Mechanics

TIMING ISSUES

1998 Pontiac Sunfire

Engine Performance problem
1998 Pontiac Sunfire 4 cyl Two Wheel Drive Automatic 129000 miles

Hi I hope you can help me. I have a 98 Sunfire SE with 2.4L dual overhead cam engine. I have had it for a year and it has run well with no problems. First, the check engine light came on. We did spark plugs, checked EGR, checked fuel getting to rails and injectors. All were fine. Then the battery started to drag. Replaced that and as we were test driving it, it died on the road. When started up again, the engine cavitated tremendously. Had it checked by a mechanic who said it jumped time. I bought new timing chain, gears and gaskets. Now he says he can't get it timed right. He is lining up both top cams with bolts as well as the bottom one. He thinks its a sensor now. Are there timing marks on the timing chain itself? What are we missing? We put the diagonostic machine on it and its coming up with a code of PO 300. Also, the ETS light will not shut off with the button any longer. All of these things were working before the original check engine light came on.
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Mkdever
September 30, 2010.



I don't know what he can be talking about. The engine can definitely be timed. One thing that usually wears out on these though are all the plastic chain guides. This is also an interference engine so valve damage can occur very easily if run out of time.

INSTALLATION PROCEDURE

NOTE: GM does not provide timing marks, or information to perform timing chain service without the special tools shown in this procedure.

NOTICE: Failure to follow this procedure could result in severe engine damage.

1. Install the intake camshaft sprocket onto the camshaft with the marked surface showing.

NOTICE: Refer to Fastener Notice in Service Precautions.

2. Install the intake camshaft sprocket retaining bolt and washer.

O Tighten the bolt to 70 Nm ( 52 ft. Lbs. ) While holding the sprocket with the J39579.

3. Use Adhesive/Sealant Compound GM P/N 12345493 or equivalent on the camshaft sprocket bolt.
4. Install the J36800 through the holes in the camshaft sprockets into the holes in the timing chain housing in order to position the camshaft for correct timing.
5. If the camshafts are out of position and must be rotated more than 1/8 turn in order to install the alignment dowel pins, use the following procedure: 5.1. The crankshaft must be rotated 90 degrees clockwise off of the TDC in order to give the valves adequate clearance to open.
5.2. Once the camshafts are in position and the dowels installed, rotate the crankshaft counter clockwise back to the top dead center.

NOTICE: Do not rotate the crankshaft clockwise to TDC. Valve or piston damage could occur.

IMPORTANT: The side of the timing chain that was marked during removal must be showing when the chain is installed.

6. Install the timing chain over the exhaust camshaft sprocket, around the idler sprocket and around the crankshaft sprocket.

7. Set the camshaft sprockets at the timed position and use the following procedure in order to install the timing chain: 7.1. Remove the alignment dowel pin from the intake camshaft.
7.2. Use the J39579 in order to rotate the intake camshaft sprocket counter clockwise enough to slide the timing chain over the intake camshaft sprocket.
7.3. Release the J39579. The length of the chain between the two camshaft sprockets will tighten.
7.4. If properly timed the intake camshaft alignment dowel pin should slide in easily. If the dowel pin does not fully index, the camshafts are not timed correctly and the procedure must be repeated.

8. Leave the alignment dowel pins installed.
9. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
10. With the slack removed from the chain between the intake camshaft sprocket and the crankshaft sprocket, the timing marks on the crankshaft and the cylinder block should be aligned. If the marks are not aligned, move the chain one tooth forward or rearward, remove the slack and the reverify the marks.
11. In order to reload the timing chain tensioner assembly to its zero position, form a keeper from a piece of heavy gauge wire.
12. Apply a slight force on the tensioner blade in order to compress the plunger.

13. Insert a small screwdriver into the reset access hole, and pry the ratchet pawl away from the ratchet teeth while forcing the plunger completely in the hole.

14. Install the keeper between the access hole and the blade.
15. Install the tensioner assembly to the chain housing. Reverify the plunger assembly installation, it is correctly installed when the long end is toward the crankshaft.
16. Install the timing chain tensioner bolts.

O Tighten the bolts to 10 Nm ( 89 inch lbs. ).

17. Lower the vehicle enough to reach and remove the alignment dowel pins.
18. Rotate the crankshaft clockwise (normal rotation) two full rotations.
19. Align the crankshaft keyway with the mark on the cylinder block and reinstall alignment dowel pins.
20. Alignment dowel pins will slide in easily if the engine is timed correctly.
21. Install the timing chain guides.
22. Install the engine front cover. Refer to Engine Front Cover Replacement
23. Connect the negative battery cable.

O Tighten the bolt to 16 Nm ( 12 ft. Lbs. ).

Wrenchtech
Sep 30, 2010.