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ProDigit Rookie Author Miami Posts:45 Points:34,345 Joined:Dec 2010	Message Posted: Jan 2, 2011 2:27:20 Ignore ProDigit Report Abuse It seems my thermostat is in the open position, keeping the engine below nominal operating temperature. You think it's dangerous? Could it also be the reason for losing 2mpg on my charts?

ProDigit

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Miami

Posts:45
Points:34,345
Joined:Dec 2010

Message Posted: Jan 2, 2011 2:27:20

Ignore ProDigit Report Abuse

It seems my thermostat is in the open position, keeping the engine below nominal operating temperature.
You think it's dangerous?

Could it also be the reason for losing 2mpg on my charts?

REPLIES (newest first)

MetroManiac Champion Author Rochester Posts:1,731 Points:281,740 Joined:Apr 2007	Message Posted: Feb 21, 2011 2:13:13 Ignore MetroManiac Report Abuse yes, if your car does not warm up, the computer is tricked into throwing excess fuel at it.
Bus936 Champion Author Lexington Posts:16,584 Points:3,247,705 Joined:May 2004	Message Posted: Feb 21, 2011 12:20:58 AM Ignore Bus936 Report Abuse You are probably losing the 2 mpg due to ethanol in the gas.
rick_evans Champion Author Boston Posts:3,859 Points:1,057,990 Joined:Aug 2005	Message Posted: Feb 19, 2011 9:41:11 AM Ignore rick_evans Report Abuse Engines are designed to reach operating tolerances in their operating temp range. A broken thermostat would certainly lower your MPG and over the long run shorten your engine life by operating the block at lower than optimum temperature.
MrNemo Sophomore Author Miami Posts:247 Points:220,945 Joined:Aug 2009	Message Posted: Feb 19, 2011 8:00:40 AM Ignore MrNemo Report Abuse If your thermostat is stuck and the car is not coming up to operating temperature you are wasting fuel. The faster your car warms up the better for it. Excess fuel in the cylinders can cause wear also. Get it fixed it will save you money in the long run and make sure the correct temperature ratting for your car is used.
JimBlake56 Veteran Author Akron Posts:378 Points:77,350 Joined:Oct 2010	Message Posted: Jan 28, 2011 10:03:02 AM Ignore JimBlake56 Report Abuse LOL Miami Florida or Miami Ohio?? I suspect with a stuck-open T-stat, it's still warm enough to dry out the oil. Especially if it's FLA. Cool operating temperature will kick in some fuel enrichment. Unless you're talking about an older carburated engine. It's not DANGEROUS exactly, but I'd fix it.
dontuknowOH Champion Author Ohio Posts:2,123 Points:37,065 Joined:Aug 2009	Message Posted: Jan 19, 2011 1:44:35 Ignore dontuknowOH Report Abuse Hemond is right about the colder engine crankcase area will suffer also,only if the Miami area is the FLORIDA area,maybe not as much as farther North Winters. Miami?... My experiences with changing out thermos are that the cheaper ones last 2- 3 years but the more expensive OEM factory supplied ones last many years longer if the rest of cooling system is normal/healthy..> Like 10-12 years... I drive three vehicles,which are 11 years old bought new,with(original OEM ones in use.Also two others "78&81" OEM thermos changed one time each veh.The cross-flow low profile radiators are more prone to plug up at the bottom on circulation(few tubes,not completely loosing partial cooling ability)can often over heat during Summer/AC ON messes the thermos(come cold weather)= poor engine temps! other problems?
Hemond Champion Author Providence Posts:8,492 Points:136,115 Joined:Oct 2006	Message Posted: Jan 19, 2011 12:14:29 AM Ignore Hemond Report Abuse Another point, a theory of mine and may not be true. But if the engine never gets up to operating temp., perhaps the oil is staying cool too. Any moisture from blowby may not get vaporized off and may lead to sludge formation over time in the oil pan. This is an acidic product which tends to corrode bearings over time. . . Like I said, a theory, not sure if this happens but seems to me likely.
