chevy dually 3500 1997 idling problems

[Eddy1]

I am thinking about buying this truck, everything seems good on it but when its cold it idols at around 600 then up to 1200 back down to 6 or 800 back up and so on, when it warmed up this didn't happen, any ideas what causes this and if it could be bad enough not to buy it?

[MT-2500]

Originally Posted by Eddy1

I am thinking about buying this truck, everything seems good on it but when its cold it idols at around 600 then up to 1200 back down to 6 or 800 back up and so on, when it warmed up this didn't happen, any ideas what causes this and if it could be bad enough not to buy it?

Hard to sday.
I would ask them to fix it befoe you buy it.

[j cAT]

Originally Posted by Eddy1

I am thinking about buying this truck, everything seems good on it but when its cold it idols at around 600 then up to 1200 back down to 6 or 800 back up and so on, when it warmed up this didn't happen, any ideas what causes this and if it could be bad enough not to buy it?

if the vehicle runs good hot shifts smooth and the body is in good condition I would buy it even though the idle cold is erratic. also mileage of less than 140,000.

could be a sensor issue. ETC TEMP sensor or the IAC/throttle body need cleaning. I would guess not an expensive fix.

[Eddy1]

It has 144k miles on it do they start going down hill after 140?
It sounds very smooth and healthy, the body is straight and no rust.

[j cAT]

Originally Posted by Eddy1

It has 144k miles on it do they start going down hill after 140?
It sounds very smooth and healthy, the body is straight and no rust.

they are good till 175,ooomi. then you get into fuel pumps/distributors/dist gear/coolant system issues esp if it was not properly maintained. transmission and drive train fluids should be replaced also tranny filter and the use of dexron VI not the disconntinued GM dexron III.

since this is a work vehicle drivetrain fluids and coolant system must be maintained on a regular basis.

checking all fluids before buy would show if it is being properly kept up.

[Eddy1]

What are these like on fuel? if towing a 10,000 lb utility trailer what sort of gas mileage can I expect? I hear these are hard on fuel. I will look into the fluids first also, thanks

[j cAT]

Originally Posted by Eddy1

What are these like on fuel? if towing a 10,000 lb utility trailer what sort of gas mileage can I expect? I hear these are hard on fuel. I will look into the fluids first also, thanks

with no load you should expect 15 MPG max...

If you have 10K load maybe 10MPG.

depends on rear diff gear ratio which is 3.73 / 4.11