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Old 01-30-2007, 11:51 PM   #1
hondaman
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Thermostat related question...

So, here's the deal.

Most of you know my car, 1997 Buick LeSabre, etc. etc...if you really don't remember the information I'd be more than happy to pass it along again.

Seeing as how my car has been running at what looks like 140* on the temperature gauge, I thought perhaps I had a thermostat that was stuck open. It took it quite a while to warm up, and the temperature could dip as low as 120* on a particularly chilly day. Allowed to idle, the temperature would climb up to around 210 or so, whereupon the radiator fans would come on and lower the temp down to 140 again. Anyway...

So today I changed the thermostat out (got a 180*, old one was a 195*) and I noticed it did get warmer upon the initial startup. Quite warm in fact, it shot up to around 230 and then cooled down to 140* and flunctuated for a while. While taking it to and from work I noticed it was still flunctuating, though not nearly as much. It runs up to about 170-180* and then drops back to 140*, repeatedly.

Checked for coolant leaks, I did a good job sealing the new thermostat and the upper radiator hose (though I did spill a little initially upon removal onto the exhaust, funky smell) and there are none.

I didn't drain the radiator, I used a siphon and lowered it to below the level of the upper radiator hose, worked well. Put most directly back into the radiator until it was full, and the rest back into the coolant recovery tank. After my trip from work, I noticed the coolant levels were back to where they were before changing thermostats.

In any event, I'm giving you all this information to help answer the question that I'm finally getting to. Which is, is this flunctuation normal? It's calmed down a bit, but will it finally stay at a certain temperature? And finally, might there be something wrong with the new thermostat? I find it odd that it's cooling itself down to 140*. At least it's not staying there like the other one.

I've never had to change a thermostat before so all this is new to me.

Any info that can be given is greatly appreciated.
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Old 01-31-2007, 12:03 AM   #2
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Quote:
Originally Posted by hondaman
So, here's the deal.

Most of you know my car, 1997 Buick LeSabre, etc. etc...if you really don't remember the information I'd be more than happy to pass it along again.

Seeing as how my car has been running at what looks like 140* on the temperature gauge, I thought perhaps I had a thermostat that was stuck open. It took it quite a while to warm up, and the temperature could dip as low as 120* on a particularly chilly day. Allowed to idle, the temperature would climb up to around 210 or so, whereupon the radiator fans would come on and lower the temp down to 140 again. Anyway...

So today I changed the thermostat out (got a 180*, old one was a 195*) and I noticed it did get warmer upon the initial startup. Quite warm in fact, it shot up to around 230 and then cooled down to 140* and flunctuated for a while. While taking it to and from work I noticed it was still flunctuating, though not nearly as much. It runs up to about 170-180* and then drops back to 140*, repeatedly.

Checked for coolant leaks, I did a good job sealing the new thermostat and the upper radiator hose (though I did spill a little initially upon removal onto the exhaust, funky smell) and there are none.

I didn't drain the radiator, I used a siphon and lowered it to below the level of the upper radiator hose, worked well. Put most directly back into the radiator until it was full, and the rest back into the coolant recovery tank. After my trip from work, I noticed the coolant levels were back to where they were before changing thermostats.

In any event, I'm giving you all this information to help answer the question that I'm finally getting to. Which is, is this flunctuation normal? It's calmed down a bit, but will it finally stay at a certain temperature? And finally, might there be something wrong with the new thermostat? I find it odd that it's cooling itself down to 140*. At least it's not staying there like the other one.

I've never had to change a thermostat before so all this is new to me.

Any info that can be given is greatly appreciated.
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1. Pay no attention to the guage. The factory guages in most cars are inaccurate at best and useless at worst. Use it only as an indication of what you've learned to be normal compared to too high, too low, etc. Fluctuation is not normal.

2. Why on earth would you put a 180 in it? It came from the factory with a 195 for a reason. Put a 195 back in ASAP.

3. The cooling system in your car is notoriously hard to bleed. Did you follow the proper procedures. If you have and it continues to fluctuate slightly, you still have air in the system. The best way to get rid of the air after a reasonably good bleed is to simply drive it. DO NOT under any circumstanses make the rookie mistake of taking of the radiator cap to look at the level. You have a closed cooling system for a reason... leave it that way.

