD engine? (I have bosh injectors). Can coolant be leaking through into the first cylinder from anywhere else?
Since I replaced the EGR cooler I failed to replicate the issue, but I still have the EGR valve, the anti shudder valve and the coolant tank cap disconnected/removed and the car's front is lifted up by half a meter so the car is angled (I don't know if this matters. I worked on the car through the weekend so all my testing was with the front wheels up in the air.).
Also, I'm reluctant to close the coolant tank cap to avoid pressure build up as perhaps this is what causes the leak to activate. Can anyone think of any issue driving without it? I need to use the car until I get a new head gasket and I have time to remove the head. Additionally, I was told by a garage a head has to be planned after it has been removed. Is this true? Can I simply remove the head and replace it without doing anything (possibly replace the gasket), or is the head likely to warp when I release the bolts making proper reassembly impossible?
Sorry about the length of this post and the number of questions, but I don't know where to turn to deal with this. Various mechanics have quoted me thousands for various repairs while it is uncertain what is broken while my fiancee tries to convince me it's time to buy a new (used) car, but I'm still hoping this can be repaired cost effectively. I ended up doing the investigation and EGR cooler replacement myself. I also have a surface grinder so I could probably plan the head if necessary, but I would prefer to avoid it if possible.