Help Finding TDC for #1 Cylinder - Toyota Nation Forum : Toyota Car and Truck Forums

MiPerroMoby · 02-04-2012, 10:03 PM

Hello,

I am trying to change the timing belt in my wife's corolla. This is by far the largest undertaking I have ever embarked on as an amateur. I am following the DIY as well as my Haynes manual, but I have hit a snag. When the crank pully notch is matched up with the "0" degrees mark, the cylinder I believe to be #1 (drivers side see picture) all valves appear to be closed, but the holes on the camshaft sprocket spoke doesn't align with the notch in the top of the camshaft bearing cap. I don't have any idea what to do. Any help is greatly appreciated:

Hiro Protagonist · 02-05-2012, 01:48 AM

Cylinder #1 is actually the one at the other end, closest to the cam gear/timing belt.....

corolla96 · 02-05-2012, 10:27 AM

cylinder #1 is the one on the timing belt end

firewall

1 2 3 4

radiator

when cylinder #1 is at TDC cylinder #4 is at TDC as well

#1 and #4 cam lobes are pointing up. (all valves closed)

Tech1984 · 02-05-2012, 11:03 AM

Look for dots on the camshaft scissors gears. The dots will come together when the hole in the cam sprocket is at 12:00. Through the hole in the cam sprocket you will see a mark on the camshaft bearing cap.

MiPerroMoby · 02-05-2012, 02:26 PM

Thanks for letting me know about the cylinder location, the haynes manual was hard to read, they said that when referring to left and right it was as if you were in the drivers seat, however the diagram of cylinder location was a picture as if you were standing in front of the car.

However, still having problems. I believe that I have found TDC on #1, and the cam lobes are off the valves, it is a tight point in the crank rotation, and the sprocket spoke hole is aligned properly with the notch in the wheel bearing, BUT the notch in the crank pully is WAY off of 0 Degrees. It is ~75 degrees to the left. Is it possible that the last person to remove and replace the pulley just put it in wrong? Does it have some sort of spline or key on the crank to keep the pulley in line? could the pully have slipped?

Tech1984 · 02-06-2012, 10:17 AM

This is interesting. It's impossible to install the pulley wrong unless the crank key was missing, but it is possible for a pulley to slip around the rubber ring. In that case, it would need replacing.
Let's yank that pulley off, see if the key way is straight up 12:00 position.

MiPerroMoby · 02-06-2012, 10:49 AM

I was wondering if the pulley could have slipped. After speaking to a friend of mine who was a mechanic he said that since I was pretty sure the #1 piston was at TDC that I should just make sure to mark the crank pulley at 0 Degrees, and proceed, making sure that it lines up exactly where I marked it when I put it back together.

When I took the pulley off, the crank key was at nearly 12:00, more like 11:30, but my timing marks on the sprocket and bearing were also a hair to the left. every time I tried to get it exactly to the top, the tension released and the crank and pulley overspun the markings.

Moving forward, when I put the new belt on, I think I accidentally rolled the crank shaft back a few degrees, so I called it quits for the night and plan to tackle it after work today. My plan was to remove the timing belt again, and re-install, making sure that my markings lined up with the old pulley, and then get a new pulley that will *hopefully* be lined up to the 0 degrees mark.

Before I finally try to crank this thing is there any other way to check for TDC? I borrowed a broken pressure tester from Autozone, and the hose got stuck in my spark plug hole for about 30 minutes. Haynes says to use the positioning of the distributor (check), cam sprocket and bearing markings (check), Is a functional pressure tester the only way to check now?

Thanks again for all the help.

Tech1984 · 02-06-2012, 08:41 PM

I like to put the bolt back in the crank and tighten it some. Then counter turn the crank 1/2 tooth with slack on the RH side of the belt. Then turn the crank with a wrench clockwise and walk the belt on. Now the slack is on the LH side you can slip the belt over the tensioner. As long as you have the tensioner spring fully stretched out and locked down.
Keep a spring clamp holding the top of the belt to the cam sprocket so it won't keep falling off. Just don't forget it's there when you finish and turn it over.

trife96 · 02-06-2012, 10:24 PM

Don't pay near as much attention to the cam lobes or the key way. The key way should be upright. That's basically it. As long as the pulley notch lines up with zero, and the mark on the cam gear is correct, you should be ok. And last, you can also remove the spark plug from the #1 cylinder, get a long extension or join a couple together and stick it down in the hole. Turn the crank and watch it go up and down. When the mark on the crank pully is zero and the extension is as high up as it can go, you will be at TDC. At that point the cam gear mark should also line up. You can check it over and over. Every two rotations of the pulley, it should line back up again.

speedy25 · 02-07-2012, 01:07 PM

TDC is easily chacked with a long screwdriver in the spark plug hole. BE CAREFUL as the piston comes uo that you dont get it caught in the plug threads. When its near the top its easy to feel when its exactly at TDC.

I always use this method because so many times the marks can be off. When its on TDC, THEN you can confirm what the marks say so you know whether to trust them. This is even more important later when you reset the timing. Yes, it needs reset if anyone changed it over the life of the belt.

-SP