I've got a gutted thermostat, so most winters the truck never warms up and has a fast-idle all the time.. Seems normal enough..

Now though, I've placed a piece of cardboard in front of the radiator, I must have been lucky to choose the right size because she runs right in the center of the temp band on the temp gauge plus the heater is working great !

Problem: at first the warm-idle was normal i.e. about 1000 rpm, maybe 1200. But lately when it's warm, it cycles between normal and 2000 rpm (fast-idle) back and forth and drives me nuts.. Fast/slow/fast/slow you get the idea...

Is there a problem with some sort of fast-idle solenoid ? What about some IAV or what-not I saw in a different post ? (I DID search but found no similar problem).

Thanks in advance !!

 

why don't you put a thermostat in it and take care of the problem

 

This 3.0 piece-o-crap has a slightly seeping head-gasket I think. It runs great (right in the middle of the temp-gauge) for about 20-25 minutes when a thermostat is installed (tried 4 times) then overheats instantly... I've heard it's common and also read that sometimes it's an air-bubble, but this is no air-bubble. No water in oil or oil in water though, so I keep running it....

The theory on this forum is that small bubbles are being released into the cooling -system from a small hole in the head-gasket. The bubbles travel with the water and accumulate on the bulb-side of the thermostat but don't go thru. When the air-bubble get's big enough, the thermostat 'sees' only air and closes... end of story...

 

I would do a compression test for sure and a pressure, that should tell you.