[PURPLEPEARLCAPRICE]

Plan on picking up this Mr.Gasket 160° thermostat for my 94 PPMCC with the 4.3 because the other day she spiked red and the check gauges light came on while I was smoking a cigarette outside of the car....first time it's ever done it and I immediately shut it off...let it cool down....it puked...it's fine now...topped it off after it cooled down and let it idle with the cap off for about a hour then let it cool down with the cap off and there isnt any air pockets...I will be replacing hoses soon and also plan on doing a Thermocure radiator flush even though my coolant doesn't look that bad...it's also got a brand new water pump and I tested the coolant temperature sensor....ever since then things seem to be fine but I just don't feel comfortable with how hot the engine gets before the fans decide to operate....can I just put the 160° stat in and call it good or will I have to program the fans like I read in a few posts so far...I'll program the ECU if absolutely necessary but just curious and wondering who would do the programming since I'm in Michigan....thank you guys for taking the time to read this!

 

[Marky Dissod]

... but I just don't feel comfortable with how hot the engine gets before the fans decide to operate

No one should feel comfortable with GM's OE fan-on thresholds for IronBlock LT1s (and L99s) if they want to keep their cars as long as possible.

... can I just put the 160°F stat in and call it good?

You COULD, but it won't address your discomfort.
The fans & the thermostat operate independently of each other.

... or will I have to program the fans like I read in a few posts so far?
I'll program the ECU if absolutely necessary but just curious and wondering who would do the programming since I'm in Michigan ...

If every cooling system component is brand new, regardless of the thermostat opening temp, GM's OE programming will still turn on the primary fan @ 225°F, & the secondary fan @ 232°F - not before.
If you want the radiator fans to come on at lower temps, either reprogram the pcm in your car, or install a different pcm programmed (for your car of course), with lower fan-on thresholds.

 

[jayoldschool]

Keep the 180, change the rad cap (which is on the tank, not the rad). Shut your car off when it's smoke time, lol

 

[Fred Kiehl]

Stop smoking it is bad for your car's health.

 

[Z09B4U]

the other day she spiked red and the check gauges light came on while I was smoking a cigarette outside of the car

Unless it was well above 100 degF in bright sun the car has a problem. A new thermostat and rad cap used to be a good bet but these days you might want to test the new ones.

A functioning 160 or 180 thermostat would be fully open long before a car overheats. The OEM fan on temperature can be debated BUT both fans would have been turned on long before the car overheated at idle. Cops and cabs idled long periods with the factory programming and did not overheat when idling when properly maintained.

Clean radiator and A/C fins, all the factory parts in place, and radiator fans that spin should spin easily are the first thing to check.

You can go down the rabbit hole of modifying the cooling system AFTER you find out why it could not keep a idling car from overheating in May.

Every one talks about the fan turn on temperatures. What is more important is the turn off temperature. In hot conditions the fans "short cycle" going on-off quickly. Better programming gets the fans to run longer so the fans do not get exposed to the extreme wear caused by startup. Longer fan on times work better for stop and go traffic as well.

I'll program the ECU if absolutely necessary but just curious and wondering who would do the programming since I'm in Michigan

You could do it your self. TunerCat($) or Eehack(free) and a cable are the starting point. This allows you to try stratagies and see how they work in your environment/driving style. If some one here will not help there are other forums that are PCM programming orientated.

 

[1slow96]

160 stat is easily accomplished ,and does no harm. Regardless of fan turn on/off temps. However temps will still climb if car is sitting still with engine running. A manual override fan switch for one/both fans is also a popular mod.

 

[jayoldschool]

160 stat is easily accomplished ,and does no harm.

Some would say that it is too cool for the LT1 to run efficiently. OBD2 cars will actually set a code for running under temp. Common issue on VWs..

 

[Z09B4U]

Some would say that it is too cool for the LT1 to run efficiently. OBD2 cars will actually set a code for running under temp. Common issue on VWs..

On OBD2 cars no programming and a 160 can prevent the "ready" data needed for emission testing.

