94 Camry - Timing Issues with Camshaft - Toyota Nation Forum : Toyota Car and Truck Forums

JJJTadpole · 03-30-2011, 07:28 AM

I've searched and searched and haven't had any luck finding a post with someone askign for a solution to the problem that I've got.

My transmission recently went out at 292K miles. While I had the engine out i decided to replace the timing belt along with the front shaft seals since its never been done before. Afterward, the engine ran smooth, started to "cam" at idle, and then got horribly rough all within 25 miles of driving it.

So I've removed the timing cover and noticed the camshaft has indexed itself back by about 45 degrees from its TDC position. I rotated the crankshaft to TDC, loosened the idler pulley, removed top portion of the timing belt from the cam sprocket, rotated the camshaft to its TDC position, and reinstalled the timing belt. After manually rotating the crankshaft 720 degrees, I noticed that the camshaft postion was not where it should be. I continued to rotate the crankshaft and the camshaft kept moving farther away (counterclockwise) from where it should be when the crankshaft returns back to TDC (0 degrees).

Maybe I mixed up the oil pump and crank sprockets. Does anyone know the tooth count difference between the oil pump sprocket and crankshaft sprocket?

***Mister_Perkins*** · 03-30-2011, 08:21 AM

The oil and water pump sprockets do not need to be in any particular order.

What you need to do is Pull the number 1 spark plug out, and rotate the motor until the piston comes all the way to the top of the stroke (use a long straw or long screw driver). This will be TDC At the compression stroke, check the camshaft alignment. If its off, Remove the belt and reposition it. Sounds like you didnt tension the belt correctly and it skipped some teeth

JJJTadpole · 03-30-2011, 01:17 PM

I was thinkg that maybe i mixed up the crank and oil pump sproket (don see how its possible, but will check).

I did all that to ensure I was at TDC and repositioned everything to TDC, but after a few rotations the cam position keeps falling behind. I have the timing cover and the engine on an engine stand. I manually rotated the engine via the crankshaft and it is not skipping any teeth.

I'm guessing there has to be something with the rotationional ratio (sounds good) and must have mixed something up because regardless of the belt tension and the belt length, the cam shaft should return to the same position each time the crankshaft makes two revolutions since it is not skipping teeth.

***Mister_Perkins*** · 03-30-2011, 01:22 PM

It seems like your manual tensioner is faulty. The crank and Camshaft are the only two things that you need to line up. The Oilpump gear and waterpump gear do not need to be TDC. The only other thing in the entire system that I can see affecting the Timing position is a faulty tensioner.

The idler pulley simply is stationary and doesn't move up or down (Tension or release).

If havent changed the idler pulley and tensioner in a while, or ever I would recommend replacing them.

Question. When TDC does the Belt from the Camshaft to the waterpump have tension on it? or is it loose feeling?

JJJTadpole · 03-30-2011, 01:31 PM

I'll work on replacing the pulley and tensioner and see if it helps.

There isn't any slack in the belt between the belt leaving the camshaft sprocket and going to the water pump sprocket. When I installed the timing belt, I started at the front side of the crankshaft sprocket, back of the idler, routed it over the front of the water pump sprocket, and ended up about a half tooth off from it going where it needed to go on the camshaft. So I rotated the crankshaft CCW slightly to get the belt in the right spot and then rotated the crank CW to put the belt in tension and then completed routing the timing belt around the backsideof the camshaft sprocket idler, etc.

Stillrunning · 03-30-2011, 02:49 PM

Quote:

Originally Posted by JJJTadpole

So I've removed the timing cover and noticed the camshaft has indexed itself back by about 45 degrees from its TDC position. I rotated the crankshaft to TDC, loosened the idler pulley, removed top portion of the timing belt from the cam sprocket, rotated the camshaft to its TDC position, and reinstalled the timing belt. After manually rotating the crankshaft 720 degrees, I noticed that the camshaft postion was not where it should be. I continued to rotate the crankshaft and the camshaft kept moving farther away (counterclockwise) from where it should be when the crankshaft returns back to TDC (0 degrees).

Did you forget to install the crankshaft pulley key?

JJJTadpole · 03-31-2011, 07:23 AM

I figured out my problem. Thank y'all for the help.

I had a brain fart and was aligning the camshaft with the round mark on the bearing cap, not the "V" mark. I had always rotated the camshaft with the belt installed and rotating the crankshaft sprocket. but when I rotated the camshaft sprocket by hand (since I missed the round mark), the camshaft aligned itself to TDC when it "snapped" into position with the "V" mark on the bearing cap. Now its dead on rotation after rotation.

***Mister_Perkins*** · 03-31-2011, 10:45 AM

Glad you figured it out!

I figured the belt was either misaligned or the tensioner was junk

and

Edit:

Where from TX Are ya If you dont mind me askin'

Oceans · 04-01-2011, 04:00 PM

Its what it sounded like to me as well and I was going to say MisterPerkins is dead on with his advice, glad to hear its fixed and all is well now.

JJJTadpole · 04-01-2011, 04:18 PM

The problem: When I would get the crank at TDC, the cam would jump to the TDC postion (since I aligned it to the wrong mark on the camshaft bearing cap) and that would introduce slack into the belt even though there wasn't any when it was installed. That slack would then travel down around the water pump and jump a tooth at the crankshaft sprocket, hence the minor indexing and the camshaft falling behind little by little each time I rotated the crankshaft.

***Mister_Perkins*** · 04-01-2011, 04:41 PM

the water pump didnt cause it to "Jump" time. The only thing that could cause it to jump time is a faulty tensioner or mis-aligned belt. You were misaligned to begin with, so the belt was already off 2 or 3 teeth.

If every time you put it at Top dead center on the compression stroke (Pistons 1 and 4 at the top of the stroke) and each time the camshaft was getting more and more unaligned, i would say that you still have a problem. It shouldn't do that. The motor will actually go TDC Twice. once on the oil stroke, once on the compression stroke. When its on the oil stroke, pistons 2 and 3 will be at the top of the block. Once the belt is tensioned though, it will not Skip teeth unless something is wrong with the tensioner or the belt is loose though.