My cousin just got a 94 Z28 and drove it from Arkansas to Dallas, TX where I live. It was overheating really badly on the way down here. We discovered that it had a cut in the heater hose, and had it replaced. The car is still overheating pretty badly. The temperature will get all the way to the redline after driving for about 10 minutes, and minutes later will drop back down to what I'm told is the proper temperature for a Z28. (between middle and next highest line) Today the car started smoking after about 15 minutes of driving. The smoke was coming from the catalytic converter. Also, the floor board of the passenger side was really hot. We assumed the cat was clogged so we went to get it replaced. They looked it over and said the cat was glowing, but wasn't clogged. I'm still learning how everything works myself, and have no idea what this could be. I do know that when the heater hose busted some of the coolant might have gotten on the optispark. It's her first car, and we have two weeks to make it safe for her to drive back home. I can easily answer any questions that might help figure out the problem. I've never dealt with a Z28 and the last time I dealt with anything close to it was 4 years ago.

 

First Overheating: When did it start overheating on the highway? Immediatly? Did your cousin keep driving when it did overheated? If so that can be very very bad for the engine, you risk blowing a head gasket or warping your heads.

Second Overheating: You need to do a proper bleed procedure on the coolant systems in these cars. Failure to do so will allow bubbles in the system causing the car to overheat. Was the car still driven even when overheating the 2nd time?

Smoke: What colour was the smoke? (White/Blue/Black).

Cat: Cat's dont smoke. I have a bad feeling that if you have white smoke you may have blown a gasket from driving the car when it was overheating.

Hows the car run otherwise? Does it accellerate smooth? Does it fall on its face after 2k rpm? Does it run really rough(bad opti)?

 

Sounds like the thermostat is sticking. I also think the cat is supposed to get pretty hot; hence the heat shield that separates it from the floor board.

 

She told me it started overheating a few minutes into her drive down here, but she didn't want to have to go home so she kept driving. Stupid I know. I didn't know until she was already here. Every time we put coolant in it we bleed the system. On two occasions however she didn't. Once was before I told her you have to bleed them and how to and the second time she was in a hurry. She still drives her car despite the fact it's overheating. She's 16 and on vacation here in Dallas. Unless I hide her keys she's going to drive it. The smoke was white. The car runs really rough. It doesn't sound mean like it should it sounds more bubbly. Another good point my fiance brought up last night was that when we took her car to the dealership to get the heater hose replaced we would assume they filled it back up with coolant. A few days ago she had to put more in it because there was noticeably less than before. I haven't noticed any coolant leaking which leads me to believe the car is burning it. I was told if the oil looks milky it's a sign of a blown head gasket. I checked the oil, and it looks normal. Are there any other ways to check for a blown head gasket?

 

check the fans. and the waterpump. you can check the oil and if its milky then you have a blown head gasket. i just had this problem man. but when my uncle fixed it he said it was the alternator.

 

if the cat is glowing someting is wrong...

is it really down on power?

 

I think you're gasket is blown. I've had the same thing happen without milky oil, coolant is just leaking into the cylinders. I also had the same symtoms, runs rough, white smoke (= Coolant) from the exahust. The next bad thing that can happen is if she lets it sit for a while the next time on startup it can hydrolock...

Also the cat could have been taken out from the coolant OR the other way around, where the cat cloggs and the car runs like crap causing the cat and the manifolds to heat up... in itself it wont take out the engine but prolonged driving can cause some bad things...

 

She took it to some little mom and pop repair shop and they replaced the spark plugs and wires. She says its back to almost full power, but is still overheating. I don't think it would be the alternator or her battery would be dead by now. She originally thought it was the water pump, but then we noticed the cut in the heater hose and that it was spewing coolant. I guess the water pump could be bad as well, or the thermostat. How long could you drive a car like that with a blown head gasket? I mean it's a 94 with 150+ miles on it, and I'm pretty sure it's been dogged on all it's life. She herself drives like a lunatic. The car as I've said is limping pretty badly, but she doesn't take it any easier on it. She tries to drift it.....nuff said. She's had this problem for close to a month and it hasn't died yet.

 

Wow, this girl has no respect for taking care of things, does she? She is going to kill that motor for sure, and it will serve her right. You might as well just let it happen now, without wasting too much of your own time on it first.

Sounds like head gasket to me for sure, and probably warped heads by now. Car needs to be parked immediately until fixed while it still can be. You understand the hydrolock issue, right? But I do NOT think you should rush to fix it for her. Explain to her that it's too far gone and can not be relied upon to safely take her home again without major work. That is true. Buy her a bus ticket home. With a motor that old and beat on, there really isn't much point in doing head gaskets to keep it going a while longer, when it's going to need an overhaul soon anyway.

It's nice of you to want to help her, but I really don't think you should. If she is so irresponsible and you bail her out, where's the fun, err I mean lesson, in that. Maybe if she has to walk or drive a rusty Civic for a year, she will learn why you don't torture your car. Have a talk with her about red lights coming on being more important than a schedule, how coolant and oil protect thousands of dollars worth of metal, all that stuff. As for how she drive's it, you already seem to understand, but that's why only a very special, unusually responsible 16YO girl gets a Z28 in my universe. Sounds like she will be better off without it.