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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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