mixalive

I have been having issues every time I hit a puddle, the 92 wants to drown out. After it sets for a while, it fires up. I first thought it was an issue with my knock sensors since they are the lowest electronic device in the front of the car that is connected to the ECM. The last time it happened, I threw a timing light on the car and noticed I was not getting spark from either the coil or the Optispark. Then it occurred to me that my Opti may be sucking water past the seal. I did a vacuum test on the unit and sure enough, it would not hold a vacuum. I spoke to technical support concerning this and they verified that the unit should hold a vacuum. Mine was leaking past the o-ring seal at the bottom but determined it also leaked significantly at the wiring harness pass through. I siliconed mine and was able to establish a consistent vacuum. I am just saying that this should be checked before you install an Optispark. The vent system does no good if it is sucking atmosphere and water into the unit.

higgyburners

Good Info thanks for the Post.

mixalive

Or you could block one side and vacuum check the other.

MatthewMiller

Bringing this back up to ask for clarification. I may be about to replace my opti, and I have a good OE (gently used) replacement to install. But the replacement does not hold a vacuum. So to fix that, did you just put silicone on the outside of the "seam," or did you remove the cap and put silicone in the mating edges?

mixalive

I would remove the cap and seal with silicone. I have an MSD, so my cap has an o-ring. Yours my have an o-ring as well. I just coat the o-ring and reinstall. Let set overnight before a vacuum test. But anywhere else it leaks will have to have a topical treatment of silicone. But let it dry before test.

MatthewMiller

Guys, mine was leaking at the wiring harness pass through. It has O-rings on main sealing surfaces for the cap and the plastic part underneath, but I went ahead and put a small bead of silicone on those surfaces.

But the wiring harness is really not sealed from the factory. It doesn't appear that they intended it to be sealed. As you noted, that's really just a pass-through for the plug to go into the sensor. So how did any of you manage to seal it with silicone? It looks to me like GM intended the waterproof seal on the plug itself to be the seal here.

A Peter C4

This is for 95-96 factory vented opti. correct? Not 94 and earlier.

mixalive

MSD or factory vented.

mixalive

I topically seal the electrical pass thru.

MatthewMiller

Correct, a factory part on a 96 vented opti. I could try to topically seal the harness pass-through, but the plug is so deep in there I think it would be really hard to get silicone where I want it and keep it out of areas I don't.

mixalive

Making an attempt is better than doing nothing at all.

Be sure to vent the weep hole on the bottom of your water pump to below the opti so the water pump doesn't dump on the opti. Here is that link:
https://www.corvetteforum.com/forums...r-lt1-lt4.html