How difficult is it to replace the stock one with a 160?

Thanks!

al

 

If you're at all comfortable with basic mechanics, it's not a big deal. The tough part is refilling the radiator.

The thermostat is on the passenger side front of the engine, directly in the water pump. You begin by draining the radiator. Remove the cap on the overflow tank, near the battery. Then open the drain valve at the lower passenger side of the radiator. There's a plastic wingnut on the back, and a drain port on the bottom of the tank. When you turn the valve (anticlockwise as you look at it from the back of the car) about a quarter turn, you can pull it back and the coolant will drain.

So it's best to do this when the car is cool, and with a pan that will hold over 8 quarts positioned under the drain port.

Okay, you've got the coolant drained. By the way, this might be a good time to do your 5 year/150,000 mile coolant change and buy a gallon of Dex-Cool at the local parts store.

You use a pair of pliers to epand the hose clamp and slip it away from the thermostat, onto the hose.

The hose should come off with a little twisting. If it doesn't, you can use a large screwdriver to pry it (gently) away from the tstat. Secure it out of the way, and remove the two bolts that hold the tstat in. It will have 10mm heads, and it helps to have a short extension.

Once you've got the stock tstat out, apply a little grease to the groove in the new 160* stat, and press the new o-ring into the grease to hold it. Just a little grease, though.

Position the new tstat in its location, and start the bolts. Torque them to 89 inch-pounds (about 7-8 ft-lbs).

Once you've got the torque set, reconnect the hose and reposition the clamp to hold the hose.

Now fill the surge tank to about half an inch above the fill line. Start the engine, let it idle for a minute or two, and top up the tank. Put the cap back on and heat the engine to over 210* by cycling the RPMs from idle to 3000 RPM, holding each for about 30 seconds per cycle.

Once you[ve hit the temperature specified, shut down the engine and carefully remove the cap from the surge tank. Unscrew it a little, until you get a hiss from pressure bleeding off. When the hissing stops, you can remove the cap. Use a rag to keep from burning your hand. Check the fluid level, top back to about half an inch above the full line, and replace the cap. Repeat the heat-up cycle and check the level.

Let the engine cool down, refill the tank, and repeat the heat-up cycle one more time. Check the fluid level, and you should be good to go.

Took me about 45 minutes, plus the cool-down time. I live in NorCal, so I used about a 40% DexCool mix. More water (to a point) makes for better cooling, but increases the risk of freezing. I also added a bottle of Water Wetter (from Redline). Some forum members prefer Purple Ice (Royal Purple), and others don't use an additive at all.

You'll need about eight quarts of mixed coolant to refill the tank. I think I actually used a little under ten quarts total - four of DexCool and six of water. Distilled water is arguably better. If you're not way overdue on the coolant change, you should be good to go - this is the normal change procedure. If the coolant is badly discolored or otherwise looks bad, you probably want to look at the flush procedure, which takes a while.

Also, this is a good time to use an air compressor to blow all crud out of the radiator and of the A/C condensor. That will help with cooling.

Hope this helps.

 

...this gets discussed on a weekly basis, so maybe you've already found some of the past discussions with a search in the C5/Z06 Tech Forum.
If you're trying to lower your coolant temperatures with a change to a 160 thermostat, this won't give you the results you're looking for w/o additional work and considerations. At the minimum, you'll need to reprogram the cooling fan(s) on/off settings.
If you're trying to "make more horsepower" with just a thermostat change, you really need to read more of those past discussions...

 

LOL.....and bring your lunchbox because you' re gomma be there awhile!!

 

I replaced mine simply by disconnecting the hoses and putting the new one on. I lost maybe a pint of fluid which I refilled through the overflow tank. Real simple.

 

Waste of time (and money). If your going to replace it, change it with a FAIL SAFE one in the factory heat range.

 

I'm inclined to agree in terms of performance improvement. But dropping the temperature of the coolant also dropped the temperatures of the engine and A/T oils, which should help with longevity. Car was due for a coolant change, and I usually change the tstat when doing one of these, at least as I get near or over 100k miles.

Prior to the 160* tstat and reprogrammed fans (which didn't do much in my case - not much in-traffic driving), the engine oil would climb to the 230* range or over on mountain drives. Last weekend, we drove through the coast range for several hours and never saw over 205*. Transmission never indicated over 190*. Coolant would run up to 205* now and then, but usually settled to about 180* for most conditions.

