We all know that some vehicle owners don’t adhere to preventative maintenance schedules for their vehicles. So when a customer’s vehicle is in for a major problem or service, take advantage of in-depth system inspections. It may be one of the few times that you get to check the vehicle for severely worn parts.
Although it’s tough to quantify, customer buying habits are affecting the way we do business in our service bays. To be more specific, some vehicles have become more reliable and demand much less maintenance than their earlier counterparts. The combination of these two factors can result in a decline in car count and/or a decline in revenue, especially in shops that are heavily dependent upon preventive maintenance repair work to keep their coffers full.
This month, we’re going to look at timing belt replacement on a 1995 Honda Odyssey that had been driven almost 80,000 miles without any scheduled maintenance performed other than oil changes. Although a timing belt replacement isn’t normally scheduled until the 90,000-mile service interval, much of the currently neglected maintenance revolved around removing components normally associated with a timing belt replacement.
To adjust the valves, for example, the camshaft cover and spark plug wires must be removed. Access to the fuel filter (see Photo 1) is slightly improved by removing the timing belt covers, so replacement is highly recommended during a timing belt replacement.
Since undercar systems are sometimes overlooked and scheduled maintenance is put off by customers, it’s a good idea to combine timing belt replacements with a thorough undercar inspection. Checking exhaust system and rear brake condition only requires a few more minutes and can generate some significant service sales in the process.
And, since the vehicle must be lifted to remove the left front wheel for access to the crankshaft pulley and lower timing cover, use a little extra time to check the front brake linings, MacPherson struts, wheel bearings and the axle shaft boots for wear.
Removing the Timing Belt
Since the Honda 2.3L engine is an interference engine, it’s important to avoid accidentally turning the engine over or engaging the starter when the timing belt is removed. On the other hand, many Hondas have anti-theft disabling devices that prevent further use of the radio if the battery is disconnected. When the radio loses power, reactivation requires an entry code that’s recorded in the owner’s information packet. If the owner has misplaced his owner’s information packet, the vehicle must be returned to the dealer to have the radio reactivated. In this case, I simply remove the ignition keys and hang them on the shop’s key rack while replacing the timing belt.
I might mention that the battery also should be tested for circuit integrity and load capacity. Electronic fuel injection engines start so easily that worn batteries may go a long time without detection. To speed battery diagnostics, I use an electronic capacitance tester that requires only that the surface charge be removed by turning on the headlamps for one minute. These testers, in my opinion, have the needed sophistication to reveal 99% of most common battery defects without running the battery down, as would a regular carbon-pile load-testing device. In addition, some models determine a numerical cold-cranking ampere capacity of the battery after the test is completed.
As with many Honda timing belt replacements, the camshaft or valve cover must be removed to allow removal of the upper timing belt cover. I also dismounted the power steering pump and air conditioning compressor, leaving the hoses connected and moved them aside to ease access to the belt. Since the left-hand engine mount (see Photo 2) also must be removed to allow removal of the timing belt, I’ve found that the simplest method is to lower the lift onto two jack stand supports and support the engine with a screw jack or similar solid support. While we’re at it, it’s also a good time to remove the spark plugs and check cylinder compression before we remove the old timing belt.
As always, removing the crankshaft bolt on late-model Hondas is a challenge because the bolt may be held in place with ample quantities of thread-locking compound. Although I highly recommend using the OEM engine pulley holders to prevent the crankshaft from turning, I’ve found several of these models requiring more than 500 ft.-lbs. of torque to shear the thread-locking compound loose. In this instance, I had to liberally heat the crankshaft bolt flange before I could get the thread-locking compound to release. To prevent heat damage, I had a helper use a garden chemical sprayer to lightly wet the timing covers and other parts. I don’t recommend this method, but, to date, this particular bolt was the most difficult I’ve had to remove.
