Cam Chain Tensioner Issues
by Pat Goss
No matter what type of vehicle, the key to a long life is good preventive maintenance. And, for example, we have this Harley-Davidson motorcycle that has 113,000 miles on it, and still runs almost like-new. Well it took this amount of preventive maintenance to make that happen.
And to give us some tips about motorcycles in general, we have Lyndon Abel from Patriot Harley-Davidson in Fairfax, Virginia. Lyndon, welcome to MotorWeek.
LYNDON ABEL: Thanks Pat.
PAT GOSS: Alright, now on Harleys, you have a…chain tensioner?
LYNDON ABEL: Yea, so like most vehicles, this Harley-Davidson has a cam support plate, and these two cams are driven by a chain. And like I said, most vehicles have something similar. And they need tension provided on this chain. In this case it’s spring loaded; but instead of the tensioner looking about like this, where this metal chain is running against this plastic tensioner, you can see that the tensioner is worn completely through. And now this chain is running against the spring itself. And it’s pulling shrapnel off of that spring, and sending it through the motor. You can see that it’s already started to destroy the cams, and you can imagine the oil pump looks similarly poor. This is a very bad thing.
PAT GOSS: Okay, now, keep in mind that virtually all engines these days have some type of chain tensioner like this, and they all wear; they’re like brake shoes or tires. So you need to check them.
LYNDON ABEL: So this is an upgrade. Harley-Davidson switched to a hydraulic tensioner, and this is a better way to go because at lower RPMs, you need less pressure on that chain, and at higher RPMs, you need more pressure. Well, the oil pump delivers greater pressure at higher RPMs; where you need it most. But at lower RPMs, you don’t have as much pressure on the chain, which means you get a longer life out of this cam chain tensioner.
PAT GOSS: Double, maybe?
LYNDON ABEL: At least double is what we’re seeing.
PAT GOSS: Okay, and to go along with this I’m assuming it has a matching oil pump?
LYNDON ABEL: It does. This oil pump provides not only the increased oil pressure that you need to handle those hydraulic tensioners, but also any increase beyond that. So your…you’ll get better flow, better pressure throughout the motor, as well as better scavenging out of the case, which is increase performance, and decrease potential oil carryover.
PAT GOSS: Okay. Lyndon, thank you. And if you have a question or comment, drop me a line, right here at MotorWeek.