Newbie here with some problems with my 96, can you help?!

[BIG CTY]

(I posted this in the wrong forum, sorry for the double!!)

Hello all,
I have been lurking and searching for quite some time now. This is my first post however. I bought a 96 Polo Green LT4 about a month ago. I'm a chevy guy at heart as I have 5 others! (In case you wanted to know, a 66 C-10, 69 Impala, 70 Monte Carlo, 91 GMC Sierra, 95 G20 conversion van) No wife and kids, so cars it is. The new to me Vet turned 100k miles on my way home from picking it up. The previous owner CLAIMED he did the following:

New spark plugs
New spark plugs wires
New distributor
oil change
New radiator
New water pump
New brakes

Well the car runs great with no misses or rough idles, but codes are popping up all over the place and its overheating. I dont hear the fan coming on and the temp climbs steadily at idle. As soon as I get going the temp comes back down where she should be. I also have a grind SOMETIMES going into first gear. Oh yeah, no reverse light either lol. I do hear a slight faint type ticking coming from what I think is the #3 spark plug, which might explain the p0303 (cylinder 3 misfire) code I have. But I also have p0305 (cylinder 5 misfire), and p0420 (catalyst efficiency below threshold, forgot which bank).

It strange because the car runs and drives fine, get exceptional gas mileage and seems to be in excellent shape. But codes come up for a reason. I thinking about changing the plugs and wires again, but I'm not sure which plugs and wires I should get. One may be cross threaded. I'm going to have a Corvette indy look at it this week, but I wanted to pos and get some info/opinions on what you all think the problems may be. I also ordered a reverse light switch. Any info you can give me would be greatly appreciated. Thanks in advance!!

 

[Guitared]

Congrats on the new LT4. I also have a 96 LT4. Too fun! The reverse switch is a good bet. I had to replace mine at 65000 miles. Also, I had problems with overheating. Turns out the radiator was just covered in road junk. I sprayed it off through the opening on the right side with a water hose. Barely goes over 200° now when it did run at 235°-240° regularly. I learned this fix from someone else on this forum. Good luck!

 

[jmccloud]

Welcome

Welcome to a great site and to Corvette ownership.
Regarding the temperatures; be aware that the LT1 and LT4 normally operate about 195F moving and in the 220's in traffic (without the A/C on). Turning on the A/C activates the low speed fan and keeps the coolant temp somewhat lower in traffic unless the outside temp is high. This is according to the digital readout, the analog readout usually reads higher and is more variable. The digital readout senses the water pump temp and the analog readout senses one of the head temps. Also, I don't hear my fans when they're running in slow. If they kick up to high (228F I believe) I can hear them, especially if the windows are down.
If the PO (previous owner) put on new wires, make sure that their boots are firmly seated at both ends. The ends on the optispark (distributor) are especially difficult to seat properly. Also look for plug wire contact with exhaust (burnt wire!) or other engine parts. Plugs 3 & 5 misfire may indicate switched wires since they are adjacent.
Your first gear grind may indicate the need to bleed the clutch slave cylinder.
Hope this helps and good luck,
PS Good to hear from a vintage car owner. I have a '66 Impala (bought new) and a '68 Camaro convertible (bought in 1974) but 2 kids and 11 grandkids who want those 'old' cars.

 

[Toms007]

I'm not sure what you are considering as "temps rising" but the LTx engines were designed to run warmer than what we are used to. Running down the road my 94 runs 195-205 and in stop and go traffic it might run as high as 230 (Secondary fan kicks on at 228 IIRC), but as soon as I start moving again, the temps come right down.

Many people like the AC/Delco OE spark plugs, me, I put NGK TR55's in mine and OE style wires.

 

[JAKE]

I have a 96 too. So does my son; I keep his while he's away at West Point.

As far as "over heating" it would be best for you to post specific numbers and whether those readings are from the analog or digital gauge. What is is, specifically, that makes you think the engine is over-heating? Is it spewing coolant? Getting a CHECK GAUGES light, etc.?

Also I can never HEAR my fans come on. Only way to tell is to look. Raise the hood, fire the engine and while watching the digital temp gauge and fan, watch to see when the fan comes on.

Without having had the PCM re-programmed, the fan won't actually come on until the coolant temp is well over 200F; that's normal. A re-programming usually includes modifications to cause them to come on at a lower temp, something like 180F.

Can't help with your tranny issue.

Keep us posted.

Jake

 

[LT4man]

Hi and welcome to the site!

As far as your high engine temperatures.

Someone said earlier to make sure to check the area between the radiator and the A/C condensor. This type of Vette is what is known as a "bottom feeder". The air that is pulled past the condensor/radiator and into the engine compartment is picked up off the road. Even running over a plastic bag (from Wal-mart, food stores, drug stores) will sometimes pull the bag right onto the A/C condensor. The bag will stay there blocking air flow until you get down on the ground and pull the bag from the condensor.

On the right hand (passenger) side of the radiator is an opening where you can shine a flashlight or trouble light into. This will illuminate the area between the A/C condensor and the radiator. There might be all sorts of debris, leaves, junk, bags etc. that is stuck in that area. Sometimes a slow stream of water from a hose nozzle will knock the junk to the ground. Be very careful of how powerful the spray is. The fins on the radiator are very thin and can easily be bent just from the water.

Check your plastic overflow tank which is located right under the access hole I was describing above. Make sure your coolant level is to the cold mark when the engine is cold.

Hope this helps. Introduce yourself in the New Member forum and you will experience how friendly the CAC is!

SAVE THE GOSH DARN

 

[Toms007]

You know LT4Man is right, here's what I did to help alleviate the problem with sucking junk up off the road.