My mechanic replaced my distributor cap and rotor yesterday on my '86 Toyota Corolla. The Haynes manual for this car says you’re supposed to get the #1 piston in the TDC position before you do so. My mechanic didn’t do so and said he didn’t need to when I asked. Was he right? My car is running fine now but am I at risk of frying my ignition coil?
I’ve never heard of that for cap and rotor. To replace the distributor itself, yes, but not just the cap and rotor.
The distributor cap and rotor can only fit one way onto the distributor. If the distributor remained in the engine, there is no problem. If you remove the distributor from the engine and do not mark its position, then you crank the engine until #1 piston is at Top Dead Center, then install the the distributor. If you mark the position of the distributor (draw a line on the distributor and on the engine) and reinstall the distributor with these marks, you are good do go if you haven’t cranked the engine.
I used to watch the mechanic install new ignition points in my dad’s 1954 Buick back in the late 1950s. He would mark the distributor and engine, pull the distributor, install new breaker points and condenser, put the distributor on a Sun machine and set the dwell, then reinstall the distributor on the car. He would then hook up the timing light and set the timing.
You aren’t at any risk of frying your ignition coil.
Your mechanic noted which plug wire went to the #1 cylinder. When he installed the new cap, he connected the wire leading to the #1 plug on the same post on the cap and then just followed the firing order.
If you pull the cap without noting the position of the #1 plug, then you need to crank the engine over until the #1 plug is on TDC, note the position of the rotor, and then connect the wire to #1 cylinder to the post pointed to by the rotor.
I’m pretty sure you missread it.
The #1 piston might have to TDC if you’re replacing the distributor…but NOT the distributor cap. That makes no sense what-so-ever.
You don’t have to note the position of the rotor if you are only replacing the distributor cap and rotor. The rotor only goes on one way and nothing gets moved to alter the timing. Even if the distributor itself were pulled from the engine and installed incorrectly, the mechanic would know very quickly. The engine would not run. As stated by others, most mechanics simply mark the distributor and rotor orientation and reinstall the distributor according to the marks they made. This works just fine. Also, the coil could care less about any of this. Worn secondary ignition parts is what usually kills ignition coils, and it sounds like you just replaced those. If the engine is running fine, the job was done correctly.
Agreed with all above.
If the car is running fine, that is all that matters. When you put a new cap and rotor on, the position of the rotor isn’t an issue, it only fits in one position. Likewise the cap only fits in one position too. The trick is making sure you hook up the plug wires to the proper position on the new cap. If you pay attention as you go along getting the plug wires on the proper nipple isn’t hard. Seems your mechanic did fine. No worry.
Sometimes you have to read a Haynes or Chiltons with a grain of salt. They just seem to cut and past from the factory service manual and don’t always get it right. There is a notch in both that won’t allow it to be put on in the wrong position.
+1 with Bing.
It pays to get the factory manual and not bother with the Haynes and Clintons. You can get cheap PDF factory manuals (copies, probably but who asks questions) off ebay for pretty much any car and maybe pay $5 shipped.
…and on installing the rotor backwards: no doubt in my mind that at one point in motor vehicle history some idiot hammered the thing on because he couldn’t figure out how to get it into the shaft.
That’s where to get shop manuals for many vehicles. Be sure to get it from there, because other places sell the same thing for double the price.
info in the wrong hands here we go again as long as the dist. was not removed not a problem .
and on installing the rotor backwards: no doubt in my mind that at one point in motor vehicle history some idiot hammered the thing on because he couldn't figure out how to get it into the shaft.
That’s probably why in some vehicles (like my the Accords)…the rotor had a little bolt for the rotor. With the bolt it then makes it IMPOSSIBLE to put it on wrong. You have to turn the rotor to align it with the hole.
Thank you all very much. The comments were very helpful.