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#2102914 - 12/11/10 03:11 PM Average thermostat life?
Eric Smith Offline


Registered: 02/26/05
Posts: 2953
Loc: Kansas, USA
What do you guys think the average life of a thermostat would be? Maybe it all depends on the engine, cooling size etc? I've seen some cars go a long time with the same thermostat and others within 50k. The reason I bring this up is I'm putting the second thermostat in a Festiva in 75-80k. Don't know the actual mileage since I went through 3 Motoraid's till I gave up and went with Stant. My dad's other Festiva I replaced the thermostat last winter with the same mileage. On that one I went the OEM Motorcraft thermostat which is a dual stage, going to do the same with this one. Maybe that's why they didn't last as long? With the mileage he's putting on now probably never know.

Our Escape at 100k, parents Vibe at 95k, sisters Focus at 85k.. and I can think of a few others over 100k with the original thermostat. Some aftermarket thermostat may be okay for a select few but I'm starting to think OEM is best regardless. FYI alot of Mazda engines spec a dual-stage.. although not sure why. Never of heard with any other manufacturers.
_________________________
05 Chevy 3500 (Class C RV) 55k (PU 5w30)
04 Escape 150k (PHM 5w20)
02 Focus 132k (PP 5w20)
91 Festiva 255k .. Rust bucket

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#2102924 - 12/11/10 03:23 PM Re: Average thermostat life? [Re: Eric Smith]
JRed Offline


Registered: 06/01/09
Posts: 1691
Loc: Virginia
I have a co-worker with a Sentra with 194k on the original everything. Only had the transmission flushed once. Oil changes with PYB every 6-9k. Fram oil filters.
_________________________
06 Subaru Impreza WRX - Sold. The only mechanical thing I'll ever love.
07 Toyota Prius - Cheap synthetic and PureOne filters.

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#2102927 - 12/11/10 03:25 PM Re: Average thermostat life? [Re: Eric Smith]
Quest Offline


Registered: 12/19/04
Posts: 7362
Loc: beaver land EH?
IMHO there's no general rule of thumb (or even guessing) for thermostat life, citing:

(a) construction quality: cheeper aftermarket ones (or for some domestic brands, their OEM quality works out to no better than aftermarkets). I've been having consistent high quality with Japanese factory OEM units (most of them last over 8+yrs and still functional when I swap them out during scheduled maintenance.

(b) frequency of termalcycling. Certain engine designs (e.g. Suzuki all aluminum engines is one of them) tend to cycle more frequently, and as a result: they tend to last much shorter than, say, a typical Honda 2.4L Accord engine block type.

Bottomline: since thermostat is so cheep to replace, yet plays such a vital role in properly maintaining engine's health (if it runs cold, you get carbon build up inside your engine, serious fuel dilution to motor oil (due to richened F/A ratio during open loop running), etc. I would treat thermostat replacement as part of the routine maintenance (every 8yrs or 100kkms, or premature failure, full cooling system flush, whichever comes first).

Those motoring joes who systematically disregard the importance of a properly functioning thermostat, or play it cheep by insisting on aftermarket ones are being penny-wise/pound foolish.

Q.

oh and btw: thermostat does get lazy if they become really old, citing wifey's 92 Camry V6 had it's original one on it for over 231kkms and while it still opens and closes properly, it gets so "lazy" that I didn't realise how "responsive" a properly functioning thermostat should be until I replace it one day...oh what a difference it makes (in warming up the engine, cycling to keep the engine at normal operating temp, etc.)


Edited by Quest (12/11/10 03:27 PM)
_________________________
"Internet discussion boards act as echo chambers for conspiracy dittoheads" A.Allen

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#2102936 - 12/11/10 03:31 PM Re: Average thermostat life? [Re: Eric Smith]
Quest Offline


Registered: 12/19/04
Posts: 7362
Loc: beaver land EH?
Oh yes: most genuine Jpn design Mazda gasoline engines for EFI typically comes equipped with a dual valved thermostat (I used to own a B6 and and a B3 block in Mazda's family, both EFI'ed). I believe they use the smaller valve to control the upper part of the temperature (regulate flow) and the big one serving as the primary (master). Replacing it with a single valve type aftermarket thermostat doesn't make good sense to me (yet I've seen too many posters insisted in doing so all these years). It defys my understanding to no end.
_________________________
"Internet discussion boards act as echo chambers for conspiracy dittoheads" A.Allen

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#2102952 - 12/11/10 03:46 PM Re: Average thermostat life? [Re: Eric Smith]
John K Offline


Registered: 09/06/03
Posts: 950
Loc: Loveland, Ohio
Had a 68 Volvo 4 dr. bought new and the thermostat failed after 6 months. 6 mo warranty at the time, had about 19k on it. Got piston slap after that in #4. I replaced the piston myself, and don't recall the final mileage on the car. It lasted a pretty good time as I recall.....


