1994 corvette start

[Richard Cooper]

Hi, We are having problems with a 1994 Corvette we are working on. We flushed the cooling system and now vehicle will not start. We started by draining the coolant and refilling with water and flush. We then let the car run for 30 minutes watching temperature so as to not overheat. We then let cool and drained and filled with clean water. We started car for a few minutes and drained, at this time we replaced thermostat and filled cooling system with coolant and rinsed off front of engine were we had some overflow from thermostat replacement. We then started the car and it ran fine but then started to run rough then stall, upon restart while turning over it would initially turn over and try to start but then sound as if the timing was advanced. We are sure we didnt over heat and was wondering if maybe we had got some water on the air sensor plug prior to connecting if this would cause this problem or what thoughts you might have. Thanks

[Terry M.]

Re: 1994 corvette start

Richard, the optical distributer on this Gen III LT1 is very sensitive to anti-freeze intrusion. Since the distributor is mounted behind and below the water pump, it is in a prime location to receive an anti-freeze bath when the cooling system is being bled. This engine, with reverse flow cooling, is also very prone to air bubbles in the cooling system. They are very hard to remove.
My guess form this long distance is that liquid -- either coolant or the bath you gave the font of the engine, has penetrated the distributor. While there are cap and rotor kits available, if quality parts are purchased they will cost nearly 80% of the cost of a new distributor. Because of the difficult access to these parts I suggest changing the entire distributor. If you have the luxury of waiting for delivery, contact Dal Slabaugh, GM Parts, toll free (877) 448-5451, email: lockitup@bright.net. Last time I checked his price on the optical distributor was $217. Be sure to replace the vacuum hoses if this car has them. They are vital to the long-term survival of the distributor.
There is a chance that the ignition wires are faulty when wet. The secondary wiring on the newer LT1 is run very close together. If all the retainers and wire loom are not in top sharp arcing can get bad enough, especially when wet, to prevent engine operation. An attempt to start the car in the dark will usually reveal arcing, if that is the problem.
If you decide to change the distributor please be careful in installing it. The alignment of the drive mechanism can be a little tricky. Don’t force anything. If the distributor doesn’t fit easily snug against the timing cover, try realigning it. It will go on easily once the pin is properly aligned.
Good luck

[Guest]

Re: 1994 corvette start

I agree with Terry that it is most likely water in the Opti-Spark. I had a neighbor a few years ago who washed his 94 engine. It too ran rough after getting the Opti-Spark wet. He dried the engine by blowing a fan over it for a few hours, and it then ran fine. There are no guarantees that it will work for you, but it only costs a little electicity to give it a try.

It is a real pain to change the Opti-Spark. If you do have to change it, you should consider changing the spark plug wires and water pump if they have not been changed in a long time. Especially the water pump. Your water pump will leak at some point and then it gets the Opti-Spark wet. You are lucky to get 50K to 60K miles out of one. I have a 95 with 130K on it and have replaced the water pump twice and Opti-Spark once.

[Joe L.]

Re: 1994 corvette start

Terry and Richard-----

1994 Corvettes use the non vacuum aspirated Opti-Spark distributor. This is the more expensive one of the two. It's GM #10457702 and it carries a current GM list of $674.14. Dal's price on this one will likely be closer to 400 bucks.

The 95-96 vacuum aspirated unit is GM #1104032. This unit carries a current GM list price of $502.94. The 2 are not interchangeable, although the later design unit can be used if other parts are also changed. While there may or may not be some durability advantage with the later unit, the cost of the parts to make the conversion exceeds the difference in price between the 2 distributors. The first design (actually, the second design since the very first design is obsolete and not serviced) can also be converted to vacuum-aspirated configuration with the expenditure od some effort.