L98 Smog Pump Replacement

By Howard S

We decided it was time to change the smog pump on our ’88 (165,000 + miles) when it started sounding like a rock tumbler.

The following steps and hints will speed the job if you should need to change the smog pump on your L98 powered Vette.

Hint -- Before you start, turn the steering wheel hard right. This give you room to step behind the tire for easier access.

1. Break the torque on the pulley bolts before you remove the drive belt. Use a 10 mm wrench. Then remove the belt, and the pulley.

2. There is an upper bracket between the alternator and pump. Loosen the bracket at the alternator with a 10 mm wrench and remove the large bolt at the pump with a 13 mm socket. Fold the bracket out of your way, over the alternator.

3. There are 2 bolts on the backside of the pump. The top bolt goes through a bracket that angles down to the intake manifold. Use a 14 mm socket to loosen the bolt in the manifold and a 13 mm wrench on the bolt into the pump. With the bracket out of the way, you can get to the lower bolt, which also uses a 13 mm wrench. Be careful of the 2-vacuum lines under the bracket, they become very brittle with age.

4. There are 2 bolts with 13 mm heads that hold the output line to the pump. On the ’88, the line is a ridged tube. On Matt’s ’87, the output fitting connects to a rubber hose. 4) If yours has the ridged line, remove the bolts. If it has the hose, remove the hose.

5. There is one more large bolt under the pump. Using a 13 mm socket, remove this bolt and lift the pump out.

6. Check the bolt holes in the replacement pump. The one we got used smaller bolts in the 2 mount points on the back of the pump.

7. Hint -- If you have the ridged line, connect it first while putting the pump in place. I found the line too ridged to bend to meet up with the pump in place. If you have the hose, install the fitting with the pump out of the car.

8. The rest of the installation is pretty much the reverse of removal.

9. Be careful when installing the pulley. Torque it down evenly so it pulls in straight against the mounting flange. Otherwise you might find that it wobbles.

That’s about it. It took less than an hour to change out the pump, plus the time to go find the correct smaller bolts. And now the rock tumbler is gone.