Edited by John K (12/11/10 03:46 PM)

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#2102983 - 12/11/10 04:16 PM Re: Average thermostat life? [Re: Quest]
Eric Smith Offline


Registered: 02/26/05
Posts: 2953
Loc: Kansas, USA
Originally Posted By: Quest
IMHO there's no general rule of thumb (or even guessing) for thermostat life, citing:

(a) construction quality: cheeper aftermarket ones (or for some domestic brands, their OEM quality works out to no better than aftermarkets). I've been having consistent high quality with Japanese factory OEM units (most of them last over 8+yrs and still functional when I swap them out during scheduled maintenance.

(b) frequency of termalcycling. Certain engine designs (e.g. Suzuki all aluminum engines is one of them) tend to cycle more frequently, and as a result: they tend to last much shorter than, say, a typical Honda 2.4L Accord engine block type.

Bottomline: since thermostat is so cheep to replace, yet plays such a vital role in properly maintaining engine's health (if it runs cold, you get carbon build up inside your engine, serious fuel dilution to motor oil (due to richened F/A ratio during open loop running), etc. I would treat thermostat replacement as part of the routine maintenance (every 8yrs or 100kkms, or premature failure, full cooling system flush, whichever comes first).

Those motoring joes who systematically disregard the importance of a properly functioning thermostat, or play it cheep by insisting on aftermarket ones are being penny-wise/pound foolish.

Q.

oh and btw: thermostat does get lazy if they become really old, citing wifey's 92 Camry V6 had it's original one on it for over 231kkms and while it still opens and closes properly, it gets so "lazy" that I didn't realise how "responsive" a properly functioning thermostat should be until I replace it one day...oh what a difference it makes (in warming up the engine, cycling to keep the engine at normal operating temp, etc.)


Excellent post! I think you answered my question in that paragraph. Mazda engines have aluminum heads with iron block. At least I'm not the only one that knows about the Mazda and dual stage.. most of those use the same thermostat also!
_________________________
05 Chevy 3500 (Class C RV) 55k (PU 5w30)
04 Escape 150k (PHM 5w20)
02 Focus 132k (PP 5w20)
91 Festiva 255k .. Rust bucket

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#2103006 - 12/11/10 04:44 PM Re: Average thermostat life? [Re: Eric Smith]
JHZR2 Offline



Registered: 12/14/02
Posts: 40422
Loc: New Jersey
My higher mileage MB diesels have original ones at 210 and 228k, and our toyota has the original at 230k.

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#2106877 - 12/15/10 01:58 PM Re: Average thermostat life? [Re: John K]
Chris B. Offline


Registered: 03/16/03
Posts: 3373
Loc: Colorado
Originally Posted By: John K
Had a 68 Volvo 4 dr. bought new and the thermostat failed after 6 months. 6 mo warranty at the time, had about 19k on it. Got piston slap after that in #4. I replaced the piston myself, and don't recall the final mileage on the car. It lasted a pretty good time as I recall.....


My 2008 Volvo S40's T-stat failed at 4,000 miles. They repleaced it under their 50,0000 mile warranty.

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#2107199 - 12/15/10 07:30 PM Re: Average thermostat life? [Re: Eric Smith]
SLCraig Offline


Registered: 12/21/08
Posts: 5627
Loc: London, ON, Canada
Depends probably on design. In my experience..
Nissans thermostats last a while.
My Saturns thermostats are always bad when I buy one of these cars used. I've replaced one on every Saturn Ive owned (3)
_________________________
2010 Civic SI sedan 6MT
PP 5w30 | Fram TG | Pennzoil MTF

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#2107913 - 12/16/10 01:23 PM Re: Average thermostat life? [Re: Eric Smith]
Eric Smith Offline


