Although the story is quite popular, it is probably just a legend.
There are many variations on the story. Sometimes, the engineer in the
story is Nikola Tesla. Other times, the engineer is Charles Steinmetz.
Sometimes, Henry Ford isn't even involved in the story!
From Snopes.com's Urban Legend Reference page:
"Nikola Tesla visited Henry Ford at his factory, which was having some
kind of difficulty. Ford asked Tesla if he could help identify the
problem area. Tesla walked up to a wall of boilerplate and made a
small X in chalk on one of the plates. Ford was thrilled, and told him
to send an invoice.
The bill arrived, for $10,000. Ford asked for a breakdown. Tesla sent
another invoice, indicating a $1 charge for marking the wall with an
X, and $9,999 for knowing where to put it."
"Know Where Man" Urban Legend, hosted by snopes.com
Here's an example of the variation involving Charles Steinmetz:
"Automaker Henry Ford asked electrical genius Charlie Steinmetz to
build the generators for his factory. One day the generators ground to
a halt, and the repairmen couldn't find the problem. So Ford called
Steinmetz, who tinkered with the machines for a few hours and then
threw the switch. The generators whirred to life--but Ford got a bill
for $10,000 from Steinmetz. Flabbergasted, the rather tightfisted car
maker inquired why the bill was so high.
Steinmetz's reply: For tinkering with the generators, $10. For
knowing where to tinker, $9,990. Ford paid the bill.
Source: Today in the Word, MBI, April 1990, p. 27.", hosted by
Here's a variation on the story which involves CBS radio:
"Kramer cites a story dating from the golden age of radio when a
malfunction in the main transmitter caused CBS to go off the air. When
the companys own engineers failed to figure out what was wrong, they
called in an outside expert. The expert walked up to the transmitter,
stared at it, then gave it a sharp kick, which put CBS back in
commission. The next day CBS got an itemized bill that read: 'One
kick, $1. Knowing where to kick, $9999.'"
Here's a variation where the story happens on a steam ship instead of
a car factory:
"EVER HEAR THE STORY of the giant ship engine that failed? The ships
owners tried one expert after another, but none of them could figure
out how to fix the engine. Then they brought in an old man who had
been fixing ships since he was a youngster. He carried a large bag of
tools with him, and when he arrived, he immediately went to work. He
inspected the engine very carefully, top to bottom. Two of the ships
owners were there, watching this man, hoping he would know what to do.
After looking things over, the old man reached into his bag and pulled
out a small hammer. He gently tapped something. Instantly, the engine
lurched into life. He carefully put his hammer away. The engine was
A week later, the owners received a bill from the old man for ten
'What?!' the owners exclaimed. 'He hardly did anything!' So they wrote
the old man a note saying, Please send us an itemized bill.
The man sent a bill that read,
Tapping with a hammer...................................$2
Knowing where to tap................................$9998"
More variations on the story:
"The Story about Henry Ford and Charles Steinmetz"
search strategy: "know where to", bill, "henry ford", etc
I hope this helps.