how to maintain and enjoy driving your antique vehicle
A properly maintained antique can be reliable and a pleasure to drive. When new, almost any antique car started, stopped, steered, and generally ran down the road just fine. We want you to enjoy driving your antique so, if that’s becoming more a chore than a pleasure, let’s see if we can steer you towards a proper repair.
Below are some common issues that plague our older 4-wheeled friends. If you don’t find what you need, please contact us via the Contact page, or Post in our Forum. Note that our focus is on antique vehicles so will not always apply to newer ones. And although electric cars (and steam powered) were made well over 100 years ago, they’re extremely rare so we don’t cover those either, but our hats are off to you if you have one and keep it going!
As much as possible, and certainly as much as you want to. An antique owner’s reply to a recent post on the AACA forum asking if it would be possible to use a 1930’s car as a daily driver rather than a museum piece and how would that affect the value said it well:
“I have 18,000 miles on my 36 Pierce and it still looks and runs as new. We regularly drive our three V-12 Packards down the highway, all three are Pebble Beach level cars, and we put 2400 miles on a Model J Duesenberg this summer. Sure you can drive it. As to value, who cares……if you are using and enjoying the car it will show wear and deprecation just like any other car. If you do extensive matainance you can drive the car and show it. I have seen cars driven 10,000 miles across the country and back and still score 100 points and win a class at one of the big shows, you just need to keep up with the details. Year, series, body style are all veriables that will come into play. Photo (right) is of my 36 Pierce and the Model J that did 1300 miles the week the photo was taken last September. Two days later I drove the Pierce up the Mount Washington (NH) Auto Road.”
An antique vehicle will require more maintenance than a modern one. The good news is that much of it is mileage based and, since most antiques aren’t driven very far or very often, some items will not have to be addressed very often
A service, or sometimes even an owner’s manual, will tell you exactly what routine maintenance is required. Reproductions of old manuals are available from numerous online sources. A service manual for your exact make, model and year is essential, but an old edition of Motor’s Auto Repair Manual covering the year of your vehicle (most of them cover multiple years) can even be better for troubleshooting and explaining repair procedures. They are readily available and not very expensive (eBay is a good place to start).
Basic maintenance is not too difficult, but if you’re not planning to do it yourself, be sure to locate a good mechanic who is knowledgeable about antique vehicles. The best way to do this is to join a local club for the specific make of vehicle you have or, if that isn’t available, join your local AACA chapter. Then go to meets and ask everyone for recommendations. If you actually join a club before even making a purchase, you can also get advice on particular vehicles and help locating good examples so, by the time a purchase is made, the person to do any necessary work has already been identified.
This is one of the easier ones to troubleshoot, although when it occurs in the middle of the night, or the middle of nowhere, that’s not of much comfort! Proceed as follows.
Does it crank? Some times a “no crank” is reported as a “no start”, so just to avoid any confusion, we assume here that when you turn the key (or depress the starter button) the engine does turn over at normal speed, but does not “fire up” or come to life. A common but often perplexing condition occurs with cars that have a “ballast resistor” in the ignition circuit. When this resistor fails, the symptom is the engine appears to start when you turn the ignition key, but then seems to die immediately when you release the key.
First, a quick overview. An engine only needs 4 things to run – air, fuel, compression, and spark. Mix the air and fuel, compress the mixture, and ignite it. And off you go! If an engine was running fine, and suddenly won’t, there’s very little chance the air intake suddenly became blocked so we won’t consider that here. Similarly, compression is solely a function of the mechanical soundness of the engine, so unless something like a timing chain or camshaft broke, we won’t consider that until the other much more likely possibilities have been checked. That leaves only two things – fuel and spark.
The first thing is to make sure you’re not out of gas. As the gauges in most antiques are almost always wrong about the level, and that’s if they’re working at all, we assume you already have some way to determine if there’s gas in your tank. So we won’t say anything else about that, except that it’s an easy problem to fix!