 

[Marky Dissod]

You can go down the rabbit hole of modifying the cooling system AFTER you find out why it could not keep a idling car from overheating in May.

Despite how close GM's OE fan-on temps are to overheating, if the rest of the cooling system works WELL, the fans will (barely) prevent overheating. It'll still run much hotter than need be.

Since they did not, I'd suspect:
the fan motors (how old are they?)
the radiator (how old is it? Is it corroded inside?)
the coolant ('doesn't look that bad' is a BAD sign - the engine and radiator may need several backflushes SEPARATELY)
the wiring / relays for the fan motors (check relays for signs of melting)
or any of the above in combination.

 

[1slow96]

160 stats begin to open at 160. My engine averages 180-185 degrees.
With a 180 stat? 195 was a cool as it ever ran. Usually 200-205 unless idling ,or in traffic

 

[MWP]

In your "new to the forum" thread I didn't see any engine compartment shots (nice color/body, by the way!), but if the radiator is original then it is overdue for replacement.

 

[PURPLEPEARLCAPRICE]

In your "new to the forum" thread I didn't see any engine compartment shots (nice color/body, by the way!), but if the radiator is original then it is overdue for replacement.

Thank you very much for the compliment! As well as everyone's help here!...over the past couple days after this happened and topping it off everything has been fine after topping it back off...tested the coolant at work and it tests good...this is just for now until I get my bottle of Thermocure hoses and 160° thermostat but I'm taking everything everyone said into consideration...I will post pictures of my engine bay for you guys below and in my intro post...I also have a flush machine at my shop so I will be pulling all the coolant out filling with water pulling it back out and then adding Thermocure and water for the flush.

 

[GoremanX]

The OEM fan on temperature can be debated BUT both fans would have been turned on long before the car overheated at idle. Cops and cabs idled long periods with the factory programming and did not overheat when idling when properly maintained.

Didn't cops and cabs have a mechanical primary fan and electric secondary fan? That mechanical fan makes a huge difference. It's always spinning, even if it's mostly just free-wheeling until the clutch engages. And the clutch never really lets go completely. So the comparison doesn't really apply.

 

[AP9]

Didn't cops and cabs have a mechanical primary fan and electric secondary fan? That mechanical fan makes a huge difference. It's always spinning, even if it's mostly just free-wheeling until the clutch engages. And the clutch never really lets go completely. So the comparison doesn't really apply.

Exactly what I was about to say. SEO 9C1 included RPO V08, using a mechanical engine-driven primary fan, and electric secondary. Also, notice how police vehicles that are parked idling for very long periods of time often times have the hood popped slightly.

 

[GoremanX]

I'm a huge fan (pun intended) of mechanical fans for most longitudinal engines. But switching from electric to mechanical isn't intuitive. I tend to agree that the factory programming for dual electric fans is... lacking. Reprogramming them isn't terribly difficult and can make a nice difference. I like a fan that runs at its highest speed by 195f. There's never any need for coolant temp to go higher than that.

 

[PURPLEPEARLCAPRICE]

Here's the pictures of the engine compartment!

 

[AP9]

Looks very clean under the hood. I'd verify correct fan operation first.
1. While engine is running, temporarily unplug the temperature switch and both fans should turn on within seconds.
2. When the vehicle is warmed up, turn the A/C on. Assuming your A/C is in proper working condition, one fan should turn on if you're at idle or driving at low speeds.

Let us know how the flush goes, would be curious if this was all caused by junk in radiator/block/core.

 

[Z09B4U]

Didn't cops and cabs have a mechanical primary fan and electric secondary fan?

I am not sure which play ground you are getting your info from. The only LT1 that got the mechanical fan was the towing packages. Look up a 9C1 police brochure. It will list the electric fans as a feature. The fan relay TSB is also for police and would make no sense for a primary mechanical fan.

 

[GoremanX]

It was a question, not a statement, because I didn't know for sure. Thank you for clarifying, regardless of the snark.

 

[Z09B4U]

https://www.xr793.com/wp-content/uploads/2017/07/1995-Chevrolet-Caprice-Police-Package.pdf