 Techline-Jan.09-H-D 110" CVO -Part I: The head gasket oil leak and other issues
This article will continue in the next thread.
Editor’s Note: This month we begin a five-part excerpt of Chapter 3: H-D 110" CVO from Donny’s Unauthorized Technical Guide to Harley-Davidson, 1936-2008, Volume I. Some content has been altered to fit AIM’s style and format.
After working on almost every version of Harley-Davidson engine over the last 35 years, there is not much left I find truly exciting. However, the challenge of understanding chronic problems and effectively repairing them, and suggesting design changes to treat the causes instead of the symptoms, is exhilarating for me. The theory and practical applications related to the CVO 110 will apply to similar situations in your engine, no matter what it might be.
Harley-Davidson’s back is really up against the wall on this one. When the Motor Company began to build big-inch engines, I had a bad feeling. How could it go big and still stay within EPA and CARB (California Air Resource Board) guidelines on a platform based on two cylinders with the notoriously inefficient 45-degree cylinder angularity? The only great things these cylinders and their firing order have contributed to the Harley world is the look, and, secondly, the potato-potato sound from the exhaust.
However, ever-quieter noise emission rules have muffled the sound almost to the point of extinction. I feel the issues with the Harley-Davidson Custom Vehicle Operation’s 110 is all about heat — excessive heat.
Part of the formula for big-inch engines is higher compression ratios. Of course, I feel the anemic 9.3:1 compression ratio of the CVO 110 is symptomatic of the factory’s attempt to control the heat produced by the engine. A lower compression engine runs cooler, since higher compression brings heat to the equation. Moreover, leanness of the fuel mixture in order to meet EPA dictates to reduce emission pollutants is a major excess heat culprit. Alternatively, is the real culprit Harley-Davidson’s reliance on an antiquated design? Well, we all know that H-D’s reliance on our beloved dinosaur technology is based on a market demand at odds with a modern, environmentally challenged world. The V-twin design and technology is based on our wants, not our needs.
H-D & EPA Mandates
The Motor Company attempted to adapt a patchwork of different technologies to an air-cooled engine that engineers felt would never run in the first place back in the early 1900s. CARB’s latest requirements were updated in 2008, while EPA regulations will substantially tighten up in 2010. There are stringent automotive miles-per-gallon limits set for 2020 that are already modifying near-future model choices such as eliminating some rear-wheel-drive cars because they are currently too heavy relative to front-wheel-drives. The future is coming fast, and it will not be kind to tradition and nostalgia.
EITMS is the acronym for engine idle temperature management system. This feature turns off the rear-cylinder fuel injector at hot idle. The rear cylinder still functions but without fuel. Air is still sucked in on the intake stroke and goes through the remaining three strokes as the engine acts as an air pump. The lower temperature air flowing through the rear cylinder cools the engine while it’s only running on the front cylinder. If H-D planned to meet EPA dictates while going big with cooperative cylinder angles (56- or 60-degree angularity) replacing the difficult 45-degree positioning, more cylinders, a water jacket, and overhead cams (OHC), then there is a good opportunity for successful compliance. However, an air-cooled, dual-cylinder, pushrod-operated relic with an awkward firing order at 315 degrees Fahrenheit and 405 degrees does not have much chance of success as the years roll by. The firing order and positioning is within the 720-degrees of crankshaft rotation to complete one full cycle. The four theoretical 180-degree strokes are intake, compression, power, and exhaust. I say “theoretical” because, in practice, the valves open and close before and after each 180-degree stroke, resulting in real-life extending and overlapping of the cycles.
Increased angularity allows for a more efficient firing order and rhythm; more cylinders allow each to compensate for and bolster others through teamwork, and overhead cams rid the engine of a bulky, inefficient valvetrain with mechanical limitations. Moreover, these directly actuating overhead cam lobes allow for an increased and responsive rpm range. The water jacket and liquid cooling combat the effects of lean-burning engine management systems. Water jackets control the excess heat required to burn all the fuel, thus eliminating noxious pollutants in a perfect world.
Furthermore, preignition and the great engine destroyer, detonation, have difficulty wreaking their havoc because the precursor, heat, is lowered to manageable, constant temperatures. Water jackets also address the second EPA anxiety: suppressing internal engine noise. Lessening internal engine noise led to the development of the Twin Cam engine and its timing chain apparatus.
Engine Specs
The 110" CVO Twin Cam motor uses the stock TC 96 flywheels, which, as we know, have a stroke of 4-3/8" while TC 88 engines have a stroke of 4". Both the TC 96 and the TC 88 have 3-3/4" stock bore cylinder diameters. If we bore out the TC 88 to 3-7/8", we will achieve a 95" engine. Boring the TC 96 to 3-7/8" will result in 103". Modifying a TC 88 to achieve a 110" displacement requires installing 4-3/8" stroke flywheels, boring out the stock engine case cylinder spigots, and fitment of 4" piston-bore cylinders. Therefore, the 2007 CVO 110" engines, as with earlier Twin Cam 110" engines, use Twin Cam engine cases with 4" piston-bore cylinders with a stock TC 96 stroke of 4-3/8". This is completely safe and reliable with all Twin Cam engine crankcases.
