OK so just before quitin' time last night, I started my truck to warm it a bit before leaving. It was about -5* so I waited for the oil pressure to build and then set the hand throttle to about 1000 RPM then go back to finish my day.

10-15 minutes later I come out and her the truck screamin' at about 2500-2700 RPM. It's running smooth but really fast. Open the door and see that the coolant temp has pegged my gauge 250*+ but I still have 50+psi oil pressure. Not good but could be worse. I undo the hand throttle and the idle comes down but so does the oil pressure. (oil is definatley hotter than it should be)It also misses at idle. Bump the Idle up a bit to maintain oil pressure then open the cold front and hit the road to cool things off a bit.

Coolant temp dropps almost imeadiatly and is down to a normal 180* in a few blocks but oil pressure is still low at idle ans the miss is still there a bit. I hit the highway and cruis along at a leisurely 55-60mph for about 15 miles. Cruising temps and pressures are all good. After my highway cruise, the idle oil pressure is back to a normal 25psi and the idle is smooth as glass again. A few minuts wait for the kid to show up then another leisurely cruise down the highway home. everything seems good.

I checked the fluids this AM and can't find anything out of the ordinary. Nothing smells burnt, there is nothing in the coolant but coolant so I THINK, I'm ok. School me if there is something else I need to think about. Everthing ran like normal today.

Now the underlying question. Why did my Idle shoot through the roof? It has happend once before last winter.(-35*F that time) Both times it has been during warm up from cold temps. It seems to me that the idle setting goes up with engine temp. Remember this is set using the hand throttle. It does have a lock on it.

Is the KSB giving me problems? The switch is bad but still connected but I also have it hot wired with a manual switch. The manual switch doesn't make a big difference to me on or off just a VERY slight change in idle sound. My pump has been advanced a bit as well.

Sorry this is so long but any advice/opinions or suggestions are appriciated.

 

I've noticed the same thing in MO, with just temps in single digits either side of 0*F.

I think it is just nature of a cold engine, starting with cold fuel. You get your idle up to 1000 real fast (all still cold as a cast iron commode on the dark side of an iceberg), and once things warm up and get going, your idle goes up because more fuel energy is being used to move the pistons, and is not lost to the -5deg block an head. In other words, it's the nature of the beast. Try waiting about a minute to speed up your idle, or just set it to 50rpm over cold idle right off. I'd say there is nothing wrong with your engine, as mine has logged over 20K since the last 0deg weather we had.

I'm surprised the water temp pegged, though. Normally, with even a 1500rpm idle, I couldnt get past the 1st mark on the OE gauge at no load.

When warmed up, if you give it enough pedal (at idle) to reach 1800rpm, does it seem to speed up and up, even though you're holding your foot steady?

 

I'm glad I'm not the only one.

Not a bad theory. You might just have something there. I do wait a minute or so before setting the idle though.

That's kinda where I'm at with it but a second opinion never hurt...

Same here but I did have the cold front in place blocking most of the radiator.


Holds steady as a genset.

 

There are a lot of possible ways to explain why the engine was running high revs. I don't think that that is a big issue. But in my mind the high engine temperature is a concern.

If it were me I'd go out the next time that it is -5* or colder and do the same thing but sit in the truck and see what happens. I'm wondering if the fan was turning. Maybe all of the heat off of the rad was going out of the front of the truck rather than going back and heating up the fan clutch.?? Was there a stiff breeze? Which way was the truck facing?

The oil being hot indicates that the whole rad was hot. Right?

At 2500 rpm there should have been a lot of (-5*F) air going through that rad, cold front open or closed.

Good Day,
JP.

 

As for the RPMs going up with a steady pedal, let me further clarify. I have had this in two trucks with newly rebuilt pumps, so I have determined it is the nature of a healthy, slightly "overfuelled" VE.

At no load ("N" in the driveway, let's say), start at idle, then give it enough fuel to gradually increase the RPMs, say +100rpm per 2-3sec. It gets to a point (usually at the RPM of torque peak, ~1700) that the increase in RPM really speeds up, and you will reach 90% of your peak RPM at literally a hair more pedal than 1700rpm. (Kinda like the governor in a BigCam4 when bobtailing- nearly impossible to keep 1400rpm in low range- it wants to just go to the governor). Putting it to the floor will give 2-300more RPM. I think it has to do with the way the governor and flywheights are set up in the VE pump. Had a buddy with a then-new 14mm rotor ask about that, and I told him mine did the same thing, only not quite as drastic (his went to about 4000rpm before he let off, with plenty of pedal under his foot.

 

My 89 will go to very high rpms with little throttle pressure. It did this after I really turned up the fuel screw. Before it was steady at evey pedal setting.

 

No breeze, Truck was facing another right in front of it. The cold front does a pretty good job of blocking off the airflow of a sitting truck.

 

They all tend to speed up from cold idle. When the engine is very cold it takes a lot more fuel to run at 1200 RPM than is needed once it warms up. An old DT466 I used to run would rev to 1800 RPM if I set the hand throttle for 1000 RPM cold. I soon learned to set the hand throttle to about 800 right after startup, then it would stabilize at about 1100.

I like the suggestion of setting throttle lock at 50 RPM over the cold idle for starters.

I think a good permanent solution would be to make a "C" shaped shim that you can slip between the throttle handle and the mount. The shim would be whittled to the right thickness to give you your desired warm idle speed. Make it out of out of wood or plastic and give it a big enough handle to make it easy to use while wearing gloves (I'm thinking of a shape like an open-end wrench). Then all you would do is fire up the truck, pull the hand throttle out enough to hook in your shim, let the hand throttle rest on the shim, and walk away.

 

Thanks for all the replies.

Good to know I don't have to go and chase a few (more) ghosts. I'll just be a bit more careful with the hand throttle although I've been using them for MANY years without incident. Oh well....