Week 4 of the basic auto mechanics class at East Brunswick Vo-Tech took place completely in the shop. It was a crappy night out, rainy and windy, so for some reason only 5 people showed up. Doesn’t matter much to me since we got more personalized attention and I was able to inquire about more advanced items that were probably not supposed to be covered in the class.
Like I said, we went straight out into the shop so I have no notes. I will try and cover what we went over in the class, but I’m sure that this post will be shorter than the rest. We started by wheeling our motors over from their storage place and getting our carts with the top ends in them together. Then we flipped the motor over and were told to take the oil pan off.
The teacher then went over what the flat spot in the oil pan was, a windage tray, and the purpose for it. It is there to catch the drippings from the oil in the motor and to keep the sump (the larger part of the pan) filled with oil so that the oil pump is always submerged in oil. We then went over the oil pump, it was described to be a positive displacement pump, meaning that oil needs to come out of the system somewhere and that it will not pump to a dead head. Dead head meaning a blockage in the oil path, oil needs to come out! If there is blockage, something is going to break, oil will come out somewhere!
We then covered how the crank is held in place with end caps. He showed us the bearings and what you are getting in a rebuild kit when you rebuild a motor. It was explained to us that the end caps only go on one way and that they should be marked somehow, this also goes for the connecting rod. The ones we were using were not, but in the real world there should be some indication of proper placement. This is important because when they build the motors at the factory, a boring machine bores a straight line through where the crank will be sitting so that the holes are perfectly straight. If the end caps are put on in the incorrect order, the bore will no longer be perfect and the motor is bound to have issues.
We then took the end caps off of the connecting rods and removed a piston. We examined its bearings and took a close look at the rings that were described to us in last week’s lesson. The motor that I was turning a wrench on did not have rings on the piston, but the other one did and we saw how to use a ring compressor to re-insert the piston, with rings, back into the bore. We each only removed one piston and then we were told to reassemble the entire motor.
It was stressed to us that when rebuilding a motor that the tolerances for dirt and dust are very low and that touching the bearings, crank, pistons, and rings are not advisable and can cause damage to a brand new part. The teacher told us that when he rebuilds motors, the shop has a wet floor to prevent dust from being kicked up and that latex rubber gloves are worn to keep your skin oils from touching the parts. He also noted that he would put plastic caps on the connecting rod ends to keep them from damaging the crank when the piston is pushed back into its bore.
I learned quite a bit in this class and was very pleased with the small number of guys that were there. It made the class more personal and hands on. I was able to ask a lot more questions and get a better understanding of exactly how a motor is assembled, even if the pieces were missing. I have to remember why I took this class; it was to make sure I really had a good understanding of what I was doing. It would have been a big mistake to assume I was more advanced than a beginner when I really wasn’t. I am learning some things in this class, which is to be expected since I am completely self taught, and am enjoying it quite a bit.