Help with timing belt on 94 lumina

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Old 11-10-09, 07:52 PM
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Help with timing belt on 94 lumina

I have a 1994 lumina with a 3400 DOHC. The timing belt is junk so I took it apart and put a new one on. It runs but idles really low and starts hard, I think one of the cams is one tooth off. Does anyone have any pointers? I guess Ill have to try again tomorrow, its way to easy to get off a little.
 
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Old 11-10-09, 08:26 PM
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let me do some research and see if this is the same as the one I did. If so, it is really a pain in the rump.


I'll be back.

I'm back.

Yep, looks like the same one. How did you set your timing alignment? There is a special tool from GM you are supposed to use to hold the cams in a specific position. The bolts on the end of the cams tighten up a cone that hold the sprocket against the cam.

here are the directions from Autozone.


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Old 11-10-09, 09:01 PM
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Originally Posted by nap View Post
let me do some research and see if this is the same as the one I did. If so, it is really a pain in the rump.


I'll be back.

I'm back.

Yep, looks like the same one. How did you set your timing alignment? There is a special tool from GM you are supposed to use to hold the cams in a specific position. The bolts on the end of the cams tighten up a cone that hold the sprocket against the cam.

here are the directions from Autozone.


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I rolled the cams until the flat spots were up. A mechanic friend has done these so instead of the GM gizmo to hold the cams I used a piece of aluminum like he did. It seemed to work fine but the side close to the firewall the cams didnt want to fit on the belt with the flat spots even.
 
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Old 11-11-09, 06:39 AM
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then you needed to release the bolt that holds the cam tight to the sprocket and get the cone to loosen up so you can adjust the cam to be in time with the rest of the stuff.




also, is your tensioner working? They are a pain in the rump as well. Special tool is required to install the tensioner (paper clip).

If the tensioner is not working, it can allow enough slack, sometimes, to allow the belt to jump a tooth.
 
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Old 11-11-09, 06:48 AM
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I know how much fun the tensioner is, what a pain. Im going to go out and start working on it again. I may have to pull the sprocket off the cam like you said. I hope I get it running today.
 
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Old 11-11-09, 08:37 AM
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You do not have to pull off the sprocket totally. It uses a cone shaped piece that the bolt tightens into a cone shaped hole in the cam end. That simply (ya, right) needs to be caused to loosen so the cam and the sprocket are disengaged from each other.

the sprocket will move freely once you have gotten that cone loose.
 
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Old 11-11-09, 10:44 AM
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Well I got all the cams lined up and the timing marks on the crank where it should be and now it wont start at all, acts like the valves are way off. What piston is #1? that way I can set it TDC.
 
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Old 11-11-09, 04:18 PM
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I won't swear to it but I believe this is correct:



I got it from: 1994 Chevrolet Firing Orders

that doesn't sound right for the actual firing order but I believe the cylinder designation is correct. Firing order could be too but it just doesn't sound right to me for some reason.
 
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Old 11-11-09, 04:48 PM
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I found TDC on #1 and the marks lined up on the crank but its still not right. It turns over hard then fires up and reves up and shuts off.
 
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Old 11-11-09, 06:49 PM
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the cranks hard sounds like it is not in time. The rest might be the same but due to the vacuum lines that run right across the timing belt cover, I would also check for a vacuum line that came off while you were doing all of this.


also, crank the engine to line up the marks again just to check the timing of the cams. Maybe something moved, maybe something came loose.

you also realize that the cams on the one head should not have the flats up when the flats are up on the other head, yes? the cams on the 2 heads will be 180 off from the other head.
 
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Old 11-11-09, 07:18 PM
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Originally Posted by nap View Post
you also realize that the cams on the one head should not have the flats up when the flats are up on the other head, yes? the cams on the 2 heads will be 180 off from the other head.

No I didnt know this, I have all 4 cams with the flats up then put the belt on.

So how do you get the cams the way they should be?
 