If your engine won’t start, it’s a common reaction to give it some more gas (i.e. pump the pedal) and keep cranking. While you should usually avoid this practice, if the engine is getting fuel, it won’t take long before it has received too much fuel. If you then remove the air cleaner to inspect the carburetor you’ll notice the unmistakable aroma of raw gasoline. Another test is, while looking down into the carburetor, to quickly move the throttle and look for a good squirt of fuel into the carburetor (this obviously won’t work with updraft carburetors). If fuel delivery were a problem, namely the fuel pump has failed, or fuel line or filter is plugged, that would not occur. Should you have a fuel injected engine, these quick tests clearly don’t apply.
Should you diagnose the no-start condition as a fuel problem and want to be 100 percent certain, the sure check is to disconnect the fuel line at the carburetor, drain it into a container (maybe after sticking a piece of flexible hose on the end), and crank the engine to confirm that no fuel is being delivered. This is really a 2 person job – one to hold the container while the other engages the ignition – so no fuel spills on hot engine parts and starts a fire. You’ll then have to trace back to see which fuel system component is at fault.
If it’s not a fuel problem, then it’s probably an ignition problem. This is easily checked with a spare plug or spark tester, or even with a screwdriver if nothing else is handy. Until we create our own videos, the one below is the best we could find on the web to demonstrate how to do this as a video is definitely worth 1,000 words here.
Should you not see any spark, your problem is an electrical failure, either with the distributor (points, rotor, cap, or condenser), high voltage coil, or perhaps an open or short circuit in the ignition system wiring. You should first make sure all high voltage cables are intact, especially the one from the coil to the distributor cap. Then remove the distributor cap and checking for a broken rotor or points, or points that are very badly pitted or welded shut. Beyond that, you’ll likely need a multimeter or other equipment to perform additional tests.
It’s really easy to check the major items that can lead to imminent overheating and a spoiled road trip. Always keep watch under the car for coolant and other leaks (e.g. by leaving a large piece of cardboard underneath), which can be caused by something as simple as a loose hose clamp, and fix the leak immediately before you lose too much coolant and overheat. But be aware that if you lose too much coolant, your temperature gauge may read artificially low and fool you into thinking there’s no problem while your engine self-destructs.
- Belts – replace any that are fraying or have cracks, and tighten if they’re slipping (although not too tight as that will prematurely wear bearings)
- Hoses – when squeezed, the rubber should feel firm and spring back to shape immediately. If your hoses feel spongy or do not quickly return to round after you squeeze them, it is an indication that the rubber is getting old and may fail. Also, check the ends of the hoses for fraying and cracks.
- Radiator – check that the proper coolant (50/50 mix, even in summer) is at the full level. If you see lots of scale or debris, it’s time (actually it’s past time) for a system flush and new coolant.
- Water Pump – if it’s leaking, noisy, or the pump shaft wobbles when you try to move it, it’s time for a repair or replacement.
- Thermostat – The wax thermostatic element was invented in 1936 so earlier vehicles don’t have one. If your car has one and it stops working, it will either fail to open, leading to your temperature gauge heading into the red zone within 10 – 15 minutes after starting the car, or fail to close, in which case your temperature gauge will never get into the normal operating range. Although the overheating case must be fixed immediately to prevent catastrophic engine damage, the opposite case of never reaching the correct temperature will also cause problems in time. The video below has a good description of this.
- Shutters – many vehicles prior to 1936, and even some after that, used movable shutters in front of the radiator to control coolant temperature. Since they’re completely visible, their operation is very easy to check, namely they should be closed when the engine is cold, and gradually open 90 degrees when it warms up.
While not part of the cooling system, there are two other critical settings that can lead to overheating. They are ignition timing and air/fuel mixture. Both overly advanced and overly retarded ignition timing can cause overheating. You must check not only the idle settings, but also insure there’s proper mechanical and vacuum advance at all speeds.
A lean air/fuel mixture will also lead to overheating. The best test for this is to use an air/fuel sensor while operating the vehicle at different speed and load conditions. Standard practice, “back in the day,” was to usually operate somewhat rich, when gas was cheap and emissions regulations didn’t exist.
TIP: Old temperature gauges aren’t always reliable, so if yours is reading high but you don’t have other symptoms, such as boiling over, consider using an infrared (IR) thermometer (gun style) to determine the true engine and cooling system temperatures. An IR gun can also be used to measure temperatures at various locations on your radiator which can detect blockages that will prevent proper cooling. It can also be pointed at the upper radiator hose to give a good indication of coolant temperature if your car doesn’t have a temperature gauge.
