It was about 3 above zero. Here in Webster on the first day in February that isn't too abnormal. We had just finished a ten day vacation in Florida and my son was driving us home from the airport. The Buick was rolling along doing its normal smooth cruising at 60. As we pulled off the ramp the dash board lit up like a Christmas tree. "Oh, oh," my son muttered. "What's up?" "It stalled" "Welllll, start the damn thing and let's get home. I'm whipped and I can't wait to get into that nice warm water bed."
Little did I know that it would be a few more hours until I could achieve that dream even though we were only a mile or so from the house. As the starter whirred and the engine cranked very unevenly I wondered if it would ever start again.
"Something's reeealy wrong, pop." Trying to be the expert and show him that he just didn't understand the temperament of the Buick I reached over and turned the key. "Here, let me have a crack at her - you just don't have the knack."
Wellll, I guess I didn't have the knack either. It didn't even hint at starting - just a weird uneven high speed cranking noise.
Now I often remarked to myself that a youngun like my son shouldn't need to carry around a cell phone - just a status symbol I always thought. Wrongo! He proceeded to whip out the little hand held magic box and the numbers on the buttons glowed an eerie green in the darkness and cold of a now near zero Webster night. A quick call to 1-800-AAA-HELP got a friendly and warm hello from a woman who I am sure was sitting in a nice cozy office sipping coffee, hot coffee, and waiting for us to call her for help. "The tow truck will be there in about twenty minutes." she said calmly. "Hang in there."
It was at least a half an hour and the windows were all frosted on the inside. My wife was beginning to unpack her suitcases looking for something warmer than a casual short sleeved shirt she was wearing - mind you not six hours earlier we were sweltering in the Florida heat.
We waited nearly an hour. I could see lights of the cars cruising along the expressway above us but it was getting difficult to distinguish just what they were looking through an ever thickening ice covering on the inside of the windows. "Hey! We don't have to wait here freezing. Call 911 and see if they will send along a police cruiser with a functioning heater. Maybe they will even take mom home where she can get warmed up."
Twenty minutes later - no cruiser - no tow truck. More ice on the windows. Suddenly from behind us we could faintly make out some flashing lights. No, they weren't red flashing lights, they were yellow. Triple A had finally arrived.
It was a short ride home on the back of the wrecker and fortunately it was late in the evening. I asked the driver to turn off the yellow beacons - don't want to wake up the neighbors you know. And of course I didn't want the embarrassment of coming home on a hook! Not the automotive expert extrodinaire - the one who always fixes the neighbors cars but somehow never seems to have the time to work on the Buick!
Well, all that was about to change. And so was I - into my coveralls and dirty sneakers. It was time for some analysis and serious reading of the ever popular Buick Service Manual.
Now everyone who knows me knows that my first piece of advice whenever attempting to fix a car or a washing machine or whatever is to get the service manual. Fortunately, our local Rochester public library has a very extensive collection of the authentic service manuals for most foreign and domestic vehicles. Here's a hint: Call your public library and request a copy of the manual for your vehicle before even lifting the hood! It will save you countless hours in the long run. In most cases you don't even have to travel to a main library like Rundell in Rochester. Just have it sent to your local library where you can pick it up and then return it full of grease smears and sweat stains.
Now, down to the nitty gritty of the problem. Just because your car exhibits the same symptoms I described, uneven and rapid cranking, don't go assuming that your problem is the same as I am describing here. Most repair shops and dealerships are just too happy to assume they know the problem with no diagnostics and they jump right in and start fixing something that isn't broken, and you know who'll pay for the unnecessary repairs - you'll just hear the famous cover-up, "Well, you needed a new frammitz anyway - it would have broken sooner or later. Sooo, how does one begin a diagnostic here. The first clue is uneven cranking speed. That means that the starter motor is seeing an uneven load in doing its job of turning the crankshaft and making the pistons go up and down. As the piston goes up on the compression stroke the starter motor sees an increase in the amount of force it takes to compress the fuel/air mixture in preparation for the firing of the ignition and the subsequent power stroke. Soooo, if the cranking speed varies wildly you can be pretty sure that the compression is not equal on all of the cylinders. First step: do a compression test.
