PROCEDURE TO FIX 4.2L COOLANT LEAK!
01-01-2013, 11:39 PM
#11
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I found that my hex head 3/8" drive bit jammed against the exterior coolant xfer tube. Had to get a second, shorter bit to get out the bolt. Helps to release te coolant tube from the oil cooler..one little bolt.
bTW, the Bufkin tube failed on me two years later, o-ring tore. It's likely I screwed up during installation but who knows. Ithe pipe was golden, no corrosion! Be very careful installing the cooler, use your fingers to shield the o-rings as you put the cooler onto the engine. Lube them with a little oil or sealant , such as a loctite high temp flexbe sealant.
I also ended up replacing the RHS lower hydraulic engine mount. Old one was loosey-goosey but new one tight. No purple fluid leaks on old one. No perceptible improvement in nvh or idle vibration so probably a wasted $250!
bTW, the Bufkin tube failed on me two years later, o-ring tore. It's likely I screwed up during installation but who knows. Ithe pipe was golden, no corrosion! Be very careful installing the cooler, use your fingers to shield the o-rings as you put the cooler onto the engine. Lube them with a little oil or sealant , such as a loctite high temp flexbe sealant.
I also ended up replacing the RHS lower hydraulic engine mount. Old one was loosey-goosey but new one tight. No purple fluid leaks on old one. No perceptible improvement in nvh or idle vibration so probably a wasted $250!
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maw1124 (01-23-2021)
01-15-2013, 11:55 PM
#12
AudiWorld Super User
I'm in the process of replacing the pipe on my A6 right now as well. Unfortunately, between my ignorance and that of the parts guy at the local Audi dealership, I didn't get all the gaskets I needed. After this much work, I don't want to put the project back together without at least two more gaskets that he didn't order, and I didn't insist on getting.
These would be the o-ring gasket that fits on the external coolant pipe, Part# 077 121 437, and the figure 8 shaped gasket that seals the oil connection to the block, I think this particular gasket can only be obtained by ordering the set of gaskets for the oil filter bracket, Part# 077 198 405.
Oh well, I may just go ahead and order the after market aluminum oil cooler pipe from ebay, replacing the plastic one I got from the Audi dealer, while I wait for my gaskets to come in- now that I know about that as well.
One thing about getting out the much feared top bolt on the oil cooler housing (I thought all of them were challenging to some degree) I just don't think there is enough room to safely get that bolt out without lifting the engine a few inches on an A6. By safely I mean not subjecting the bolt to the possibility of stripping it. I had already removed the motor mounts on that side of the vehicle so sliding a jack under the engine (using a piece of two by six set flat under the oil pan as a buffer between jack and engine) and lifting the engine a few inches was no big deal. I was then able to get a visual and a straight shot at the formerly hidden bolt. In fact, by proceeding this way,the removal of that bolt the easiest and cleanest of any of the five in my humble opinion. I can't wait to put it back in
These would be the o-ring gasket that fits on the external coolant pipe, Part# 077 121 437, and the figure 8 shaped gasket that seals the oil connection to the block, I think this particular gasket can only be obtained by ordering the set of gaskets for the oil filter bracket, Part# 077 198 405.
Oh well, I may just go ahead and order the after market aluminum oil cooler pipe from ebay, replacing the plastic one I got from the Audi dealer, while I wait for my gaskets to come in- now that I know about that as well.
One thing about getting out the much feared top bolt on the oil cooler housing (I thought all of them were challenging to some degree) I just don't think there is enough room to safely get that bolt out without lifting the engine a few inches on an A6. By safely I mean not subjecting the bolt to the possibility of stripping it. I had already removed the motor mounts on that side of the vehicle so sliding a jack under the engine (using a piece of two by six set flat under the oil pan as a buffer between jack and engine) and lifting the engine a few inches was no big deal. I was then able to get a visual and a straight shot at the formerly hidden bolt. In fact, by proceeding this way,the removal of that bolt the easiest and cleanest of any of the five in my humble opinion. I can't wait to put it back in
Do you have a wrap up of your project? Did you go with the aluminum oil cooler pipe or did you stick with the plastic one?
