Will not start after replacing timing chain

Tiny
RICH4200
  • MEMBER
  • 1984 GMC S15
  • 2.8L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Replace timing chain, now in won't start. Lined everything up like it was. Does it have a computer?
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Sunday, December 20th, 2020 AT 5:23 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
Hi,

First, take a look at these directions. They explain how the chain is replaced. The attached pic indicates the timing mark alignment.

_________________

1984 GMC Truck S15/T15 2WD P/U V6-173 2.8L VIN B 2-bbl
Timing Chain Replace
Vehicle Engine, Cooling and Exhaust Engine Timing Components Timing Chain Service and Repair Procedures Timing Chain Replace
TIMING CHAIN REPLACE
Fig. 7 Valve timing marks

Pic 1

1. Remove front cover as described under ``Front Cover, Replace.''
2. Place No. 1 piston at top dead center with marks on camshaft and crankshaft sprockets aligned, Fig. 7.
3. Remove camshaft sprocket bolts, then remove sprocket and timing chain. If sprocket does not come off easily, tap lower edge of sprocket with a plastic mallet.
4. Install timing chain on camshaft sprocket. Hold sprocket vertically with chain hanging down and align marks on camshaft and crankshaft sprockets.
5. Align dowel pin hole in sprocket with dowel pin on camshaft, then install sprocket on camshaft.
6. Using camshaft sprocket attaching bolts, draw sprocket on camshaft. Torque bolts to 15 to 20 ft. lbs.
7. Lubricate timing chain with engine oil, then install front cover as outlined previously.

_______________________________

Also, it does have a somewhat primitive PCM. Do me a favor. Check to see if there are any diagnostic trouble codes present. You don't need a scan tool. A short jumper wire or even a paper clip is all that's needed. Follow this link:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Let me know what you find and if possible, record the engine cranking so I can hear it.

Take care,
Joe
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Sunday, December 20th, 2020 AT 10:52 PM
Tiny
RICH4200
  • MEMBER
  • 2 POSTS
I did all that buddy and did it twice to make sure I didn't do nothing wrong and still nothing. It sounds like it's just free spinning.
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Monday, December 21st, 2020 AT 12:47 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
Then you have no compression. If it is free spinning, something is off. Were there any issues with the cylinder head prior to the timing chain? Can you record it cranking so I can hear it?

Check compression and let me know what you find. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-test-engine-compression

Here are the directions specific to this vehicle:

__________________

1984 GMC Truck S15/T15 2WD P/U V6-173 2.8L VIN B 2-bbl
Compression Test
Vehicle Powertrain Management Tune-up and Engine Performance Checks Compression Check Testing and Inspection Component Tests and General Diagnostics Compression Test
COMPRESSION TEST
COMPRESSION CHECK
- Disconnect the primary terminal from the ignition coil.
- Remove all spark plugs.
- Block the throttle plate wide open.
- Make sure the battery is fully charged.
- Starting with the compression gauge at zero, crank the engine through four compression strokes (four "puffs").
- Make the compression check at each cylinder and record each reading.
- If some cylinders have low compression, inject 15 ml (one table spoon, or 3 squirts from a pump type oil can) of engine oil into the combustion chamber through the spark plug hole.
- Minimum compression recorded in any one cylinder should not be less than 70 percent of the highest cylinder, and no cylinder should read less than 690 kPa (100 psi).

Normal Compression: Compression builds up quickly and evenly to specified compression on each cylinder.

Piston Rings Leaking: Compression low on first stroke, tends to build up on following strokes, but does not reach normal. Improves considerably with addition of oil.

Valves Leaking: Low on first stroke. Does not tend to build up on following strokes. Does not improve much with addition of oil.

Head Gasket Leakage: If two adjacent cylinder have lower than normal compression, and injecting oil into cylinders does not increase the compression, the cause may be a head gasket leak between the cylinders.

________________________

Let me know what you find. Also, if you could record it cranking and upload it for me, it may help me.

Take care,
Joe
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Monday, December 21st, 2020 AT 7:28 PM

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