The Stovebolt Site Forums The Shop Area Engine Shop Only runs at 140

So with the cold temps approaching ive notcied that the truck only runs smooth at 140 degrees. It will idle rough, wont shift properly and sounds like its bogging down. Once it warms up it runs fine. Any ideas?

you need to clarify that - "only runs smooth at 140 degrees" doesn't match with "Once it warms up it runs fine" .... are you saying 140 is warmed up? what's your thermostat rating? are you using the choke? .... by "wont shift properly" do you mean the manual movement of the shift linkage is stiff?

Bill

When's the last time the plugs, wires, etc. were changed or checked?

Is your truck equipped with a heat riser on the exhaust manifold? These were designed to stop your carburetor from icing up in cooler weather, most do not function properly. You can get away without one if you let the engine warm up before driving it, that's what the old timers used to do. Make sure your flapper is in the open position even if you are not using it, so as not to damage the engine.

i have a 7lb tstat, runs excellent when it the truck temp reaches 140. in the summer months there is no issue at all. as far as the shifting goes it doesnt feel stiff shifting but the truck struggles as if i wasnt letting go of the clutch. tune up was done year and half ago. i do not believe that it has a heat riser on the exhaust

you have a 7 lb rad cap, that's not a thermostat, they're rated for temperature - if the gauge shows 140 when it's well warmed up then you have a bad gauge [stock?] or NO thermostat - you need to open the housing and check for a thermostat and replace it with a 180 degree new one, especially for winter, which will mean when warmed up the engine will hold 180 or above .... and like George says. make sure it's warmed up before driving, 140 is not warm

Bill

yes no tstat. With original gauge

Are you saying that it runs fine after it reaches 140 degrees? You said yes.

What temperature thermostat are you using? You said no thermostat at all? You need at least a 160 degree thermostat.

What do you mean by it doesn't shift properly? 3-speed or 4-speed transmission (original or a modification)? Does it shift poorly at all times?

Im saying that once temp reaches 140 it runs fine. before that it runs as if the engine is starving for fuel. i use the choke when i first start it to idle a bit higher. the shifting part I mean that before it gets to 140 degrees it acts as if im pressing the clutch half way and trying to drive like that. it is a 3 speed on the column. the actual movement of putting it into gear is not the issue. i have to check in the am what tstat is in there.

the existing tstat was shot. put in a 180 and runs great again thanks.