Puzzler Answer, 3/14/97: Vintage Volvo
Ray:
This really happened. A few weeks ago a customer who works down the street
came in with an older Volvo, a 60's vintage, one of those P-1800's --Volvo's
feeble attempt at a sports car in those days of the 60's and 70's.
Anyway, it was an interesting looking car
and his complaint was that the car didn't seem to stop very well and he was
sure that his power brakes weren't working. A quick test drive revealed this
to be the case. When you first stepped on the brake pedal, when you first slowed
down, the car seemed to stop quite well. But in fact, if you applied the brakes
several times as if slowing down to avoid crashing into the back of some
other vehicle, after 2 or 3 applications of the pedal it would be pretty rock
hard and didn't really want to stop unless you stood on the pedal. So we pulled
into the shop and I said, "Geez, I don't know, it could very likely be the booster."
And he said, "Great. I have a used one which I know is good."
Tom:
Um.
Ray:
So a few days later he brings the car in again and the booster and we install the
booster. I drive the car. I call the customer and ask him to drive it because I
didn't notice any significant improvement. And we are sure now that the replacement
booster is okay and it turns out the original booster was okay. So we look around.
And the first suspect is the hose that leads from the manifold to the booster --
is it plugged, is it restricted, it gets replaced. Still no improvement. After
a few more minutes of tinkering and doing various tests, Ralph -- the Volvo wizard
-- finally figures out what's wrong with the car and it has to do with the kind
of gas he's been using. Moreover, he does an adjustment that fixes the car.
What's going on here? What adjustment does he perform that fixes the car and
it's not adjusting the timing either. Now you might think that if he couldn't get premium gas that would
retard the timing and
lower the vacuum, and we thought that at first.
Tom: What Ralph discovered was that there was no vacuum.
Ray: There was insufficient vacuum because the valves were too tight.
Tom: Oooh.
Ray: And the valves were too tight because this car was designed to burn leaded gas and the tetra-ethyl lead used to act as a cushion between the valves and the seats. And because leaded gas is no longer available and he's been using regular unleaded in the thing -- he's got a bad case of valve seat recession which makes the valves pound into the seats and reduces the amount ...
Tom: ... We're heading for that I think. Alan Greenspan is sure of it.
Ray: Reduces the amount of play in the valve train and causes eventually the valves to get too tight. Hence low compression.
Tom: 'Cos they don't really close.
Ray: Just on the hairy edge. The car still ran, actually ran pretty decently. Being unfamiliar with car as I am, I didn't know how much power it was supposed to have.
Tom: Yea. None.
Ray: Who's our winner?
Tom: Alisa Para from Santa Fe, New Mexico.
[ Car Talk Puzzler ]