PathfinderSC Champion Author South Carolina Posts:9,657 Points:1,858,340 Joined:Mar 2008	Message Posted: Jan 18, 2011 6:25:07 Ignore PathfinderSC Report Abuse get it fixed, the gas you save will pay for the thermostat. At these gas prices.
GManCo Champion Author Colorado Springs Posts:5,126 Points:977,340 Joined:Sep 2010	Message Posted: Jan 17, 2011 9:48:23 Ignore GManCo Report Abuse Depends where you live and how cold it is. It is not dangerous, but the engine temperature allows the fuel to be injected at a warmer temperature and provides better fuel economy. Get it fixed, or better, fix it yourself.
dontuknowOH Champion Author Ohio Posts:2,123 Points:37,065 Joined:Aug 2009	Message Posted: Jan 15, 2011 3:55:04 Ignore dontuknowOH Report Abuse ProDigit; There is an old trick I did once,by cutting a piece of wood from a 2x4 about this size 3" long x the width of the top radiator hose 2-1/2". Then wittled a 5/8" groove across the middle of the narrow part side to side. Placed a stainless steel hose clamp around the radiator hose,over the fabricated groove in the wooden block(strapping the block against the hose),then tighten the clamp to choke the hose shut. This restricts the flow similiar to what the thermo does,but you will have to loosen the clamp as the engine heats up,so not to overheat. The heater blower turned on high will control a small % of the engine temp.BUT.... that CLAMP must be ADJUSTED to let some flow get through!! Careful monitoring of E-Temp guage is needed!!!!!! If you don't have a working guage don't even try this! THE CLAMP CANNOT BE TIGHTENED AS TO COMPLETELY SHUT OFF FLOW! It does cause more coolant to travel the heater route. Cold weather is the only time I ever used this trick(Dollar Poor at the time) Jan.-Mar. years ago. If your the only one driving the vehicle it could temporarily help,But....Risky!
ProDigit Rookie Author Miami Posts:45 Points:34,345 Joined:Dec 2010	Message Posted: Jan 15, 2011 12:05:26 Ignore ProDigit Report Abuse I temporarily fixed it by placing a cardboard in front of my grille. (covering 50% of the grille). The temp runs a bit higher that way, but still nowhere near the right temp. One of these days I'll go to the mechanic, it's just a pain he opens for the mornings only...
Hemond Champion Author Providence Posts:8,492 Points:136,115 Joined:Oct 2006	Message Posted: Jan 14, 2011 11:25:56 Ignore Hemond Report Abuse QUOTE<<<phil has got it your vehicle will stay in "open loop" until it reaches the set operating temp >>> . .. 'Open or Closed Loop' is determined by the O2 sensor getting to operating temperature and sending a true voltage signal to the computer. It has nothing to do with the coolant temp. Closed loop is achieved in a couple of minutes regardless of the coolant temp. Rest assured your engine is in closed loop even if the thermostat was removed. . The computer will factor in the low coolant temp and set the engine parameters to run with the correct stoichiometric mix. . . QUOTE <<<<<excess unburnt fuel will be going out the tailpipe; over time that'll wear out the catalytic converter and o2 sensor faster than "normal">>>> . . .There is no excess unburned fuel, thats what the catylitic converter does, converts excess unburned hydrocarbons. Also the O2 sensor simply measures oxygen, it does not 'burn out' if excess HC is in the exhaust stream. The converter is extremely durable and can easily handle a slightly enriched stream. But as I already explained, there is no extra unburned gas as the computer adjusts accordingly for the low engine temp.
gvan Champion Author Chicago Posts:21,749 Points:2,863,015 Joined:Dec 2004	Message Posted: Jan 12, 2011 11:13:39 AM Ignore gvan Report Abuse "Could it also be the reason for losing 2mpg on my charts?" Yes. Poor mileage is expected before the engine gets to proper operating temperature even with a car/truck that has a properly operating thermostat.
