Electronic shifting

elecronic shifting

directional headlights

directional headlights

Another way to find A/C leaks

older cars- why don't they make them?

older cars- why don't they make them?

how to get air out of radiator with broken bleeder valve

air out of radiator with broken bleeder valve

Another way this problem could present

Using a smoke machine to find an A/C Problem

VALVE STEM MAYHEM

Joe was a very meticulous mechanic. His productivity level was on the low side but when he finished a job, it never came back. That was until he met the Dodge van with the V-8. It came in for a timing chain and waterpump. "Piece of cake" Joe thought to himself. Instead, the cake turned out to be a bitter pill he would never forget.



The job went smoothly; too smoothly. For good measure, Joe ran a compression test as soon as he had the new timing gears in place. It was the thorough thing to do. The readings weren't bad, but they weren't good either. He suspected the valves weren't in great shape and suggested the heads be pulled so the engine could get a valve job. The owner was perfectly happy to comply.



The rest of the job passed smoothly, at least until the owner came roaring back into the shop yelling "What have you done to my engine!" He was steaming mad and wanted an immediate explanation. Joe asked what the problem was and the owner threw his keys at him and said, "Just drive it. It's pretty obvious!"



A test drive revealed a total lack of power. Ironically, the engine didn't idle rough. But under power, it was a real dog. The first thing he did was take compression readings. They were all normal. Next he warmed up the gas analyzer.



The exhaust gas analysis readings were so high they went right off the scale. "It must be the carburetor. Nothing could make the exhaust readings that high except a carburetor problem. It's flooding," he thought.



Rebuilding the carburetor made no difference. Reasoning that it may have an internal flaw, he installed another carburetor. No difference. Maybe the timing isn't advancing or is wrong. Joe began to suspect the timing chain. Could he have installed it wrong? It wasn't a happy thought. The entire front of the van would have to be pulled apart in order to get to the chain. But, doggedly, Joe took it back apart again. The timing chain was on correctly.



He took the gears off and matched them up with the gears from a different manufacturer in hopes that the gears were mis-boxed and for a different application. No such luck. They matched perfectly. What about the distributor?



Despite the fact that he never touched it, he would try another one just to see.



Once again, no difference. It still ran very badly.



Joe was at his wits end. He went over every thing he had done again and again without so much as a clue to the new problem. He feared he might have gotten back the wrong cylinder heads from the machine shop, but the casting numbers were found to be correct. He checked for exhaust restrictions, emission control problems, secondary ignition problems. In short, Joe was fresh out of ideas.



The van sat, like a dejected child, over in a corner of the shop for a week. The owner was becoming more and more outraged each day. Rightfully so! Joe did not know what to do. In desperation, he decided to visit an old mechanic friend for some advice. As Joe explained the gory details to his friend, he looked into his eyes for some glimmer of hope.



When he got to the part about the valve job, his friends eyes widened and he exclaimed, "That happened to me too!" "Really?" said Joe. "Yep. and I know how to fix it." Joe's heart sang. "What! What! You gotta tell me," he exclaimed.



Instead of talking, the old mechanic slowly walked over to his tool box and reached into the back of one of the bottom drawers, pulling out a thin strip of brass sheetmetal.



"That's shim stock. What's that got to do with it?" The old man told him to cut the metal into thin strips and place one strip between the rocker arm shaft and the cylinder head. "What will that do?" Joe asked. "Just do it and call me back to tell me the problem is fixed." The trick did the trick. The engine ran with full power and the emission levels were now back to normal.



Joe could hardly wait to call. "What did I do? Why did it work?" His old friend explained that he had the same predicament once upon a time. The problem was caused by the machine shop not cutting the valve stems after doing the valve job. "It's a problem with what is called installed valve stem height. Your machine shop is sloppy."



Joe couldn't wait to rip the heads off and take them to a different machine shop to be checked. Sure enough, the valve stems were protruding much too far into the cylinder head. The valves were burned where they had been held open by the lifters. "But what about the normal compression tests? Why were the compression readings good if the valves were held open?" He asked the old man. "Because the oil pressure had not come up when the engine was cranking over. After it started, the oil pressure was enough to pump up the lifters and hold open the valves."

Finding Evidence. Bad Blower Motor