Sure enough the compression on two out of the six cylinders was well within range (you can find the range in the service manual that you got from the library). The remaining four cylinders were way below specification. Now there are a few possible causes for this. Basically, the cylinder is leaking the fuel/air mixture somewhere. It could be a blown piston and the leak is into the crankcase. It could be a blown head gasket and the leak is either into the atmosphere or into another adjacent cylinder. It could be a valve that is not seating correctly, either burned or possibly hanging so it doesn't close all the way, or it could be a bent valve also not allowing it to seat properly.
Now a long time ago I learned a trick from a fellow Ford mechanic. You see, if you could get air to flow back through the leak you could possibly identify the source of the leak and your diagnosis would be complete. So, what I did was to take a spark plug, break up the porcelain part so that all I had was the metal threaded piece. Then I brazed an air fitting onto the sparkplug body. When I was finished I had a way to thread an air fitting into the sparkplug hole and hook up my compressor to the fitting. Then I turned on the air. A bit of caution here. As the air pressure builds up in the cylinder, the piston will be forced down and the engine will rotate accordingly. Keep your hands clear of anything that may turn with the engine such as a fan blade on the older style engines or just an engine belt which might snip off a finger or two.
Welll, when I did my experiment I found that there was air rushing out of the exhaust pipe. Think now, if that piston was just coming up on the exhaust stroke the exhaust valve would normally be open and one would expect to see air coming out of the exhaust pipe, right? So further work is required.
I removed a valve cover and turned the engine over by hand using the flywheel pulley bolt and a breaker bar. I turned it over until the intake valve opened and then closed and then turned the engine another 1/4 turn. That means that the piston is now on its way up on the compression stroke and both valves are closed. I verified that by watching the valves for that piston and seeing that they were indeed closed. Now I wedged the breaker bar against the frame so that the engine could not turn when I applied air pressure. I could still hear air coming from the exhaust system. There was no air coming back through the intake manifold. I could verify that by opening the throttle and inserting one end of a piece of hose into the throttle body and putting my ear near the other end. Quiet as a church. I then listened through the oil filler cap hole in the other valve cover to see if air was leaking out through the piston and into the crankcase. Also quiet.
My diagnosis was then confirmed with each of the other three low cylinders. Each of them was leaking through the exhaust port.
Soooo, what makes an otherwise smoothly operating motor suddenly stop dead on the expressway and exhibit the signs of bad exhaust valves? Well, if the camshaft to crankshaft timing suddenly changed drastically, the valves might be open when the pistons were at top dead center. How could that happen? If the timing gears and chain failed, that's how.
A quick check of the cam timing showed that my suspicion was correct. I turned the crankshaft until the timing mark came into view. As it approached I watched the valve sequence for the number one piston. If everything was timed correctly I would see one of two possible valve actions. If the piston were coming up on the compression stroke both valves would be closing. If it were coming up on the exhaust stroke, the exhaust valve would be closing and the intake valve opening. Neither was the case. The cam timing was off. With confidence that my diagnosis was correct I began the task of removing and replacing the timing gears and removing the cylinder heads to replace the bent valves.
I attacked the timing gears first. After about a half an hour's work I had removed the timing gear cover and saw the devastation. Buick, in all its wisdom, has supplied older motors with a nylon coated cam gear. After some time of running (the estimate is about 90K miles) the nylon starts to get brittle. The brittle nylon pieces break off and sit in the sludge at the bottom of the oil pan. Finally, after most of the nylon has broken off, the aluminum gear underneath the nylon begins to wear off, also settling at the bottom of the oil pan. Now I have a clue here for all of you who are wondering if you are about to go through all the pain and agony (and big bucks) of losing timing gears the hard way - along with your exhaust valves! Is there a predictor that warns the unwary Buick (and most other GM products) that there is trouble in River City? You bet there is! At your next oil and filter change try this. Get a clean coffee can and a clean piece of sheet or towel that you no longer want. Punch a hole in the oil filter can that you have just removed. Let the oil drain out of the hole and into the coffee can through the clean cloth. If you see a lot of fine aluminum power in the oil or on the rag you probably are a few miles from a timing gear failure. If you also see fine pieces of light green (Buick color) nylon in the filtrate - same message.
