Timing Gear

Removal and Installation

Removal - L4 models

I have an '87 Sport Coupe with the 2.5L "Iron Duke". This past July, with 126,000 miles on the engine, the timing tear sheared off about 30% of its teeth and stopped the engine dead.

At the time all of this happened I was living in an apartment complex which did not allow any mechanical work in the driveways. A check with local mechanics indicated anywhere from $500 to $800 to replace the timing gear.

Much to the dismay of my 17 year old son, the car was parked until we could get into our new house in September and get the garage/shop put together and do the work ourselves.

A question put to the net in August on any possible shortcuts for replacing the timing gear (the manual said REMOVE the engine) brought a response from Frank Martin. Frank said to remove the intake manifold, lifters, struts, exhaust and swing the engine cradle down on the front bolts. I liked this idea since I didn't have to disconnect the cooling hoses, AC, wiring connectors, cables, etc.

A little over two weeks ago we started the job. I ordered all the parts from NAPA, which included a new cam timing gear, intake gasket and valve cover gasket. We followed Frank's procedure, with a "few" (-; additional steps, and had the cam out of the car in a little less than 4 hours. A quick trip to NAPA to get the new gear pressed on and by dinner time we had the engine reassembled and ready for "the test".

It didn't want to start. A shot of starting fluid brought it to life, but the tach quickly soared to 4,000 rpm at idle. I asked Lee if he was sure he had everything back together the way it came apart. He assured me he did. Fearing I had the wrong cam gear (two different ones were listed for the car) and perhaps incorrect cam timing I began to go over everything I could think of that might possibly cause a problem.... TPS switch, vacuum leaks, grounding, right plug wires to proper places. Everything "seemed" to check out. Finally, tired and disgusted - we quit.

It was several days before we could get back to the car. Again, I asked Lee the same questions. "Is there a chance you didn't get the intake manifold on right?" "You know, a vacuum leak can cause these symptoms!" He assured me it was on correctly. Finally, we began to work backwards, disassembling the engine. When Lee took the intake manifold off he hollered' "hey, I think I found the problem." The gasket was the WRONG gasket (correct part number - wrong gasket) and was mismatched enough to cause massive vacuum leakage. We picked up the RIGHT gasket, bolted it all together again and VIOLA. It purred like a kitten.

At 126,000 miles this little engine doesn't burn any oil, keeps a clean white plug and now it really sounds good. We don't have that noisy thrashing from the timing gear (but I know it will return) and Lee is once more zipping around in his beloved little '87 SC. He did most of the work himself, with my oversight - and is very proud.

Thanks, Frank, for the help on reducing our time and effort. Wonder why Pontiac didn't think of that?

The following is a listing of what we had to remove and/or disconnect (in our order). I don't think I left anything out - but it is possible I may have omitted a step.

Support car on jackstands placed under FRAME, just in front of the front cradle bolts. Four 50# bags of fertlizer laying in the garage floor and placed in the front trunk helped to keep the nose down when the jack was removed from the back of the cradle. The jackstands are at sort of a fulcrum point and the extra weight in the front gets rid of the "rocking".

  1. Disconnect battery
  2. Deck lid (could have stayed on - easier to work on car with it off)
  3. Air cleaner assembly
  4. EGR valve (blocks valve cover bolt)
  5. Valve cover (may need special puller/tool)
  6. Fuel lines
  7. Throttle plate & linkage
  8. TPS & MAP conectors
  9. Vacuum hoses & spark plugs
  10. Intake manifold (left on coolant hose, just hung manifold over into trunk. Watch out for some lost coolant on floor)
  11. Loosen rocker nuts, swing rockers to side. Pull out push rods, note where the came from so they can go back in same location.
  12. Side cover on engine where lifters are.
  13. lifter retainer clips
  14. lifters - put in numbered 3oz. Dixie cups so they stay clean and can go back in same location.
  15. Oil pump gear
  16. (Pre 87 cars - remove distributor ?)
  17. Braided ground strap (we broke ours because we didn't see it)
  18. Starter
  19. Exhaust system
  20. Both rear wheels
  21. Both rear calapers & Emergency brake cable (do not disconnect calipers from lines)
  22. Inner wheel well lining on Right side
  23. Left strut at top (3 bolts)
  24. Remove Right strut completely (mark position on knuckle so you don't have to go to an alignment shop)
  25. Put floor jack under cradle, remove two rear bolts, lower cradle.
  26. Fan belt
  27. Crankshaft pulley (may need puller)
  28. Timing cover (DO NOT need to remove motor mount or support engine)
  29. Camshaft thrust plate retaining bolts
  30. Carefully pull out camshaft - have old gear pressed off & new on. Align timing marks and work backwards.
  31. Change engine oil
  32. Make sure you have the correct intake gasket!

Special tools needed:

Valve cover removal tool - maybe could have done it with a tap by a rubber hammer. DO NOT pry cover off or you will bend flange.
Had to fabracate a puller for flywheel pulley. Used two 1/4" butterfly toggle bolts about 3" long and a piece of oak flooring. Drilled holes so toggle bolts could slip inside holes in front of pulley. Placed a socket on the shaft end and tightened screws to butterflys. Pulley came off without bending or messing up groves.
Very small 10 mm socket to fit in cam gear holes and remove thrust plate nuts. Ended up slightly grinding down a 1/4" drive socket to fit - one with thin walls would have done it as-is.
Good collection of metric sockets, extensions, universal joint, and wrenches in at least 3/8" drive - 1/2" and 1/4" helpful. I have air tools that really made the job easier. Think the biggest nuts are on the Struts at the lower knuckle - was it a 7/8" SAE that worked OK on my impact wrench?

Hope you don't have to repeat the job on your car - it is a bitch. But, it can be done at home and save a bundle!

From: Randy T. Agee

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