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Engine Education - What is a waterboxer engine found in 80's to 90's Vanagon Westfalia's?

The early 80's vanagon's were air cooled. Between 83 and 84 model years the engines were converted to water-cooled. The uniqueness of this engine was it's low profile box shape, it didn't need to go in a deep engine compartment. Another feature thought to be good was "vibration cancellation". Since the cylinders are opposite each other, the forces of combustion cancel each other. BMW motorcycles employ these engines claiming that it causes a very smooth, "vibration free" ride. In VW's, the 1.9L water boxer with Digijet fuel-injection can be identified by engine code "DH" and is rated at 80 BHP. The 2.1L water boxer with Digifant fuel-injection can be identified by the engine code "MV" and is rated at 90 BHP

image courtesy of

article by Jim Digennaro

Also, Subaru and Porsche have been using them successfully for years. The boxer engine is a decent design. Its major flaw in the Vanagon was the cooling system and cooling leaks of the cylinder heads. In fact, if you look at the engine, some of the parts are borrowed off the venerable old Type one beetle. The valve rockers arms, valve covers and oil pump come off a 1600 bug motor. The crank shaft has the same stroke as the type one and even the rod bearings are from a beetle. You remember how reliable the old bug was?

There are many theories floating around as to why the heads fail. The most common is air getting into the system. The theory goes, because the engine uses different materials in its construction, the metals expands and contracts at different rates when heated and cooled. During this time, when at operating temperature, coolant is under pressure and then a vacuum created when it cools. During this time a small amount of air gets trapped under the head gasket. (which is basically an o-ring around the outside of the head) If you look at the engine the black rubber gasket between the engine block and the head is the gasket that holds in the coolant. So over time, the air interacts with the moister under the gasket and corrodes the cylinder head, leading to coolant leaks.

If you get this type of coolant leak, its not a stop driving event. You can try some stop gap measures to stem the flow, Bars Leak and that type of engine stop leak will slow it down for a time. You can continue to drive the bus, its more of an environmental issue than anything. The damage is done. I drove my old Turtle Van for about 15K miles with a coolant leak. I would have to put about a 1/2 gallon of coolant in a week. But it was cheaper than replacing the heads. Eventually, I rebuilt the engine because it had 179K miles on it. Its my opinion that, because of its limited production numbers, VW never put the resources into finding a permanent solution to this problem. I was told they experimented with different RVT gasket material but never had any real long term solutions.

In my travels, even regular maintenance doesn't prevent coolant leaks. I've seen people flush the system religiously and the engine started leaking at 60K miles. Then I've seen people don't do anything and they go 150K miles on the same coolant it left Germany with. If you have a solution, besides replacing the engine with one of those South African Jetta motors, lets hear from you.

Good luck. -Jim

A little history and evolution of VW Bus and Van engines

article by Stan Wohlfarth

1980-1983 Vanagons were available with an air-cooled 2.0 Liter 4-cylinder gasoline engine or a 1.6 Liter in-line 4 cylinder diesel.

The 1.6L diesel is basically a version of the diesel engine that was installed in early 80's Golfs and Jettas. This is a non-turbo charged motor that nets 50 Brake Horse Power (BHP/SAE). In a Golf (Rabbit) or Jetta it wasn't a bad choice and certainly was fuel efficient. However, in a much heavier van or Westy, 50 horsepower can seem a little limiting. These diesel vans are frequently upgraded to more powerful in-line 4-cylinder turbo-diesel or gasoline motors. Components from these vans can also be used to convert other vans to use in-line 4-cylinder gasoline motors (i.e. 1.8L or 2.0L found in VWs from about 1985-on). The 1.6L diesel can be identified by the "CS" engine code stamped on the block.

The 2.0L air-cooled 4-cylinder gasoline engine is basically an evolution of the 1.8L motor used in the mid-70's "Bay Window" buses. A version of this 70 horsepower motor was also used in the Porsche 914 models. These engines are also known as Type 4 (IV) or "pancake" motors due to their compact flat design with a "squirrel cage" type fan and fan shroud on the back end of the motor. These can be very durable motors and have a fairly simple fuel injection system.

Non-California 2.0L motors still use ignition points which require occasional maintenance, but are also fairly easy to service and diagnose problems. A nice upgrade for this motor is to use a 914 cam, or similar, that has more exhaust duration to help get the hot gasses out faster. Vans with a healthy 2.0L motor will cruise nicely on the highway at 70-80mph, however long hills may drop your speed down to 50-55mph. The key is to just be patient, don't flog it and let the motor do what it can, when it can. I've (Stan) got 50k+ fairly trouble-free miles on my '81 Westy with a Boston Engine built motor and a 914 cam. The 2.0L engine can be identified by the "CV" engine code stamped on the block.

1968-1979 buses were available with four different versions of the air-cooled four cylinder engine.

The 2.0L air-cooled Type 4 fuel-injected motor (as described above in the 1980-83 Vanagons) was available for 1976-1979 buses. Horse power rating was 70 DIN at 4200 rpm. Manual transmissions with this engine got a different 4th gear and final drive ratios (compared to the previous 1.8L motor) and the 2.0L was available with an automatic transmission as well. These can be identified by the "GD" or "GE" engine code stamped on the block.

The 1.8L air-cooled Type 4 motor is very similar to the later 2.0L motor and were available starting in November of '73 (1974 model year). This engine was fuel injected for the U.S. and Canadian markets and was rated at 68 DIN horsepower. These engines can be identified by the "AW" or "ED" engine code stamped on the block.

The 1.7L air-cooled Type 4 motor was the first iteration of the "pancake motor" used in the Transporter series, available from 1972-1973. This engine had dual carburetors and produced 66 DIN horsepower at 4800rpm. Versions of this motor had previously been used in the Type 4 models, hence the Type 4 designation. These can be identified by the "CB" or "CD" engine codes stamped on the block.

The 1.6L air-cooled Type 1 (upright) motor was the same motor used in VW Beetles (Type 1 models) and was available from 1968-1971 in the buses. This motor has a special support bar at the rear of the motor that the Beetles did not have. Because of this the engine case for the bus version of this motor will have additional mounting points on the back of the case. Adapters are available, or cases can be machined for this rear mount bar if using an engine that was originally installed in a Beetle. This engine had a single carburetor and a single port intake manifold from 1968-1970 and was rated at 47 DIN horsepower at 4000 rpm. The 1.6L single port motor can be identified by the "B" engine code stamped on the block. In 1971 the 1.6L motor was available with a dual port intake manifold and was rated at 50 DIN horsepower. Many other modifications were made to this new dual port motor and it's use continued in Beetles until 1974. The bus version of this motor can be identified by the "AE" engine code stamped on the block. This motor can also be found in Beetles with the "AE", "AK", and "AH" engine codes stamped on the block. The '72-'74 engines with the "AK" or "AH" engine code, are considered by some engine builders (Boston Bob) to be superior to the earlier 1.6L motors ("AE") for rebuilding. This is due to the head stud inserts and 8mm "stretch" head studs which allow for better expansion and contraction during the heat cycle of the motor.

- Stan

Sources used for the above information are:
Volkswagen Model Documentation by Joachim Kuch;
Volkswagen Station Wagon/Bus Official Service Manual: 1968-1979 by Bentley Publishers;
Volkswagen Vanagon Official Factory Repair Manual: 1980-1991 by Bentley Publishers;
Boston Engine (Boston Bob) website is down;;