4. I know that replacing a t-stat seems like a cool thing to do, especially when you can use one of the wrong temp, but did you ever consider that your only problem might be a faulty temperature sending unit?
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Old 01-31-2007, 12:18 AM   #3
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Quote:
Originally Posted by vwhobo
1. Pay no attention to the guage. The factory guages in most cars are inaccurate at best and useless at worst. Use it only as an indication of what you've learned to be normal compared to too high, too low, etc. Fluctuation is not normal.

2. Why on earth would you put a 180 in it? It came from the factory with a 195 for a reason. Put a 195 back in ASAP.

3. The cooling system in your car is notoriously hard to bleed. Did you follow the proper procedures. If you have and it continues to fluctuate slightly, you still have air in the system. The best way to get rid of the air after a reasonably good bleed is to simply drive it. DO NOT under any circumstanses make the rookie mistake of taking of the radiator cap to look at the level. You have a closed cooling system for a reason... leave it that way.

4. I know that replacing a t-stat seems like a cool thing to do, especially when you can use one of the wrong temp, but did you ever consider that your only problem might be a faulty temperature sending unit?

1. Gotcha.

2. Someone who I thought knew what they were talking about said to get a 180*, guess they were mistaken. I wasn't aware that the stock thermostat was a 195 until I had it out and in my hand.

3. You're right about that, draining the thing to change the water pump took longer than changing the pump itself. In any event, I followed my Hayne's manual so I'm going to assume that's a yes. I have noticed the flunctuations are becoming more and more subdued (I've only driven a grand total of maybe 15 miles since changing the part) so, yes.

4. That I did, but I also encountered another symptom of a failed thermostat. The heater took a long time to come on (it's automatic and won't start blowing air until it's warm). Since the thermostat change, it comes on within five minutes of startup. In any event, the 180 is running hotter than the 195 was, so my guess is that it was dead.
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Old 01-31-2007, 02:37 AM   #4
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An ~82°C stat instead of the factory ~90°C is asking for problems, but then again you've been driving around with ~60°C, so at least you may have arrested some of the bore reeming and sludge production.

How does the gauge behave with the heater off? Put the stat in the correct way around? Does stat have a burp valve?
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Old 01-31-2007, 05:04 AM   #5
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Quote:
Originally Posted by Wally
An ~82C stat instead of the factory ~90C is asking for problems, but then again you've been driving around with ~60C, so at least you may have arrested some of the bore reeming and sludge production.

How does the gauge behave with the heater off? Put the stat in the correct way around? Does stat have a burp valve?
Yeah, I hate to rip the thing off again but I might have to do that soon. Probably best to find out what's going on this time though so I don't do it again!

1. I haven't a clue. I'll try to see the next time I take it out tomorrow. Fortunately it doesn't flunctuate too much so I feel comfortable driving it.

2. Haha, I sure did. With the spring end down in the engine block. Checked twice to make sure.

3. That it does. It says on the box "Built in bypass valve to remove air pockets." Hopefully it will.

I tried bleeding the system once more through the bleeder screw on top of the thermostat housing, just got pure coolant. Went for a 2-3 mile drive to get it up to as close to operating temperatures as possible, repeated, same deal. I realize the first try was probably pointless but hey, just for kicks. Was still flunctuating all the while.

I think perhaps tomorrow I'll go pick up another 195. I can probably get it in there tomorrow afternoon, we'll see how it goes as far as if it flunctuates and all that. I'll try to get one with a similar bypass valve as the 180.
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Old 01-31-2007, 05:49 PM   #6
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Alrighty.

I swapped out the 180 for a Stant heavy duty 195. It only took me 45 minutes as opposed to yesterday's hour and a half, so it would appear that if nothing else, yesterday's venture was educational.

