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Eric's VW Page |
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Technical Help Section
Clicking these links will jump down to that section on the page. General: Maintenance: Misc:
The thing to try and remember with an aircooled VW is that they aren't cars. They are Volkswagens. They weren't designed to be driven fast because of their handling and aerodynamics. The brakes are good, but aren't designed to bring you to a quick stop from high speeds. On the same note, you should always keep your stock VW engine from revving much past 3,000 rpm. That translates to a top speed of 60 mph. This sets up a pattern of driving that will make your VW engine last over 100,000 miles. If you want to continually rev past this point, I recommend that when you rebuild your engine, go with a few performance modifications. Namely, you need to have a counterweighted crankshaft and perfectly balanced pistons and connecting rods. You might also look into an aftermarket carburetor setup to improve the mixture getting to the cylinders. You should shift before the indicators on your speedo, but never let your engine lug. I recommend purchasing a VDO tachometer to monitor your rpms. You should also let your VW warm up well when you start it, regardless of the air temperature outside. Never drive your VW on the Interstate. You feel a need to drive faster than you should and you can't always stop when you need to let it cool or check your oil. Besides it's dangerous in a VW. Use lesser traveled highways and monitor your engine's temperature. Stop for ice cream if it gets warm and let it cool a little. This way of thinking allows you to pull in to smaller out of the way gas stations so you can take your time filling and checking your oil. I suggest a tachometer and an oil temperature gauge so you can more easily monitor the happenings in the engine. Read my section on gauges.
The single worst enemy of the aircooled engine is overheating. However, proper warmup is also vital to proper lubrication and long engine life. How do you achieve a balance? It's really pretty simple and basic. First, you have to make sure all the components of the heating and cooling system on the engine are in place. You should check the engine compartment seals for missing sections or cracks. There's one that starts on the left front and goes all the way around the back and ends up at the right front of the engine compartment. Another seal is in the front of the engine and goes over top of the transaxle. You should also make sure your decklid seals are in place so that fresh air is pulled in through the inlets. Next you need to make sure all the engine tin is in place and fits properly. The dipstick test is a quick test for determining if you're running too hot. When the engine is hot, remove the dipstick. Wipe off the oil and grab the stick about 3/4 of the way down. You should be able to hold the dipstick for a few seconds then pass it to your other hand, and vice versa. If, however, you touch the dipstick and think "YIKES! That thing is HOT!" then you're running too hot. Timing is another important concern for engine longevity.
Contrary to the advice in the books, a VW engine should be timed at total advance, not at idle. The idle settings described in the books are not nearly as important as establishing total advance. Too much advance will cause overheating. Total advance is the point at which no more advance is occurring as the engine is revved higher and higher. For a stock engine, total advance should never exceed 28 degrees before top dead center at 3,000 rpm. Do not rev your engine to 4,000 or 4,500 rpm EVER, even when you're timing it. If you rev to 3,500, you can go to 30 BTDC but no more. I'm firm in my belief that you must drive your VW with respect. That means you don't rev over 3,000, and with your timing set at 28 BTDC at 3,000 you'll have your current engine a long time. Most distributors are pretty much "full in" by 3,000 rpm's anyway. If your idle is erratic, recheck your mixture and turn up the idle a little. The acceptable range is 900 to 1100 rpm's at idle. Point gap will also affect timing. The more closed they are the more retarded the spark will be, although it isn't much. You should probably use a tach-dwell meter to set your point gap, but don't let it fall below .012 inches. Likewise don't exceed a gap of .016 inches for the points.
Oil is responsible for cooling your VW engine as much as air is. It's important to have the proper amount in the engine as well as the right viscosity for the type of weather you're driving in. First, the oil capacity. Your Beetle engine holds 5.3 pints of oil which is about 2.7 quarts. It is very important not to overfill the crankcase with oil because you run the risk of ruining seals and burning oil. I'm not going to go into HOW to change your oil, the manuals will describe that. Carry plenty of oil with you in your car. A VW engine will use oil, and it's not always possible to buy oil when you need it, especially the same oil as what you put in initially. I carry three quarts in the spare tire area, one more behind the trunk hinge, and some behind the rear seat or under it. You should check your oil at every fillup of gas. Use out of the way gas stations so you're not rushed, and never travel on Interstates. Put in the gas, pay, then check your oil. This gives it time to return to the sump so you get an accurate reading. VW used to recommend single viscosity oil for your engine. This has changed since then, mainly because everyone wants a one product fits all kind of oil. I'll give my recommendations. For summertime driving in moderate climates, basically everywhere in the U.S., you should use straight 30 weight oil. For spring and fall, use 20w-50. For winter use 10w-30. The 10w will ensure that on the coldest days you've still got a pourable oil which will lubricate your engine better. Oil should be changed at 2,000 mile intervals without exception. The oil bath air cleaner should also be cleaned and refilled (about one pint) with each oil change.
