Timing problem

Tiny
KATHY RAPER
  • MEMBER
  • 1992 ISUZU TRUCK
  • 2.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 250,000 MILES
Changed heads, replaced with one from 1997 trooper 2.6. Number one and number four and pistons are closed. Timing marks line up at the bottom center, all marks are in line. Afraid to try to crank for fear of ruining entire motor. How did this happen and can it be right? Everything I have seen says must line up TDC.
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Friday, June 7th, 2019 AT 8:15 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome to 2CarPros.

First, this is an interference engine, so I understand your concern. Do not engage the starter if you question it. Simply turn the crankshaft slowly with a wrench to confirm there is nothing interfering between the pistons and cylinder head.

I'm not sure what you mean by the pistons are closed. Please explain. Also, I looked at both 02 and 07 timing marks in the manual and they are the same. Explain exactly what is happening.

Here are the directions specific to a 1992. Take a look through these directions to see if you missed anything. The attached pictures correlate with the directions.

_____________________________

TIMING BELT REMOVAL AND INSTALLATION
TIMING BELT REMOVAL

pic 1

Disassembly steps

Timing belt removal
1. Remove the tension spring.

Pic 2

2. Loosen bolt "B", and draw the tension pulley fully to the water pump side and temporarily tighten bolt "B".
3. Remove the timing belt.

TIMING BELT INSPECTION

Caution in handling

pic 3

1. Do not bend in less than 20 mm in radius.

Pic 4

2. Avoid twisting or kinking the belt and keep it free from water, oil, dust and other foreign matter.

Visual check

pic 5

1. The belt must be replaced if cracks or lacerations are found in the side and rear faces.

Pic 6

2. Replacement is necessary when abnormal wear is found in the side face.

Pic 7

3. Replacement is necessary when belt fabric is found to be cracked or disintegrated.

Pic 8

4. Replacement is also necessary when cogs are found to have abnormal wear.

Pic 9

5. Take measurements at 3 - 5 points around the circumference of the belt The belt must be replaced even if a single measurement is beyond the limit.

Limit of rubber hardness - 90 (HS)

TIMING PULLEY AND TENSION SPRING INSPECTION

Visual Check
Crankshaft pulley
Camshaft pulley
Oil pump pulley
Idler pulley

If uneven wear, cracks or wear exceeding the limit are found in the pulley, replace it with a new one.

Pic 10

pic 11

Timing Pulley Outside Diameter

pic 12

pic 13

Tension pulley outside diameter
1. Check the roller for excessive wear and damage.
2. Check to see that the roller rotates smoothly.
3. Check to see that there is no play in the pulley shaft/fixing plate sealing area.

Pic 14

pic 15

Tension Spring Tension
If the set length or set force is out of the specified range, replace the tension spring with a new one.

TIMING BELT INSTALLATION

pic 16

Reassembly steps

1. Timing belt
Install the timing belt in the sequence indicated.

Pic 17

1. Align the matchmarks of the crankshaft timing pulley with that of the front oil seal retainer.

Fig. 20 Aligning camshaft timing pulley & front plate
pic 18

2. Align the matchmarks of the camshaft timing pulley with that of the front plate.

Note: At this point the No.4 cylinder comes to its compression, top dead center.

Pic 19

3. Lay the timing belt over the crank pulley, oil pump pulley, cam pulley, and tension pulley in the indicated order, avoiding any loosening between them.

Pic 20

4. Loosen bolt "B" to allow the tension spring to tighten the belt.
5. Temporarily tighten bolt "B".
6. Temporarily attach the crank pulley.

Pic 21

7. Turn the crankshaft two revolutions in the opposite direction of normal rotation to align the crankshaft matchmarks with the crankshaft timing pulley matchmarks.
8. Loosen bolt "B" and tighten the belt with the tension pulley.
9. Tighten bolt "B" to the specified torque.

Torque: 1.9 kg-m (13.7 ft. Lbs)

pic 22

2. Timing belt cover (upper and lower)
Attach the timing belt cover and tighten to the specified torque.

Torque: 0.6 kg-m (4.4 ft. Lbs)

pic 23

3. Crankshaft pulley
Apply Pulley to the crankshaft and tighten crankshaft pulley bolt to the specified torque.

Torque: 12.0 kg-m (86.7 ft. Lbs)

______________________________________

Let me know if this helps or if you have other questions.

Take care,
Joe
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Friday, June 7th, 2019 AT 7:37 PM
Tiny
KATHY RAPER
  • MEMBER
By closed, I mean that the pistons are all the way to the top. Please tell me what you mean by "interference engine".I have never heard that term. The crankshaft pulley mark and oil seal retainer mark are correct. The pin on the camshaft pulley is on the bottom. That is the way it fit. It lined up that way.I am the mechanics wife giving you this information.I have assisted him in a lot of his work and I have never seen him run into anything like this.
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Saturday, June 8th, 2019 AT 7:58 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

An interference engine is this. If the timing belt breaks or is put on incorrectly, there isn't enough room between the tops of the pistons and the valves in the head and they will hit and cause major damage. He indicated that he was concerned to try to start it, so I assumed he was already aware of that.

Here is what it actually says in my manual:

CAUTION: Incorrect removal or installation of the timing belt can result in damage to internal engine components.

For complete Timing Belt Removal and Installation information: See: Timing Belt > Procedures

The removal and install is what I sent you in my first reply.

Now, the timing marks should both be at 12 oclock. I am going to attach three pics for you to look through. Please let me know if this helps. Also, is he using the original cam gear or the one from the newer engine? Although the marks align the same, there could be something different with how they mount. It's just a thought.

Joe
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Saturday, June 8th, 2019 AT 8:37 PM
Tiny
KATHY RAPER
  • MEMBER
https://www.2carpros.com/images/question_images/273031/original.jpg I tried to drag and drop the image but I don'tknow if it worked.Anyway, See the pin right above the nut?It is under the nut on his motor.That puts the timing mark at the bottom.I am sure he used the original camshaft.
Is there any other four cylinder Isuzu engine other than the 2.6?I ask because I saw a diagram where the marks were at the bottom,but not sure which one it was.I am wondering if someone had already changed engines before we got it.We thought it was a 2.6 because that is what is on the paper under the hood.I am grasping at straws here.
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Saturday, June 8th, 2019 AT 11:27 PM
Tiny
KATHY RAPER
  • MEMBER
Oh, forgot to add he cleaned up the original head and put it back on. Everything still lines up the same with the mark at the bottom.
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Saturday, June 8th, 2019 AT 11:35 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi Kathy:

Is there a reason he can't turn the cam so the marks are in the 12 oclock position? When you say everything lines up, he should be able to determine how it lines up. Maybe I'm missing something you are saying, but I'm a bit confused. When he first puts the belt on, are the cam and crank timing marks at 12 oclock? You have to keep in mind, the crank and cam gears are different sizes, so it may not be the same once you rotate the crank one turn. You may have to turn it two or more times for it to align again.

Let me know.

Joe
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Sunday, June 9th, 2019 AT 6:20 PM

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