Itinerant Air-Cooled Greetings From Pahrump II
Posted: Sat Jul 26, 2008 10:12 am
It is hot, hot, hot. It is 105* and sunny. I have changed race. I belong now to a brown race.
My poor bus is misbehaving. I know not why just yet. The new fuel pump has been rattling ominously too. What is different about my bus THIS summer that would annoy a fuel pump to death?
At my dad's ex-wife's house (Charlene), I removed the engine to check out the endplay situation. What a situation, too. It read .007", which is just about .0047" more endplay than last July in Indiana. What I noticed was that two of the shims had sort of bonded with each other, thus increasing the shear speed between the thrust face of #1 bearing and the shim adjacent to it. Let's say I am doing 4,000 rpm at 72 mph. The thrust face is doing 0 rpm. First shim should be doing about 1,000, the next one should be doing 2,000, the next one 3,000, and the flywheel 4,000, right? These shims would not be stripping the oil film. But what if two of my German Supply $8.00 shims were cut/machined so roughly that they locked to each other? Then we would have 0 rpm thrust surface of the main bearing, 1,333 rpm against it with two locked-up shims, 2,666 at the next shim, and 4,000 rpm at the flywheel. That's if everyone divided the shear forces equally. But what I had was a great deal of shiny wear at the thrust surface of #1 bearing, and shims that did not look like they were spinning against each other. I had to sand them all smooth smooth smooth with 400 grit sandcloth, wash them carefully and then. . . oh then, yes, I had to figure out the real endplay with this toasted #1 thrust bearing that is moving in the case. I used five shims to make sure that the flywheel locked up against bearing, and found over .002" movement of the bearing inside the case. Ouch. Set the endplay to .0045" to allow for some of that reading to be the bearing movement, and the engine is sounding less thumpy. . . but.
Then I retorqued the left cylinder head with those Air-Cooled Net copper sealing rings. Wow. 7 ft/lbs initial torque. Then I painted a lot of tins that had been eaten by the road salt when I was in Rochester NY last Thanksgiving (I hate road salt). And put the engine back in the car with a Normandy Invasion of red ants going on under my back in the 102* heat.
So the fuel pump has always been here:
Held on with a hose clamp to the diagonal bracket that helps support the fuel tank, it seemed a cool enough spot, close enough to the tank that it pushes fuel instead of sucks fuel. For years, it had been on the left side away from the starter. But after all of this rattling death, I moved it closer to the tank outlet over on the right, so I could route the fuel hose through the outside hole in the firewall where a wiring loom once travelled. This kept the hose away from the hot engine. Ran the hose into free air above the air filter intake where it tees to the carbs. But for some reason, rattle-o-death STILL happened. So, I took the opportunity to upgrade the heater outlets to '78-'79 bus style. I removed the bell caps from the heater valves:
Then I attached 1 3/4" aluminum "pre-heater" hoses available from local FLAPS:
And ducted them to underneath the bumpers:
And with my new muffler heat shield (obtained in Austin in April) finally installed 28 years after I jotted it on my "to-do" list, I thought, "this bus is now ready for more hot days." BUT. The damn fuel pump goes off into death rattle (vapor lock) AGAIN. So I re-positioned the fuel pump on the right side diagonal brace that welds to the torsion tube. Lots of relatively cool air there! BUT IT STILL DEATH-RATTLED! Now I am Officially Pissed.
This morning, (it is only 100* so far) I may have stumbled across the solution. I noticed that the heater valve, though fully closed, was still warming up the big black accordian tube near the new fuel pump location.
Yes, the actual flapper deal inside the valve has lost its little spring that keeps it firmly closed. I whipped up a little spring hook for the time being, to keep it pulled closed, and we SHALL see if it works.
Hot, hot, hot. I am off to replace the ball joints, it is going to be 106* today!
Colin
My poor bus is misbehaving. I know not why just yet. The new fuel pump has been rattling ominously too. What is different about my bus THIS summer that would annoy a fuel pump to death?
At my dad's ex-wife's house (Charlene), I removed the engine to check out the endplay situation. What a situation, too. It read .007", which is just about .0047" more endplay than last July in Indiana. What I noticed was that two of the shims had sort of bonded with each other, thus increasing the shear speed between the thrust face of #1 bearing and the shim adjacent to it. Let's say I am doing 4,000 rpm at 72 mph. The thrust face is doing 0 rpm. First shim should be doing about 1,000, the next one should be doing 2,000, the next one 3,000, and the flywheel 4,000, right? These shims would not be stripping the oil film. But what if two of my German Supply $8.00 shims were cut/machined so roughly that they locked to each other? Then we would have 0 rpm thrust surface of the main bearing, 1,333 rpm against it with two locked-up shims, 2,666 at the next shim, and 4,000 rpm at the flywheel. That's if everyone divided the shear forces equally. But what I had was a great deal of shiny wear at the thrust surface of #1 bearing, and shims that did not look like they were spinning against each other. I had to sand them all smooth smooth smooth with 400 grit sandcloth, wash them carefully and then. . . oh then, yes, I had to figure out the real endplay with this toasted #1 thrust bearing that is moving in the case. I used five shims to make sure that the flywheel locked up against bearing, and found over .002" movement of the bearing inside the case. Ouch. Set the endplay to .0045" to allow for some of that reading to be the bearing movement, and the engine is sounding less thumpy. . . but.
Then I retorqued the left cylinder head with those Air-Cooled Net copper sealing rings. Wow. 7 ft/lbs initial torque. Then I painted a lot of tins that had been eaten by the road salt when I was in Rochester NY last Thanksgiving (I hate road salt). And put the engine back in the car with a Normandy Invasion of red ants going on under my back in the 102* heat.
So the fuel pump has always been here:
Held on with a hose clamp to the diagonal bracket that helps support the fuel tank, it seemed a cool enough spot, close enough to the tank that it pushes fuel instead of sucks fuel. For years, it had been on the left side away from the starter. But after all of this rattling death, I moved it closer to the tank outlet over on the right, so I could route the fuel hose through the outside hole in the firewall where a wiring loom once travelled. This kept the hose away from the hot engine. Ran the hose into free air above the air filter intake where it tees to the carbs. But for some reason, rattle-o-death STILL happened. So, I took the opportunity to upgrade the heater outlets to '78-'79 bus style. I removed the bell caps from the heater valves:
Then I attached 1 3/4" aluminum "pre-heater" hoses available from local FLAPS:
And ducted them to underneath the bumpers:
And with my new muffler heat shield (obtained in Austin in April) finally installed 28 years after I jotted it on my "to-do" list, I thought, "this bus is now ready for more hot days." BUT. The damn fuel pump goes off into death rattle (vapor lock) AGAIN. So I re-positioned the fuel pump on the right side diagonal brace that welds to the torsion tube. Lots of relatively cool air there! BUT IT STILL DEATH-RATTLED! Now I am Officially Pissed.
This morning, (it is only 100* so far) I may have stumbled across the solution. I noticed that the heater valve, though fully closed, was still warming up the big black accordian tube near the new fuel pump location.
Yes, the actual flapper deal inside the valve has lost its little spring that keeps it firmly closed. I whipped up a little spring hook for the time being, to keep it pulled closed, and we SHALL see if it works.
Hot, hot, hot. I am off to replace the ball joints, it is going to be 106* today!
Colin