OT-Back to dieseling

[JIPJOBXX]

I posted just a couple of days ago that my little pickup truck had a problem when turning oft the ignition key to stop the engine that the engine would keep on running or dieseling. I notice when I removed the thermostat a few days ago that it does not diesel when the temperature of the engine is cooler. I can leave the thermostat out and it will not cause the engine to misfire but will I hurt the engine? When I had the thermostat in place it would run at about 180 degrees and with it out probably 100 or so? So what to do? Any more answers:confused:

[JIPJOBXX]

Could I possibly have had the thermostat in backwards? Which way does a thermoset open? I noticed where the thermostat sits the water flow is back to the radiator. I checked the instructions out on the packaging and put it in accordingly so. Could this be wrong and it is 180 degrees out of position and would it still work if it was????

[Niel Hoback]

Did you put the sat in so that the sensing pellet is towards the block? If so, it's in right. Put it in backwards, (pellet up), and it will overheat.

[Ed Fleming]

Did you try putting the thermostat in boilling water to see if it opening .

[JIPJOBXX]

Yep and it open at the right setting at 185 degrees. But this is not the problem its the dieseling and why does it not diesel at about 100 degrees. Oh well a friend of mine that I talked to said I should sacrifice my old thermostat and drill a few hole in it and get the water to circulate at a lower temperature but still have my thermostat. Maybe this will work and I can keep the car from dieseling at say around 140 or 150-sound kind of mickey mouse but its just a 500 dollar truck.

[kencombs]

I think you hit on the cause earlier with the mention of a high idle speed.

Lower temps will reduce the tendency to diesel, but are not the cure. Get the idle speed down and it will probably fix it.

Which engine do you have? Look for an idle speed solenoid, lots of early carbed engines had those to reduce idle speed when the key was shut off.

[Niel Hoback]

check the egr valve to see if its closing all the way. just grabbing at straws here.

[JIPJOBXX]

Unfortunately who ever owned my rig in the past took all the air pollution equipment oft and I'm sure that this might just be part of the problem. Today I bleed all the air out of the heater hoses and now I have a full flow of H2O passing through my heater core. As for the dieseling I'm fooling around with the timming but I still have the thermostat out and like I said before when its running cooler it doesn't diesel. So I'm going to sacrifice my old extra thermostat and drill a couple of holes in it so that maybe I can get the engine to run at about 150 degrees and see what happens at that temperature. