Optispark Preventive Maintenance

The '95 Roadmaster wagon I just bought has 80,000 miles on it. I don't want to be left alongside the road when the Optispark fails. What can I do to prevent that from happening?

I'm not against replacing the whole system--or parts of it. Complete OEM or aftermarket Optispark distributors are regularly sold on eBay for $75-125. Since I don't know the history of the engine, I'd replace the water pump at the same time work is done on the distributor.

I know others will disagree with me, but I say do nothing. In my experience, the OPTI works well, and is very reliable. I've never had an opti issue with any of my LT1 cars in almost 15 years of driving. When I first got my SS, the water pump dripped on the opti for two years before I finally changed the WP. Didn't change the opti, and it is still going strong.

Preventative maintenance is one thing, but changing out expensive parts that are good doesn't make sense. Replacements can fail just as easily as OE parts.

Like Jay, I have driven them a long time, 17 years. I have never had one problem. My first RMW I put on 237K and the original OPTI was fine the day I sold it.

My advice, find something else to worry about, as they are pretty reliable.

Tom C.

Thank you for the responses. I kind of thought problems with Optispark are overblown. There were a tremendous number of cars built with it on the 5.7 V8's.

A friend of mine has a '95 Roadmaster sedan with 18,000 miles and a potential buyer backed out because of what he has heard about Optispark being a problem. Too bad, since this Roadmaster is absolutely like new--never been driven in snow.

Only thing to remember is no deep water period!

I bought one wagon with 135K and there was an opti issue. metal back plate had a whole burned through and it missed on number 7 cylinder. Got shitty gas mileage and ran like crap (unlesss WOT) but it didn't leave me stranded. probably put 700 miles on it, before I properly diagnosed it. New cap and rotor and all was fine. Didn't change the opti itself. Car has 220 K on it now and runs like a top.

Leave it alone as Jay said.

Agreed... and:

Get a working coil and ignition control module (ICM) assembly from a junkyard and keep it in your storage compartment along with a cheapo ratchet and a deepwell socket for the coil studs. 90% of opti failures leave you with a misfire but the car still runs. 90% of ICM failures leave you stranded. Undo two bolts and three plugs and you can swap the coil/ICM assembly and keep going.

A good check that I learned from Sherlock is to check that the opti holds vacuum (confirms if the seals are doing their job). Pull the hoses off the intake manifold and the rubber elbow, cover the one from the elbow with your finger and suck on the one off the manifold. If it holds a vacuum then your all set. If it won't hold it consider a cap and rotor kit. If you don't have any oil or water pump leaks on it you will probably be fine though.
I did this test on one of mine and there was no vacuum and it tasted like oil. While mine ran fine, I did find a good amount of oil in there when I opened it.

Also, stay away from those cheap eBay units. All they are good for is getting practice replacing them when they fail 100 miles later. Ask me how I know

The Optispark is like fracking is like nuclear radiation; once you understand it, it's not scary at all.

It's worth saying that the optispark is a very simple component and is definitely gearhead-serviceable. It contains these parts:
1. the housing and trigger wheel,
2. the optical sensor,
3. the cap and rotor.

Usually either the cap and rotor simply wear out or the optical sensor fails. Occasionally the trigger wheel rusts and gets coated with oil. Occasionally the two screws holding the rotor in place will get loose and/or back out (I've read somewhere that it's wise to loctite those before you install the opti. I think there is a bearing in there that can get loose overtime too.

If you get trouble codes and the opti interior is clean, then the sensor failed. If you replace an opti because of a bad cap/rotor/secondary issue, save the optical sensor as it can be reused and is not cheap to buy on its own. Caps/rotors are wear items so just buy new ones of them.

David was kind enough to post the GM optispark service video which is very informative here:
http://www.impalassforum.com/vBulletin/showthread.php?t=255280

The 2 failures I have seen both were caused by a leaking Water Pump, the pump bearing starts to go bad and the coolant starts seeping onto the optispark unit. This causes its weather seal to deteriate, and then if they get wet (both cars were 95-97 T/A's with Ram Air Hoods that let water in during rain storms or even car washes) And the cars would not start until they dried out. Usually about 1 hour or so.
One owner finally replaced the Opti Spark, and when he did he threadded the hole in the bottom of the water pump, inserted a 90 degree nipple with a plastic drain hose to rought any coolant around the optispark.

Just something to think about.

Yeah, there's a lot of material there to drill and tap with. I put a fitting in as well - at least a good 3/8" of metal to work with.

cammerjeff wrote:

The 2 failures I have seen both were caused by a leaking Water Pump, the pump bearing starts to go bad and the coolant starts seeping onto the optispark unit. This causes its weather seal to deteriate, and then if they get wet (both cars were 95-97 T/A's with Ram Air Hoods that let water in during rain storms or even car washes) And the cars would not start until they dried out. Usually about 1 hour or so.
One owner finally replaced the Opti Spark, and when he did he threadded the hole in the bottom of the water pump, inserted a 90 degree nipple with a plastic drain hose to rought any coolant around the optispark.

Just something to think about.

opti's don't get wet then dry out,.they are sealed,.if they get wet inside,. they take months to dry out,.
as was mentioned it.d be the coil wire or module,. or crappy plug wires,.very common for lt1 coil wires to ground to the water pump when they are old and its wet out side,.
I threw one in a bucket of antifreeze with the vacuum hoses sticking out,.left it there for a year,. just to debunk the BS about opti's,.
pulled it out blew it off with shop air and it worked fine,.

My experiences are from the real world,. not the internet world,.

jm2c
Nick

I've had more issues with leaky WP seals than the opti itself. Make sure you get the tool from Buffman.

When I've had the opti out for various reasons, I've done the following:

1) use an E4 reverse torx socket to take it apart;
2) Apply red loctite to the 2 small screws mentioned above;
3) reseal the opti with a constant SMALL bead permatex #2 or equivalent;
4) replace the WP seal (as required). Felpro Timing cover gasket set TCS 45956 has all the gaskets you need. The 2 small o-ring are for the WP driveshaft, not the opti;
5) replace opti o-rings with 2x GM p/n 10474278 Distributor drive shaft seal;
6) Clean the opti electrical harness contacts with contact cleaner, then shrinkwrap the connector on the opti side; and
7) Replace the opti vent harness.


YMMV