Aftermarket oil sumps, coolers, and filters Aftermarket oil sumps are available for your VW. They bolt on in place of the drain plate and add 1 1/2 quarts to the capacity of your crankcase. They also include a pickup tube extension for the oil pump. For stock engines, these aren't necessary. In theory, it makes a lot of sense, more oil can never hurt and you run less risk of running too low on oil. The truth is, it takes longer to heat up the oil. This is especially dangerous if you don't drive your VW for an hour or more at a time. Just as too much heat can damage your VW engine, running too cool of oil through can too. Oil lubricates best about 200 degrees F. Another, slightly less, concern is the reduced ground clearance afforded by the sump. External filters and coolers are also unnecessary. Should you decide to go with one of these products, you need to buy the sets that include plumbing to get the product out of the engine area and under a rear fender. Having the oil filter down by the muffler is not acceptable. It can actually pick up heat dissipated by the muffler. In the case of the oil cooler, a thermostat should be installed to make sure your oil gets up to 220 degrees before it opens up for added cooling. Remember, a stock cooling system is adequate for stock driving situations. Make sure it is fully functional at all times. If you're experiencing overheating in stock driving situations, you need to find the source of the heat because adding oil coolers, sumps, or filters won't make the source go away. You could simply mask a problem that will surface when you don't want it to.
The stock warning system, although adequate, can be improved upon a little. In general, if the idiot lights don't come on while the engine is running or idling, you're OK. First of all, you need to ensure that both warning lights work each time you turn your key on to start the engine. If one or both lights don't come on when you turn the key, you need to stop and fix that problem first. It might be a short or a burned out bulb. Every VW should be equipped with several gauges as you can afford them. A tachometer, oil temperature, and oil pressure. The best is VDO, the original equipment supplier to VW. There are instrument panels available specifically designed to hold VDO gauges that mount in place of the speaker grill to the left of the speedometer. A tachometer is pretty much optional, but is very nice for timing and shift points. Oil temperature is one of the first gauges you should buy. If the oil pressure light doesn't come on at idle, you're generally OK, but a gauge to monitor the relative temperature is a must. Is it hotter than before? Is the temp climbing or leveling off? Generally, 225 degrees is the upper limit for how hot you want to let your engine get before stopping to cool. Read the dipstick test procedure under how to keep your VW cool. This is more relevant than what the gauge actually reads, and you can correlate the gauge reading to how hot the engine feels on the dipstick. The oil pressure gauge is less important as long as your idiot light works and should be purchased last of these three if money is an issue. You need the sender that also allows a terminal for the idiot light to be hooked up along with the gauge as sort of a redundancy safety feature. At 220 degrees, oil pressure should be staying close to 30 psi, 28 on a well worn engine as you go down the road at 3,000 rpm. If your oil pressure falls below these figures, you might want to check into a new oil pump, especially if it wasn't replaced at the last rebuild. Replace it with a stock pump. Another area to check is the pressure relief system, described well in the manuals. You might need to replace the springs and plungers which isn't a huge deal if you follow the manual's procedures. Aftermarket extra capacity oil pumps are a no-no. Designed for higher performance engines, they pump too much volume and pressure for the stock system. You don't want to burst the cooler, and also too much pressure can be present at the engine bearings causing the oil to actually squirt out too much, spraying all over the cylinder walls and increasing oil consumption. A word on gauges in general, mainly the temp and pressure gauges: don't be intimidated or panic stricken by them. Like I said before, in general if the oil light doesn't come on at idle, you're OK. The gauges give you a forewarning of things going on in the engine but shouldn't be a cause for alarm all the time. In general, if your oil temp levels off even at 225, you're probably OK (as long as the oil light stays off). But if it acts like it wants to keep climbing, you need to stop for a break. |