01-21-2013, 06:43 PM
#13
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With the New Year holiday, it took exactly one week for delivery. I am in Central Oregon and the aluminum pipe came from Austin, Texas. Fortunately, other than the fact my A6 was torn apart in someone else's garage, making for an awkward set of excuses as to why it was in there for so long, I did have an abundance of my time available this past month on my side- I am a landscaper- we don't get too much done in January in this part of the world.
Despite the lag time between the tear apart and the re-install, everything went together without a hitch. The most difficult cooler bolt I found to be the middle one, the one just above the oil filter connection: I used an actual 8mm allen key (not socket) for that one, slipping a piece of 12"x 3/4" steel pipe over the long end of the key to break the bolt loose while the key was in a vertical position and the running it long ways, horizontal over oil filter bracket for the most part until it came out, and doing the reverse to upon re-install to tighten. I ended up guessing on the final torque for each bolt, as in reality, getting a torque wrench applied the same way to each bolt was impossible. At least for me.
Another trick I found (online somewhere) was using a c-clamp and a large socket to push the bushing on the back of the alternator mounting bracket out a bit (the bushing/nut that receives the long allen bolt), I had really struggled getting the alternator out, and not knowing if by finally beating on the thing to get it off was going to cost me a lot more money (it didn't) I didn't want to repeat the process upon install and loosing up the tight fit by using that technique with the alternator off made the re-install go so much easier.
When finished, the car fired up with no leaks and we have already made a long run out into the high desert up here. I find myself more confident in my ability for having gone through the process. The Audi A6 with a V8 4.2, cruising out on the open road is a beautiful thing.
04-06-2013, 01:02 PM
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Great information. I have my whole front end off after having timing belt done and I think I should replace this as well ( as the original problem was a coolant leak) Does anyone have the exact part numbers needed for this or know where I can find them? Or do I just go to the deal and mention them as described? Also does anyone have a link to the aluminum part? Thanks in advance.
Keith
Keith
04-06-2013, 01:18 PM
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Great information. I have my whole front end off after having timing belt done and I think I should replace this as well ( as the original problem was a coolant leak) Does anyone have the exact part numbers needed for this or know where I can find them? Or do I just go to the deal and mention them as described? Also does anyone have a link to the aluminum part? Thanks in advance.
Keith
Keith
I found the aluminum on ebay that comes with the 4 O-rings. Is there any other O-rings or seals that I need to complete this? Thanks again in advance.
Keith
04-08-2013, 10:55 AM
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yes....
077-198-405 is the seal kit that contains the 'figure 8' o-ring visible in the 2nd of sloop's pictures. Mine looked ok & might have worked w/o replacement, but I had a new one on hand just in case.
077-121-437 is the seal for the pipe that runs back to the rear of the engine. None of the o-rings that came with the figure 8 seal fit that pipe. (i imagine they are for the inards of the cooler which I left alone)
04-08-2013, 01:06 PM
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See a couple posts up. Suspect you found the Al pipe with its own 4 o-rings.. 2 on each side, yes? You also will need:
077-198-405 is the seal kit that contains the 'figure 8' o-ring visible in the 2nd of sloop's pictures. Mine looked ok & might have worked w/o replacement, but I had a new one on hand just in case.
077-121-437 is the seal for the pipe that runs back to the rear of the engine. None of the o-rings that came with the figure 8 seal fit that pipe. (i imagine they are for the inards of the cooler which I left alone)
077-198-405 is the seal kit that contains the 'figure 8' o-ring visible in the 2nd of sloop's pictures. Mine looked ok & might have worked w/o replacement, but I had a new one on hand just in case.
077-121-437 is the seal for the pipe that runs back to the rear of the engine. None of the o-rings that came with the figure 8 seal fit that pipe. (i imagine they are for the inards of the cooler which I left alone)
04-08-2013, 07:02 PM
#18
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Please post the part number of the 8 gasket. My dealer doesn't sell it separate....
