Purpose for different t-stat settings?

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I have an 84 Caprice coupe that I am looking to get running again. I have not had it on the road since 2006 and the kids really want me to get it running. They think it will be fun to take to the drive in.
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Anyway, I got it started easily enough today, but I noticed what looks like a small coolant leak coming from where the t-stat is located. I figure it is most likely just a gasket that is leaking, but I'll probably just replace the t-stat while I have it apart anyway. So my question is what's the purpose of t-stats with different temp settings? When I look up replacement ones I see the OE is 195 degrees, but they also sell 180 and 165. What would be the reasoning for using one of the ones that open at a lower temp?

Thanks,
Ryan
 
Use the OEM. Using a cooler thermostat can lead to oil sludge and other maladies. Why don't you put the thermostat in pot of water and if it opens at ~190, use it with a new gasket.
 
I believe back in the day cooler stats were the norm. Probably due to oil issues, possibly because of cooling issues. Then emissions came into play, and hotter running engines ran cleaner. Thus the oems changed.

I recall reading in the mags how one could gain a few hp from dropping from a 195 to a 160. Cooler air intake temps. At least until the engine was pushed, and got warm anyhow.

Today I am not sure there is a good reason to run cooler than oem, unless if a particular motor just does not running at that temp. In your application I would stick with oem.
 
You can get less pinging with a cooler engine but with all the tradeoffs listed above.

You run the risk of having a corroded t-stat gooseneck; I'd have some RTV on hand or at least a quality thick gasket.
 
use the 190. Check the old one as suggested by Oil Changer. I even test new ones, i have had bad new ones before, that opened way too early. I drill a small 1/16 inch hole in mine for air bubbles to go through when flushing.
The older colder stats were from the 60's era, high compression and iron heads, you didn't want detonation so you kept the heads cooler. Probably caused a lot of sludge.
 
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Often Carbureated cars don't like hotter stats. Can lead to vapor lock especially with today's alcohol fuels. There's only a a handfull of stat sizes so another temp stat will fit you car
 
Caprice Coupes are kinda rare any more! Pictures?

At 30+ years old & only 28,000 you have a ton of work to do.

If the T-stat housing gasket rotted out...You most likely have other cooling system issues from the coolant not being changed on a time basis.

Sitting for years at a time is HARD on a vehicle, Mostly the Fuel & Cooling systems.
 
No one mentioned the most publicized and actually PROVEN reason to run a hotter stat: Wear.

Ford published the data in the 60's showing that hotter cylinder walls wore less.

But this may not even be applicable anymore as oils have changed just a bit!

Specialized apps like my sig car benefit greatly from a cooler stat because of extremely sensitive knock sensor programming. The KS retards timing significantly above 185 degree coolant temp. But for most cars hotter is better in many ways...
 
The car cover blew off of it last fall and it got covered with leaves. It's pretty filthy right now. Once I get it cleaned up I can post pics. It's actually in really good condition. The interior is pristine. The body is in good shape. A couple little dings here and there where my grandmother had clipped the side of the garage when she was backing out, but nothing serious.

I would gather they are rare now. From what I read just over 19k coupes were produced for the 1984 model year. I can't imaging there are too many left by now. I even still have the original window sticker from the dealer.

I know it's not high value or a real "classic" car, but I like it and that's all the counts right?
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I wish I could get a hotter stat than OE. Both my Hyundais have 180F and I cannot find any AM ones with higher ratings.
 
Originally Posted By: SHOZ
I wish I could get a hotter stat than OE. Both my Hyundais have 180F and I cannot find any AM ones with higher ratings.


It's possible that 180 at the outlet means 195 (or more) at the cylinder walls, or whatever "bias" the engineers came up with.
 
Originally Posted By: SteveSRT8
Ford published the data in the 60's showing that hotter cylinder walls wore less.

But this may not even be applicable anymore as oils have changed just a bit!


Yeah, it may not be. Our Honda's engine runs at about 190*F, and our Acura's engine runs at about 180*F. I understand that many Nissans have (or had) 170*F thermostats.

It seems common for American-branded engines to run pretty warm...like in the 200-220*F range...while Japanese-branded engines seem to be designed to run cooler.

Both approaches are proven durable, though... The moral of the story is to use what the factory installed (unless you have a very specific reason otherwise, such as performance tuning, etc).
 
Higher engine temperatures can mean fuel burns more completely, and that is why as smog laws were introduced, some cars got 195 degree thermostats.
 
I use to have a Festiva that was a Mazda 121 clone with a 1.3L motor. It had a t-stat that had a mini t-stat built in.

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Originally Posted By: eljefino
Originally Posted By: SHOZ
I wish I could get a hotter stat than OE. Both my Hyundais have 180F and I cannot find any AM ones with higher ratings.


It's possible that 180 at the outlet means 195 (or more) at the cylinder walls, or whatever "bias" the engineers came up with.


This! My Kia also uses a 180F t-stat, which seems low by today's standards. But as eljefino said, 180 at the t-stat may mean much higher temps elsewhere. Who knows what the engineers had in mind, but I'd rather not second guess them with nothing to back my assumptions up.
 
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