If you want further proof, put the oil drain plug back and pour a quart of kerosene into the oil filler hole. Leave the oil filler cap off. Then take an air hose and blow air down through the dipstick tube for about a minute. This will loosen up all the crud that has settled in the crankcase at the bottom of the oil pan. Drain the kerosene into a clean can and filter it through a clean cloth. You will be amazed at what you find! But if you find chunks of green nylon you know what to do!
Well, the timing gears were now replaced and it was time to see if the valves had been damaged by the traumatic failure of the timing gears. I had already done a compression test and knew that there was low compression on four of the cylinders. Next step was to remove the rocker arms for those cylinders and try the forced air trick. If the valves were bent the air would continue to rush out through the exhaust valves. Sure enough, air went easily out the exhaust ports. The valves were bent. It took another hour to get the cylinder heads off and examine the damage. I could see small indentations in the top of the pistons where the exhaust valves had hit them. A quick cleanup of the carbon with my trusty Dremel Tool got me down to clean aluminum. Inspection under a bright light told me that there was no serious damage to the pistons. I changed tools on the Dremel and ground and polished the small dings in the pistons to the point where they were hardly noticeable.
The Exhaust valves cost about six bucks each and the valve stem seals about a buck a valve, well worth it to prevent any oil seepage past the old hardened seals. About an hour later the system was ready to be cleaned up and the carbon and old gasket material removed. A scraper took the bulk of the heavy carbon off and the Dremel Tool did the rest. While I was at it I used a stone in the Dremel Tool and polished the ports, both intake and exhaust, to a bright finish with none of the factory casting flash that can cause poor dynamics of air flow both into and out of the cylinders.
With all surfaces cleaned and polished I was ready for re-assembly. That took another hour or two. I finally got up enough courage to crank it up. It started on the first crank and ran as smoothly as a new engine. I buttoned it up and ran it for an hour or so and then drained the oil to make sure that I had gotten all of the loose crud from the timing gears out of the system. I changed the oil filter and filled it with fresh Penzoil 10W30 and it has been running like a top ever since.
The total time for the job was about 12 hours spread over a few weeks. The total investment was about a hundred fifty dollars, valves, gears, gaskets etc. well worth the cost!
Tools required: Extensive set of 3/8 drive sockets to get at the hard to reach places. Flex sockets are a must. An air wrench speeds the job along as does an air ratchet. Of course you will need a compressor to tun these tools. A set of metric open end and box wrenches is needed. Also a good sharp gasket scraper and a Dremel Tool for polishing critical surfaces. A set of jack stands and a floor jack make it easy and safe to remove the oil pan.
Afterthought: Since I did the job and wrote this page I have been thinking about whether there is a diagnostic that would better detect a worn gear or loose chain and I came up with the following idea: The timing gears and chain connect the crankshaft to the camshaft. The distributor is driven by the camshaft. If there is a lot of slack in the timing gear/chain system then one could detect it by removing the distributor cap and observing the rotor while turning the engine in one direction to take up any slack in the chain/gear system. Then one would mark the position of the crankshaft damper pulley. Then while watching the distributor rotor one would turn the crankshaft backwards until one detected motion of the distributor rotor, then mark the new position of the crankshaft damper pulley. If there was more than a few degrees of backlash in the system one could predict that the chain was loose and/or the gears were trashed and immediately change the gears and chain and prevent a disaster like I had. Of course if there is no distributor then one would have to remove a valve cover and observe the motion of a rocker arm since that is driven by the camshaft too.
If you would like to see what the gear looks like after it has failed, go here.
Copyright © 1996 by Bob Hewitt - All rights reserved
