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.
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.
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.
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
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.
"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!
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.
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