Dealing with Ford Probes can be filled with tricks you don't see coming.
There are some days when it doesn't seem profitable to come to work. Ever had one of those? A long time ago (1983) when I was a technician working at the VW dealer, a valve adjustment on a VW Rabbit (diesel or gas powered) cost about $20. The valve cover added a little to the bill, and $20 doesn't sound like much, but it was fairly profitable once a tech gained the skill to get it done quickly.
I drew a ticket one day on a diesel Rabbit that was a routine job, but it smoked my bacon. I had done dozens if not hundreds of valve adjustments on those cars, and this one had the loosest valves I had ever seen. I had to replace all the shims with very thick ones to get the valves in spec. After I was done, I drove the car and parked it.
When the customer came to pick the car up the next morning, it made a horrible noise while the starter was spinning it and the noise remained after it was started until it warmed up. The problem was that the cam followers hadn't been going nearly as deep into their machined bores before I adjusted the valves and now some of them were sticking on the thick varnish in the previously undisturbed part of the bore. The valve would stick, the piston would contact the valve and pop it shut, and, well, you can imagine what it sounded like. The customer was apoplectic. I was blind-sided by this, because I had never seen anything like it, and after I figured out what had happened I took stock and realized that I had a couple of options.Option 1: I could tear everything down, and clean the varnish from the valve bores, but our friendly customer wasn't about to pay for that repair and I knew I'd be doing that job on my own time.
Option 2: I could put the valves back like they were and send him on his way, which was what I decided to do. I hadn't done anything wrong on the job and quite frankly I didn't see any point in burning hours and hours of my own time on a problem that would have blindsided anybody who had drawn this dirty hand. It was what I call a "circumstantial land mine," because I was strolling along doing everything according to Hoyle and it blew up in my face.Painful Probe
When my dad was running his shop in the 1960s, he made the remark that whenever he worked on a Corvair he had to do it with the shop doors closed. When asked why, his answer was that if somebody sees you working on a Corvair, they'll bring you another one.Joe brought his Probe to us with an inoperative A/C and a dead charging system, and both concerns had happened simultaneously. When I opened the hood I saw that the 2.5L had tossed its outboard serpentine belt (the one that drives the compressor and the alternator) but the inboard belt (which drives the water pump and power steering) was still in place. As the students and I evaluated the underhood situation, the owner handed me the pulley ring that he had picked up in his driveway one morning when the two accessory components went offline. The ring was the larger of the two pulleys that are married to the rubber ringed hub of the balancer on that car, and this balancer had left its partner behind on the driveway.
This would be a simple repair (somewhat). A replacement balancer was easy enough to obtain for about $130, and while it took some gymnastics with the puller to negotiate the space between the balancer and the vehicle frame, we managed to get it off.
I inspected the part of the timing belt that was visible with the balancer removed (it looked new) and slid the new pulley on the end of the crank. I then applied the necessary torque to overcome the interference fit, seat the gear and pinch it against the crankshaft boss. While I was doing this, I explained to the students that the key and keyway that locate the gear on the crankshaft don't have the strength to carry the load of spinning the cam gear over a long period of time, thus a loose balancer can bring a delayed reaction disaster. If the balancer isn't properly tightened to pinch the gear, it follows that the rotational torque of the crankshaft is applied to the key so that it shears. In a case like that, the car will be back on the hook with the valves out of time.
New belts were installed and tightened, the splash shield and the tire were reinstalled, and the Probe was ready to push some wind. I fired it up and backed it out of the shop; it ran well. But the next day when the customer started the Probe and drove away from the shop, he didn't go 300 feet before the engine died. We had stumbled onto a land mine.
New Diagnosis
The Probe spun and acted like it wanted to start, but it just wouldn't. It deteriorated to the point that it was backfiring through the intake and puffing smoke through a narrow crack in the dry-rotted air inlet hose that previously had gone unnoticed. It would need that $100 part when all this was over. This was the first time we had worked on Joe's car, and he was visibly shaken, probably wondering if he should have trusted us at all.
I apologized for the inconvenience and sent him on his way with the promise that we'd figure it out.
We checked the fuel pressure. It was 40 pounds-plus. We checked fuel quality and spark, which both were fine. Why was it firing like it had crossed spark plug wires? We hadn't done anything to the ignition system. But since the crankshaft tone wheel was on the balancer we had just replaced and since the crank sensor was so close, I had the students remove the right front wheel and the splash shield again to see if maybe we had disturbed the crank sensor wire so that it had been damaged by the belt or pulley. We hadn't.
With the timing covers removed to the point that the marks were visible (and the cam pulley marks aren't easy to find or figure out without an illustration), we determined that the timing belt wasn't the problem. All the marks lined up perfectly. The engine should have been on TDC No. 1 at this point – was it? What was the easiest thing to check? Well, the distributor is driven by the exhaust camshaft on the front head, so why not snatch the distributor cap and see where the rotor was pointing? It made sense, because the engine was cross firing like the wires had been swapped around.
With the cap off and the position of the No. 1 firing post noted and marked on the distributor housing, we found that the rotor was pointing at No. 6. The firing order on this Probe is 123456, so it wasn't a 180 out situation. With the valve cover off, we found that we could use the wrench flats on that camshaft to turn the shaft independently of the cam drive gear. The cam gear bolt was loose, and the engine died when that gear spun ahead and left its shaft behind, thus causing the cross firing ignition and the engine stall.
That guilty bolt was far away from balancer we had replaced. Was it possible that our use of an impact wrench to remove and reinstall the crankshaft balancer bolt had transferred enough disturbance through the belt to compromise the torque on the camshaft gear bolt? Maybe, but who knows. Is this 2.5L a free-spinning engine? Fortunately, yes.
Second Repair
There are some crummy pictures in the shop manual literature we have concerning the location of the timing marks, but there was no information we had about how the camshaft gear is to be indexed to the camshaft. There is, I discovered, a "knock pin" in the end of the camshaft that is supposed to locate the gear, but it was long gone. So we opted to find the sweet spot and let the torque of the bolt hold the gear the way it does on a 4.0L SOHC Explorer. But how did we find the sweet spot?
I used an old Jeep 4.0L rotor alignment trick to decide where the camshaft should be in relation to the cam gear. With the crank and cam timing marks in place and the distributor installed, I used the Sharpie mark we originally made on the distributor housing to reference the No. 1 firing post in the cap and we set the camshaft so that the distributor rotor was just passing the No. 1 firing post. That way, as timing advances and retards, each firing post will find itself in the center of the window where the spark takes place. If the rotor is set to point directly at the No. 1 post, the spark will jump to the wrong post in extreme timing advance situations such as highway cruise, and a surge can result.
That trick worked well. We torqued the camshaft bolt to 100 foot-pounds, slid the valve cover back on it and the engine ran smooth and quiet. It was one of those "whew" moments when I heard it fire up and purr. We set the ignition timing, tightened the distributor, installed the covers, belts, splash shield and the tire, installed the new air inlet hose and put one more circumstantial land mine behind us.
It was a tremendously beneficial lesson for the students. Not everything that goes wrong is necessarily the technician's fault, regardless of how logic may seem to counter that.
Richard McCuistian is an ASE-certified Master Auto Technician and was a professional mechanic for more than 25 years. He is now an auto mechanics instructor at LBW Community College/MacArthur Campus in Opp, Ala. E-mail him at [email protected].