Baron62nd Champion Author Illinois Posts:7,156 Points:1,696,945 Joined:Sep 2007	Message Posted: Jan 12, 2011 11:11:08 AM Ignore Baron62nd Report Abuse Engine temperature is a contributing factor the on board computer uses to determine the fuel/air mixture. If the temperature is below normal operating temperature the computer will use that lower temperature to increase the amount of fuel to the engine, this is the same as running with the choke part way closed on the old carburetor equipped vehicles. So, yes, this is the reason for losing 2 mpg. If you can do it yourself the parts would probably run you less than $15 or $20. The one I changed last summer ran me about $13 and it was easy to get to.
dontuknowOH Champion Author Ohio Posts:2,123 Points:37,065 Joined:Aug 2009	Message Posted: Jan 11, 2011 5:49:34 AM Ignore dontuknowOH Report Abuse Get Err Done,I mean repair,replaced! That faulty thermo... part costs as much extra fuel $$,probably more than running two low inflated tires. Temp.sensors due get faulty connectors over time,some do go bad,not too expensive,for a DIYer to repair. The old cardboard trick doesn't work well on cars since the 70's LOL
kephar Champion Author Utah Posts:3,277 Points:703,340 Joined:Nov 2010	Message Posted: Jan 10, 2011 12:38:45 Ignore kephar Report Abuse It effects engine performance
ProDigit Rookie Author Miami Posts:45 Points:34,345 Joined:Dec 2010	Message Posted: Jan 10, 2011 12:35:53 Ignore ProDigit Report Abuse with the cold winter my car now has more like 5mpg loss.
chipote Champion Author Washington Posts:1,274 Points:393,305 Joined:Nov 2010	Message Posted: Jan 7, 2011 10:21:13 AM Ignore chipote Report Abuse It could cause other problems as well, especially in winter.
doeslayersr Champion Author Illinois Posts:9,298 Points:898,730 Joined:Dec 2010	Message Posted: Jan 7, 2011 9:11:38 AM Ignore doeslayersr Report Abuse Yes, you need to get it repaired. I do not know what year your vehicle is, but today's engines are designed to run at a specific temperature range. A removed thermostat or one which is stuck open or one which opens too quickly(i.e. if you put in a thermostat designed to open at a lower temp), will cause the engine to run colder and not reach the designed operating temperature range. The end result is incomplete combustion of the fuel. This can result in the premature end of life of your catalytic converter (because it has to work harder to burn off the unspent fuel) or other worst case problems (such as the excess fuel washing down the cylinder walls ending up mixing with your engine oil (which defeats the lubrication efficiency of the oil). The damage indicated above won't occur overnight or even right away, but can occur if the problem is not corrected over a prolonged period. In any case, this would explain your mpg drop on your charts.
WEPSMAN Champion Author South Dakota Posts:10,604 Points:2,048,050 Joined:Mar 2005	Message Posted: Jan 7, 2011 8:25:12 AM Ignore WEPSMAN Report Abuse It will affect performance. It will not allow the engine to run at optimum performance which will lower mileage.
oilpan4 Champion Author Virginia Posts:12,136 Points:308,040 Joined:Jul 2006	Message Posted: Jan 6, 2011 6:41:22 Ignore oilpan4 Report Abuse Yes it can lower mpg. My thermostat died in the closed position once on a road trip. So I just took it out. I was running cold and fuel milage was off 2-3mpg. The fact that is winter can drop fuel milage by a few mpg too.
rick_evans Champion Author Boston Posts:3,859 Points:1,057,990 Joined:Aug 2005	Message Posted: Jan 6, 2011 1:30:48 Ignore rick_evans Report Abuse "It seems my thermostat is in the open position, keeping the engine below nominal operating temperature.You think it's dangerous? Could it also be the reason for losing 2mpg on my charts?" -- I'm surprised you're only losing 2mpg. Is your temperature below the operating range. If not it might just be a seasonal, cold winter hit to your mpg.