Pay particular attention to how the lower cover is removed because it can be very difficult to reinstall (see Photo 3). Perhaps some slight dimensional variation in the vehicle’s manufacture caused this specific difficulty, or perhaps it was the lack of experience with this application, but reinstalling the cover can use up a lot of time if things don’t go right.
As a matter of habit, I always bring the belt timing marks into alignment before removing the belt. If the belt is on its second replacement interval, any previous timing errors can be discovered using this process. In addition, the reassembly process will be speeded up if each timing mark is highlighted with typewriter correction fluid (Wite-out) before the belt is removed.
Smoothing the Balance
Unlike earlier Honda engines, the operation of the 2.3L engine is smoothed out by using two balance shafts to counteract engine vibration (see Photo 4).
Basically, when a cylinder fires in an in-line three- or four-cylinder engine, the engine block tends to “rock” up and down in a lateral plane like a seesaw. The balance shaft applies an opposing force that dampens this seesaw vibration condition as the cylinders fire. Consequently, the balance shafts must be timed with the crankshaft to prevent undesirable vibrations from taking place at higher engine speeds.
The front balance shaft is timed by aligning a slot stamped into the sprocket with a pointer cast into the engine block. The rear balance shaft is timed by removing a maintenance hole plug from the backside of the engine block and inserting a 6×100 mm bolt to lock the balance shaft in place. Six millimeters is only a few thousandths of an inch less than a 15/64″ drill bit, so a clean drill bit could be substituted. It’s a good idea to index the balance shafts with the engine block with typewriter correction fluid (see Photo 5) before removing the original timing belt to make sure that the shaft is timed with the crankshaft. By the way, don’t forget to remove the bolt immediately after the new timing belt is installed!
As an aside, it’s particularly important to thoroughly read a shop manual before proceeding with even the most routine repair. Some repair literature, for example, may mention the balance shaft locating procedure in only one or two sentences, so it’s easy to miss.
As a precautionary measure, I also installed a balance shaft seal retainer (see Photo 6) on the front shaft to prevent the seal from spinning out of the seal bore. Although I haven’t experienced balance shaft seal failure in Hondas, a number of technicians have reported such failures on the International Automotive Technicians’ Network (iATN), particularly after the timing belt is replaced. Since a catastrophic oil leak results when the seal spins out of its bore, an ounce of prevention is worth a pound of cure in this instance.
Associated Inspections and Service
Most good techs inspect all accessory drive belts for wear and drive bearings for roughness or dryness. Although most Honda water pumps last at least through the first timing belt replacement, the water pump seal should always be inspected for leakage. A basic rule is, if a bearing or belt doesn’t feel like new, it should be replaced since the labor charge is minimal at this point.
Some Honda service schedules are recommending coolant flushes at 60,000 miles or earlier. If the water pump is changed, the radiator and block should also be drained and the old coolant replaced with new coolant meeting Honda specifications. By the way, don’t forget that Honda uses an air bleed to vent air from the thermostat housing during a coolant refill. Failure to properly bleed air from the system will result in an immediate overheating condition, so pay particular attention to this important step.
In my locality, I haven’t seen excessive sprocket wear on Hondas. Nevertheless, I always check the condition of the sprockets and tensioner pulley to prevent damage to the new timing belt. In addition, inspect the timing cover seals for deterioration or separation from the cover. If the vehicle is being operated on dusty or sandy roads, good cover integrity is critical for long timing belt life.
Putting It Back Together
The most difficult part of timing belt installation is to remove excessive slack without over-tightening the belt. In this application, Honda uses a dual tensioner pulley (see Photo 7) to correctly tension the camshaft and balance-shaft timing belts.
In this instance, I think it’s best to turn the engine over several times with the new belts installed with the tensioner bolt and crankshaft pulley snuggly in place. Now would also be a good time to check the valve adjustment as you turn the engine over. Next, with light torque applied to the crankshaft pulley bolt in the direction of engine rotation (counterclockwise), tighten the tensioner pulley bolt to specification. As a rule of thumb, you should be able to twist the belts not more than 90