GM Vented Opti Is a Joke!

compyelc4 · 03-02-03, 01:17 AM

This is for those of you who are acquainted with Opti's or have read a fine Opti disassembly article archived on this site (Mike Chaney's Optispark Disection Page). I welcome constructive comments and suggestions. Please offer me help if you can. I love my C4 but I can no longer afford $450 Opti annually. This would be an excellent reason to get a C5............but I don't WANT a C5. I want a reliable yaller C4!!!!!!!!!!!!!

Here is my story. I am replacing my '95 water pump at 20K! Inner seal failed, bearings compromised with antifreeze, leading to outer seal failure. I caught this very early. There were no telltale signs of antifreeze on the Opti. A previous post on this site started me thinking about my Opti-Spark which was replaced last summer and now has 5K on it. The pump is off at the moment and is waiting for me to install the new pump.

I pulled the 4-pin harness on the newly replaced Opti, peered down into the receptacle and behold the pins are sulfated blue just like my old Opti-Spark at 15k.

I know there has been no water intrusion into the receptable because GM sealed that up real good when the Opti was replaced and I have made sure that the engine compartment has stayed dry as a bone since then. Sure enough, the channel was clean as a pin. So how did the receptacle pins sulfate. Eureka! Those pins must be exposed to the inside of the Opti somehow! For grins, I grabbed my old Opti-Spark and blew down through the receptacle channel. Sure enough it was not a sealed channel.

I opened up the old Opti (which is vented). What a freaking mess. The "distributor cap" of the Opti has 8 pins just like the inside of a standard GM distributor cap. Also there is that familiar-looking rotor too. Each pin, and the brass tip of the rotor are so badly sufated (pins are thick with white sulfate and the rotor tip is blue with sulfate) that I am amazed that I got any spark at all. I can see no sign of water intrusion but there is this this anomoly: There are a few very tiny (head of a pin size) beads of what appears to be turquoise blue goop. I did the old micro-taste test to see if it could be caused by anti-freeze. It was NOT. It was acidic! Burned my tonque a bit. How the heck did that acid form? I used a strong magnifying glass and light to look very carefully at the areas around the neoprene seals. The seals are applied circumferentially around two of the three "pancake-looking" parts of the Opti unit so that the system is COMPLETELY sealed to the outside EXCEPT through the forced vent system. There is absolutely not one sign that any liquid compromised those seals FROM THE OUTSIDE! For the record the external 4-wire receptacle channel opens into that part of the Opti that contains the optical pickup and sending unit (that is the heart of the system). Actually, the receptacle pins protrude directly from the pickup! Simply, the pickup sends and receives pulse signals to and from the CPU to help control engine timing. For some reason though, that enclosure had absolutely no sign of condensation, even though it is open to the other portions of the Opti that did have evidence of acidic condensation. So why were the pins that are exposed to the same internal air sulfated while nothing else was? How the heck can I stop it?

Regarding the Miracle Vent, it is my theory that GM recognized a problem with the pre-92 (I think) Opti. I understand they have a free replacement program on those now. GM figures that the water pump or washing engines down with a hose caused water to enter the Opti, or maybe condense in some magical way (the thing is sealed like H_LL folks!). They surmize that, hey, lets get rid of the water vapor by sucking air out from engine vacuum and drawing air in from downwind of the air cleaner . This recirculating air will certainly keep the inside of the Opti dry. Wrong. Wrong. At least, in my opti, the venting does NOTHING. Somehow condensation is still occuring at a rate greater than the vent system's ability to draw it out. Also, somehow, the electric arcing between the rotor and pins creates an atmosphere (ozone?) which turns the MARTIAN condensation to acid thereby rendering all the metal contacts as effective as if they were barnacles.

I am very ****ed at GM right now. There must be some way to prove to those engineers that they HAVE NOT SOLVED THE PROBLEM! SO DO THE RIGHT THING. My pristine C4 is about 6 water pump bolts away from being sold traded for a C5.

Can anyone tell me how to keep that acid crap out of the Opti so that it does not corrode itself to death every 5,000 to 15,000 miles). I'm going to open up the new Opti tomorrow. I am expecting to find the same acidic crap starting to build up.

Thank you for taking the time to read my VENT!

sumoboy · 03-02-03, 02:06 AM

My 94 has 60k+ and the original owner never replace the optispark and has not had any probs yet. Mine isn't vented but I'm going with the DTE DynaSpark, it might cost more but someone has to make a better optispark than GM. I can do the install myself which will save the labor cost. I just don't feel like buying a new GM optispark then buying the vacuum kit and having to rig up a perfectly new one.
About yours, how's the coil and the wires? If you get some cold day after you run the car and then park it you might get condensation even if it's a sealed unit like yours. Check your vacuum lines and filter for the optispark also. Just remember that it's not air tight because if it was the vacuum would be useless.
About your waterpump seals see if you have a sticker under the hood about using dexcool. I think some 95's started to use them.
Do you have to taste everything?

compyelc4 · 03-02-03, 02:25 AM

Sumoboy,

Thanks for the response so quickly.
You say:

1. but I'm going with the DTE DynaSpark>>
2. even if it's a sealed unit like yours>>
3. Check your vacuum lines and filter for the optispark >>
4. About your waterpump seals see if you have a sticker under the hood about using dexcool. >>
5. Do you have to taste everything?>>

Ted Says:

1. I looked at one of those today. The picture looks identical to my vented factory one.
2. My '95 IS vented!
3. Yes. I will check for suction and vacuum as soon as I get her back together.
4. I'll do that. What color is Dexcool? My fluid was lime green and VERY clean.
5. Yes, but I'm definitely not anal about it.

