Dabney's Smokin' Cougar
Doctor Crankshaft had just poured himself a cup of coffee and was settling in at his dining room table with a pile of seed catalogs. Time to start thinking about what he was going to plant in his garden this year. He
had just turned to the page with the vegetables and Dabney knocked on the back door. Doc looked up, saw Dabney grinning and waving. Doc groaned and slowly got up and opened the door.
"Mornin', Dabney," mumbled the Doctor.
"Mornin', Doc. Lookin' at your seed catalogs, huh? Dabney picked up one of the catalogs and started thumbing through it.
"Be sure to get some of those Beef Jerky tomatoes you had last year....they were great."
"That's 'Beefsteak' tomatos, Dabney. Glad you liked them. What brings you out this way, Dabney?"
"Sorry to disturb your seed shopping, but I'm going crazy trying to find out why my Cougar is burning oil. When you're done here, can you drop by the garage and check it out?"
Doc looked at his seed catalogs, then looked at Dabney, then back to the seed catalogs. "Ok, I'll finish this later. This will take some time and I don't want to be rushed. Let's go."
Dabney drove over in his 1952 Hillman Minx. Doc climbed in and as they drove away he noticed that the Minx had a 4 speed on-the-column gear shift (you pulled out on the gearshift knob to shift into reverse). Doc mumbled "I'll help you with your Cougar, but you gotta do better than this when you bring me back..."
They pulled into Dabney's garage and the 1967 Cougar XR7 GT was front and center.
"Hey, Dabney, where did you get this beauty?" asked the Doctor.
"I bought it at an estate sale, Doc, and it's only got 28,000 miles on the odometer," said Dabney. "It's a rare, 390 cubic inch car."
That was right. Very few of the Cougars built that year were fitted with the big-block Ford engine, and very few still exist today. The Cougar was a beautifully executed version of the Mustang that Mercury sold, but the car never caught on the way the Mustang did. Cougars were heavier, quieter and far more luxurious, especially the XR7 versions with their wood grain dash, toggle switches and leather seating.
"I really like the styling of the old Cougars," said the Doctor, "and this dark green color was perfect for the XR7 models."
"You're right, Doc," said Dabney, "I couldn't have chosen a better color combination than the green with saddle interior. It runs great, but as you'll see it burns oil."
Dabney started the car and the big 390 smoothed to a nice idle. A trace of whitish smoke was coming out of the exhausts, but nothing very significant.
"I thought you said it's burning oil," said the Doctor. "I see white smoke, not blue."
"I know what you're about to say, Doc," said Dabney, "white smoke indicates coolant being sucked into the cylinders. However, the coolant level is perfect and there's no overheating. I think we need to drive the car to demonstrate what's happening."
The pair got into the car and headed out over the local roads. As they drove steadily they looked out the mirrors for smoke. A slight cloud of white smoke followed them, but it was only when they coasted down a grade and then accelerated that a heavy cloud of white/blue smoke billowed out.
"Well, look at that!" exclaimed the Doctor. "Let's do that a few times and note the circumstances when the big cloud comes out."
They did so, carefully noting that the only major symptom occurred when they coasted downgrade and then accelerated.
"You see, Doc?" said Dabney, "This is crazy! I've never seen such anything like this before and even if I drive a hundred miles or so the oil level and coolant level are fine. There's no trace of cross-contamination."
"No, I wouldn't expect there to be any," replied the Doctor.
"Does this mean you think you know what's wrong?" asked Dabney.
"Of course, my dear boy, of course," said the Doctor smugly. "It's the transmission."
"What?" asked Dabney, in a voice of disbelief. "The car shifts fine. How can it be the transmission?"
"Well, let's look at the symptoms. First, the color of the smoke is white with a little blue in it. That means it could be coolant and a little oil, right? However, the car has been driven a couple hundred miles and the coolant level is fine, there's no overheating and there's no evidence of oil in the coolant. That pretty much rules out the cause as being anti-freeze."
"Okay so far, Doc," said Dabney, "but what would burn whitish if it weren't coolant?"
"Transmission oil burns white, my boy," replied the Doctor. "We need to take this thing back to the garage and put it on the lift."
Dabney didn't say anything on the way back and neither did the Doctor. Dabney was too busy puzzling over Doc's diagnosis and Doc was too proud of himself for coming up with a solution and he didn't want to spoil the moment. When they returned to the shop they put the Cougar on the lift and the Doctor took out a screwdriver to point things out.
"See this little plenum attached to the outside of this C4 Ford transmission?" asked the Doctor.
"Yes, Doc, I see it but it doesn't look loose," replied Dabney.
"Take off that vacuum line attached to the front of it and I'll bet you a bunch of fluid pours out," said the Doctor smugly.
Dabney pulled the vacuum line and, sure enough, about a half-cup of transmission fluid poured out on the floor. "Now, how did you know that would happen?" asked the incredulous Dabney.
"Because I've seen this before. Fords in the 60s used to suffer this problem a lot. The vacuum modulator (the part that they were looking at, the purpose of which was to control upshifting) tended to develop leaks in the internal diaphram. Since fluid was on the other side of the diaphram, engine vacuum would slowly draw the fluid up and into the intake manifold, where it would find its way into the cylinders. Since the greatest vacuum was upon decelerating downhill, the greatest amount of fluid would be drawn up and then burned as the engine revved up accelerating," explained the Doctor.
"Well, I'll be darned," said Dabney. "What do we do to fix the problem?"
"That's the easy part," said the Doctor, "all we need to do is buy a new modulator and screw it on, then reconnect the vacuum hose. Of course, that doesn't address the slight blue smoke that's mixed with the white. I suspect that's due to worn valve seals, but we'll just have to examine that when this mess is cleaned up."
Doc moved out from under the lift and made it obvious that he was looking around the garage for something.
"Aha, there it is!" Doc said and started walking through the garage to Dabney's 1938 Cadillac Series Seventy-Five Fleetwood town sedan. With its 141 inch wheelbase, it took up a large part of the garage. Doc opened the back door on the passenger side and climbed in.
Dabney had followed him to the car. "What are you doing, Doc?" Dabney said.
"I'm ready for you to drive me back home," Doc said. "I told you you'd have to do better on the return trip....Home! Dabney."