I think I bled the system better this time too, it didn't go crazy initially like it did last time. It's still fluctuating very slowly, but through a narrow range on the gauge. From what looks like 150-190*. This thermostat doesn't have a bypass valve, but the guy at Advance Auto said that the air would work it's way out anyway. I assume that's true?

I'm also definitely sure that the old thermo was bad, the new 180 was holding coolant back in the thermostat housing whereas yesterday I found none when I took it off. Not to mention it's running at higher temperatures now, so yeah. My fuel mileage has been kind of bad lately, falling just under the city rating. Will the engine runnning at higher temps help my fuel economy?

I'm going to see if Autozone will let me return the 180, it's only slightly used. If not I'll chunk it at the dick that told me to buy it in the first place.

Thanks for all the help!
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Old 01-31-2007, 08:52 PM   #7
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Quote:
Originally Posted by hondaman
I'm going to see if Autozone will let me return the 180, it's only slightly used. If not I'll chunk it at the dick that told me to buy it in the first place.
If they're reluctant to give you a refund, tell them you thought that their company policy was to put the customers first, make the customer happy. I can't tell you how many times I've had to do returns where i know the product has been used but the customer claims it wasn't. I ask my manager and everytime it's "customers first".
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Old 01-31-2007, 09:09 PM   #8
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Quote:
Originally Posted by Wally
An ~82C stat instead of the factory ~90C is asking for problems

what kind of problems? i have been running a 180 t-stat for over 2 years with no problems. the stock one was 195 just like his.
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Old 01-31-2007, 11:30 PM   #9
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Originally Posted by elchango36
If they're reluctant to give you a refund, tell them you thought that their company policy was to put the customers first, make the customer happy. I can't tell you how many times I've had to do returns where i know the product has been used but the customer claims it wasn't. I ask my manager and everytime it's "customers first".
Thanks, that worked. I got my $8.xx back.

So everything has finally calmed down. It varies very little, in between 160* and 180* on the gauge. I'm going to assume that's not the actual temperature but merely an innaccuracy.

Does anyone think it may be a good idea to drain and flush the system after all this? I've had the coolant out of the radiator twice and as careful as I was, there are probably some small bits of old gasket running around in there.
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Old 02-01-2007, 02:19 AM   #10
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Originally Posted by jackal2000
what kind of problems? i have been running a 180 t-stat for over 2 years with no problems. the stock one was 195 just like his.

Wear factor will be about twice, fuel economy suffers, bores washes, oil sludges, oil filter/screen cakes, etc. By now I would suspect you have some nice bore ridges at the top of the pots.

Simply put, if a manufacturer has gone to all the trouble of finding the optimum temperature for wear vs performance, why deviate?
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Old 02-01-2007, 04:55 AM   #11
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Originally Posted by hondaman
Thanks, that worked. I got my $8.xx back.

NP. Anything for a fellow CF member!
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Old 02-01-2007, 07:51 PM   #12
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Originally Posted by tbaxleyjr
Not only those reasons but the ECM on a modern car is programmed to control the various engine variables with the temperature @ spec. Use the OEM temperature thermostat.

i changed those variables with my tuner.

Quote:
Wear factor will be about twice, fuel economy suffers, bores washes, oil sludges, oil filter/screen cakes, etc. By now I would suspect you have some nice bore ridges at the top of the pots.

Simply put, if a manufacturer has gone to all the trouble of finding the optimum temperature for wear vs performance, why deviate?

i had the motor rebuilt 5k miles ago due to a blown head gasket plus some upgrades i did. the block looked fine considering the trauma it went through and only had to be bored .005 to fit the new pistons i bought. im not sure what you mean "top of the pots", i never heard that before.
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Old 02-01-2007, 10:12 PM   #13
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How many miles on the clock?
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Old 02-01-2007, 10:26 PM   #14
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97k

i had the t-stat put in during a repair for a lower intake manifold gasket leak around 60k. the headgasket was also failing if not blown then too but i didnt have the cash to fix it. yes i drove 32k miles with it burning oil. 1qt of oil every ten days or so.
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