If you think all old cars had cooling system problems, here’s a 1936 video on the subject produced by Chevrolet. Not all manufacturers may have done testing like this in the desert, but obviously Chevrolet did!
Since there are hundreds of things that can result in this nebulous symptom, the first thing you have to do is diagnose the problem. Much as you’d like to pull out the wrenches and get to work, time spent thinking about what to do will actually get the repair done sooner. Even if someone you know had the same problem with the same engine, the cause could very well be different. To illustrate, if it turns out you have a “dead” cylinder, it could, among other things, be a sticky valve, defective spark plug, broken distributor cap, or simply a loose spark plug wire. The point is you want to first check the most likely causes that are the easiest to examine. Violating this simple principle often leads to unnecessary (and expensive) rebuilds and replacement of good parts and a lot of wasted time.
What do you mean by “doesn’t run well.” Here are some questions you should ask.
- Does the engine run smooth or rough? If rough, that points to a cylinder misfire and most likely an electrical problem. If smooth, and just down on power, that’s more suggestive of an air/fuel mixture problem.
- Did the problem start suddenly or develop over a period of time? If sudden, something probably broke or came loose (e.g. spark plug wire) and could be easy to spot with nothing more than a visual inspection. If gradually, you’d look for other things, such as a clogged fuel filter, that develop over time.
- Are there any obvious signs? One would be smoke from the exhaust, and if so the color can tell you a lot. What about unusual noises? if so, what’s the sound (click, knock, etc) and how often does it occur (e.g. does it change with engine speed)?
- Is there more than one symptom? For example, is the engine temperature higher or lower than normal? Have you noticed increased fuel consumption? Has starting it become more difficult? Have the lights become dimmer?
- At what engine speed is the problem most noticeable? Is it fine at idle? Is it ok at steady speeds and only occurs during acceleration? Is the problem only at wide open throttle?
- What’s the general history of the car? Has it been sitting unused for more than a year? Are you aware of a similar problem it had in the past? Was any repair work performed recently, even if not for the same symptom?
As you consider the above, you’ll think of possible areas to examine. It’s most important, though, that you think through the entire list before opening your toolbox. If the first idea you have turns out to be correct, it’s your lucky day. It’s much more likely that you’ll have to follow some dead end paths before you find the real culprit. Another likelihood is that there may actually be more than one thing wrong, which is more common than you might think, or along the way you’ll find some questionable parts and decide to take care of those even though they aren’t the cause of the immediate problem. This happens almost all the time when we’re working on these antiques!
Once you’ve thought through the symptoms, it’s time to diagnose the problem. For help with this, try the following.
- Motor’s Auto Repair Manuals often contain diagnostic advice based on the symptoms.
- Research your problem on the internet. AACA and many single marque organizations have technical forums.
- Post your problem in our forum under the “Driving & Maintaining” category.
“Antique vehicles” as we define them span at least 9 decades of production. During that time, enormous changes have occurred in the fuels, lubricants, and coolants needed to run them. Some of these changes have not been kind to older vehicles that were designed when these fluids were very different from what they are today. A short history illustrates this.
Until the early 1900s, gasoline was considered a useless byproduct of the refining of crude oil to make kerosene and was usually discarded. Even into the early 1920s, gasoline was of such poor quality that much engineering went into designing engines that could reliably run on it, and power output was low because of low octane. This wasn’t solved until the addition of lead in the late 1920s, and that worked very well until catalytic converters required its removal in the 1970s. The substitutes since then have included MTBE, which was discontinued due to its polluting effects, and most recently ethanol, which even Henry Ford pursued as a fuel additive in the 20s and 30s. Ethanol has caused numerous problems for older vehicles.
Lubricants, especially motor oil, have had a similar trajectory. While the low mechanical stresses on pre-WWII engines were tolerant of oils made at the time, the post-war development of much higher rpm engines demanded better quality lubricants. While oil has many more jobs to do than you might think (see how many you know about at bobistheoilguy), wear protection is the best known, and was well served for many decades by the addition of a zinc compound (ZDDP). Once again, catalytic converters necessitated a reduction in this additive, leading to today’s oils having significantly less zinc than what your antique vehicle engine may have been designed to run on. Although since ZDDP was not introduced until the late 1930s, earlier engines had to survive without it.
