That effect sounds so improbable, in the sense of how could anyone design the engine interior so it was possible? OTOH, I remember when smaller cars became more popular in the 80s, hearing from my mechanic that the under-hood environment had become very hard to work with.
Ann, you machanic waqs probably used to the large American cars with plenty of room under the hood. I once owned a Doge Dart from the 1970s. You could almost stand in the engine compartment -- there was so much room. With the smaller cars, everything was crammed together. Now when you look under the hood, not only is it compact, it's hard to know what you're looking at.
You're right, Rob, this was back when most cars in the US were bigger and most mechanics were used to working on them. I had a boyfriend with a Dodge Dart--I remember all that room under the hood. Sure made it easier to find things.
They kept going so long that the bodies started falling apart while the engine was still intact. We were living near the ocean then, so the salt air probably was instrumental in that car's demise. But the engine still ran!
I didn't have a Dart, but I did have a Plymouth Satellite. My car rusted out so bad that I had a gas tray. That platform of Mopar cars had the gas tank under the trunk, so the trapped water between the tank and trunk would rust the top right off the tank and the bottom off the trunk. I always wondered if I could fill up the trunk and consider it an extended range tank.
Yes, Ann, Berkeley was a bit more mature than the typical hippie ghetto -- although Telegraph had its hippie ghetto flashbacks. What I loved most about Berkeley during the early 70s was the music. Live music was everywhere, and it was all great. It was in the clubs, the coffeee houses, the bars, the theaters, even the parks.
You remember incorrectly. The points, which make and break the primary circuit of the ignition coil, were typically located in the distributor. One contact of the points was grounded at the distributor; the points broke the ground-side contact to the coil. When the ignition switch was on, battery voltage was connected to the other primary terminal of the coil. The subject short caused by the dipstick would have been on the ground side of the coil primary; at the points terminal. The short would not have caused excessive current to flow because shorting that side of the coil periodically was normal. The short didn't allow contact to be broken when it was supposed to be, though, which killed the ignition at times.
Many cars (including this Volvo) from this era did not have fuses in the ignition circuit, so even if the battery side of the coil primary was shorted, it wouldn't have blown a fuse. It might have caused some wiring damage. Some later cars had fusible links (wires that were designed to melt, basically) in the ignition circuit, but these might not have been damaged by an intermittent short on the battery side, if there were one.
Later cars also had ballast resistors in the primary circuit. The ballast resistor would limit the current to increase the life span of the points (and coil and battery if the ignition is left on when the car is parked). The ballast resistor was typically bypassed during cranking for a hotter spark initially.
You and I are talking about the same thing. I say the points get 12 volts through the ignition coil. When the points are open, the voltage at the high side of the points is indeed twelve volts (yes, I know, nominal!).
You say the points ground the ignition coil. Yep, they sure do. They complete the circuit that energizes the coil so that it can provide the spark when the field collapses.
I can understand that there are two approaches to describing this. What I don't understand is your not seeing that your approach and mine are different points of view of the same thing.
I was wrong about a fuse in the circuit. But surely the dipstick running into and making contact with the lead from the ignition coil would interfere with operation. If the dipstick contacted the lead at any time near the points' release, a spark would be inhibited and/or would fire randomly later.
The original poster may have intended to say that the dipstick shunted high voltage to ground, reducing the spark. High voltage is also input to the distributor.
One point I was making was that he was not explicit as to which "input to the distributor" he was talking about.
If your "approach and mine are different points of view of the same thing," then why would you think that shorting a terminal that is shorted by the points during normal operation would blow a fuse? Grounding the distributor side of the coil primary does not generally cause an over-current condition.
How do we know that the dipstick didn't short the secondary (high-voltage) terminal? The article says that the dipstick shorted a terminal on the side of the distributor. The high-voltage terminal is on the top of the distributor.
Here is a picture that shows the positions of the dipstick and distributor: www.californiaclassix.com/Bernard/PV544-6.html
As I said, I was wrong about the fuse, and yes, wrong on two counts.
However, you're focusing on one detail rather than the overall idea. You said
"You remember incorrectly. The points, which make and break the primary circuit of the ignition coil, were typically located in the distributor. One contact of the points was grounded at the distributor; the points broke the ground-side contact to the coil."
I had said
"If I remember my old cars properly, the INPUT to the distributor is 12 volts from the primary of the ignition coil. How could repeated contact with the dipstick not result in a fuse blowing?"
So you're saying that the points broke the ground-side contact to the coil (which is at 12 volts when the contacts are open), while I said the input to the distributor is 12 volts from the coil (which falls to ground when the contacts close. Both of those are true so it's not possible for ONE of us to be correct on these points. Those statements are
"different points of view of the same thing."
I already said I was wrong about the fuse. And you're right about the high voltage wire being on the top of the distributor, though I have the nagging sense that I've seen one come in from the side and make a 90 degree turn down into the distributor. Let me rephrase, turn downward at some angle less than 90 degrees to the ground, lest someone point out that distributors don't always sit with their shafts normal to the ground.
I am a firm believer in graphical documents like schematics and wiring diagrams that make clear how things are connected for this very reason. Words are inadequate when it comes to describing how things are interconnected, and are not an efficient way to convey the information. I don't think that my ways of saying things are any more correct than the ways that most other people say them; there is no right or wrong when it comes to languages, nor is there any right or wrong language. The best we can do is to take steps to verify that we are on the same page, and I think you and I are on that page.
