AlaskaZ28

Hi

I'm new to the forums and to 4th gen Camaros too. I just picked up a 95 Z28 6 speed from the original owner with a service history. Pretty excited and really wishing it weren't winter. It has higher mileage, but it's obviously been well taken care of.

So here's my question (and I've searched the forums and haven't found an obvious answer), haven't driven it much, but when I got it the guy I bought it from mentioned that the temp sensor was bad and hence it wasn't getting a temp reading - he gave me a new sensor to put in and even offered to do it, but I said I'd take care of it.

I got around to putting the sensor in, filled the coolant I lost doing it, took it for a spin and the gauge when up to about 240 and leveled out. So, checked my coolant level, which was fine, the upper radiator hose has flow, so I'm assuming my thermostat is fine, bled the system and didn't really get any air bubbles - so I'm kinda stumped. Could it be that the new sensor is faulty? Has anyone ever had that happen? Or is there something else, more major that I should be checking? It seems to drive fine (no smoking, etc.) other than maybe needing a tune-up (stumbles a bit under a load at real low rpms).

Thanks!!

Injuneer

You can check the sensor, using Shoebox's procedure. He also has some good info on how the system operates:

4th Gen LT1 F-body Tech Articles - Test Temp Sensors

4th Gen LT1 F-body Tech Articles - Cooling System Operation

In any case, normal operating temp, with the stock 180-degF t'stat should be near the middle of the gauge (~210-degF) at idle. Should drop lower with air velocity through the radiator while cruising. Note that with stock programming, the fans come on at low speed at 226-degF, and high speed at 235-degF.

I'll copy this to the correct forum, since there isn't typically a lot of tech response in the "New Member Intro" forum.

AlaskaZ28

Thanks for the link. Is there anything else I should check in terms of the cooling system that might be causing the problem? I suppose a better way of phrasing that would, are LT1 cooling systems prone to any particularly usual problems that might be the cause of my woes?

Thanks -

Injuneer

The most common problem is air in the system. That's why you need to check the level in the radiator, not in the reservoir. The unique "reverse flow" system provides a huge advantage on head cooling, but it's a bit ornery at times.

The second link above has a lot of info.

Note that the LT1 takes a thermostat made specifically for the LT1 engine, and not the same one used in the typical small block Chevy engine.

http://shbox.com/1/tstat.jpg

A problem that seems to be showing up more frequently as these engines show their age - the splined drive shaft for the water pump may strip it's teeth.

Take the time to read through Shoebox's complete guide.

For future reference, start here when you need info on the LT1/4th Gen:

4th Gen LT1 F-Body Tech Aids

8cylinders>4

It definitely mentions this in the articles posted and maybe you did it this way and didn't mention.

I have drained and refilled my cooling system several times and have never had an issue with air in my system.

Did you find or realize there are two air bleeders? One on top of the thermostat housing and another on the heater hose close to the alternator. Since your engine does apparently stay somewhat cool you must have some flow. For that, I would make sure you have coolant in your overflow, then get your engine warmed up enough that the thermostat should be open. once its warmed up you should have pressure in your system and radiator hoses should be pretty hard.

Now you just crack the bleeders open until you get a good stream of coolant, start with the lowest one on the thermostat housing, then move to the upper, once you get the air out, don't open the radiator cap, as it cools off it should draw the coolant back into the radiator.

Another tip, if you happen to have an empty system like you are flushing or draining and refilling with fresh coolant, and easy way to avoid a lot of air pockets is to remove the thermostat and refill the system as high as you can from there. reinstall the thermostat and pour the rest into the radiator, leave both bleeds open as you're refilling and close each one as coolant starts spilling out.

Also right below the filler neck on the radiator is where the steam pipe connects, you should get a smooth stream from this once most/all the air is removed from the system.

This whole setup gets a bad rep for being air pocket prone but if you use the bleeders correctly you should never have any problems