1981 Volkswagen Rabbit L from North America - Comments

I've had to have the shifter rebuilt, when a bushing wore out.

This car got about 46 miles to the gallon on a 300 mile highway trip.

I enjoy driving it.

Also, I intend to run it on bio-diesel fuel and save even more money.

I have a 1981 and get 36 mpg, what should I do to get 40+ mpg?

I have a 81 Rabbit.. Am having problems with keeping the car running. Sometimes in order to keep it running, I have to manually open the injector pump. Also, checking Ignition timing against the book, give me no results, if I put the cam timing mark at 12 o'clock I get the car running, its the first rabbit I own, don't know too much about it.. Anyone out there with any suggestions or help... I would really appreciate that very much.

You want to have you car timed. The beauty of the diesel motor is once you set the timing, it's set, and there's nothing to wear out. Then you just change the oil and filters and that's all the maintainence. To set the timing you first have to set the valves, then you set the injector pump and then you adjust it. The basis of timing is it's all based around the engines number 1 cylinder being at top dead center. You go over to the flywheel housing on the transaxle and there is a access port with a plug you remove. Once it's removed you'll find it has an arrow and there's an arrow on the flywheel and when they're lined up the number 1 cylinder, which is the cylinder on the far left, is completely at top dead center. Then you remove the cam cover and the timing belt cover. At the far right end of the cam there is a flat cut in the cam. You put a tool in this call a cam lock. This locks the cam at top dead center. You have to make sure the two came lobes on number one are symetrically pointed up. If not you need to turn the motor over one more revolution. The cam lock needs to fit in perfectly when the flywheel TDC mark is perfectly lined up. You cannot be one tooth of on the belt. If the timing is off the valve will still be out when the cylinder comes up and they will hit and the valve will be bent and the cylinder head will be destroyed. If your half a tooth off, undo the bolt on the cam timing cog, and tap it with a plastic hammer, that's how you fine tune it. On older motor you might consider having the valve seats ground. A lot of the efficiency in the motor has to do with how well sealed the chamber is, how well the valves seal, and how well the cylinder rings are sealed. You can find out by having a compression test. To set the injection pump you need a dial indicator. You insert the dial indicator into the injection pump. The indicator has a feeler needle that goes up against the plunger in the pump. The plunger goes back and forth and turns around pumping and distributing the fuel to the proper injectors. As you turn the motor the plunger will push out until it stops. You then center the dial indicator and you turn the engine back to top dead center, and the number one the dial indicator is the number you time the motor by. The closer to top dead center you inject the fuel the higher the pressure in the combustion chamber, the longer the time the fuel has to burn, the cleaner the motor runs, but when the crank is directly up the conecting rod doesn't have much leverage over it, so as you delay the timing you start buring the fuel in a area where the connecting rod has more torque over the crankshaft. The power will be longer and more mature, if the timing is to late, the engine will start to smoke a lot because the fuel will not have the time or temperature to completely combust. Anyway just stick with the factory spec on timing, it's very precise stuff. Timing is everything. It all has to come together precisely at the right time, and when it does, it's almost magical, the way the motor fires on the first rev, and how smooth and precisely it makes every explosion like clockwork. Once you got the timing right you set the idle speed and the top speed on the motor. You don't want to put to much fuel in the motor, or it will not have enough oxygen to fully combust, and it will produce lots of black soot. Diesel have no throttles, because they need to suck up as much air as possible, so they have as high a pressure in the cylinder at all times, becasue they use compression to ignite the fuel. The air is always the same and the way you adjust the power in a diesel is by the quantity of fuel injected in the motor, and therefore by adjusting the air fuel ratio. Diesels have very high air fuel ratio 40:1 up to 120:1 at idle. Basically the less fuel you put in the chamber the more air there is to combust that fuel, and the more efficiently the motor burns the fuel. For this reason diesel have very high part and low throttle efficiency. This is a way in which the diesel is superior to a petroleum motor. Very little fuel goes a long way in a diesel. So if you're timing is correct and you see lots of soot coming out the exhaust pipe of your diesel under full throttle situations, it means you need to back off the full throttle stop a bit. Also have all your wheels aligned so your car rolls down the road easily. I don't know how to do that.