Changing Timing belt on my '86 tercel, need help.

[per]

So my trusty old tercel blew its timing belt a while back. I towed it home and me and although I might scrap it soon I decided to try my hand on the dreaded timing belt replacement just for the fun of it and for learning. If it runs, I can at least sell it when I want to.

Me and my dad got a belt and some instructions on paper from our mechanic. So we loosened the crankshaft pulley nut with some extreme force, and got the pulley off, and aligned the marks on the camshaft and crankshaft. It seemed a bit too easy, and browsing further in the instructions, it says "turn the crankshaft 2 revolutions until piston no. 1 is in TDC".

How do I know if it is in TDC? I found out that it means the position where the piston is at its very highest, plus the manual I downloaded from this site shows a picture of a mark that can be aligned with numbers when the shaft is turned, but where are these numbers? Do I have to remove the engine head to be able to adjust these correctly?

I read about one guy who did this on his audi, he just put a stick in the spark plug hole and checked to see where it was at its highest, and then looked in the dis to see if it was pointed to cylinder no. 1. But that seems a bit too easy...


Thankful for any assistance

Edit: the engine is a 3AC non-interference engine.

[splatterdog]

There's a notch/hole on the sprockets that match up to the oil pump and cyl head(pages em-11 and 12). And yes you will have to pull the dist cap to get the cam right since it blew. Just make sure the rotor is pointed at #1 and you are fine. No need to go inside the engine or pull a plug.

If you think there's a chance you are keeping it, do the water pump and cam/crank seals.

[Neu]

YOu can take the plug out of cylinder one and just look down into it..that would work.

[keith]

Every time the crankshaft makes two revolutions, the cam makes one. If the mark on the crankshaft timing gear is pointed to the mark on the block and the marks on the camshaft are aligned so that the two opposing marks are level with the cover rail gasket surface and the hole is up so thaat you can see the mark on the head through it, then the engine is at TDC on #1.

If you are just starting, then you can use the timing marks. There is a scale on the lower timing belt cover next to the inner belt pulley. There is a notch in the pulley, find it and paint it white. You can find it best by looking up at the pulley while someone turns the engine, then mark it and turn the engine until the mark is opposite the 0 on the scale on the timing belt cover. Then pull the valve cover, you'll have to anyway, and check if both rockers on the #1 cylinder have some slack (lash), then you are on #1. Otherwise turn the crank one full turn and check again.

[per]

I feel like trying to take a shortcut here... I couple people said one should be fine just looking through the spark plug hole or checking it with a screwdriver, or see when it blows a piece of paper out if I stick one in the hole.

[ChrisC]

To find #1 TDC just use a long phillips screw driver. Turn to motor over slowly by hand while the screw driver is inside the sparkplug hole. Once you feel the piston touch the screwdriver feel for it to come to the top of its stroke. Go a little farther until it starts the next stroke. Then bring it back half way between the two points.
Ive never done any motor work on my tercel, but there should be timing marks on the cam gear to help aid in propper cam timing. Dont feel too bad, timing belt replacement on the 3A is very simple, and has easy acess compared to other vehicles. Good luck with the job man.

[keith]

You better do it my way. Sticking something in the spark plug hole only tells you that the piston is at the top of its stroke, but it doesn't tell you which stroke. The TDC the book is looking for is the TDC of the compression stroke, not the exhaust stroke.

[splatterdog]

At least you have one of the easiest timing jobs in front of you. Here was my last one. A lovely fifteen piece timing set for a 2000 dodge 4.7 Over $600 worth of parts. Ouch! That's more than most of us spent on our whole car.

In case you are wondering about the srewdriver, that was for show and tell. Tensioner piston was maxed and I could get my finger under the old slappy chain.

[ChrisC]

You better do it my way. Sticking something in the spark plug hole only tells you that the piston is at the top of its stroke, but it doesn't tell you which stroke. The TDC the book is looking for is the TDC of the compression stroke, not the exhaust stroke.

Kieth you are correct in being on TDC compression. But in this case it is irrelivant because the timing has to do with the cylinder head. With the timing belt off already the motor is out of time. So once you hace the #1 cylinder at the top of its stroke, then you time the head to TDC compression ensuring it is not on TDC exhaust.

[takza]

At least you have one of the easiest timing jobs in front of you. Here was my last one. A lovely fifteen piece timing set for a 2000 dodge 4.7 Over $600 worth of parts. Ouch! That's more than most of us spent on our whole car.

Dayuuuuuum! That doesn't look good...not good at all.

[keith]

Kieth you are correct in being on TDC compression. But in this case it is irrelivant because the timing has to do with the cylinder head. With the timing belt off already the motor is out of time. So once you hace the #1 cylinder at the top of its stroke, then you time the head to TDC compression ensuring it is not on TDC exhaust.

I believe that they are at the point where they have installed the new belt. It is at this point where the instructions call for turning the crankshaft two full turns to return to TDC compression and then check the belt for looseness. So it is kinda critical to be on the compression stroke. If the mark on the crank pulley is lined up with the mark in the block, he does not need to stick anything into the sparkplug hole. If the cam marks are right, then he is on the compression stroke and can check to make sure the distributor is lined up to the number 1 cylinder.

[ChrisC]

I believe that they are at the point where they have installed the new belt. It is at this point where the instructions call for turning the crankshaft two full turns to return to TDC compression and then check the belt for looseness. So it is kinda critical to be on the compression stroke. If the mark on the crank pulley is lined up with the mark in the block, he does not need to stick anything into the sparkplug hole. If the cam marks are right, then he is on the compression stroke and can check to make sure the distributor is lined up to the number 1 cylinder.

Sorry kieth I think you misunderstood the idea I was trying to get across, no need to get defensive We both are thinking about to different things here. I thought per was just trying to find TDC of #1 cylinder, not checking to see if his motor was in time.

It is fine to use a screwdriver to see if #1 is at TDC. Make sure the timing marks on the head are lined up correctly. Then put on the timing belt.

Just different ways of doing it. If I was to do a belt replacement I would use the timing marks on the block, just to follow the service manual.

[keith]

I just hate to see people sticking hard, sharp objects into the cylinder when its not necessary.

[per]

So my 'cel is now rolling again!

As always when something happens with the car I did my reading around and got useful tips from the forums, and felt quite confused... In the end I thought I was probably (as usual) making things more difficult than necessary. The instructions called for removing the radiator and clutch and air intake....? I left all that in place and simply tore off the belt covers, generator belt and crankshaft pulley, lined it all up according to the marks on the block, and put the new belt on. I started the engine and it ran! Very badly though. As I checked things out I realised I had forgotten to replace the no. 2 spark plug wire, and even the no. 1 spark plug... It ran though on only 2 cylinders so I put it all back together and it now works like a charm. As for exact tensions and bolt momentums, I just went by feel and tightened things up. Seems to work just fine.

I have understood that the 3AC is as easy a timing belt job as one can find, but I don't have to tell my friends that, haha....

I just changed my timing belt on my own. Yay!

EDIT: Oh, and thanks for all the help, guys. These forums are gold.

[takza]

As far as belt tension...I have an old scale I use with some coat hanger wire to tension it to specs. I know real mechanics just snug 'em up real tight...but sometimes that causes failures...usually of the tensioner.

I've got my plug wires labeled...1...2...3...4...seems I can never get them back on right.