Running too cool?
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Tuned
Joined: Jun 2003
Posts: 489
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Running too cool?
Flushed my radiator and put a new Tstat in (robertShaw GenII 195).
the old one was a motorcraft 195. Temps used to hit between the O and R on normal. Now it goes no farther than N and sometimes hangs around just below N.
I know the guages are relative, but since this is the only thing that I changed, do you think the Tstat is a defective one? I still get decent heat, but don't want the thing running lean or bad MPG either.
the old one was a motorcraft 195. Temps used to hit between the O and R on normal. Now it goes no farther than N and sometimes hangs around just below N.
I know the guages are relative, but since this is the only thing that I changed, do you think the Tstat is a defective one? I still get decent heat, but don't want the thing running lean or bad MPG either.
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Tuned
Joined: Jun 2003
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I also noticed another thing...the small coolant hose that runs from the top of the throttle body doesn't get hot or even warm...I remember this hose/tube used to get too hot to touch. Wonder if I got a blockage too...I just did a flush though.
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Joined: Nov 2003
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From: El Paso Texas
Sounds like the 'stat is stuck wide open. Not a good situation. Running too cool can cause it to stay in open loop and / or run too rich (not lean). The rich condition will accelerate engine wear, and cause the truck to fail the smog check. Sounds like your new 'stat is defective, good idea to replace it again.
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Joined: Jul 2003
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From: Moore, OK
Not to hijack this thread, but running a truck in a "cool" state will cause the truck to run very lean and/or induce more engine wear? On a normal day, the needle on my '95 F-150 will hang around the N of normal. On a hot day (100+), it will hang around the R portion of normal. Could this be why I'm getting such crappy gas mileage?
Even my old Ranger did the same thing. Even swapped out thermostats too. It always stayed around the N portion of normal.
Any explanation would greatly be appreciated.
Even my old Ranger did the same thing. Even swapped out thermostats too. It always stayed around the N portion of normal.
Any explanation would greatly be appreciated.
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Tuned
Joined: Jun 2003
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If you sure about the tstat, have you ever looked into your fan clutch? If it is not working right, it could always be engaged and bring your temps down too low. If it is always engaged, you will hear a roar under the hood all the time.
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Senior User
Joined: Nov 2003
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From: El Paso Texas
Originally posted by Bimmer ese
Not to hijack this thread, but running a truck in a "cool" state will cause the truck to run very lean and/or induce more engine wear? On a normal day, the needle on my '95 F-150 will hang around the N of normal. On a hot day (100+), it will hang around the R portion of normal. Could this be why I'm getting such crappy gas mileage?
Even my old Ranger did the same thing. Even swapped out thermostats too. It always stayed around the N portion of normal.
Any explanation would greatly be appreciated.
Not to hijack this thread, but running a truck in a "cool" state will cause the truck to run very lean and/or induce more engine wear? On a normal day, the needle on my '95 F-150 will hang around the N of normal. On a hot day (100+), it will hang around the R portion of normal. Could this be why I'm getting such crappy gas mileage?
Even my old Ranger did the same thing. Even swapped out thermostats too. It always stayed around the N portion of normal.
Any explanation would greatly be appreciated.
Running too rich will dramatically shorten the life of your engine as well. Too much fuel dilutes the oil on the cylinder walls, and if the engine is run for long periods like this, it will dilute the oil in the crankcase as well.
Of course, in the short term your engine will also run like crap because it will foul the plugs very shortly as well. And you will be belching black smoke and choking the drivers behind you.
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Senior User
Joined: Nov 2003
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From: El Paso Texas
Oh, by the way, if the needle is hanging out in the "normal" portion of the gauge, I don't think the running temperature is the culprit of your poor gas mileage. If the 'stat has failed and is stuck open, the gauge (particularly in December) will stay pegged on cold.
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Joined: Jul 2003
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From: Moore, OK
Originally posted by Frizlefrak
Not exactly, but kinda. Running too cool will cause the engine to run too RICH, not too lean. Running excessively rich will cause your gas mileage to go in the toilet. Remember that your engine needs a rich mixture for a cold start. If the computer thinks your engine is cold, it will richen the mixture. If it never warms up, the computer still thinks it's cold, and never leans out the mixture.
Running too rich will dramatically shorten the life of your engine as well. Too much fuel dilutes the oil on the cylinder walls, and if the engine is run for long periods like this, it will dilute the oil in the crankcase as well.
Of course, in the short term your engine will also run like crap because it will foul the plugs very shortly as well. And you will be belching black smoke and choking the drivers behind you.
Not exactly, but kinda. Running too cool will cause the engine to run too RICH, not too lean. Running excessively rich will cause your gas mileage to go in the toilet. Remember that your engine needs a rich mixture for a cold start. If the computer thinks your engine is cold, it will richen the mixture. If it never warms up, the computer still thinks it's cold, and never leans out the mixture.
Running too rich will dramatically shorten the life of your engine as well. Too much fuel dilutes the oil on the cylinder walls, and if the engine is run for long periods like this, it will dilute the oil in the crankcase as well.
Of course, in the short term your engine will also run like crap because it will foul the plugs very shortly as well. And you will be belching black smoke and choking the drivers behind you.
