A lesson in lubrication, by Tom Dobush.
One of our clients came in concerned about a knocking noise their Audi was making. After checking the oil and finding it three courts low, we began to do some further investigation. What we ended up finding was not pretty. Actually it was pretty amazing that the car was still running so well. A testament to the robustness of the Audi design. However, very few engines will continue to run for very long without proper lubrication and this one was no exception, we probably caught it just in time.
Above is an image of two camshaft seals side by side. On the left is a new seal, in original, perfect condition, only slightly dirty from being handled by greasy paws. On the right we have quite a contrast. This is the front passenger side camshaft seal that was on the car when it came in. You might be able to guess from the photo, she got hot and began to melt. This damage was a clear indication that more investigation was required and from our experience what we were about to uncover was not going to be good.
Here we have the exposed camshaft laying inside of the cylinder head as it would normally prior to disassembly. The view here is from the rear of the cylinder head on the back side of the engine. You can see in the foreground the clean camshaft is smooth and fits tight and neatly inside the head. This camshaft spins in time with the crankshaft while the engine is running. There is an oiling port in the head that is under the camshaft that allows for a very thin film of oil to keep the camshaft lubricated as it spins. This reduces friction, keeping everything cool and moving freely. The cam lobes (you can see one sticking up in the middle left of the image) rotate in a specific pattern to actuate (open and close) the intake and exhaust valves by pushing on them as the camshaft spins. It is a fairly simple, reliable system that most cars on the road today use, known as an "over head cam."
Above is the view of the cylinder head with the camshaft removed. The oiling port mentioned previously is now clearly visible along with a light film of oil. This photo is a little misleading as you can see some metal filing debris in the oil. Those surfaces should and would normally be free of any dirt and debris, however this illustrates an important point. Dirt and debris do build up in your engine oil over time, which is one reason we have oil filters on our cars and also why we change our oil at regular intervals. This dirt and debris could cause premature wear on the moving parts inside of your engine, which is why we always recommend changing your oil more often than not. Better safe than sorry after all. These filings came from some work that was done on the bench next to the head. Normally this would be very bad to have filings like this in the cylinder head like this as they would cause damage pretty quickly if we put the engine back together dirty like this. However this cylinder head was already damaged and headed to the scrap heap rather than reassembly, so we weren't worried about it getting dirty. The next few pictures will illustrate as to why this head is no longer any good and will ultimately be recycled.
This is the same cylinder head looking at it from the opposite end. This is the result of low oil pressure caused by a lack of oil in the engine. Remember the melted camshaft seal in the first image? It got hot because there was not enough oil getting to this part of the cylinder head. Without the thin film of oil to keep things moving freely, heat builds rapidly and damage ensues.
Another view with the camshaft in place. The friction created from the metal surfaces spinning quite rapidly against each other without proper lubrication literally began to machine down the diameter of the camshaft just like it would have if on a lathe. Not pretty. The knocking noise our client heard was from this system not functioning properly and vibrating. This is beyond repair and these parts had to be replaced. As mentioned earlier, we were lucky to catch this when we did. Had it gone like this much longer the camshaft could have seized or broken, which would have caused a chain reaction, possibly breaking the timing belt and causing the valves to hit the pistons inside the combustion chambers. The knocking noise would have gone from bad to worse and ended with a very expensive crunch, effectively destroying the entire engine.
A slightly different angle shows just how much damage was done and how much material had been displaced. In the right half of the image, where the camshaft meets the cylinder head, the profile is all wavy where it used to be completely straight. We were able to source another cylinder head and camshaft and swap them in and she was back to normal. While we were in there she received new lifters, seals, a fresh oil change and a new oil filter along with a few other items.
A lesson learned the hard way, but it could have been much worse. We were able to save the engine which meant also saving the car, as the cost of replacing or rebuilding an entire engine on an older Audi might have been cost prohibitive and resulted in the car being sent to the scrap yard.
We hope this article emphasizes the importance of proper maintenance, oil change intervals and routine check ups for your beloved automobile. When we see our clients cars more often, rather than less, we can prevent these types of things from happening or at least catch them before severe damage is done.
Do you stretch the time (or mileage) between recommended oil changes a little bit? When was the last time you actually checked your oil? Is it clean? (Golden in color and fairly clear) Or is it dirty and black?
Ideally, your oil should be checked every time you drive your vehicle. Perhaps more realistically, every other time you gas up your car, you should peak under the hood and check it. Another option might be to swing by your trusted repair shop monthly so a mechanic can do it for you. It's free and could save you and your car a lot of pain in the long run! Remember, if you love it, lube it.