Sadist Engineering

I'm taking a quick break from the TDI install retrospectives for a rant, and an update on the A4 efforts. We'll be back to our regular posts next week.

With modern cars, the effort to wedge more features and power into a steadily shrinking engine compartment makes maintenance increasingly difficult. Back when we had the Saturn (Dude), we learned that in order to change the light bulb in the speedometer, the dashboard needed to be removed. What? Yep, that's right; we didn't bother. There are plenty of examples of this, but today's post comes from the efforts to get to the head gasket on a 1997 Audi A4 1.8 Turbo.

1.8 Turbo Head Job
Once I ruled out all other possible causes for the coolant losses in T's Audi A4 1.8 Turbo, I started trying to find someone else to do the work. After 4 months of attempts, and numerous rejections, I finally got a quote from someone: $1250US. Since we paid less than that for the car, I couldn't do that, but we are unable to use or sell the car in it's current shape either. So... into the darkness we go. We start with the usual internet searches for steps and find very lengthy descriptions. Unfortunately, many how-to's neglect to mention key points in a timely manner (I'm sure I'm guilty of this too). For example, the best step-by-step I found did not mention that you needed to disconnect the fuel pump relay and run the engine to depressurize the fuel rail. So, once you got through 15 or so steps and you were told to dismantle the fuel rail... you couldn't. There's 100psi of fuel in there, and no way to safely depressurize it now because the timing belt is no longer on the engine, and the front end has been completely removed.. Sweet. So, rather than follow bad directions, or release fuel all over the engine bay and shop space, we get to go our own way where the fuel rail is not disturbed.

This is when we discover just how sadistic the German auto engineers really are... or were in 1997.

1.8 Turbo Intake
The intake manifold is held on with 10 fasteners: 2 10mm nuts, 2 10mm bolts and 6 5mm Allen bolts. The 10mm nuts and bolts are on the ends and the Allens are between the intake runners. Of course, they are also mostly obstructed by the fuel injectors, so, again, if you want to remove the intake, it is best to dismantle the fuel rail. Grr.. With a wobble-head attachment on my 3/8" ratchet, I was able to crack all of the bolts except one. That one bolt eventually broke free after throwing various bits at it. I will need to replace at least that one bolt for re-install.

1.8 Turbo Exhaust
With the timing belt off, the evil coolant flange removed and the intake separated from the head (with shop towels covering up all openings), we shift to the exhaust side. The exhaust manifold is held on with 2 13mm nuts, 2 12mm nuts (yes, that's right. we've got both kinds of nuts) and, on this car, 3 6mm Allen bolts and 3 13mm bolts. I say that because someone swapped out some of the 6mm Allen bolts and replaced them with hex bolts. Now, the car is usually equipped with a heat shield which is held on with Allen and hex bolts. This car did not have the heat shield but all of the bolt holes were occupied with hex bolts which were in place nice and super-tight. Ugh. Love PO's. Regardless, the nuts are on studs at either end of the head, making them hard to get to, driving you to using old-skool spanners especially near the firewall. Once removed, I shifted focus onto the Allen bolts, and things got interesting. The exhaust manifold is very short, wrapping into a turbo that sits almost directly in front of the lower mounting bolts. So, from above, you need to thread a long Allen key between everything and torque the bolts free. Penetrating oil and long-stemmed Allen sockets recommended. Even then, you can't reasonably get to all of the Allen bolts under the exhaust manifold.

The best solution is to remove the turbo from the exhaust manifold and pull the head with the manifold still attached. Then, you can get after those Allen bolts. The turbo is held to the manifold with 3 17mm bolts. These bolts point straight up and have a slight recess around them in the manifold. Water likes to build there when the car is parked outdoors, so what do you get when you leave water standing on iron? That's right. Rust. Enter the penetrating oil again while you think about how you're gonna get a socket onto those bolts. Realizing you can't, again, you go old-skool with a spanner. I was very grateful for my penetrating oil comparison (See Hammered Rims Part 1) when I discovered the Kroil. After a few days of spray-and-wait, those bolts came off with very little extra coaxing.

Head Out
With the intake off, all the other little bits remove, the outlet flange off and now the turbo released from the exhaust, there was nothing more in the way. Except the valve cover and the 10 mystery head bolts hidden within. The valve cover is held on with a bunch of 10mm nuts and bolts. Once removed, the cover should just lift off, but nah. I applied some convincing with a rubber mallet and then with a pry bar on each corner. With the pry bar, I made sure to apply very light pressure so I didn't crack anything. With the valve cover off, we could see what king of fastener held on the head. After the swap-about on the exhaust, I couldn't just assume based on make-model-year. Turned out the bolts were the 10mm RIBE-style, so they could have been original. Regardless, these are typically sold as part of head gasket kits. With a bit in hand, I made to remove them and this was my first indication that the head had been removed at some point. I put my torque wrench on, and they required very little effort to loosen. By "very little effort" I mean I put my torque wrench on there and gave it a good bump with my hip and they broke free. I should have needed a breaker bar.

With the bolts all loose, I was able to wiggle the head. So, I put fingers into the coolant outlet, and my other hand around the belt tensioner and pulled straight up. It came free, and dropped the head gasket out as the head lifted out. What I saw was very interesting. The coolant passages rising up from the engine block met the gasket, but the hole in the gasket wasn't the same size as the hole in the block. The gasket has a little pin hole and the block was a decent-sized triangle. While I thought this was the application of the wrong gasket, according to Fel-Pro, it isn't. This is by design to correctly meter the coolant through the engine.

I will be taking the head to a shop to get pressure tested, decked and otherwise refreshed while I clean up the block face. The coolant passages look like some build up occurred behind the gasket, so I'll clean that up with a pick and a shopvac (so no bits fall deeper into the engine). I'll return to this effort blog-post-wise once I have the head back and the install is happening.

Thanks for following along. More next time-