Breakdown on the Santiam Pass – by Bob Wallace
Click for large view
Driving from Portland, Oregon to Redmond, Oregon is a trip of about 170 miles. The high point of the journey is the Santiam Pass at 4817 feet. If you examine the photo to the left (click to enlarge) you can see that my 1960 BT7 decided to make an unscheduled rest top just at the summit of the pass.
It was running beautifully for over 100 miles, purring along, when at the very top of the summit is started to miss and then die. Fortunately there was plenty of room on the side of the road to pull over. To make a long story short, it was about 105 degrees F. and the result was vapor lock. John Carter and Mark Schneider continued on, leaving me to wait for the car to cool off. It takes a while to cool off at 105 degrees. I finally got going again and pulled into our destination about an hour after everyone else. At that point I think I was suffering from vapor lock. There was a tub of ice with bottles of beer in it. I skipped the beer and shoved my hands into the ice.
So this was my first experience with vapor lock. Googling it gives this definition at wikipedia:
Vapor lock (also known as vapour lock) is a problem that mostly affects gasoline-fueled internal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporize due to being heated by the engine, by the local climate or due to a lower boiling point at high altitude.
The last sentence tells the story: Austin Healey (not a cool running car), 105 degrees outside and 4817 feet. So what do you do about it. Well once it happens you typically have to wait for the car to cool down enough. But being at a club meeting, it was expected that there would be some suggestions made. Especially since the next day I was going to drive back over the pass. But I have to admit, I was somewhat skeptical when it was suggested that I used wooden cloths pins on the fuel line. Not that our club members would ever stoop to a practical joke.
Well further googling found plenty of people saying the same thing. That clothes pins act as heat sinks to dissipate the heat from the fuel line. Of course half the people claimed it worked and half claimed it was an old wives tale. Since it didn’t get up to 105 on the return trip I can’t say one way or the other.
More permanent and rational fixes are replacing your mechanical fuel pump with a low pressure electric one, adding an electric fan with a heat sensor, and not driving over passes on 105 degree August days.
References:
Thank You’s:
- To John and Mark for the moral support on the side of the road.
- To John Wilson who first suggested Vapor Lock
- To the club member whose name I forgot (after standing in 105 degrees for an hour) who pulled over to help.
- To Gary Jackson for the bucket of ice, bottle of water and other first aid when I showed up at his house soaked in sweat and babbling incoherently
- Jack Jacobson for lending me his cell phone and pen. I owe him a pen, I returned the phone.