Pleasure Cruise Breakdown. . .
Decided to take the Mrs, kiddos and pooch for a Saturday drive in Lowly truck between the snow flurries. This was Mrs' first real drive in the truck and it was a splendid outing until we broke down a couple miles from home on the return leg. Slowed down coming to a stop sign on a residential street (thankfully this happened on backroads!) and the compressed air reservoir's low pressure alarm started its mind-numbing note. Dash lights began coming on: air pressure tank low, parking brake on. Then the two needles on the dashboard's air pressure gauge slowly dropped below acceptable operating pressure.
For those not familiar with air brakes (and I'll admit that I am a newbie), when air pressure is lost the parking brakes are activated mechanically. Lowly was not going anywhere and I couldn't shut him off; I'm guessing the electronic kill switch fires off some pneumatic valve/cylinder that kills the engine. So, with the truck idling, unmovable and blocking a lane of traffic I unloaded the family and began a very long trouble shooting of what the heck was going on. Thankfully my parents were called in to shuttle the family home and my long-suffering dad stuck around to help me.
With my systematic process of elimination and a call to a diesel mechanic friend, the culprit was located - some sort of stuck valve in the compressed air cleaner/relief apparatus upstream of the pressure tanks. When you hear an idling truck or bus emit a loud pop/hiss, that is the air relief valve doing its job. Lowly's was stuck in the open position, letting all the air headed to the tanks vent to atmosphere. We decided to unscrew the incoming and outgoing air lines and mate them up, effectively bypassing the pressure relief apparatus to temporarily restore pressure to the tanks and let me limp the 2 miles back home.
Meanwhile a friendly man living nearby directed traffic around our Mercedes roadblock as night descended and I frantically Mcguyvered a fix using a plumbing union in an attempt to get home before the next rain/snow squall descended. Here is a pic of the fix with the culprit in the background.
Limped back home, stopping every time the pressure gauge needles crept above the "happy zone" to activate the parking brake and relieve the tank pressure as my pressure relief was no longer in the loop. Got home to a dinner of spaghetti. The kids thought it was a great adventure. When asked, Mrs said she enjoyed her first ride in Lowly. Whew! I just hope it isn't a sign of things to come!
- Sheik