imariverrat

Ok here is my first post..
94 z28 LT1. New water pump and coupler, New 180 thermostat.
When in park idling, she warms up to 185-190, then when I drive, instantly the temp drops to below 160!

rngilliland

When your car isn't moving, and the A/C is off, it will warm up until the fans come on. Stock temperature is about 225 for the first fan and 235 for the second fan. I think on the later production 94s both fans come on at low speed and then high speed at the same temperatures. When you start driving the temperature drops because of the air flow. Even though your temperatures seem a little low my 94 does the same thing.

jayrod2

Sounds pretty normal, even a bit cool.

imariverrat

Well first, the temp goes well below 160 while driving, and stays there... until I park then goes back up to 210-220 range I know it's not over heating and nothing to worry about.. and Yes it is the correct thermostat, I am NOT a newbie to the mechanic end, I have had 3 older Camaros that I have built the motors the last one was a '68 with a 396/427 heads dual quads 513 gear, and so on, so these "mods" are just simple, right now, it's just a project car I picked up to tinker with. I am just trying to get a little understanding with this major cool down while driving, the heater obviously stops blowing hot and goes darn near cool!

Injuneer

Just to be clear.... 1) when you start to move, and the temp drops, the dash gauge indicates less than 160*F... AND 2) the air coming out of the heater turns from hot to sort of cool?

Are you sure you have all the air bled out of the system? That will usually make it run hot, but who knows if there is an air posket around the coolant temp sensor ini the head.

While you indicate the t'stat is the correct 180*F, and you indicate you have the correct knowledge to select the correct LT1-specific t'stat (not a Gen 1 SBC t'stat), it sounds like it may be stuck open.

imariverrat

#1- Yes #2- Yes. All air is bled from the system, the problem I am having was the reason I changed the thermostat, water pump and coupler. I was also thinking that the thermostat was stuck open, but its a Brand New Hypertech 1022 PowerStat. The first thing I did when I bought the car last week was put in a autozone thermostat, and had the same issue, so I picked up this one thinking it was a better one. same thing, so I changed the water pump and coupler... same thing... This why I am posting looking for answers??

imariverrat

I was hoping for some answers sooner than this weekend its getting cold here in chicago!

timnfxr

When you bled the cooling system did you also bleed the the heater line?

imariverrat

Yes ALL air is bled from the System.
I was having this problem when I bought the car, and the prior owner hadn't done any work to the car in 2 years. I am the first to open up the coolant system. And it IS bled properly, ALL air is out, I picked up the shop manuals for this year Camaro and after doing research in the books I am going to replace the sensor in the water pump, this one sends the info to the computer, the one in the block is for the gauge.

John95z28

This may be annoying since you've clearly bled the system correctly.
I bleed mine while warm and on ramps/jacked up in front.

That sensor is very possible though. It can get junk on it causing the wrong reading, or just plain faulty.

Injuneer

We know the coolant temp sensor in the water pump housing is for the PCM. The other one, for the temp gauge, is in the driver's side head, not the block.

Are your fans possibly running all the time? Or are they operating at the temperatures mentioned above - 226*F for first fan (or both low speed - late production) and 235*F for second fan (or both high speed)?

Have you scanned it for codes? A faulty coolant temp sensor may set a code, and there are other codes that turn on the fans full time. Or the fan will continue to run if you have the A/C or defrost on.

I apologize in advance for any way these questions may annoy you, but we ARE trying to help, not offend.

John95z28

I am confused a little, how are you measuring that temp now? by dash gauge or computer/cable software?

If the gauge is the one reading erratically then wouldn't you replace the sensor in the head/block? That is unless you are reading the temp through software and thinking the water pump sensor is faulty.