Registered: 02/26/05
Posts: 2953
Loc: Kansas, USA
I had to order a dual stage thermostat for Festiva and got here yesterday. Took me a hour to put it in most of that was finding stuff. Figured it really should of only taken 30 minutes. I think the Stant thermostat was frozen shut. I tried to open it up with a pair of pliers.. let out a loud pop and opened but never really closed back. This morning it warmed up way quicker and held the temp higher than the single stage ever did. Boy I hope the one in the Escape never goes out that'll be a bear to replace.
_________________________
05 Chevy 3500 (Class C RV) 55k (PU 5w30)
04 Escape 150k (PHM 5w20)
02 Focus 132k (PP 5w20)
91 Festiva 255k .. Rust bucket

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#2119544 - 12/28/10 11:55 AM Re: Average thermostat life? [Re: Eric Smith]
turbochem Offline


Registered: 12/13/02
Posts: 436
Loc: PHX
Originally Posted By: Eric Smith
What do you guys think the average life of a thermostat would be? Maybe it all depends on the engine, cooling size etc? I've seen some cars go a long time with the same thermostat and others within 50k. The reason I bring this up is I'm putting the second thermostat in a Festiva in 75-80k. Don't know the actual mileage since I went through 3 Motoraid's till I gave up and went with Stant. My dad's other Festiva I replaced the thermostat last winter with the same mileage. On that one I went the OEM Motorcraft thermostat which is a dual stage, going to do the same with this one. Maybe that's why they didn't last as long? With the mileage he's putting on now probably never know.

Our Escape at 100k, parents Vibe at 95k, sisters Focus at 85k.. and I can think of a few others over 100k with the original thermostat. Some aftermarket thermostat may be okay for a select few but I'm starting to think OEM is best regardless. FYI alot of Mazda engines spec a dual-stage.. although not sure why. Never of heard with any other manufacturers.


In those cases where the thermostat went "bad", how did you check them (I'm guessing water, pot, stove, etc.)?

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#2119793 - 12/28/10 04:17 PM Re: Average thermostat life? [Re: Eric Smith]
Kaie Offline


Registered: 10/31/10
Posts: 259
Loc: TEXAS
I've always replaced my water pump, tstat, and all belts when doings a timing belt change. ALL for under 100 bucks.

So ive never had a tstat go out in my VW.

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#2120705 - 12/29/10 01:44 PM Re: Average thermostat life? [Re: Eric Smith]
Colt45ws Offline


Registered: 08/15/06
Posts: 9399
Loc: Central Washington
My original was toast after 5 years. It would never warm up past 180F in cold weather no matter how long it was running.
_________________________
-Colton
2002 Ford Crown Vic PI 207k, Ex-Kootenai County, ID Unit #42
Down for engine swap
2003 Ford Crown Vic PI 70k
Havoline HM 5W20, Supertech ST2

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#2120944 - 12/29/10 06:09 PM Re: Average thermostat life? [Re: Eric Smith]
Greggy_D Offline


Registered: 03/03/05
Posts: 1619
Loc: Michigan
I had an '89 Ranger that used to eat thermostats yearly. But ever since that, my vehicles have gone over 100k on the original thermostats.
_________________________
Greggy D.


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#2122593 - 12/31/10 10:37 AM Re: Average thermostat life? [Re: turbochem]
Quest Offline


Registered: 12/19/04
Posts: 7362
Loc: beaver land EH?
Originally Posted By: turbochem


In those cases where the thermostat went "bad", how did you check them (I'm guessing water, pot, stove, etc.)?


You have the options of either (a) cut to the chase and buy brand new OE thermostat (you are guaranteed to function as per original engine manufacturer's design and operational characteristics) and just simply replace the "suspected" one with a fresh new one; or (b) spend your own free time to drain the coolant, pull the old one, test it with a thermometer in a gradual boiling pot of hot water, watching the thermostat valve opens as it hits the designated temperature, etc.) and then put it back into the car, reinstall with fresh new gasket and then re-fill with coolant (or sometimes, it would be desirable to might as well perform a cooling system flush and fill while you are at it).

I, for one, do not re-use thermostats unless I'm in a very desperate situation. Yeah, on the surface it may seem very "wasteful" but in reality: with the time/effort required to test/inspect thermostats on some vehicles, which the dismantling of the cooling system may well take over an hour (I'm not an amateur mechanic BTW), it' makes absolutely no sense to reuse an otherwise questionable (esp. aftermarket ones) or lazy thermostats realising that further down the road I may have to perform a RE&RE again, either on my own expense or the car owner's.

Q.


Edited by Quest (12/31/10 10:37 AM)
_________________________
"Internet discussion boards act as echo chambers for conspiracy dittoheads" A.Allen

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