I have also seen distributors with secondary terminals that point sideways, on cars that had limited hood clearance. This Volvo didn't have limited clearance above the distributor, though.
Secondary wires are usually well insulated, so even if they do touch something like a dipstick, there is no short. It is not at all unusual for secondary wires to touch grounded metal parts and still perform as intended. Low voltage terminals are often exposed because there is no hazard and no expectation or corona or arcing.
My father bought a used '72 Dart... and had to sell it. Not that that car had any real problem, THE problem was it was so fast, that Dad had to stop my sister and me, both teens, from running drag races with other young people. Ours was a two door olive green with black vynil top, and was labeled as a "Dodge GTS", with a factory modified 318 engine with some 340 parts, high compression, forged rods, 4-barrel and the very first "windage tray" that I saw in any production engine. functional air intake hood scoop with tachometer on top, dual exhaust and (then) wide Oval Firestone series-70 tires. It ran 0-60 times under 8 seconds and burned rubber in first, second and third. It was assembled in Mexico's Toluca plant. that engine sounded absolutely gorgeous, and required high octane (100) gas at sea level. The Hurst shifter was the fastest, more reliably shifting that I have handled in many years.
We were very sad to see it depart, but probably my Dad was right. It was too much of a toy for two young and fearless teens.
I hope the product design people at Dodge learns about the heritage of the brand, and installs the SRT-4 turbocharged four engine into a new Dart 2014, and keeps the tradition alive. Amclaussen.
Actually, yes! When I was stationed in Germany I had a Volvo PV544 which after a long stint driving down the autobahn backfired while pulling into a rest area. After coffee and a meall, I started the car up and while attempting to accelerate accross the parking area the engine started missfiring. Driving on the autobahn with a significant misfire was patently unsafe and stopping on the highway was illegal so an immediate fix was required. I raised the hood and found the dipstick was about half out of the hole and the handle was against the distributor, probably pushed up from crankase overpressure after the backfire. I pushed in the dipstick and proceeded on my journey. As I remember, the dipstick was split and this provided some friction inside the tube to prevent movement. After many miles and hundreds or thousands of removals of the dipstick the split portion had compressed somewhat and it was necessary to use a pocket knife to spread the split portion a little in order to make it fight tightly into the tube. Good design doesn't necessarily prevent failure, but it should make repair possible.
I think your PV544 was a 1960 or later model, with the B18D engine. I had a 1959, and I don't think Volvo used the "PV" prefix in 1959; that one had the B16B engine. The distinguishing factor that was pretty obvious was the B16B was the last one to still have a 6V electrical system. The 1960 B18D introduced the 12V electrical version, with a slightly larger engine displacement. That drive train was also used in the successor model 122S for some years. While I never experienced this problem, I would classify this as an example of "serviced by monkeys," not "designed by..." I still have my SU carb service kit including the "synchronizer tools." Originally bought for my 1959 bug-eye Sprite, I used it until I retired my 1968 Rover 2000TC (which replaced the Volvo; it was the first new car I ever bought!).
Ratsky; It was a '61 PV544 Amazon, B18B. Same engine/drive train as used in the succeeding 122 and 144. Volvo stayed with this engine/drive train for many model years until stringent emission laws made carburators unworkable. The 144 was my first and only-ever new car. I felt so "used" by the new car process I vowed to never purchase a new car again. Every Volvo I've owned has safely seen me through well overe 200K miles with no major - though some perplexing problems. I once put four SU carbs on a flathead Ford V8 (they were cheap in junk-yards). Tuning was tricky but it was truly unique. Cars of that era were the culmination of years of incremental improvements and really didn't seem to represent any novel design features. I have a 1924 Chrysler and you can trace virtually every automotive improvement from that car and others of that era.
It been years since I have was under the hood but I recall the the old Volvos had an inline 4 cylinder engine. As was typical of the inline engines, the oil dipstick on the side of the block. I think the Volvo dipsticks had more of a 'handle' (L shaped) than a loop or hook on the end of the dipstick. With the distributor nearby, I see that the dipstick handle could turn and possibly touch other things.
Since the oil pump and distributor are driven from the same crossed helical gearset on this engine type, it shouldn't be surprising that the dipstick is near the distributor: the dipstick needs to reach well into the oil sump near the pump pickup screen. What is surprising is that crankcase pressure would be a contributor to the problem. Being of a vintage before emissions controls, this engine had a "draft tube" instead of a PCV system. Here is a link to a photo of a nice example under restoration: http://canadianrodder.com/pv/photos/update8/update8d2.jpg
Good to see another 'straight 4' going back into service! I've got mine re-seated, re-you-name-it, and heading back into a '72 Volvo 1800ES. Good on you getting the 544 spruced up, I'll buy the coffee when we meet on the road-
"Dipstick Messes With the Distributor": I thought maybe they were talking about me trying to set the timing on my GM computer controlled engine! I could not get it to work right until, duh, read the instructions. Have to unplug some wire to disable the computer controlling the advance. Boy did I feel like a dipstick!
Reminded me of my friend. He took his car in to one of those oil change places. The guy didn't put the filter on correctly. Let's just say he didn't make it too far before things went bad. I guess when you do something like that(the checking of the oil as well) so many many times you might get a bit careless.
The quality of the help in these quicky lubes can be a nightmare. I took my Ranchero into one of those along with 6 quarts of mobil 1. They drained the oil and then refilled forgetting to replace the drain plug. All of my oil in the pit. The manager offered to only charge me half price. Unbelievable! Of course I never went back.
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