No improvement noted in fuel economy. Performance seemed a bit better, but that's just as likely because I spent the previous week driving a rented Taurus around New York. But running the oil temperatures lower seems worthwhile to me - I'll probably get the value of the tstat and time back through a few thousand extra miles out of major drivetrain components.

This gets to be a religious argument. Do as you will. Modern engines are a trade-off. Less emissions from an engine running hotter. But higher temperatures make any deviation from normal more dangerous - worst case, cracked heads and so on. Mileage increased when the engines were refitted to run at 220* instead of 180* due to more complete burn, but you're closer to the point of doing damage right along. And lower temperatures = more air density = more oxygen for combustion, so more power out of each explosion. But less complete combustion. Cam profiles also affect completeness of combustion vs. power of each combustion. Lots of variables. Definitely got more out of my Vararam in terms of power - more air and colder air, compared to the stock '99 airbox.

But the Vararam was useless (as is any other induction or exhaust mod), since the addition didn't increase drivetrain longevity. It's all perspective

If I listened to all the "it will do no good" posts I've seen here, I'd have decided against any of my modifications. Any mod will suit some folks and not others, based on objectives. Got the colored flag "enhancement" for your air bridge? It does no good. For performance. If you're into appearance, what the heck. Vortech supercharger? Does no good. Speed limit is 70, can't break traction or even accelerate hard and be legal, increaes stress on engine and transmission internals - leave it off.

I'll get off the soap box. It's just frustrating that someone thinks everything is useless. May as well trade in for a Prius.

Question was how hard to change, not whether it would add 5hp and shave .1 off the quarter. To that question, I have to agree with Doug. Also with the FAIL SAFE suggestion. Not sure where to find them unless that's the default for LSx engines. All the tstats I've found are either GM OEM, or from something like Moto-Rad out of Germany. Catalogs and Summit (and NAPA) don't call it out. If you have a source you can recommend, that would be helpful.

 

What is a fail-safe tstat?

 

One that's designed to fail open, rather than closed. Most of them I've had, OEM or otherwise, since 1990 have been this way. I remember a Jeep pickup, dead of winter in Chicago. Tstat failed, and the heater didn't work worth a d@mn until I changed it - failed open, so the truck was never getting over about 90*F on those 15*F mornings. Maybe not even that.

The alternative is the old school. It's closed when the engine is cold. If it fails, it stays closed. Took out the engine on my Dad's '57 Chevy 210 Delray back in about 1962 on the Harbor Freeway in Los Angeles. He was already in traffic when the car overheated, and before he could get off the road, damage occurred...

Oh, and I use tstat to shorten thermostat. Typing is getting harder with the arthritis...

 

AGAIN, a colder thermostat only opens SOONER. Your steady state engine temp will NOT change-it will just take a little longer to get some heat inside and your mileage will suffer a little. Once it's open-it's no different than the one you had in there to start with.

 

Not totally true. I changed mine out before I got my exhaust and tune done. Originally it ran at 220 degrees just sitting and on the road. I put the 160 in and on the road I read 174, but at idle it would still creep up. Once I got the fans turned down, which is stupid simple, by a tuner, it runs no hotter then 190.

 

Well in my case that would be stupid. It is set that high for emissions purposes and I removed them all. So now I would be running a modified car, with a hot motor all of the time....doesn't makes since! I say worth the money....it also brings down your oil temp some!

 

except that it will close back down if the temp goes under the rated temp of the tstat....So if it is a 190, if the coolant goes below 190, the tstat closes to raise the temp. and as I said before, my steady state engine temp never goes above 190 now that I have the 160 and the fans adjusted. So it does change the steady state engine temp!

 

BowTieRocket,

Read the section in your Owner's Manual called "Engine Over Temp Protection Mode" .... you won't crack heads or other such dire consequences in a "modern day" GM vehicle. If the engine reaches a pre-set heat level the PCM goes into "limp home" mode to protect the engine. One car magazine tested a Caddy by draining ALL of the coolant from it and drove it 300 (or more, I don't remember the exact number) miles with no ill effects in this mode.

 

whatever you choose to do when draining and refilling the coolant you must make sure there are no air pockets.(very important) they make a tool mine is called an Air Lift. it makes a vacuum of the cooling system then after this is done it sucks in the coolant till it full. no air pockets no running the car and getting it hot its a great tool as i am a mechanic and all engines have different ways of bleeding the cooling system for air pockets this one is the way to go.just a suggestion.