There’s so much misinformation floating around in old car forums we strongly advise that you ignore all of it. Your author spent close to 40 hours some years ago doing research on oils alone and ended up writing 8 pages of material with dozens of references to cover all the important aspects of this subject. So we’re going to keep this as simple as possible and, if you have questions, please feel free to post them in our “Drive & Maintain” forum and we’ll try to answer them as succinctly as possible.
What’s wrong with today’s gasoline?
All of our problems with gasoline arise from its having ethanol. Those include:
- ethanol deteriorates old style carburetor floats and gaskets, rubber hoses, and other fuel system components
- ethanol absorbs water and separates out of the gasoline, in as little as 30 days, leading to all sorts of problems including oxidation of fuel tanks and lines (i.e. rust)
More about the above can be read at mossmotors.com
Another problem with today’s gasolines is that for high compression engines (e.g. classic muscle cars), the octane rating may not be adequate to prevent detonation. While that is not due to the presence of ethanol, which is actually an octane booster, it does necessitate steps be taken to prevent engine damage under high load conditions.
The consequences can be costly. Untreated ethanol gasoline that sits unused can clog everything in your fuel system and necessitate removal and cleaning (or replacement) of the gas tank itself, fuel lines, fuel pump and carburetor. Even treated gasoline may only be good for a year, whereas old fashioned leaded gasoline used to have a shelf life of many years.
Here’s what is usually recommended. First, unless you have access to ethanol-free gas (see pure-gas.org), make sure your fuel system has been upgraded to be compatible with ethanol. That includes hoses, pump, and carburetor. Then you should add a fuel stabilizer (e.g. Sta-Bil 360) at each fillup. If you burn all of it in less than a year you shouldn’t have any problems.
What’s wrong with today’s oil?
As noted above, it really doesn’t have enough zinc to prevent premature wear, usually of the camshaft or other components where high pressures occur on rubbing surfaces. (Note: the reason today’s oils are adequate without high levels of zinc is because most problems with wear involved camshaft lobes, and all of today’s engines use roller style lifters which do not experience the extremem pressures and wear problems that our flat tappet lifters did.) However, there is such a thing a too much zinc which will also cause damage, so not all zinc-containing oils are appropriate, nor should you try to use an additive and “mix it yourself” as it will be hard to determine the final concentration. The easiest thing is to use an oil that contains about 1200 – 1400 parts-per-million (PPM) ZDDP, and those include:
- Valvoline VR-1
- Hemmings Classic Oil
- Classic Car Motor Oil (Indiana region of CCCA)
Yes, we know there are a lot of others that claim to have ZDDP or be formulated for classic cars, but it’s often hard to confirm that because oil formulations are constantly changing. Do not use “racing oils” that are not indicated as being suitable for street driven vehicles, as they will not have the proper combination of additives for your engine (unless you actually do use it for racing).
What about coolants?
Once upon a time, there was water and ethylene glycol based antifreeze. In the past 15 or so years, this has become more complicated. Antifreeze can now be divided into several camps. To the original, always yellow-green colored types, we’ve added organic acid technology (OAT) and hybrid OAT (HOAT) which come in orange and many other colors, and should NEVER be used in vehicles that have the old style yellow-green antifreeze. Doing so can destroy copper radiators and other components.
Unless you use premixed antifreeze (into which 50% water has already been added), always mix full strength antifreeze with distilled water. It’s only 99 cents a gallon at the market and helps prevent scale buildup.
That 6 volt electrical systems must be upgraded to 12 volts, that mechanical fuel pumps should all be replaced by electric ones, or that overheating cars need an electric fan or updated radiator, are all very questionable bits of advice when facing a drivability problem. Prior to undertaking any such modification, remember that the original design probably worked just fine, and the original components can be restored to work as new provided you can find someone qualified to do so. Here are some examples.
Slow engine cranking and dim lights are often caused by poor connections and old wiring. Converting from a 6 to 12 volt system will only mask this problem, not solve it. The only good reasons we’ve heard to make such a change is if you do a lot of night driving and need the improved lighting it would provide, or are adding non-original electrical devices to the vehicle that require 12 volts.
