There is a potential major issue in the Harley-Davidson Twin-Cam engines. This is a statement of fact, not a bunch of wild guesses. I’m not here to bash Mother Harley, but you should be educated to its causes, and possible solutions.
Okay, what issue are we looking at? It’s a very serious one that is enough to alarm you. However, you can fix these defects and end up with a nice bike. Our objective today is to educate, and we are also going to outline some ways to fight back. Yes, even the new Harley’s have serious, potential problems. Even the expensive CVO (Custom Vehicle Operations) bikes have issues not to be taken lightly.
Here we go…..
The problem is the design of the cam chain system. It uses plastic “shoes” riding on the cam chains that can (and do) wear out. Harley has made some changes in later model bikes, but even with the new hydraulic tensioning system, it is not a true fix. What is the problem? The shoes rub against the two chains and the plastic shoes wear out. When they wear in extreme cases, there will be metal to metal contact and this grinding creates metal shavings that can result in a catastrophic engine failure. If not caught soon enough, this can be so bad that the entire engine can be destroyed; cams, pistons, crankshaft and even engine cases broken. It is a wickedly serious possible engine problem. Be aware… it can fail as soon 15,000 miles (in extreme cases). Even the newer hydraulic system can fail at 50,000 miles or less. The cam chain tensioners have a section in every service manual that covers the Twin Cam engines and is very enlightening.
If your pipes are loud, you may not hear or get any warning. The oil pump passages can clog up without making any noise whatsoever except when the engine starts tearing itself to pieces.
The scary thing is every Twin-Cam engine has the potential to have the cam chain follower issue, even the new models. Check things out before this happens to you. If it has a cam chains, it has the potential problem.
It is our intent to make you aware that pre ’06 Dyna’s and the 1999 to 2006 Twin-Cam Harley-Davidson engines have possible, serious issues and they can mess up. How? In the most severe cases, as the spring loaded cam chain follower fails it shreds plastic material that fouls the rotary gear oil pump cutting off oil flow to the engine that can cause sudden catastrophic engine failure and destruction. Also, metal to metal contact in these shoes produces metal filings to disperse into the oil prior to being filtered by the oil filter. If this happens be prepared (worst case) to buy a completely new motor as rebuilding the engine may not be feasible. This is not a likely situation, but a realistic possibility
OK, now that we have ruffled everybody’s feathers, how can we combat this? S&S has truly been visionary in solving this issue. They had the foresight to develop a gear drive system to combat this very issue. It is my opinion, that all Twin Cam engines should have this conversion done, so you can rest easy on your higher mileage TC engines. The gear drive replacement is an excellent and the only true bulletproof solution.