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Old 11-11-09, 07:28 PM
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you set the crank and do the two cams on the right. Then you turn the crank 360 and set the cams on the left head.


To install:
Install new belt or old belt taking note of direction of rotation.

Install the tensioner pulley to the mounting base. Tighten the bolt to 37 ft. lbs. (50 Nm).

Rotate the tensioner pulley counterclockwise into the belt using the cast square lug on body and engage ball end of the actuator into socket on pulley arm.

Remove the tensioner lockpin, allowing tensioner shaft to extend and the pulley to move into the belt.

Rotate the tensioner pully counterclockwise applying 12-15 ft. lbs. (16-20 Nm) of torque.

Rotate the engine clockwise 3 times to seat belt. Align the crankshaft reference marks during final rotation to TDC. Do NOT allow crankshaft to spring back or reverse direction of rotation.

Seat the lockring on the right exhaust and right intake camshaft into the bore by threading in the attaching bolts.

Hold the sprocket from turning, using tool J38614 or equivalent. Tighten the attaching bolt to 81 ft. lbs. (110 Nm), taking note of running torque; torque required to turn bolt before seating. Running torque of bolt should be 44-66 ft. lbs. (60-89 Nm). If less torque is required, replace the shim and lockrings and inspect the nose of the camshaft for brinelling. If more torque is required than replace the shim and lockrings and check the attaching bolt threads for burrs or foreign material.

Rotate engine clockwise 1 revolution and realign the balancer marks at TDC. Make sure timing mark on damper lines up with front cover timing mark.

Repeat steps, starting with left intake then left exhaust camshaft.

Install secondary timing belt covers and retaining bolts.

Connect negative battery cable.
 
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Old 11-11-09, 11:39 PM
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Originally Posted by nap View Post
you set the crank and do the two cams on the right. Then you turn the crank 360 and set the cams on the left head.
Whats the right side of the engine? the firewall side or the radiator side?

What city do you live in Nap? I see your in MI.
 
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Old 11-12-09, 07:18 AM
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Originally Posted by michaeljp86 View Post
Whats the right side of the engine? the firewall side or the radiator side?

What city do you live in Nap? I see your in MI.
as you fact the engine (from the passenger side of the car like you were working on the timing belt or such). That makes the right bank the one closest to the front of the car and the left bank the one closes to the windshield. It really shouldn't make any difference but that is my understanding of which is which.


as to the city; didn't we go through this before? I am in Niles and if we went through this before, you are in Sodus or Baroda or somewhere around there.
 
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Old 11-12-09, 07:23 AM
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Originally Posted by nap View Post
as you fact the engine (from the passenger side of the car like you were working on the timing belt or such). That makes the right bank the one closest to the front of the car and the left bank the one closes to the windshield. It really shouldn't make any difference but that is my understanding of which is which.


as to the city; didn't we go through this before? I am in Niles and if we went through this before, you are in Sodus or Baroda or somewhere around there.
I figured that was the right side but figured Id ask since I dont want to make any mistakes this time.


I remember someone on here was close to me but forgot the name, Im in baroda.

Ill get set it up this way and see what happens.
 
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Old 11-12-09, 10:53 AM
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Well the engine starts up fine but revs up to like 3500 then drops way down and almost dies. Then it revs back up again and then dies. I pulled off the battery cable to clear the computer. Ill try it again later and see what happens.
 
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Old 11-12-09, 12:32 PM
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that sounds like a vacuum leak. There is that vacuum line that runs across the top of the timing belt cover and around the back of the engine. If you pulled it loose, that may be your problem/
 
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Old 11-12-09, 02:09 PM
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It seems to be fine now, may have been a code on the computer or something, or maybe gas in the cylinder from trying to start it before. I took it for a drive and so far so good.

Now the turn signals dont work and no brake lights except the one in the back window.

Thanks for the help nap, I really appreciate it.
 
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Old 11-12-09, 02:30 PM
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Originally Posted by michaeljp86 View Post

Thanks for the help nap, I really appreciate it.
that's why we are on this forum.
 
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