Frank Condelli & Associates
Phone: (613) 256-6763 Mail: Fkc43@aol.com
Vanagon 1.9 and 2.1 waterboxer head gasket leak repair
First off you will need to have the Bentley workshop manual as this document does not address the full working procedures and technical information necessary to complete this job correctly. This document is a supplement to the workshop manual that will guide you through the correct steps needed to insure the gaskets will seal correctly and not leak again. The Bentley manual is lacking in this department.
The head gaskets can be replaced with the engine in the vehicle or removed. There are pros and cons to both methods. Whichever way you’re more comfortable with will work. Circumstances will determine which is best in each case.
Remove the heads. If the cylinders are stuck to the heads, there are tabs on the barrels that you can pry against to free them from the heads. If the heads are to be reused the area where the pry bar touches the head will have to be protected from damage from the pry bar. If you cannot free the heads from the cylinders then the engine will have to be removed and the heads and cylinders removed together and separated on the workbench.
If there is any question regarding the value of the heads, have them pressure tested and renew valves, seats and guides as necessary if the head castings are still in relative good condition. Pitting of the rubber head gasket surface is not necessarily a reason to scrap the heads. Small cracks between the valves are also not a reason to scrap the heads. If new heads are in order use only AMC head assemblies. The alloy is better and will resist future pitting and cracking between the valves better than the OEM heads.
If there is any question about the hydraulic lifters now is the time to remove them and either disassemble and clean them thoroughly in lacquer thinner or replace them with new ones. Now is also the time to check the rod bearings if you have concern for them, especially if the engine has high mileage. Damaged or worn rod bearings may indicate worn main bearings and indicte a waste of time and money in refurbishing the top end. A complete engine rebuild is called for in these circumstances.
Repairing the coroaded pitted area on the heads. There are two methods that work. One is to use the sealant that is used on the rubber head gasket. The other is with J.B. Weld. To use either method the heads must first have been refurbished by your local machine shop if that’s the route you’re taking and they will come back with cleaned surfaces otherwise you need to clean the pitted area well. Use a wire brush and lacquer thinner to get down in all the pits. Blow out with compressed air. Getting a good clean surface for the sealant or JB Weld to bond to is very important. Use a hard plastic squeegee to force the JB Weld into the pits. You can leave a slight amount of the JB Weld on the surface of the head as the JB Weld will contract upon drying. After the JB Weld has dried overnight sand the surface of the head flat using a good flat block or orbital sander with 100/120 grit sandpaper. Leave the surface of the head unpolished as the sealing compound for the gasket will make better contact. This goes for new heads also. The bright shiny surface of the new heads will not allow the gasket sealant to adhere properly.
It is necessary to renew the O-rings at the base of the cylinder barrels. Not doing so may cause eventual leaking of coolant into the crankcase. Removal of the pistons is not necessary to replace these O-rings unless they need to be removed for other reasons. If the cylinders and pistons assemblies need to be removed then the engine must be removed from the vehicle to perform this operation. To replace the O-rings with the engine in the vehicle, turn the crank slowly so that the piston of the barrel you want to change the O-ring on is at the top of the barrel. Make sure all the barrels stay tight against the case while turning the crank. Now move the cylinder barrel up on that piston until the piston pin is showing and it could be removed and the bottom ring is still in the barrel. Be careful to not let the bottom ring get out of the barrel otherwise you will have a very difficult time to get the ring back in place. Once you have the barrel up, use a long, right angled, pointed pick to remove the old O-ring, making sure you get it all out. Use the pick and compressed air to make sure the groove is clean and ready to accept the new O-ring. Make sure the surface on the case where this O-ring sits is clean and flat. If this surface is damaged for any reason you will have to remove the engine and then the piston and cylinder assemblies to repair this surface so that there is a perfect seal between the bottom of the cylinder and the case. Once the area where the O-ring sits is clean and the barrel sides are clean take the O-ring and coat it lightly with grease and roll it down over the barrel until it goes into its place. You can use the pick to run around the bottom of the barrel to make sure it is seated properly then push the barrel down on the case and go on to the next cylinder.
If the cylinders and piston assemblies have been removed, re-install them as described in the Bentley workshop manual. Use a very light coating of grease on both O-rings on the cylinder barrels. Make sure the surface where the bases of the barrels and O-rings rest are clean and undamaged to achieve proper sealing there.
Installing the heads and gaskets. Use Loctite or Permatex “The Right Stuff” or “Ultra Copper High Temp Silicon RTV Sealant” on the rubber head gaskets. I prefer “The Right Stuff as it allows more working time before it sets up and seems to seal better. Do not use the sealant that is furnished with the head gasket sets, it does not work well. Use grease to hold the metal combustion chamber fire rings in place in the heads while installing the heads, by greasing the area in the heads where they sit then inserting the fire rings and spreading the grease around on top of them and the sides of the head where the barrels will go in, this will keep the fire rings in place while getting the heads in place and allow the cylinders with the O-ring to slip into the heads easier without damaging the cylinder top O-ring. The rubber head gaskets should be sealed to the head and the engine case. After you have the fire rings in place, clean all surfaces where the rubber head gaskets sit with lacquer thinner or other suitable cleaning agent that will not leave a residue. Make sure the edge of the case where this gasket sits is clean and free of debris. If it is damaged from corrosion the sealant will fill in as long as the surface is clean. Apply a small bead of sealant inside the groove of the rubber gasket and install it on the engine case. Clean again the top of the gasket then apply a small bead of sealant to the top of the rubber gasket or the head where it will contact, whichever is easier for you, then install the head along with the push rod tubes as described in the Bentley workshop manual. Make sure the head goes down on the barrels evenly so as not to damage the cylinder top O-rings. Use a small bead of the yellow sealant provided in the gasket sets on the head cap nuts seating flange. These cap nuts must be cleaned inside and out, a wire wheel and lacquer thinner works well for this. Apply a light coating of anti-seize on the threads of the cap nut or the threads of the head studs where they go. The studs and their respective threads must be clean and checked for any defects, corrosion or stretching. If any are suspect they must be replaced otherwise proper torque of the head will not be achieved and leaking of the rubber gasket will soon follow.
Torque the head cap nuts as described in the workshop manual. Install push rods and rocker shaft assemblies making sure the push rods are seated properly in the lifters. Set the valve lash at 1-1/2 turns from 0. Do not use the 2 turns from 0 method as described in the Bentley.
This page was last updated on May 29, 2010
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All rights reserved. April 2010