04-08-2013, 07:05 PM
#19
AudiWorld Super User
After going through all the trouble of learning what Audi engineering is about during the tear down, I had no shop manual mind you: every thing I dismantled, pulled apart, or disconnected was different than any other vehicle this shade tree mechanic has ever laid his hands on... I decided to wait for the aluminum pipe rather than put another piece very uncharacteristic Audi engineering plastic pipe in a bad application back in that critical part of the car.
With the New Year holiday, it took exactly one week for delivery. I am in Central Oregon and the aluminum pipe came from Austin, Texas. Fortunately, other than the fact my A6 was torn apart in someone else's garage, making for an awkward set of excuses as to why it was in there for so long, I did have an abundance of my time available this past month on my side- I am a landscaper- we don't get too much done in January in this part of the world.
Despite the lag time between the tear apart and the re-install, everything went together without a hitch. The most difficult cooler bolt I found to be the middle one, the one just above the oil filter connection: I used an actual 8mm allen key (not socket) for that one, slipping a piece of 12"x 3/4" steel pipe over the long end of the key to break the bolt loose while the key was in a vertical position and the running it long ways, horizontal over oil filter bracket for the most part until it came out, and doing the reverse to upon re-install to tighten. I ended up guessing on the final torque for each bolt, as in reality, getting a torque wrench applied the same way to each bolt was impossible. At least for me.
Another trick I found (online somewhere) was using a c-clamp and a large socket to push the bushing on the back of the alternator mounting bracket out a bit (the bushing/nut that receives the long allen bolt), I had really struggled getting the alternator out, and not knowing if by finally beating on the thing to get it off was going to cost me a lot more money (it didn't) I didn't want to repeat the process upon install and loosing up the tight fit by using that technique with the alternator off made the re-install go so much easier.
When finished, the car fired up with no leaks and we have already made a long run out into the high desert up here. I find myself more confident in my ability for having gone through the process. The Audi A6 with a V8 4.2, cruising out on the open road is a beautiful thing.
With the New Year holiday, it took exactly one week for delivery. I am in Central Oregon and the aluminum pipe came from Austin, Texas. Fortunately, other than the fact my A6 was torn apart in someone else's garage, making for an awkward set of excuses as to why it was in there for so long, I did have an abundance of my time available this past month on my side- I am a landscaper- we don't get too much done in January in this part of the world.
Despite the lag time between the tear apart and the re-install, everything went together without a hitch. The most difficult cooler bolt I found to be the middle one, the one just above the oil filter connection: I used an actual 8mm allen key (not socket) for that one, slipping a piece of 12"x 3/4" steel pipe over the long end of the key to break the bolt loose while the key was in a vertical position and the running it long ways, horizontal over oil filter bracket for the most part until it came out, and doing the reverse to upon re-install to tighten. I ended up guessing on the final torque for each bolt, as in reality, getting a torque wrench applied the same way to each bolt was impossible. At least for me.
Another trick I found (online somewhere) was using a c-clamp and a large socket to push the bushing on the back of the alternator mounting bracket out a bit (the bushing/nut that receives the long allen bolt), I had really struggled getting the alternator out, and not knowing if by finally beating on the thing to get it off was going to cost me a lot more money (it didn't) I didn't want to repeat the process upon install and loosing up the tight fit by using that technique with the alternator off made the re-install go so much easier.
When finished, the car fired up with no leaks and we have already made a long run out into the high desert up here. I find myself more confident in my ability for having gone through the process. The Audi A6 with a V8 4.2, cruising out on the open road is a beautiful thing.
04-08-2013, 07:07 PM
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That's really the only one you need, reuse everything else. However, I like to use new o rings on the radiator connections and depending on the age of the car probably a new one on the coolant pipe to the outside of the oil cooler.
Please post the part number of the 8 gasket. My dealer doesn't sell it separate....
Please post the part number of the 8 gasket. My dealer doesn't sell it separate....