|
|
Tech Tips
Use this comprehensive information library whenever you need helpful hints from car repair professionals. Whether you are a professional or a DIY mechanic, you’re sure to find the tips you need to insure a job well done. Click here to go back to the previous page any time during your search.
Volvo
Volvo Oil and Fluid Leaks
edited from an article by Boe Kalinoski, ImportCar, April 2001
The challenge in repairing any fluid leak is identifying the source. When the engine is covered with oil and grease for a long period of time, it is almost impossible to find the culprit. The first step in discovering the source of any oil leak is to try to clean the areas where dirt, grime and oil are present (I’ve found that steam cleaning is best). In our shop, we use a fluorescent/black light along with a special dye. Simply add it to the engine or transmission and run the vehicle while the fluorescent light is warmed up. Most of the time, the leak instantly appears in the form of a bright glow. The most expensive repairs are the front and rear main seals, which necessitate disassembling the transmission and/or timing belt area(s).
Leaks in Volvo B230 engines (See Photo 1) can occur when the crankcase ventilation becomes restricted (Volvo uses a flame trap). It consists of a small, black plastic tube located under the rear of the intake manifold (See Photo 2), that is changed at normal service intervals. In addition, the canister that is bolted to the engine block above the starter can crack and deteriorate with heat (See Photo 3).
On the front of the B230 engine, there are three seals located behind the timing belt — cam seal, idler shaft seal and front crankshaft seal (See Photo 4). In our shop, we recommend changing the timing belt along with the seals at the 100,000-mile service interval.
Some rear engine oil leaks can originate from the distributor shaft and/or O-ring, causing misdiagnosis of a rear main seal leak (See Photo 5). A simple problem with the oil cap seal or the valve cover gasket, can be easily overlooked.
On rear-wheel-drive Volvos, a leak coming from the transmission can be caused by a worn out tailshaft bushing that leads to excessive play on the shaft and a leaking seal that spews ATF all around the tail section. Deterioration of the rubber transmission mount will result.
A special tool (p/n TO159) was developed to aid in the replacement of the bushing and seal in the car, eliminating the need to take off the tail section of the transmission (See Photo 6). The supplier is IPD of Portland, OR, 1-800-444-6473. At $170, the price is high, but it will save time on many procedures.
OTHER LEAK CULPRITS
The power steering rack and rubber hoses can cause small, disturbing leaks as well. Check the boots on the steering rack for the presence of fluid. The seals could be leaking internally. Another common place for leakage is at the input shaft spool valve seals. At this point, you should recommend replacing the rack assembly, as steering assist will be lost if the power steering pump runs out of fluid, resulting in pump failure.
When diagnosing oil leakage on a front-wheel-drive Volvo, check for failure at the rear main seal. The most complicated to repair, it is necessary to remove the engine/transmission cradle with the front suspension disconnected when correcting this problem. Hold up the engine with a suitable fixture and remove the gearbox.
Volvo has updated the rear main seal and the use of special factory tools is recommended to install the seal correctly. Tap in the new greased seal using a drift (p/n 5430) and installer (p/n 1801) to position the flywheel. Apply some threadlocker to the new bolts and tighten to 33 ft.-lbs., plus an additional 50 degrees.
While the comeback rate in repairing oil and fluid leaks can be high, especially in older Volvo models, taking the time reinspect problem areas after a repair is completed can avoid future problems.
The first step in replacing a timing belt is to order the correct replacement belt. The length, width, tooth profile and pitch must be the same on the replacement belt as the original.
The next step is to remove the belt cover and align the timing marks. On most engines, you want the number one piston at TDC (top dead center) on its compression stroke (not exhaust stroke). If the engine has ignition timing marks on the crank pulley, it makes the job easier. But you still might have to open the distributor cap or remove the valve cover to see if number one is on its compression or exhaust stroke.
Getting to the belt itself requires removing anything that’s in the way. This includes any external drive belts, the lower timing belt cover and usually the crankshaft pulley. On many engines, you may also have to reposition certain wiring and A/C, emissions or heater hose plumbing, remove one or more additional engine covers or splash shields, and loosen or reposition some external belt-driven accessories (such as the A/C compressor, alternator, power steering pump or water pump) to get at the belt. On some transverse-mounted engines, you’ll also have to disconnect the right motor mount (don’t forget to support the engine) before you can replace the belt.
Once you’ve uncovered the belt, confirm the alignment of the timing marks, then follow the recommended procedure to loosen or relieve the belt tensioner and remove the belt. If the engine has one or more balance shafts, make sure the timing marks on these are also correctly aligned.