At Heavy Duty Cycles we routinely build 116" and 124" engines (first introduced by S&S Cycle) using the stock Twin Cam cases with stellar results. Using a 4-5/8"-stroke flywheel assembly is still a safe way to achieve the 116" and 124" larger displacement engines. A 4" piston-bore with these 4-5/8" flywheels results in 116.2". A 4-1/8" piston-bore with the 4-5/8" stroke produces 123.6". Again, the engine case cylinder spigots need boring for fitment of these monster cylinders.
Rear Cylinder Issues
It appears that a number of 2007 CVO 110" engines are developing an oil leak on the backside of the rear cylinder just below the exhaust port. Typically, this begins to occur between 2,000 and 6,000 miles. I’ve received reports of this malady also occurring on the stock
TC 96, although I’ve not personally seen one. Even if there are TC 96 occurrences, I feel they will be far less of an issue than with the 110s. (However, both the TC 96 and the CVO 110 are experiencing a flywheel scissoring problem. More on this later.)
I’ve been receiving many e-mails and queries from worried CVO 110 owners. Jerry Rice from Memphis, Tennessee, wrote, “Here’s info on the problem on 2007 FLHTCUSE2 Screamin’ Eagle Ultras with the 110" motor. The rear cylinder head gasket develops a leak, typically around 3,000 to 5,000 miles. Not a compression leak, but an oil leak. It presents itself on the backside of the rear cylinder, just below the exhaust port. Harley-Davidson Motor Company has a new head gasket (#16801-07A), but this has not been a fix. I had mine replaced (along with the rear cylinder itself) at 9,000 miles; after 4,000 miles it began to weep again. By the time I got back home with 8,000 miles on the repair, it was a pretty good leak with oil dripping down on top of the primary case and baked on the entire back of the rear cylinder and head. Also, it seems that in the rear cylinder the steel insert is showing some degree of separation from the aluminum cylinder. So H-D is replacing the rear cylinder and head gasket for a second time.
“I personally know several folks with the problem, and through my main Internet forum, I have become acquainted with dozens more. This is not an isolated issue and seems to be a problem more of design than manufacturing. Thanks in advance for any advice/recommendations. If you have a fix, I’ll be glad to head up your way to get the work done.”
Chuck Matthews from Marietta, Georgia, wrote “I really do hope all of the recent activity on the AIM forum regarding the repetitive problems owners of the 110" motors are having will persuade the magazine to do some good solid investigative reporting to dig up the true facts regarding the unacceptable number of bikes plagued with this problem. This problem is so severe that the three other 2007 FLHTCUSE owners I know have had this problem at least twice apiece. One is currently talking about a new motor since his leak reappeared for the third time. Another is getting a new motor right now, but he’s gone through two sets of replacement jugs trying to fix the problem. The third one called me last week to tell me he just found out that his bike, previously thought to have been fixed, is once again leaking. My bike is leaking again, too, after being ‘fixed’ with the revised head gasket. I just saw today that there is now a new (#16801-07C) gasket out. I haven’t verified that, but I currently have the #16801-07A versions installed (replacing the #16801-07 gasket). The #16801-07A gaskets were new in April of 2007. That’s a whole lot of gasket designs to go through in eight months if there isn’t a real problem.”
“Talk to dealers,” wrote one reader. “Talk to me. Talk to my friends that also have this problem.
We’ll give you VINs you can check with to see what’s happened and when. This is a very serious problem that so far has gone unnoticed in the press. Harley is working on it, but I think it needs a little shove to get really serious about it. When we all went through the cam bearing saga in 1999 and 2000, the failure rate was a whole lot less and that problem got a whole lot more press time. Everyone was talking about that one. This time around, the failure rate is enormous, and as of yet, nothing has been printed about it. Sure, the number of potential problems is a lot less this time around since it’s primarily only CVOs, but the failure rate, even without including multiple failures, blows the cam bearing problem away.”
Another discouraged reader wrote, “I have recently purchased an ’07 SE Springer with the 110" engine. I really love the bike and it had 1,800 miles on it as of last week. I have heard all of the bad press on the 110 engine and I was hopeful that I would not experience any problems. I noticed an oil mist around the rear head/cylinder joint. When I took it to my local H-D dealer for a service, I had it inspected and the dealer said the head gasket was leaking. The mechanic replaced it, took it for a test ride, and inspected it again only to see that it was still leaking. This is what shocked me. He called some H-D tech line and was informed that, yes, the Motor Company is having issues with the 110 engines, and he needed to pull both heads off for inspection of the liners. He pulled them off the next day, and both liners had shifted (he showed me; there was a noticeable lip on both liners that your fingernail would catch on). Both cylinders are being ordered Monday, along with new rings and a new fourth-generation gasket. While I understand why Harley-Davidson Motor Company is not coming out with this information to the public, the shocking thing, and what was frustrating to me, is that it’s not being communicated to the service network. My mechanic was very frustrated with that.” This same reader was very complimentary to his dealership and the concerned service he is receiving.
Article continues in the next thread. Check back issue for pix and extra information. |
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