2khawk Champion Author Iowa Posts:5,418 Points:955,705 Joined:Oct 2010	Message Posted: Jan 5, 2011 9:22:11 Ignore 2khawk Report Abuse Just change the thermostat for $10. If you want to test it take it out and if it's open when you get it out it's bad. If it's closed when you take it out then you need to get a pan of water. Put the thermostat and a thermometer that reads at least 250 degrees (if you have one or you can buy one for $15) in the water and watch for what temp the thermostat opens at which should be around 195 degrees in most of todays cars. If it opens well below that point it is bad. Personally I would run with the first option.
CoolPriusGuy Champion Author Detroit Posts:1,799 Points:95,730 Joined:Sep 2005	Message Posted: Jan 5, 2011 8:52:21 Ignore CoolPriusGuy Report Abuse There may be nothing wrong with the thermostat, a faulty engine coolant temperature sensor can also cause a 2 MPG FE drop. Good luck.
jes Champion Author Pennsylvania Posts:16,295 Points:3,378,225 Joined:Jun 2003	Message Posted: Jan 3, 2011 4:54:34 Ignore jes Report Abuse It's not dangerous, but I would bet this is why your mileage has gone down. Get it fixed.
ricebike Champion Author New Jersey Posts:10,106 Points:1,870,850 Joined:Oct 2005	Message Posted: Jan 3, 2011 9:21:38 AM Ignore ricebike Report Abuse phil has got it your vehicle will stay in "open loop" until it reaches the set operating temp excess unburnt fuel will be going out the tailpipe; over time that'll wear out the catalytic converter and o2 sensor faster than "normal"
dontuknowOH Champion Author Ohio Posts:2,123 Points:37,065 Joined:Aug 2009	Message Posted: Jan 3, 2011 6:14:08 AM Ignore dontuknowOH Report Abuse I agree with the other posters,and have seen other results of thermos getting sluggish,sticking shut,causing other cooling system problems that were dangerous. A work friend had one stick shut(wife dropping him off at factory,2nd shift).I saw the hood up,both were watching steam departing,the top radiator hose was swelled to about the size of a volley ball! Slammed hood shut,shut off engine(hose didn't blow)heater core did! Faulty thermo and pressure cap,blown heater core. No one SCAULDED!! Sometimes a good thermostat can get ruined by just one overheating event(summer/fall),and go unnoticed till colder ually(due to other existing unnoticed problem with cooling system). 70's...80's.... year cars more likely.
Boyrr Champion Author Allentown Posts:15,305 Points:3,190,930 Joined:May 2004	Message Posted: Jan 3, 2011 6:06:03 AM Ignore Boyrr Report Abuse well, it's not going to help
PhilT08 Champion Author Buffalo Posts:2,108 Points:123,285 Joined:Oct 2008	Message Posted: Jan 2, 2011 11:06:07 Ignore PhilT08 Report Abuse there are 3 things that will happen from the thermostat being stuck in the open position. 1) it will run rich wasting gas 2) poor heat 3) over time the catalytic converter can be ruined from excessive emissions in the exhaust. a converter can cost hundreds or over $1,000 depending on the vehicle. it is not quote "dangerous" but will cost you a lot if left as it is. and yes that is most likely the cause of losing 2mpg
blubyu Champion Author Indiana Posts:2,819 Points:1,404,405 Joined:Jul 2006	Message Posted: Jan 2, 2011 8:05:51 Ignore blubyu Report Abuse Not dangerous,an engine is designed to operate at 180-195 deg. it will run rich until it reaches the operating temperature, replace your thermostat, they are less than $5.00
cheapmonkee Champion Author Portland Posts:30,487 Points:3,199,110 Joined:Jun 2004	Message Posted: Jan 2, 2011 6:21:28 Ignore cheapmonkee Report Abuse Yes I had that problem a couple years ago. I think it feeds a little more gas until it senses the temperature is in proper range.
2khawk Champion Author Iowa Posts:5,418 Points:955,705 Joined:Oct 2010	Message Posted: Jan 2, 2011 3:42:48 Ignore 2khawk Report Abuse Probably not dangerous but most cars these days like an operating temperature around 195 degrees.