I was less than a mile from home in my 1993 C4 when it totally died. I would not restart, got up and lifted the hood and saw that I had a small leak from a busted heater core hose where it attaches to the water pump. Also noticed slight electrical burning smell. Towed it home, went on vacation for a week and went out hoping the water had drained from the Optispark. Still would not start but initially some popping like I was gettting a little bit of spark. I did notice that the OptiSpark wiring connection is directly below this leak. Do you guys have any ideas for drying the Optispark out short of changing it out? Could it be anything else in that area that the water damaged? I'm thinking that I'll have to change the Optispark out but was hoping you guys might have some better ideas. Which is the current best Optispark replacement? Also, I changed the water pump out 2 years ago, but I do live in San Antonio and the car does get up to 230 or so during the summer in slow driving. Would it be worth it to change to an electric water pump since I'll have it off anyway? I'm not too worried about the money involved with any of this stuff, my time is more important and I don't want to be doing it again later. BTW, I'm wishing I'd have changed that heater core hose while I had the chance two years ago!
Thanks,
Jerry Barth

 

Hate to be the bearer of bad news, but your Opti is likely toast- classic symptoms. They do not swim worth a damn. As far as replacements, there are various opinions on which one to use, you will find much info using "search". Water temp on C4's is supposed to be high, unless you have had actual overheating issues, I would stick with the stock pump.

 

+1 on the toasted opti. There are options like the Mesiere (sp?) electric pump which is commonly used on the C4. Whether or not you replace your water pump you can istall a weep hose into the weep hole which will route the coolant away from the opti upon future failure. A leaking hose can't be so easily remedied. Again do some searching, but you won't find any absolute answer on which opti to buy. I did a LOT of searches and the more I read the more unsure I was on which to buy. Good luck.

 

On my 3rd Opti. Original killed by waterpump leak.
1st time replaced it with what I thought was going to be the best because it was the most expensive=MSD. Well it didn't work worth a damn from the first day, and I used up the entire waranty period serching for some other problem that was causing my misfire. Finally the MSD died from optical sensor failure. Next I bought a cheapie API from e-bay. They claim to have the best optical sensor, that's made by Mitsubishi who makes them for GM also. I figured if I'm going to have to keep replacing these things, at least make it affordable ones. I took that one apart and did some modifying to it's shielding and venting before I installed it, and so far (just this summer) it's been good.
I went the electric waterpump route and I love it. The biggest hassle with that was taking the front cover off to remove the waterpump drive gear & shaft from the engine. President Kennedy $.50, held in place with JB Weld, now fills the hole vacated by the old drive shaft. Car still runs warm just like all C4's but with the A/C on or on the Hwy. it stays right on 209*.
I dried out the original opti once by using a little fishtank air pump plugged into the vent hose from the air cleaner. I let it sit and puff air into the opti overnight and it started the next day, but didn't live long. Antifreeze eventually kills the photocells.
Also in San Antonio. Member of TCA that meets 1st Tue of the month @ Biff Buzbys burgers IH10 & Topperwein. Hang out there on Fridays for the weekly cruise night.

 

Just got my MSD...hoping it fires right up

 

Nice choice

I have MSD on both Vettes and no issues yet.

Betty Boop since 2008, this year alone over 15,000 miles of USA road tripping

The Ghost since 2009 fewer miles but, lots of high reving ones and no issues.

 

I don't own an optispark, but I have read a lot of threads on here about them. The MSD just looks like a 100% better built unit. It even looks like it's sealed better. Did you see a power increase? Cleaner running?

 

The MSD is built like a tank! It has beautiful machining and is well engineered. The extra bolt holding the cap on helps hold the cap and a new square edged gasket seals it tight. The adjustable timing screw is a nice touch as long as it doesn't come from the factory stuck from corrosion. To bad they filled mine with defective electronics too, and argued with me that something else must be wrong till the warranty ran out. How dare me accuse them of shipping out anything defective!
You can put a turd in a vault and it's still a turd. I MIGHT use their stuff if it was free!

 

I replaced my Optispark this summer with a Chandler unit. Before I put it on I sealed it with RTV. The previous owner had already added a manual fan switch to override the programmed logic. In one position everything is automatic, but in position two one fan comes on, no matter what. In position three both fans come on. It really takes the temps down fast! Usually, I can leave it on auto and run at 220 or so.

The Chandler Opti works great. no complaints after the few months I've had it on. Lifetime warranty.

Good Luck.
Paul