What a difference a new T-stat makes . . .

[HTSS_TR]

Originally Posted By: Donald
People should realize that T-stats are a maint. item and need to be replaced every few years. The engine needs to run at the operating temp the engineers designed it for. If its easy to replace then it should be done every few years, not when you notice something odd.


My '94 LS400 with more than 200k miles has original thermostat and water pump, so is '00 E430 with 100k miles. Both cars' coolant are getting to normal operating temperature in less than 7-8 minutes or 2-3 miles as when new, why should I change it out ? The maintenance item in coolant system is coolant fluid, I do a complete flush every 3-4 years.

Both cars have original upper and lower radiator hoses without any sign of cracks therefore I did not change them. The accessory belt on Lexus was changed only one time at 160k miles and MB's belt is original.

 

[Benzadmiral]

Originally Posted By: The Critic
How many miles do you have on the Buick? I'm at 120k on the Saturn and I still have the original thermostat. I've never considered the actual warm-up time until reading your post, perhaps that's something that I should look into as well.

What brand of thermostat did you use for the replacement?

Hi, Critic,

I've got almost 58,000 miles on the Buick, which I bought in August of '07 with about 44K on it.

Along with the other fluids, I had the Dex-Cool replaced during the first six months, but didn't think about the thermostat, because (1) I got heat inside very quickly in the sad excuse for cold weather we get down here in The Swamp, and (2) I wasn't sure at first what the operating temp was. Some of the discussions of the 3800 engine on the Bonneville and other forums I've visited made me think a 180 degree T-stat was the norm. After I found out otherwise, and my radiator blocking experiments showed me just how long the car was taking to hit that proper temp, I went ahead with it.

I'm not sure of the brand. My regular mechanic -- the car was in for rear brake pads, so I added this item to it -- ordered the 195 F. T-stat from his regular supplier.

 

[mrsilv04]

There's not many times that you'll catch me at the parts counter at the dealership.... but when I have to replace a thermostat, then that's where I'll be getting it.

 

[-Clayton-]

Well I guess I'm gonna end up replacing a brand new thermostat, Normally the gauge on my van stays exactly halfway at normal operating temperature. Since I put the new 195 degree stant in it it's been all over the place usually not even coming close to the halfway point. I've always used stant thermostat's but this is like the third one I've had trouble with maintaining a steady temperature.

What brand should I try next? I could try one from the dealer but those are probably made by stant as well.

 

[The Critic]

Originally Posted By: -Clayton-
Well I guess I'm gonna end up replacing a brand new thermostat, Normally the gauge on my van stays exactly halfway at normal operating temperature. Since I put the new 195 degree stant in it it's been all over the place usually not even coming close to the halfway point. I've always used stant thermostat's but this is like the third one I've had trouble with maintaining a steady temperature.

What brand should I try next? I could try one from the dealer but those are probably made by stant as well.

Even if the dealer one was made by Stant, it was probably built to different specifications.

Gates also makes thermostats, but I think those might be made by Stant as well.

 

[Buffman]

I always just buy whatever when it comes to t-stats for my cars, but after experiencing issues with my Subaru, I'm going to stick with OEM. Thing would get up to 1/2 mark and anything under 3000rpm it would climb to the 5/8 mark for no reason. Floor it or go 70mph and it would immediately drop.

I've never seen such a difference in T-stat design from OEM to aftermarket either. My duralast one looked almost like the napa one in the picture on right. Look at the difference. OEM Left.

 

[kingrob]

^^^ See, this is the reason I recommended the 195 Degree Stant for the Saturn. The OEM Saturn resembles the one pictured on the left, with a longer spring. The only non-OEM that has the same length that I've seen is the Stant- rumored to be the OEM T-Stat on S-series saturns in the first place. All the other ones I've seen come up short, so to speak, like the one pictured on the right.

I've used pretty much whatever brand of T-stat I could get over the years and I've never had any problems with any of them. Some go bad at 30k, some at 50k, some go 200k or more. But I've never had a problem with inaccurate or erratic operating temps after switching over.

 

[The Critic]

Originally Posted By: kingrob
^^^ See, this is the reason I recommended the 195 Degree Stant for the Saturn. The OEM Saturn resembles the one pictured on the left, with a longer spring. The only non-OEM that has the same length that I've seen is the Stant- rumored to be the OEM T-Stat on S-series saturns in the first place. All the other ones I've seen come up short, so to speak, like the one pictured on the right.


Really? I read on SaturnFans that the OE thermostat is a German one. Someone reported that they purchased a Stant 195F thermostat from AutoZone and it was German produced as well. However, when I look up the Saturn in AutoZone's online catalog, only Duralast branded thermostats appear.

 

[kingrob]

I believe the one I purchased was made in Mexico... but I bought it at AZ in favor of the Duralast, so their in-store catalog may differ from the online catalog (I know this is true of their filters and brakes).

 

[ARB1977]

My wifes Jetta takes some time to fully warm up. Makes me wonder if its the tstat.

 

[The Critic]

Originally Posted By: ARB1977
My wifes Jetta takes some time to fully warm up. Makes me wonder if its the tstat.

Most likely.