SPANISHVETTS · 03-02-03, 04:15 AM

Compyelc4

Thanks, that was a well thought out and insightful post.

I only had my 93 for 8 months and 2 Optis. I tore the old one apart as you did and came to the same conclusion. It is a piece of crap. It was my understanding that the newer Optis cured the problems. Sorry to hear that it is still plaguing you.

My buddy here has a Z06. That is an awesome car. It does everything my car does, only better and has a much nicer ride.

Like you I prefer the C4 body but if you must go for the C5 you will not be disappointed. Heck, if somebody would buy my Kart-Track I would buy the wife a Red 50th and sneak it out for Sunday morning drives.

´never drove a Vette I didn´t love.

69MyWay · 03-02-03, 05:25 AM

I have been through this now half a dozen times on non-vette LT1 engines. I have also removed and inspected them.

Jut fyi, the water pump, engine washing water gets in the opti through the upper four wire plug. It only takes a few drips to work down past the weather pack and into the unit. From there, it has a free ride down along the side of the housing, through the innards, and to the bottom.

I built a street rod for a fellow with a LT1. Everytime the car got out of my sight for a few months, the owner would call me up complaining it runs bad. Come to find out it was blowing optis. We have put four on it now. Turns out that the body shop, the owner, and his detail guy kept getting the engine wet....then to top it off, the owner lives on a salt marsh. So everytime the car was flatbedded back to me, the opti, and other connectors were corroded.

I "think" they finally have the message. I made it clear I was not going to change any more optis for free on that car. I lost everything I "made" from doing the conversion in the first place by chacing the bad optis down. I also vented his into the air cleaner--it seemed to buy it a little more time. However, when that thing gets wet on a repeated basis.....it is doomed! Give me a good old HEI on a sbc anyday!

Corvette-Pilot · 03-02-03, 12:25 PM

Quote:

Originally posted by compyelc4
Ted Says:
4. I'll do that. What color is Dexcool? My fluid was lime green and VERY clean.

I think this stuff is red so you shoulb be fine.

redc4corvette · 05-13-04, 05:12 AM

Try one of these http://www.delteq.com/opti_stage1.htm
quick fix go to ace hardware and buy some tc 11 it works great for me.

warren s · 05-13-04, 07:40 AM

That Delteq kit looks real sweet, how long has that been around? Anyone have one of those ?

Vettelt193 · 05-13-04, 01:35 PM

it has been around for years, but it seemed to vanish from the market for awhile... I wanted the kit back when i had my '93. When the opti goes on my LT4, I am getting it.

DRTH VTR · 05-13-04, 01:45 PM

Quote:

Originally Posted by Corvette-Pilot

I think this stuff is red so you shoulb be fine.

It is an orange color

froggy47 · 05-14-04, 07:48 PM

Where is the "intake" of the opti? Or is it just an "out" vacuum vent that sort of creates a vacuum atmosphere inside the opti?

Grizzly · 05-14-04, 11:10 PM

I've been reading these threads on the opti ever since I got my '92 wondering what I am going to do.

One thought about the venting, unless there are one way valves in the system there is nothing to prevent moisture laden air from moving backwards into the system from the vents.

Are there any sure fixes, short of a transplanted 350 with HEI? Can't imagine how much fun it is going to be trying to keep the engine compartment clean!

redc4corvette · 05-15-04, 12:37 AM

http://www.charm.net/~mchaney/optisprk/optisprk.htm
http://corvettefever.com/howto/16758/
then try these sites.
http://www.gmhightechperformance.co...0htp_optispark/ http://www.charm.net/~mchaney/optisprk/optisprk.htm http://www.fierolt1.com/lt1_95_up_OptiReplace.htm http://www.noid.org/~muttvette/opti.html
http://www.houston-f-body.org/tech/optispark/ http://www.dynotech-eng.com/dynaspark.htm http://www.corvetteclinicinc.com http://www.corvettefever.com/howto/16758

Notorious · 06-24-07, 07:11 PM

Quote:

Originally Posted by froggy47

Where is the "intake" of the opti? Or is it just an "out" vacuum vent that sort of creates a vacuum atmosphere inside the opti?

There are two hoses on the vented optis. One is a "breather" that is sourced from the accordian hose on the air intake. There's also a vacuum hose that runs to a fitting at the front of the intake manifold. Compyelc4, I'm unclear on something. Is it your car or just the water pump that has just 20K miles on it? The reason I ask is because optis are more prone to cause problems on cars which don't see a lot of use. This is also true of many types of seals, such as on your water pump. So you see where my question's coming from. I replaced my original opti ('95 LT1) at nearly 100K miles simply because I had it off while doing major mods. It was still working well as has it's replacement in the many miles since. But I also added the electric water pump conversion long ago too, so worries about it ever leaking onto the opti are a non-issue. There are still OEM later style optis available for well under $300. I'm assuming the $450 price you mentioned is full dealership retail.

aboatguy · 06-30-07, 01:02 PM

I changed my OPTI at around 50K when I did a head cam install the opti looked pristine, pins and all. It looked so good I posted pics and sold it on EBAY. Something must be going on with yours because I wash my engine and drive in inclement weather.
Where are you getting the 450 dollar optis? I paid about half that including shipping.

mike