Finally got some room in my garage this weekend (son moved out one of his projects). I've been having the the typical misfire, stumble, and backfire. I bought a code reader and confirmed the DTC 36 (loss of high speed pulse signal). So saturday I pulled the water pump (just in the knick of time, no leak, but the bearing was starting to come apart), and pulled the opti spark distributor.

I took apart the opti, and carefully removed the slotted optical disk (had to grind off a small spot weld). The interior was covered with a red oxide dust which I cleaned off with rubbing alcohol. I removed the bearing and lubed it. Interesting note, the optical reader is made by Mitsubishi.

I bought a new cap and rotor from Pep Boys for $142. Its a vented cap for the 1995-1996. The cover that comes with it will not fit the older model internal parts (harnes wiring for the optical reader) so I reused the older cover which did match up to the cap.

Now since I had a vent fitting in the cap, I needed a vent outlet in the base of the distributor. The 1993-1994 distributor has 3 small weep holes in the bottom, I plugged the two outter ones with pop rivets and a small amount of gasket sealer. I then drilled the center hole to 3/16" and installed a 90 deg. plastic vacum hose fitting pointing to the right. You need this fitting because there is only a 1/2" between the bottom of the distributor and the top of the crank pully shaft. Now I have the outlets needed for the opti vacum hose harness #12555323.

This is a much simpler and cheaper way to get a vented distributor than replacing the timing cover, cam shaft, and drive shaft for the 1995-1996 distributor, or going to Dynotech's replacement (which is only for the 1995-1996 models.

The last opt-spark has lasted me 65k, we'll see how much longer this vented and cleaned unit will now last.

Since I was set for drilling holes, I drilled out the weep hole in the bottom of the water pump, installed a 90 deg 3/16" elbow, and added about 2' of vacum hose that I routed down and past the steering rack. So when this pump dies, I'll be able to notice the anti-freeze comming from the hose and know its from the pump.

I drove it 45 miles to work this morning, so far so good...

The Old Guy: '94 z-28, m-6, t-tops go fast red, 219k

 

Well done, you should be an engineer.

 

He is a engineer!
That's a great idea for the waterpump.

I have heard and seen the exact same thing that other people have done on the non-vented opti. It's alot cheaper to do that than convert to the vented opti, because you would have to get the timing cover changed. Good Job!

Or you could of converted it to a electric waterpump and never have to worry about it leaking again.

 

i thought about doing the water pump drain too. I made a post on it but no one thought it was that good of an idea so i didn't do it. I guess when the motor comes out in the summer i will be doing it.

 

why bother if u can get a new OPTI for 190 shipped to your door?

 

Just a note.

I went 95K miles on my non-vented opti.

Just swapped it out for the hell of it.

 

I dismantled my old opti as well and found the red oxide (fretting corrosion I think) from the bearing. It is the play in the bearing that causes a loss of high resolution pulse, and another DTC (can't remember the number) whose comment is "secondary high res pulse detected". If the bearing just needed lube fine. If it is worn however (mine was quite noisy) then the problem may return. Apparently the bearings in the vented opti's are an improved design over the non-vented.

 

My opti just went bad, where do you get one for $190, I want to save as much $$$ as I can.

 

You can't get a 'new' early opti for 190 try more like 280...
I cleaned mine too it can be done...
I found that the metal 'shield 'inside was very rusty... [I almost wanted to leave that out but decided not to as it no doubt shields the ignition system..
BTW curious how you 'lubed' that sealed bearing[which is also usually 'bad', as it is the weak link in the early opti]

 

I am now on the third water pump in 9 years, and 219k. Bought the original replacement at Pep boys 4 years ago, so they give them to me on lifetime warranty now.

I got the roughness out of the opti's bearing with wd-40. Then injected wheel bearing grease between the flange and bearing with large bent hypo-needle. I hope I got enough in there, if thats a weakness.

Interesting note, the opti-reader is made by Mitsubishi.

 

I am going to make my old opti into a DVD player.

 

great idea...how long did it take youto change the opti.?

 

Hi Z28=Pete.I like the water pump idea.How far did you tap into the waterpump with a drill?,and what size bit?Did you use a brass elbow,and how did you get it to thread inside of it?This is the greatest news since slice bread.When my waterpump took a dump,it spread all it's contents onto the opti,but was able to gingerly drive it to the mechanic,and was lucky the opti lived.(Even now with a new waterpump,the thing is leaking a little tiny bit,cause it's kinda black at the weep hole.)Thanks.

 

It is probably a several hour job for someone who has not done one before, but is handy with tools.

 

Search LT1 tech for "Jason Cromer". You'll pull up his phone # in one of the threads, he works at a dealership and gives killer deals on just about any GM part