Inspect the belt cogs for signs of unusual wear that would indicate a damaged or misaligned pulley. If the cogs are chewed up, don’t install the new belt until you’ve identified and repaired what’s causing the damage. It makes no sense to install a new belt on an engine with one or more bad pulleys because it will doom the belt to early failure.
Before the old belt comes off, make a mental note of how it is routed. On some engines, the routing is like that of a serpentine belt looping around numerous pulleys.
On some vehicles, you may have to use a special tool to hold the crankshaft and/or camshaft(s) in position while the new timing belt is being installed and tightened.
Some engines have a hydraulic tensioner that uses oil pressure to keep the belt tight. On these engines, the tensioner must be prepared before it is reinstalled by draining out the oil, fully retracting the plunger and refilling it with 5W-30 motor oil.
When installing the new belt, use care not to nick, twist or squeeze the belt excessively while you’re working it into place. Squeezing or crimping a belt to a small radius may damage the internal cords. Timing belts do not stretch, so never attempt to force one around a pulley. If the belt won’t go on, something is misaligned or misrouted, or you have the wrong belt for the application (it happens!).
Once the belt is in place, make sure all the timing marks are in alignment, then install or adjust the tensioner so the belt has the correct amount of load. Automatic tensioners and hydraulic tensioners will apply just the right amount of pressure, but if you have to set belt tension manually don’t overdo it. Excessive tension puts added stress on the belt and pulleys and can lead to premature belt failure. Follow the vehicle manufacturers’ recommendations for belt tension and use a belt gauge to be accurate. In most cases, tension is checked between the two furthest pulleys.
As a final check, rotate the crankshaft twice and recheck the timing marks to make sure they are still in proper alignment. If everything appears to be okay, replace the belt cover and other components that had to be removed or relocated to finish the installation. Then place a label on the engine indicating the belt has been replaced and the odometer reading. This will alert other technicians that this service has already been performed. And should the vehicle rack up another 60,000 miles, it will serve as a reminder that the belt needs to be replaced again. ß
WHY IDLERS AND TENSIONERS ALSO REQUIRE REPLACEMENT WHEN CHANGING A TIMING BELT
Timing belts have a limited service life. That’s why belts should always be replaced at the vehicle manufacturer’s recommended mileage interval. But a belt change alone may not be enough because the majority of belt failures are actually caused by faulty belt tensioners and idlers. These failures can result in major engine damage and expensive repairs. Consequently, the new timing belt you’ve just installed may fail after a few thousand miles if the tensioner or idler is worn or loose.
The eccentric idlers and/or pulleys that are used on many OHC engines to maintain belt tension also have a limited service life — which in some cases may be less than that of the belt! Their lifespan depends on their location, operating temperature, load, engine rpm and other environmental factors. Most tensioner and idlers have a design life of around 2,000 hours, which may be the equivalent of 40,000 to 60,000 or more miles of service depending on how the vehicle is driven. Unless these components are also replaced when the belt is changed, it could lead to premature failure of the new belt.
Tensioner bearings are "sealed for life" and are not serviceable. So there’s no way to clean, inspect or relubricate the bearings when a timing belt is changed. Over time, the grease inside breaks down and oxidizes, accelerating bearing wear and increasing the risk of a bearing failure or seizure. And the hotter the operating environment, the shorter the lifespan of the grease and the bearings. The location of these components under the timing belt cover prevents them from receiving much cooling, so they tend to run quite hot.
If a tensioner bearing seal fails, dirt and humidity can enter the bearing. At the same time, a leaky seal will allow the grease inside to escape, dooming the bearing to rapid failure.
On many newer engines, spring-loaded automatic tensioners are used to keep the timing belt tight. A slide plate allows the tensioner roller to move against the belt. As the miles accumulate, though, wear can cause the plate to stick against the engine block, preventing the tensioner from maintaining proper pressure. High underhood temperatures can also cause a loss of spring tension over time.
If the belt loses tension, it may jump time or slip. And if an idler pulley or tensioner seizes, it may cause the belt to suddenly snap.
Unfortunately, you can’t always determine the true condition of these components by a simple visual inspection. Any pulley bearing that has visible looseness, grease streaks radiating outward from a damaged seal, makes noise or does not turn freely, obviously needs to be replaced. But many tensioner pulleys that appear to be okay may be at or near the end of their useful service life. Reusing them is a risky proposition. That’s why the tensioner and idlers should always be replaced when installing a new belt.
Timing component kits are now available in the aftermarket, that make it much easier to replace the tensioner idlers and pulleys along with the belt. The kits include a new timing belt, idler and/or tensioner assembly along with detailed installation instructions. Do the job right the first time and significantly reduce the risk of component failure. |
Go back
|