I know the VW guys usually recommend replacing the t-stat as part of the 80K timing belt service.

 

[eljefino]

If you have a choice, the stant super-stat is a clear winner. Look at the size of the copper/wax pellet compared to "standard duty" and it's no contest.

Robert Shaw is also a good name.

Incredible how something so important to longevity and economy is produced so sloppily.

My saturn s-series thermostats still open and close fine after several years, but a rubber seal deteriorates through friction letting cool water by. Am considering tracking the receipt for the next one I buy, so I can finally start cashing in on warranty.

 

[The Critic]

Originally Posted By: eljefino
If you have a choice, the stant super-stat is a clear winner. Look at the size of the copper/wax pellet compared to "standard duty" and it's no contest.

Robert Shaw is also a good name.

Incredible how something so important to longevity and economy is produced so sloppily.

My saturn s-series thermostats still open and close fine after several years, but a rubber seal deteriorates through friction letting cool water by. Am considering tracking the receipt for the next one I buy, so I can finally start cashing in on warranty.


The Super Stat isn't avaliable for the S-Series. Do you know if it's true that the Stant thermostat for the S-Series is indeed identical to the OE one?

If the rubber seal degrades after a few years, am I better off using something such as RTV instead?

 

[eljefino]

Nein, the rubber seal is on the moving part that seals up against the inside of the metal "gooseneck". Seems unique to the s-car.

I've had slightly better heat with the Stant from Advance Auto compared to whomever makes/sources (as of several years ago) the NAPA part in this application.

 

[The Critic]

The NAPA thermostats are all made by Stant, so the Advanced Auto part should be identical to the NAPA one.

So the o-ring that you are talking about is not the one on the water jacket?

 

[kingrob]

Originally Posted By: The Critic
The NAPA thermostats are all made by Stant, so the Advanced Auto part should be identical to the NAPA one.


I don't know, the NAPA t-stat may be made by Stant but the t-stat they sell is the "short" version, completely different from the regular Stant for the S-series.

 

[Jon]

I just replaced a SuperStant with a Motorrad (Motorad?) from O'Reilly Autoparts. The SuperStant claims to be one of those 'v-notch' designs which claims to be one of those that only opens a bit at a time, instead of snapping open and closed. However, I've had 2 of them and both produced really erratic temps before settling down. I'd see 220 for up to 30 seconds before it would drop (slowly).

With the motorad, that must be one quick responding unit - as temps climb *bam* the head south. And then they climb, hit a point, and *bam* head south. The overall temperature of the engine is lower but, oddly, I'm getting more heat out of my heater.

I can't really explain it except perhaps the thermostat spends more time completely closed versus partially open (superstant).

I wanted to try the Mr. Gasket style (they claim to behave like the superstants) but I heard SOO much bad stuff....

Doesn't anybody make a thermostat that does what I *want*?

I want it start to open a bit before 195F and be fully open shortly after that. I don't want it to snap open and closed. Thermostats are to keep the engine heat *in* and only let it out as necessary.

For the record, I like the subjective performance of the motorrad better than the last pair of superstants. I bought the "heavy duty" motorrad and it appear way beefier than the stant, much more like the OEM, *and* it had a weep/bobbler hole. The stant did NOT have a bobbler.

What else is there other than motorrad or stant? OEM?
I'll go OEM if I have to but what design is it (snap-open or progressive-open)?

How is it my dad's 6.0L suburban comes up to heat fairly quickly and his temp gauge doesn't wiggle a bit and mine is all over the place?

 

[sciphi]

That's one reason I went with a 180* stat in my 99 Buick LeSabre. Same engine and transmission as Benzadmiral's 03.

The stat I put in, the more expensive AZ Duralast part, seems to open progressively. Then again, I drilled a tiny hole near the rim that lets a small amount of coolant through before the stat fully opens.

According to my ScanGaugeII the temperature stays right around 175-177 when I'm cruising anywhere, so it seems to be working all right.

 

[soldierman]

I recently had to replace my radiator in my 91 mitsubshi galant. The cheap napa radiator (one year warrenty) I had installed it somewhere about 2001 and it had leaked since it was just out of warrenty. I had intsalled an OEM thermostat as well as gates belts and hoses during the same service.

Then the other day the top tank cracked. I installed a CSF all brass radaitor as it was the only 2 core that I could find for this car. The temp comes up from a cold start in about 2 miles. I also checked it with a cooking thermometer after a short drive and get 197F at the outlet hose. So I'm satisfied the OEM stat is still doing good after about 7 years.

I might add the OEM was within $2.00 of any parts store ones. The guy at the parts counter (dodge dealer) wondered why I didn't just grab one from any parts store.

OEM only for me on thermostats.

I would say the same for caps as well... But the last cap my dad bought was for his K10 chevy and he took his cap/radator tester with him and checked 3 caps right at the GM parts counter before finding a good one. The guy behind the counter couldn't belive it.

 

[Benzadmiral]

Update: The big car warms up swiftly, hitting 196 within about 3 miles/ten minutes' drive at 35-40.

I gassed up this morning, and there's no improvement in gas mileage since the last fillup. I don't know if we even get winter mix gasoline down here in The Swamp, so I can't be sure that's the reason. . . .