I'll admit it, I'm pretty confused about why GM makes so many different physical sizes of thermostats that have identical temp ratings. Makes no sense to me. But hey, I just machined what the engineers wanted, until "engineering changes" forced an alteration of the part, or a completely new part had to be made. Didn't the Gen 1 SBC use the same physically sized T-stats for nearly 50 years? Anyway, here's the issue. I have had a 160° T-stat in my C5 for years. I want to change that to a 174° stat from Lingenfelter. I also have an Edelbrock 8896 water pump. I'm also running the separate stat and neck. Summit said the LPE stat would work. So I had them send it. Guess what-Doesnt fit!! Too large of diameter for the rubber seal to fit in the neck!! I called Summit, who I must say, were great. They told me to keep the 174° stat, but told me that's the only 174° stat LPE makes. So, it either fits, or it doesn't. In my case, it doesnt!!! So, they told me a 180° stat was the next closest stat, and sent me a 180° stat.......That STILL doesn't fit!!!! The part# is L310055204. I think the # is right, but the stat is even larger than the 174° that was also too big. Plus, it says 203°F (!!) on it, so even if it did fit, it's WAY too hot!! Maybe the right box, but the wrong part inside?? HELP!!!!!!

 

The T stat is not that different between a 160 or 180 The key to correct cooling is WHEN the fans come on !!! Stock fan settings are horrible Something like # 1 on at 219 and # 2 on at 235 !!!!! way too late
Even with a 160 the eng will not run that cold set the fans something like this
#1 on at 204 off at 195
#2 on at 210 off at 205
This will make your eng run about 185 to 195 all the time and will also cool your trans temp if you have an auto trans How can you cool an auto trans below 200* if the radiator temp is 219 ?? as the trans fluid is also cooled via a cooler built into the radiator ?

 

I have a custom tune. Way past that stage. I'm trying to find a stat that is the same physical size as my 160°, but in a 174° or 180° rating. Sorry if I wasn't clear. I'm trying to raise my minimum temps, slightly. My old, correct sized stat measures around 2.280" with the seal in place. The 174° is around 2.370" w/seal, and the supposed 180°, which is stamped 203°(!) is around 2.580" w/seal, plus its about 3/8" shorter than the correct 160° stat. There is no way the LPE 174° will work, and neither will the 203°, which I wouldn't run if it DID fit! A 203° stat is way too hot. Thank you for responding, but the physical size is my biggest problem, that and I think the the L310055204 box, which is supposed to contain a 180° stat, had a 203° stat. Anyone know if that L310055204 is supposed to be a 180° stat? That's what I'm finding online, so far. Maybe just the incorrect part in the correct box? Sheesh, what a vegetable soup of stats!!!

 

Anyone???? Any help greatly appreciated!!

 

Go to the parts store with your housing and see if a stock stat fits.
You do have a gm housing, correct?
Post 2000 I believe gm changed from the one piece setup to the separate stat and housing. If I had one here I’d measure the opening, but I don’t.
Also, is the gasket the issue? Or the actual stat itself?

I have the 160 as well. It’s fine at slow speeds as the fans control the temp. But freeway when it’s cool out it runs a little cold. I never saw any difference between the 180 and 203 under any conditions.

I have a Dewitt’s radiator.

 

I bought the Mr Gasket 180° for my 2004, but have not installed yet…. In any case, this stat appears to be the same size as your old one.

 

Yes, I have the GM housing. It's both the stat and the seal. I also have the DeWitts radiator. The only problem with the auto parts stores is they don't have what I want. I already know the dimensions I need. I have the 160° dimensions as listed. But they don't have the temp I want. Maybe I'll try a couple different auto parts stores than the ones Ive been to. Thanks, Ron.

 

YES!! You are right. It appears it has the same dims as the one I need. Now, if I can find a 174° in those dims, I'd be all set. I guess a 180° would be OK, but I'd prefer the 174° for my setup. Thanks for the assist......

 

I sent an email to Katech. I believe they have modified the OEM stats for different opening temps.

 

Katech replied they don’t have stats for ls engines, only LT engines.

 

Sounds like summit was sending you thermostats for 2009-2013 corvettes. Only 160 and 180 are available for the size you need

 

I don't understand what core problem you have, OP. Why specifically do you need a non-factory-stock thermostat on your car? And now, why specifically do you need to change it? Are you seeing temperatures that are too cold? Is it taking too long to warm up?

Ideally, here's how your cooling system works: you turn the car on from cold; coolant and oil temperature comes up as fast as possible to the correct temperatures, and then it stays flat forever. That's the ideal. In reality the temperature goes up or down as you drive depending on how much work you're asking it to do. The stock thermostat is designed to 1) get you up to temp as fast as possible, and 2) keep you at that temp as much as possible. Once a thermostat is fully open, it cannot possibly do more work than it already is in aiding your fluid flow - so if you are seeing overheating problems, 160 or 180 or 200 won't make a lick of difference. If you are on the other hand seeing too-cold temperatures (like 160F) then certainly going back to stock temp (186.8F, if google is correct) will help you.

So now the follow-up question is: are you using a stock size thermostat or are you using some strange size thermostat in an aftermarket housing of some sort? If you are using a stock size thermostat ... and if you don't have forced induction ... spend $11 with acdelco and get a stock replacement. Better yet, if you are not seeing your car take too long to warm up and you are not seeing your coolant temperatures too low in the steady-state, then don't make any changes at all and don't fix what ain't broke. 160F is too cold to daily in the winter where there is actually winter, but it's fine if you live and drive in a warmer climate; it'll just take an extra minute or three to get to the proper final temp, which is likely to be in the 190-200F range.

Nothing to do with fans, either. Fans have nothing to do with a 160F or 180F thermostat.

 

It does run a bit cool. Thank you for trying to help, but I have a solid understanding of cooling system operation. This is a part#/packaging issue, and also on GM for whipping up a concoction of thermostat vegetable soup, which didn't have to happen. Same with the oil pump O-ring fiasco. I digress.......

 

OK, Summit, who has been excellent, verified I got the right part# BOX, with the wrong stat inside!! Supplier error. They're sending a 3rd stat, and requesting the box be opened to verify it's a 180° stat, NOT the 203° stat I received last time. Hopefully, the 3rd time will be the charm, as they say......