Engines that routinely overheat do so because of a failing water pump, a dirty or clogged radiator or thermostat, wrong ignition timing, bad carburetor tuning, improperly installed or missing fan shroud, or other issue that can be solved by proper diagnosis and repair. All these items should be carefully checked before you determine that your vehicle’s design is basically faulty. See our section on Overeheating Problems for more information.
A switch from mechanical to electric fuel pump is one of the more common modifications to an older vehicle. The justification is that it’s a cure for vapor lock. Though that may be true in some cases, it is likely not the best or easiest cure. Vapor lock occurs when fuel in the line from the gas tank to the carburetor gets too hot and “boils.” Depending on the particular formulation of the fuel, which will vary from one brand to another and also from season to season, that temperature is around 160 degrees Fahrenheit. So if you’re driving around on a 100 degree day, and sitting in traffic so your cooling fan isn’t too effective at idle speed, and your fuel lines are routed such that they tend to pick up heat from the engine or exhaust, you could experience vapor lock. But here in New England our temperatures rarely reach that mark. If you have a vapor lock problem, prior to an electric pump conversion, you should see if a bigger (more blades) fan is available for your vehicle, check that the proper shroud is installed correctly, and possibly re-route and insulate the fuel lines. A different fuel might also make a noticeable difference.
What is vapor lock?
Liquid gasoline will not burn. That’s why you may have heard stories of old mechanics surviving the stunt of tossing a lit match or cigarette into an open can of gasoline only to see the flame extinguished when it hit the fuel. Gasoline must be in its vapor form to burn and, like any liquid (including water), its conversion from liquid to vapor depends on only 2 things – temperature and pressure. As you know, we expect the gasoline to still be in a liquid state as it sits in the carburetor. It is only after the carburetor mixes it with air and sends it on its way to the cylinders do we want it to vaporize.
“Vapor lock” occurs when the gas changes state from liquid to gas (vapor) prematurely while still in the fuel delivery system, namely anywhere between the fuel tank and the carburetor. The only items between those two are fuel lines and a fuel pump (unless you have a gravity fed system as in a Ford model T). As we said, the 2 factors that affect vaporization are temperature and pressure, so we’ll look at those.
At what temperature does gasoline vaporize, or “boil?” Every one of the hundreds of hydrocarbons in gasoline has its own vaporization temperature, as do the additives (the prime one being ethanol), so there’s no single answer. Components of the gasoline “boil off” at different temperatures between about 100 and 400 degrees Fahrenheit. However, since this is so important a characteristic, a few simple measures are used to describe a gasoline’s volatility, or its ability to vaporize. Among these are Reid vapor pressure (RVP), and volatility percentages, called E200 and E300. There’s also a chart called a “distillation curve” that fills in all the points between these single point measurements.
Reid vapor pressure (RVP) is defined as “the absolute vapor pressure exerted by a liquid at 100° Fahrenheit.” The higher the tendency to vaporize, the higher the RVP. So a gasoline with a 12 PSI (pounds per square inch) RVP is more volatile than one with an 8 PSI rating.
Volatility percentages are the percent of the fuel mixture that will evaporate at a certain temperature, in the case of E200 that’s 200° Fahrenheit, and 300° for E300. In order to facilitate starting a cold engine, a small percentage of gasoline consists of hydrocarbons that vaporize at much lower temperatures, beginning somewhere around 100 degrees, or exactly where the RVP is specified. You can find more information about E200, E300 and other ratings in the links later in this article.
Put simply, the higher the pressure, the less volatile gas will be. That’s why fuel injected systems, with pumps in the fuel tank and running around 30 – 40 PSI, are not prone to vapor lock. However, mechanical fuel pumps, usually mounted on the engine, use vacuum to pull the fuel from the tank. This vacuum makes the fuel vaporize more easily than at atmospheric pressure. So if a gas would start causing a vapor lock problem at 200 degrees, putting it in a vacuum will lower that temperature point.
While we’re on the subject of fuel pumps, note that an electric pump mounted in the fuel tank will be at a much lower temperature than a mechanical pump mounted on the side of the engine block, so in addition to the pressure issue, the type of fuel pump and location will make a big difference in vapor lock issues.
