Timing

120

Asked by Apr 06, 2017 at 07:49 PM about the 1998 GMC Sierra 1500 K1500 SL 4WD Extended Cab LB

Question type: Maintenance & Repair

Trying to replace timing chain

31 Answers

87,135

So whats the problem? Line up the gears dot to dot.

2 people found this helpful.
120

I got the timing gears lined up, bottom crankshaft mark (dot) pointing at 12 o'clock and the camshaft gear mark (dot) pointing at 6 o'clock, # 1 cylinder is at TDC but when I check it is not on the compression stroke shouldn't the #1cylinder be on the compression stroke?

1 people found this helpful.
124,085

Yes it should be on the compression stroke

2 people found this helpful.
87,135

What size engine is this?

2 people found this helpful.
120

Ok so I need to take the chain off and rotate the camshaft gear until the intake and exhaust valves on the #1cylinder are closed and the mark (dot) on the gear is pointing at 6 o'clock aligning with the mark (dot) on the crankshaft

1 people found this helpful.
120

5.7

87,135

The engine gets to the compression stroke when the dots come around and line back up. Crankshaft turns 2 revolutions per 1 revolution of the camshaft gear.

2 people found this helpful.
87,135

Yes, 6 o-clock on the cam gear, 12 o-clock on the crankshaft gear.

2 people found this helpful.
120

Ok so what your saying is I do not need to take the chain off and rotate the camshaft just turn the engine over time the marks line up and my #1 cylinder is at TDC of. The compression stroke

1 people found this helpful.
87,135

Correct. Rotate the crankshaft over twice and the timing marks will line back up and it will be on the compression stroke. It is good to do this to verify that the gears are in the correct position, so to see that your not off a tooth or two.

2 people found this helpful.
120

Ok understood but I tried to do just that and when I turned the engine over to bring the #1cylinder to TDC on the compression stroke the marks did not line up the crankshaft mark was pointing 12 o'clock and the camshaft was pointing to 12 o'clock as well. Maybe I need to turn the engine a few more times.

1 people found this helpful.
87,135

For that point 12 to 12 o-clock just one more rotation of the crankshaft. The marks should line back up and you will be on the compression stroke.

2 people found this helpful.
67,825

The number 1 cylinder on a Chevy is driver's side front cylinder. Are you using the correct cylinder?

2 people found this helpful.
87,135

Oh god I hope so,

2 people found this helpful.
120

Yes lol

1 people found this helpful.
87,135

Did the marks line back up? You can't leave me hanging here...lol

2 people found this helpful.
120

Yes they lined up perfectly

1 people found this helpful.
120

But like I said when I checked the #1cylinder it was TDC but not on the compression stroke

1 people found this helpful.
87,135

So where do you feel the compression stroke, when the camshaft gear timing mark is at 6 o-clock or at 12 o-clock position. No matter what the crankshaft gear would be on zero, TDC. It may be the compression stoke for GMC at the 12-o-clock position.

2 people found this helpful.
120

When the camshaft points 12 o'clock along with the crankshaft

1 people found this helpful.
87,135

Then that is it. That is when the rotor would point to the #1 spark plug tower on the distributor cap.

2 people found this helpful.
120

This is what Im trying to find out, I need to install the distributor so all I need to do is to make sure the #1cylinder is on TDC of. The compression stroke

1 people found this helpful.
120

I thank you for you help I'm going to reassembled the timing chain cover and the distributor and give it a go!

1 people found this helpful.
87,135

Your engine timing is right on now and the rotor point to number one distributor contact inside the distributor cap on the compression stroke. Now depending on what distributor cap is on there, say if the towers are in a horizontal position, #1 contact is at like the 8 o-clock position and that is where the rotor would need to point. If the distributor cap has vertical towers then the rotor just points to the #1 distributor cap tower. On the low profile distributor caps, the spark plug towers are in a horizontal position, #1 tower is still at like 5 0-clock but its contact under the cap is at like 8 o-clock.

2 people found this helpful.
120

Very good thank you!!I will get back with the results

1 people found this helpful.
81,395

Hi Rowefast, deja vu all over again!! -Jim

87,135

Well it is now morning, so good morning to you Jim!

1 people found this helpful.
120

Rowefast just wanted to let you know that my truck is purring like a kitten, thanks for you help

1 people found this helpful.
87,135

Far out! Glad it is fixed. Happy trails...

2 people found this helpful.
120

Rowefast have you ever swamped out a rear end with drums for one with disk breaks on a gmc k1500 if so what do you recommend

87,135

I have not done this, but seen it done after they had it all done. At the time I didn't think to ask about any details.

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