my dad just got a 96 all stock with auto and lt1,he says runs great but that the cooling fans do not come on at all and he has checked both fuses and that the engine gets to 260 but cools at speeds even as low as 10 mph.?Also when he floors it it refuses to upshift unless he lets off the gas.any help would be appreciated as this is a little different than my car.

 

Tons of threads on this. Start motor, turn on AC, if fans come on then they obviously work. Check at right front of radiator cover, look in there with flashlight for debris and clean as needed. Use the bleeder screw on t/stat housing to bleed air out of system, being careful not to drip coolant down onto the optispark. Factory fan settings are primary on @ 227*f and aux on at 236*f, while watching the digital gauge. If none of these 'fix' it get back to us.

If he floors it it won't up shift until near redline (5700), that is what it is supposed to do.

 

thanks I will see if he can post for himself.I think he means that it wont shift at all unless he lets up.?

 

Here's the fan schematic for a '96... the fan relays are mounted on the drivers side radiator shroud, can't miss 'em there's three mounted in close proximity to each other in a bundle.



Use test jumper to ground some terminals here, there should be a nice little ground near the horn on that side. Clip one end to ground, use a paper clip unfolded clipped to the other end of the jumper to go into the underside of the relay plugs. We're trying to ground some terminals while the relays are still plugged into their sockets, so what ever way works best for you.

With the key turned to "run" ground the dark green wire's terminal on relay #1, the fans should run at low speed.

Then with that jumper still grounding that terminal, do the same with another jumper and paper clip for the dark blue wire's terminal, it can be found on either relay #2 or #3 it doesn't matter which one. The fans should then run at high speed.

Make sure to check fan fuse #29 also, it supplies ignition voltage to the relay coils. It's in the right side of the dash on the passenger side.



If the fans check out by all means do the things suggested above in the earlier post, these cars have an area that does clog up with debris between the radiator and condenser, sometimes the front of the condenser when looking from under the front of the car in the air scoop area gets nasty also.

If that turns out to be clean and not an issue, run the car and let it idle. Hit the gauges button until your looking at the coolant temperature on the digital display.

Let it continue to idle until it gets to 230 and the fan(s) should come on, don't let it go too much further than that if they don't come on. Maybe 240 at the MOST. When you see the digital gauge displaying 225 see if the analog gauge is reading about the same.

I'm assuming when you say it goes to 260 you're looking at the analog gauge? This is already too hot and the fans should have come on before that. Don't let anyone tell you this is normal, and they will, because this is not normal! If the fans are programmed to come on at 230 or 228 the temperature should go down and we should NEVER see 260 on either gauge!

Yes we have had MANY heated discussions about the cooling or lack thereof in LT1 cars. I want to see if there is really a problem with all these cars or we just think it's too hot.

Like I said earlier, compare the two readings, if the digital gauge (the one the PCM uses for fan control) is reading much lower than the analog gauge, I believe we have a sender that is falling out of calibration on many of these cars and sending erroneously low temperature readings. Therefore the PCM thinks the engine is cooler than what it actually is and sits there and waits until it sees what it believes to be 230. Meanwhile the correct temperature on the analog gauge is going past 250 to 260. TOO FREAKIN HOT!!!

If you find this to be the case ask your Dad if he would be willing to buy a new sender, it's the one installed into the water pump body. I'm truly starting to believe these senders are going bad causing many of us LT1 owners to think we need to take additional cooling steps or remedies.

The accuracy of this sender can't be stressed enough so don't buy a cheapie, get a new factory correct GM sender for the car.

I had this problem and may have masked the problem by installing a 160 t-stat and programming my fans to come on sooner. This did bring the temperatures down dramatically however now I can't see for myself if a new sender would have cured my problem without undoing a lot of stuff. Furthermore I don't have any way of setting my fans back to stock settings. They were changed by PCMforless.

 

WELL SAID ALLT4!!!

Billy

 

thanks a lot guys,I will tell my dad

 

I am new but already hooked. this is really great
Thanks to all
John Aguilera

 

I feel like GM intentionally sabotaged their cars by programming the cooling fan(s) to turn on at 226 to 238 degrees. Even though its for emissions purposes, that is still much hotter than it should be. No wonder why many V8 cars of the late 80 - mid 90s had leaky valve cover/intake/head gaskets. No wonder why heater hoses in GM vehicles blew so often.