"Careful, Phil!" warned Milt. "The old engine's getting too hot again. Better slow up!"
"What's the matter?" asked Speed, anxiously.
"Nothing much," answered Milt, "Only we can't hit it up too fast for too long a time. Might burn out a bearing or something!"
Phil reduced the speed from fifty to twenty miles an hour and still the knocking persisted.
"Sounds like it's almost out of gas," said Speed. "It's commencing to cough now!"
"Maybe it caught cold standing out there to-night," suggested Milt. "It is acting strangely. Wouldn't you say so, Phil?"
"Something's gone wrong," was Phil's grave comment. "I think there's some foreign substance clogging the carburetor!"
Pulling to the side of the road, Phil stopped the car.
"Now what?" gasped Speed, glancing at his watch.
"Have to take a look," said Phil, getting out and raising the hood. "Pass out the flashlight, Milt!"