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Neon Spark Plug Tube Seals

2000 Dodge/Plymouth/Chrysler Neon Spark Plug Tube Seal Replacement


I have created this page to chronicle the repair of a common failure point on higher mileage 2.0L Dodge/Plymouth/Chrysler Neons of the spark plug tube seals. These seals nearly always fail on higher mileage 2.0L engines, causing oil from underneath the valve cover to pool at the bottom of the spark plug tubes. Neglect of the Postive Crankcase Ventilation (PCV) system can accelerate this failure by allowing pressure to build up in the crankcase, forcing oil past the seals. Another related failure that shows exactly the same symptoms is the separation of the spark plug tubes themselves from their seats in the cylinder head.

This page is not an official guide on how to complete the required repair. It is for informational purposes only. If you choose to attempt the repair using this page as a guide you do so at your own risk.

This job does not require exceptional skill or access to special tools beyond a torque wrench and a seal pick/remover. With slow, careful work and attention to detail the job is not difficult at all.
The vehicle shown is a 2000 Plymouth Neon with a 2.0L four cylinder engine and five speed manual transmission with 150,000 miles on it. It has not been altered from stock form in any meaningful way.

Loose tube seals
The spark plug tubes sometimes migrate out of the head, resulting in leaks.

In order to correct this, the spark plug tubes must be reseated in the head and ideally the rubber seals at the tops of the tubes should be replaced also. To access the tubes and tube seals, the valve cover must be removed. Begin by unplugging the spark plug wires and igntion coil harness from the ignition coil. The harness is secured by a plastic clip that must be disengaged before it can be removed. Take notes of of the spark plug wire order before they are removed as well so they can be reinstalled in the same order. Then remove the ignition coil, is secured by four bolts, one at each corner. Be aware these can sometimes be siezed up, and that they screw into metal inserts in a plastic valve cover, so take care in their removal ... excessive force may either break the bolt, or damage the valve cover. Use a good penetrating oil and let it sit for a while if it looks like they will not come free easily.

Once the ignition components are removed disconnect the two PCV system hoses from the side and rear of the valve cover, then the valve cover can be removed. It is secured to the cylinder head by ten bolts, five at the front and rear of the cover. For convenience the plastic emblem showing "2.0L 16 Valve" that is present on older engines may be removed by gently pulling upward on it to disengage the retainers. This will grant additional working room for removing the front five bolts. Once all ten bolts are removed, the valve cover should lift free of the cylinder head. If it does not, strike it lightly with a rubber mallet to break the bond between the gasket and the sealing surface. Be gentle, it's only plastic. If the spark plug tube seals have migrated especially far out of the cylinder head, they may come out of the head with the valve cover.

Valve Cover Removed
Sometimes the tube seals will pull free with the valve cover.

With the valve cover removed it can be seen how bad the problem is. Often the spark plugs will be completely submerged in oil, especially if the tube pulled free of the head with the valve cover.

Plug submerged in oil
One or more plugs may be completely submerged in oil.

The spark plug tubes are interference-fit, they are simply pressed into the cylinder head and retained by friction. If they are leaking this is obviously a poor solution, so they will be re-seated into the cylinder head with the addtion of sleeve-retaining compound: the same compound used to retain cylinder sleeves and other press-fit components when you do not want them to vibrate apart.

Unforunately the surfaces of the press fit components must be clean and reasonably free of oil in order to use such a compound, so the oil must be cleaned out of the spark plug tube seats. This is nearly impossible to do with the rocker arm assembly in the vehicle unless you have incredibly small hands. If a means is available, siphon or absorb as much of the oil as possible from around the spark plugs. If not, the plug can be removed toallow it to drain into the cylinder, but this will cause the vehicle to smoke severely for a while the next time it is started as all the oil gets burned off. Once as much oil has been removed as possible, remove the spark plugs from the vehicle and store them in a clean place if they will be reused.

