You know, when I got the car home the first time, I noticed that the bolts securing the cover where possibly overtightened, in that one of them was tightened so much that the threaded shaft was protruding through the cap whereas before it was not. The oil, I believe, came through the back part of the cover because there was oil all over the intake manifold and the rear part of the engine compartment, but not to the sides or front. It was a mess regardless, and quite a frustrating ordeal to have to go through.
I’ve re-used the old gasket on my Corolla on occasion, provided it isn’t distorted or otherwise ruined. I wouldn’t say re-installing the valve cover gasket is a fundamental error
That’s a fundamental error and a common reason for valve cover gasket leaks on diy’er serviced cars. Normally an experienced mechanic wouldn’t make that mistake. In any event your did a good job of proactively monitoring for new oil leaks after you got the car back. Otherwise, could have been a much worse result.
If I had this same problem, at this point I’d be taking the car to the local dealership shop to get everything leak free & working correctly again.
I almost didn’t get the car back home. If I had gone another even 1/4 mile further the engine could have locked up. I think God was watching out for me! Thankfully I had some motor oil in the garage and I put it in so I could put the car on the street for the tow truck to more easily get to. As for continued work, I’m going to stop in at a shop next week and talk with the owner to see what they can do. I talked to his mechanic but he said talking to the boss would be a good idea before proceeding with any repairs/diagnostics. I did try a local Toyota dealership a few weeks back, but they wouldn’t do more than plug the car up to their computers and go with what it spit out. I need someone who will take the time to do some old fashioned repair work.
So the saga continues… 
I think that’s one aspect of vehicle maintenance that repair shops don’t like about me. I’m very proactive in many aspects of my life, including car maintenance. I dig for facts, ask many people for their help and opinions (like I’m doing here now). I try not to leave anything to chance. They don’t like it when I try to quiz them a bit and try to pull information out of them that they don’t like to divulge. I guess it goes to “job security” but I think of it more as me trying to stay informed about how my car works and why. I’m that way with computers too. That’s why I still like to use Windows 7 or Linux, and not Windows 10/11. I want to control my life, not have someone or something else control it.
Way back to #50, why don’t you just have the crank sensor replaced? Then the can check the balancer at th3 same time.
That’s what I plan on suggesting they do, but I also don’t want to go there and be perceived as being a “know it all” or “cocky.” Hopefully this mechanic will let me lay out what’s happened the past two months and go with that suggestion.
Looks like I’ll have to wait another 17 days before the car gets into the shop again. I visited a local mechanic and when I described what happened after the oil seal was replaced, he immediately said it was timing. I also mentioned the crankshaft sensor but when I take it back I’ll foot stomp my desire to have that replaced no matter what else he finds.
After almost 100 comments, I’ve kinda lost track of the problem. Oil leak, hesitation on heavy acceleration or what.
At any rate they already checked the timing that you paid dearly for. Reminded me of a problem with my 86 park avenue. I had a 50k warranty on it so no charge but I had a front seal oil leak and some stumbling. They ended up replacing the seal and the balancer. Which caused which I don’t know but they said the balancer was wobbly causing the seal damage. So I’m still focused on the balancer, and crank sensor. I think I’ve had three or four balancers go bad with little or no symptoms.
I think when they go bad on an 86 what happens is that the tune-up shop is not able to set the ignition timing correctly using their timing light by pointing it at the balancer pulley b/c the outside diameter of the balancer pulley has shifted w/respect to the crankshaft. For example the timing light shows the idle timing is at 8 deg before, but it is really at 10 deg after . They might not realized this, b/c they’d have to measure the piston motion to know the harmonic balancer timing mark was incorrect. If a faulty harmonic balancer hadn’t yet shifted very much, probably wouldn’t expect symptoms.
Suggest to ask shop techs that mention “timing”, whether they are referring to the “ignition timing” or the “valve timing”. That info may assist the folks here in offering up ideas.
Why would anyone try to change the ignition timing for a computer-controlled ignition?
It depends on the configuration, varies car to car. My early 90’s Corolla also has a computer controlled ignition. The timing is set at tune-up time using a timing light. If 86 Park Ave isn’t not so-configured, the timing isn’t set using that method.
Sorry I brought it up but just saying a bad balancer can cause problems too and may have been over looked when replacing the oil seal or could have caused the oil seal problem in the
First place. Just as a consumer and not a mechanic.
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If problem continues w/out any viable explanation, a problematic crank-shaft pulley should indeed be considered . But it doesn’t seem very likely on a 97 Corolla.
I have seen the bushing loosen in harmonic balancers, they squeal and the pulley can shift out of position and throw the belts.
The tone wheel for the crankshaft position sensor is part of the timing belt sprocket, unlikely to fail.
There’s likely a published spec for the crank position sensor resistance, probably varies w/temperature. Easy enough for a tech to check. There may be a spec’d allowable distance range between the sensor and the timing belt sprocket as well. Might not be easy to check though. Not sure how the idle ignition timing is checked. Might require a scan tool.
OP: The crank position sensor is usually just a coil of wire that is positioned very close to a magnet located on something that rotates along with the crankshaft. As the magnet rotates past the sensor, a voltage pulse is induced in the sensor’s coil, which is used to tell the drivetrain computer the orientation of the crankshaft. The most common sensor failure mode for that sort of sensor is the wire that forms the coil breaks from vibration or heat/cooling cycles. When that occurs the symptom is usually that the engine stops running, and afterword won’t start at all. That’s obviously not the failure mode you are experiencing. It is possible for this sort of sensor to fail intermittently though, so that’s always a possibility. And if the coil of wire is too far away from the magnet, or the magnet gets demagnetized, those are other possibilities for an intermittent crank sensor failure. As you can probably tell the crank sensor failure possibility for your car’s symptoms comes close to grasping at straws. But sometimes grasping at straws works.
Not sure if it is possible to place the timing belt sproket on w/ a reverse orientation. If it is, that’s another possibility.
The initial problem was an oil leak. After that was repaired, the car will hesitate, stutter when I try to accelerate at a normal rate. The only way to get the car to speed is a very, slow, gradual acceleration and to back off the gas (just a bit) when the car goes to shift between the gears. That takes a special touch because I have to anticipate when the transmission is going to shift. The Toyota dealer says the car is not throwing any error codes, as did the mechanic who caused the problem and the latest one who failed to install a good valve cover gasket. That mechanic also said the catalytic converter is ok.
But this all started when the oil seal was replaced and was not a problem before.
When I take the car back in I’ll ask him.
Those two parts shown in post 95 above had to be removed in order for the tech to replace the leaking seal. The bottom part is the sprocket the timing belt goes around, and is important for proper valve timing. It also contains the magnet, important for ignition timing.
I truly believe something was probably damaged or not reinstalled correctly when the oil seal was replaced. Whether it be the crankshaft position sensor, the sprocket, I dunno, but I hope this next mechanic can figure it out. If, to make the repair correctly, all of those items listed in #95 and the sensor need to be replaced then so be it, I just want the repair done right so I no longer have these problems.