�96 LT4 Owners Input

[John S.]

[Floyd B.]

[Mark E.]

[Joe L.]

John,

I have owned my LT4 vert for 13 years. Mine had 98k on the clock when I bought it. The interior was shot. The center console plastic is covered with a rubbery material GM called Dulso. It's very soft and scratches off easily so check this area for wear. Original and NOS parts are getting difficult to find and very expensive. Some folks simply strip the remaining dulso to expose the shinny plastic underneath. It looks ok this way but not original. The LT4 (and LT1 for that matter) is pretty bullet proof. Pulls real hard through the first three gears. The one infamous trouble spot on these motors is the Optispark distributor. If you develop a water pump leak, you'll have ignition troubles. If you develop an oil leak from the water pump drive shaft seal, you can multiply the troubles by 2x. If you google "optispark" you get no shortage of complaining posts on various forums.

The good news is there are plenty of aftermarket Opti's to choose from and they're not expensive. You can still get GM water pumps that are virtually identical to the originals. These pumps have no date codes or part numbers that are visible on the judging field. Also, I was easily able to swap out my opti and water pump and replace both the seals in the timing chain cover without removing the engine. Just had to remove the radiator and I completed the job in one weekend.

If you are really a purist and don't want to forfeit the 1 or 2 points for the after market Opti, then that will be a challenge. Up to about 5 years ago you would come across the occasional NOS unit for about $300 - $500 dollars. I haven't seen any the past 3 or 4 years. I'm sure there are still a few around but it is the one difficult part to find. I think remanufactured opti's have now started appearing on the market but I don't know if they are any good. If you ever do need to replace it, make sure you get one of the 2nd version vented units. Virtually every other part on the car can be found from several good salvagers that specialize in C4 parts.

Good luck with it,

-Floyd-

Floyd------


There were three iterations of the Optispark. The first was a completely non-vented version and was used only for very early 1992's. The second was exactly the same as the first except that it had 3 small holes for venting drilled on the bottom of the aluminum frame of the Optispark. These were used on later 92's thru 1994 and were retrofitted under recall to early 1992's. All of these distributors used a spline drive.

1995-96 Optisparks used a vacuum extraction type of venting and a "paddle" drive. These distributors cannot be retrofitted to 1992-94 without making considerable other modifications and part replacements. I have heard that there are 1992-94 style Optisparks which are modified to vacuum extraction venting and there are kits available to do so to the original 1992-94 Optisparks.

[John S.]

[Joe L.]

Floyd, Mark thanks for the input. Our one and only C4 was a new ‘86, only owned it for a couple years then sold it to build a house. Great car, never had any issues. I thought I had died and gone to heaven driving a new Corvette with 200+ hp. I’ve read a lot about the water pump and Opti Spark issues so I think I’m prepared to deal it if need be.

The owner states the original pump and Opti Spark are still present with no issues. I wasn’t aware of the OBD II, I’ll have to do some research on it, thanks for the heads up.

I’m sure my first concern if we make the purchase will be tires, 15k mile 25 year old originals. Sounds like a second set of wheels and new tires if we go the judging route.

Now just some serious negotiations with my wife, her initial criteria was a modern convert, stick and no black interiors. Her eyes lit up when she saw pics of the Competition yellow and heard about the LT4, we’ll see.

Thanks again for the input.

John------


The OBD II which did begin for the 1996 model year is actually a benefit and not a detriment. OBD II makes it much easier to diagnose problems. OBD I is frequently useless.

[John S.]

John------


The OBD II which did begin for the 1996 model year is actually a benefit and not a detriment. OBD II makes it much easier to diagnose problems. OBD I is frequently useless.

[Mark E.]

John------


The OBD II which did begin for the 1996 model year is actually a benefit and not a detriment. OBD II makes it much easier to diagnose problems. OBD I is frequently useless.

OBD II may be an improvement, but the question is how many OBD II C4 components are unique to that year, and what's their availability?

[Joe L.]

OBD II may be an improvement, but the question is how many OBD II C4 components are unique to that year, and what's their availability?

Mark------


I can't think of a single OBD I or OBD II sensor that's a "stand-alone" sensor. In other words, a sensor that's not part of a component with primary functionality. It is true that many of these components for both OBD I and OBD II systems are GM discontinued. However, a great many are available from aftermarket manufacturers like Standard Motor Products. The older the application, the less likely the components are going to be available. So, because of that, folks with OBD I systems have more to worry about than those with OBD II.

[Floyd B.]

Tech II scanners. It will be the best $300 you will ever spend. You will not find a better scanner for GM cars of this era. You can even use this scanner to initiate automated service procedures like cycling the ABS valves when bleeding the system - as I had to do on my wife's '98 after changing the steering pump. If you are really fussy about knock-offs from China, you can find original Tech II's for about $2000 to $3000 but I think you are just throwing away $1700 to $2700 on a unit that is probably showing its wear.

John, there was a recall on the LT4 drive train. You might want to verify that this service was done. Just for grins, here is a pic of my rockers when I had the valve covers removed. Notice the service etchings in the rockers. BTW, oil leaks at various locations are common on these motors.

IMG_1898.jpg

[Terry M.]

[Floyd B.]

John,
I did the same thing. I had my saw blades refurbished and put original GSC's on them. These are for flight judging only. I happen to like the '96 GS A-mold's. I have a red/black car so IMO the black A-molds look nice. I think they would look great on a yellow car too. Original GS wheels aren't particularly hard to find but good repro's are much cheaper.

[Pat M.]