To adequately clean the tube sealing surfaces the rocker arm assembly must be removed. Before this is done, very careful notes must be taken to ensure that they are reinstalled in the exact orientation as when they were removed. Also, piston number one (the lefthand one if facing the engine from the front of the vehicle) must be set to top-dead-center before rocker arm removal. To accomplish this, remove the spark plug from that cylinder and insert a probe other clean and straight tool into the cylinder until it makes contact with the piston. Using a wrench, slowly turn the crankshaft pulley and watch the probe in the cylinder. Turn engine and watch for the probe to rise out of the cylinder. At the instant where it no longer rises and begins to sink back into the cylinder, that cylinder is at top-dead-center.

The rocker arm assembly is secured to the cylinder head by ten bolts that run along the camshaft. Starting at the outermost bolts and working inward, slowly loosen each one by one quater of a turn at a time until certain there is no pressure left on the valve springs. If piston number one is correctly set at TDC, all the valves should be closed and there should be minimal spring pressure. Once any pressure is relieved from the springs loosen, but do not remove the rocker arm assembly bolts. If the bolts are removed then all of the rocker arm assembly components can slide off of their shafts and it is critical that they all remain on each shaft in precisely the same order as when they came off the vehicle. Once removed, place each rocker arm shaft assembly in a clean, secure place.

Removed rocker assemblies
Keep the rocker arm assemblies in a clean, secure place.

Once the rocker arm assemblies have been removed, access to the tube seats is much easier. Working carefully, clean as much of the oil as possible out of the tube seats, and as much out of the surrounding area as well so that it does not seep or run into the tubes while the repair is underway. If necessary, use a residue free solvent to remove any varnish or baked on oil that is present on the tubes themselves, or in the seats. Once the tubes and seats are as clean as possible, apply a little bit of sleeve retainer to the bottom of a tube and place it into the seat. Using a soft-faced hammer, or a block of wood, drive the tube squarely into the cylinder head until it is seated. Repeat this for the other tubes if they are being reseated as well.

Once the spark plug tubes have been reseated, the rubber seals can be replaced in the valve cover. Working from the underside of the valve cover, use a seal pick or other tool to remove the seals from their bores. They can sometimes be stuck pretty well, take great care to not scratch or otherwise damage the bores attempting to pry them out.

Rubber seal removal
Take care not to scratch the seal bore when removing the rubber seals.

Once the old seals have been removed, clean the sealing bores as well as possible and press new rubber seals into them. Then, if it is still in its groove, remove the valve cover gasket from the valve cover. Once the gasket has been removed, thoroughly clean all dirt and traces of gasket material out of the sealing groove. Then, working from the ends press the new gasket into the bore until it is uniformly seated and there are no kinks. Do not use RTV silicone in combination with the gasket unless it is recommended by the gasket manufacturer.

After all the new seals and gaskets are in place and ready to install, position the rocker arm assembly on the cylinder head. Using a torque wrench begin tightening the bolts in this sequence:

Rocker Tightening Sequence
Tighten the rocker arm bolts in this sequence to 20 ft/lbs

Tighten each fastener to 20 ft/lbs. Then, working carefully to not pinch any of the gaskets or seals, reinstall the valve cover onto the cylinder head. Tighten the valve cover bolts in a pattern like the one used to install the rocker arm assembly. Tighten each fastener to 105 inch/lbs (approx 8.75 ft/lbs). Then reconnect both PCV system hoses to the valve cover, and reinstall the ignition coil. There is no torque spec for the ignition coil bolts, but do not overtighten them. Also reinstall the spark plugs, tightening to 20 ft/lbs and then reinstall the spark plug wires in the same order in which they were removed. Once all components are reinstalled, make a quick check around to make sure all parts have been correctly installed and all tools are free and clear of the engine. Then start the engine and check for oil leaks. If any oil was allowed to seep into the engine while the plugs were removed the engine may smoke upon first start up.

All work done properly, the spark plug tubes should be clean and free of oil for quite a time to come.