A smell of burning oil in the cabin is usually an indicator of a leaking valve cover gasket or cam chain tensioner gasket (for B5 Passats, at least). There may also be an accumulation of oil on the belly pan and various engine components (illustration). Note that if there is a smell of gasoline in the cabin, it may be time to replace fuel injector seals.
The valve cover gasket seals the surfaces of the cylinder head to the valve cover, which houses the engine's camshafts (illustration). Oil leaks usually occur at the rear passenger corner of the engine (for the 1.8t), most likely due to the orientation of the engine. The commonly leaky cam chain tensioner gasket is also here at the rear of the engine.
Replacing the valve cover gasket is a straightforward procedure. Besides the cost savings of replacing the gasket yourself, you can be assured of a correct installation. Many of the stories of repeated visits to the dealership for gasket replacement can likely be attributed to hurried technicians incorrectly tightening the valve cover fasteners.
Part Information & Sources:
|1.8t||058 198 025 A|
|V6||078 198 025 (two sets required)|
Tools & Materials:
- Torque wrench
- Deep 10mm socket
- 5mm hex driver (Allen) - must be socketed.
- Mineral spirits (paint thinner, acetone, etc)
Due to the sensitive nature of gaskets in general, it is essential to have a good quality torque wrench available. If you enjoy working on your car, a torque wrench is a wonderful investment. A good compromise is to purchase a high quality torque wrench designed for low-torque applications (up to 20 ft-lbs or so) and a second, less expensive torque wrench for the high torque applications (up to 150 ft-lbs works well), where the wrench can be less accurate without causing problems. Expect to spend $70 or so for the low range torque wrench and $15-$30 for the high range torque wrench.
Time Required: 1-2 hours, depending on individual pace.
Valve Cover Removal:
- Begin by removing the plastic engine cover.
- To access all valve cover fasteners, the breather hose and heatshield on the passenger side of the engine need to be moved aside. The breather hose is held in place to the valve cover with a bolt - remove this. (illustration).
- The end of the breather hose is held onto the air intake assembly by a hose clamp - loosen the hose clamp and you'll be able to pull the end of the breather hose free. Move it aside to access the heatshield. (illustration)
- The heatshield is held in place by two philips screws - you may need to use a socket wrench with an angle adapter and philips bit to access the screws. Remove the heatshield.
- Unscrew the coilpack ground strap from the valve cover. (illustration)
- Using the 5mm hex driver, unscrew the coil pack fasteners. There are two bolts per coil pack. (illustration)
- Remove the coil packs, taking care not to bend wiring sharply or excessively flexing the coil pack's spark plug connector. (illustration)
- The upper plastic timing belt cover also needs to be removed to gain full access to the valve cover. Remove the two clips securing the cover and pull upward. You'll also get a chance to examine part of the timing belt at this stage for damage, though visual examination will not reveal impending failure due to age or wear.
- The valve cover is held in place by several nuts on bolts threaded into the cylinder head. Remove the nuts. On a few of the fasteners, the nut may be locked onto the bolt, causing the bolt to rotate with the nut during removal - as the bolt is threaded into the cylinder head, the bolt is now being unthreaded from the cylinder head. To prevent this, hold the bolt while unscrewing the nut, using padded pliers to preserve the bolt threads. This occurred on two of the bolts during this removal.
- With the nuts removed, grab the valve cover and pull on it vertically. The valve cover will stick at first due to the gasket seal, but it will loosen as you pull on it. It's important to pull the valve cover from both ends at the same time, to prevent warping the cover or damaging the mating surfaces. Also, as tempting as it is, do not pry the cover apart from the cylinder head. The mating surfaces need to be kept perfectly flat to ensure a good gasket seal. Set the valve cover aside. (illustration)
- The valve cover gasket is made up of the perimeter gasket and spark plug gasket. Pull and remove these gaskets. (illustration)
Cleaning and replacement:
- The mating surfaces of the valve cover and cylinder head need to be cleaned before placing the new gaskets. Simple Green (a nontoxic, mild degreaser) with a cloth towel worked well here. There will usually be some hard deposits along the mating surfaces - it takes some time to remove these. Other solvents may remove these deposits more quickly, but keep in mind that solvents should be kept away from the camshafts, lifters, etc. For the valve cover itself, there may be substantial buildup on the underside. Soaking the entire valve cover in diluted Simple Green followed by some scrubbing removed much of the material. I suspect that much of the deposit occurred with the previous owners, who had used conventional oils. Note that this photo was taken before cleaning. (illustration)
- The area surrounding the camshaft chain tensioner should also be cleaned and sealed before applying the new gasket. RTV sealant works well - only a small amount is needed at the corners where the camshaft chain tensioner meets the cylinder head mating surface. (illustration)
- Install the new gaskets.
- Guide the valve cover over the cylinder head bolts and lay the cover over the gaskets.
- Begin tightening the valve cover nuts. This is the step to take your time. To ensure a good seal, the gasket need to be compressed equally during tightening. After threading the nuts onto the bolts, begin tightening the nuts a turn or two at a time in a star pattern, as you would with car tire bolts. Be sure to include the spark plug gasket bolts in this sequence. Tighten to 84 inch-lbs / 10 Nm.
- Replace the coilpacks. Tighten the coilpack bolts to 84 inch-lbs / 10 Nm (as with the valve cover nuts).
- Reattach the ground strap - the torque isn't critical.
- Reattach the heatshield - again, the torque isn't critical.
- Reattach the breather hose bolt and hose clamp - and yet again, the torque isn't critical.
That's it! Check over the engine components to ensure you haven't missed anything, remove all tools from the engine bay, and start it up. If a leak again develops after a few days in the same location as the original, there is a possibility that the valve cover is warped. Fortunately, if this is diagnosed as the problem, a new valve cover is not outrageously expensive.