On most older Vanagon motors, the cylinder heads are just too corroded to rebuild. We recommend Vanagon cylinder head replacement. Karmakanix will always confirm that the rest of the motor is in good enough condition to proceed. We check compression, wet and dry, and cylinder leakdown to confirm that the pistons and cylinders are still usable. We then check the oil pressure to be sure that the bearings and crankshaft are OK. We also listen carefully to the valve train for any sign of collapsed lifters or severe camshaft wear. Valve lifters can be replaced when the heads are removed.
The factory chose not to use sealant on these rubber headgaskets, and just coated the heads with an anti-corrosive paint. Which did not work out well. Since the headgaskets compress every time the motor heats up from cold, the coolant eventually seeped in and corrosion began. Karmakanix noticed years ago that some heads that had been rebuilt or replaced came off the Vanagon engines with the sealant sticking to them, most did not. We figured out that if one cleans the aluminum surface and applies the sealant directly to the head instead of the gasket, the sealer adheres to the head much better. This ensures that the cylinder heads are less likely to undergo future corrosion.
Last century, most cylinder heads we removed had minimal corrosion, and were reusable. This century, pretty much all Vanagon cylinder head jobs get new heads. All new heads get disassembled to remachine the guides and seats. We usually find the replacement cylinder heads do not meet the factory valve seat width specifications. The valves get hand lapped to the valve seats, and then pressure tested. This labor is included in our price for a cylinder head replacement job.
We use the proper sealants, lubricants and anti seize to assure your head job is right. All critical nuts and bolts are hand tightened, and a dial type torque wrench is used for cylinder head nuts as per factory requirements. All settings and specifications are correctly reset. The oxygen sensor signal and the fuel injection ground loss is checked and recorded. We make sure that the radiator fan is operational on both speeds, and nothing is weak or leaking anywhere in the cooling system. Karmakanix takes every measure to ensure that your job is done right.
On older engines, we like to check on the compression and/or leakdown to verify that the pistons and cylinders are good enough to last for some years, and check the engine for oil pressure to assure that the bearings and bottom end components are good. Engines from 1986 and later can get the oil pressure basically checked using the high pressure oil switch signal. Engines from 1985 and earlier require that oil pressure gets checked with a gauge. The specification for minimum oil pressure is 2 bar at 2000 rpm at 80 °Celcius. On 1986 and later systems, the high pressure oil switch voltage needs to drop to zero just above idle, and poor oil pressure is assumed if the voltage change occurs over 1500 rpm. If poor oil pressure is suspected, an official oil pressure test with a gauge needs to be done. And often we change the oil and filter then retest the oil pressure, as the wrong oil filter and/or dirty or incorrect weight oil can cause low oil pressure. Basically, we need to be sure that the engine will last for some years after the head job is done.
Port and Polish Services
We offer Port and Polish upgrades to the new cylinder heads, in three progressive stages. The essence of port and polish work is to decrease turbulence and increase laminar flow, meaning smooth air movement. The size of the port is augmented differently with each stage, as are the flow characteristics. Karmakanix has decades of experience in port work to increase power output and, more importantly, increase gas mileage. A 6% to 12% mileage increase can be expected, depending on the level of port and polish work selected. The results are easily discernible, the Van runs down the freeway with the pedal just slightly depressed. Your gas mileage increases enough to put a dent in your annual fuel bill. Ask your service advisor to explain the 3 levels thoroughly. Port and Polish work does NOT void the warranty on our work or the parts.
Stage 1 Port and Polish evens out the valve holes in the casting, as the castings are always off center in respect to the valve seats. This eliminates the ledges behind each seat that impede air flow. The exhaust ports are slightly modified to reduce the inside radius of the almost right angle bend from valve seat to port exit. Then the rough mounds from the casting process are ground down even with the rest of the port.
Stage 2 Port and Polish goes on to augment the size of the ports through a process called gasket matching. Note the black rings around the ports in the above picture. This is the inside edge of the gasket and corrosponds well to the size of the exhaust and intake manifolds. The size of the ports is increased to match these marks. The exhaust ports are modified further to reduce the inside radius of the bend from valve seat to port exit. The ports get a basic polish to smooth out the walls.
Stage 3 Port and Polish includes a more complete polishing the walls of the ports, and a more decreased radius of the exhaust port. The ledges in the combustion chambers around the outside of the valve seats get trimmed to a 30 degree radius. And the combustion chambers get a basic polish job to smooth them out.
With all stages of porting, we check the welds inside the ends of the exhaust pipes. Most times, we need to trim those welds, as they are often the most restrictive point. Intake manifolds are usually fine for shape, but often contain large amounts of carbon, especially in motors subjected to poor quality fuel.
Understand that we are not providing a full-on racing head. We have done this work in the past, and achieved over 15% increases. The guides get removed, and the exhaust guide boss reshaped. the intake guide pocket gets welded in and reshaped, then bored out. The intake guides are then installed and trimmed to match the intake port walls. The port tracts get reshaped according to a mathematical formula concerning size increase and decrease. The ports get flow matched. The combustion chambers get reshaped and highly polished. The intake manifold and exhaust pipes get reworked and polished. These heads produce an amazing amount of power but are not reliable enough for customer usage due thermal issues with the thin port walls. And it takes over 60 hours of work. Do the math.