What Gasoline Should I Use?
Based on the above, you want gasoline with the lowest possible RVP and volatility percentages. As these have to meet EPA standards, they won’t vary much from one brand to another, but can vary from one location to another, and vary a lot from summer to winter. Seasonal blending is the result, again, of environmental concerns, and surprisingly, the EPA is kind of our friend in this regard, as the volatile components of gasoline contribute to smog and ozone layer depletion. So they require a lower RVP to minimize emissions, especially in the summer when weather conditions dictate lower emission limits. Typical numbers are (reformulated gasoline, RFG, contains ethanol):
- Conventional Gasoline RVP (summer): 8.27 – 9.23 PSI
- Reformulated Gasoline RVP (summer): 6.78 – 7.63 PSI
- Conventional Gasoline RVP (winter): 12.0 – 12.8 PSI
- Reformulated Gasoline RVP (winter): 11.7 – 13.0 PSI
You’ll immediately notice 2 things. First, RFG (ethanol gas) has a lower RVP than non-ethanol gas and secondly, winter RVPs are way higher than summer ones. So, especially in the summer, you want to be using summer blend RFG. If you have cold start problems in the winter, at which point most of us aren’t driving our antiques anyway, you might want to add some winter gas.
Other Cures For Vapor Lock
Installation of an electric fuel pump, while it will solve most (but not all) vapor lock problems, is something of a last resort in that there are many other things you can try first. The most important is to identify where, in the fuel delivery system (tank to carburetor), the gasoline is being exposed to excess heat. That involves inspecting the fuel path from the tank to insure it’s not close to the exhaust system – and that includes not having the exhaust pipe(s) close to the tank. While there’s no set number, at least 3 inches separation is a good goal. If that can’t be met, a shield should be installed.
Another approach is to use an infrared temperature gun to check temperatures on the lines, pump, and carburetor to identify the hot spots. This can be done with the car sitting at idle and hood closed, then open the hood and check after 15 or so minutes, or when a vapor lock problem starts to present itself. Note that if the fuel is vaporizing in the carburetor bowl, that will certainly cause all sorts of problems with running and starting. However, that’s not “vapor lock” but “percolation” and involves a completely different set of diagnostics and potential cures.
Secondly, you want to keep the engine compartment as cool as possible, and that’s very dependent on air flow design through it. Proper fan shrouds must be in place and installed correctly. If you have a 4 or 5 blade fan, check to see if one with more blades is available. Make sure your fan belt is not slipping. And be sure:
- your cooling system is 100% up to snuff (belt, pump, radiator, etc)
- coolant is correct and system is very clean (no scale, sediment or rust)
- your ignition timing is correct (both too much and too little advance can cause overheating)
- your carburetor is adjusted properly (a lean air/fuel mixture will cause overheating)
- insulate fuel lines, or install a heat shield, if they’re near hot engine parts (e.g. exhaust) – this is why some vehicles are more susceptible than others, as well as location of the fuel pump and carburetor
If all the above seem to be fine, you also want to check your fuel pump. Fuel pumps are designed to handle a significant amount of vapor and still deliver liquid, but if they’re old and not functioning well, they may not be able to handle excess vapor. So if yours hasn’t been rebuilt in the last 30 years, you may want to try that.
We should mention the old school trick you’ve probably heard about, which is to place 5 wooden clothes pins on the steel fuel line running to your fuel pump and/or carburetor. Some folks say this acts to remove heat, which isn’t likely since wood is a very poor conductor of heat, while others say the opposite, namely that it helps insulate the line. Either way, many people claim excellent results with this inexpensive remedy, so if you try it please let us know how it works for you!
Finally, if you’re going to stop for an extended period in extremely hot weather, open the hood to allow heat to escape – on side opening hoods, open the side with the carburetor and fuel pump (or vacuum tank).
For More Information
If you’d like to read more about this subject, here are some links.
For more than you’d ever want to know about gasoline, from its history to chemical composition and regulatory requirements, courtesy of Chevron, click HERE.
For a map of the U.S. showing EPA gasoline requirements by county, click HERE.
Some interesting EPA data on gasoline formulations, showing RVP, E200 and other measures, from 1997 – 2015, is available HERE.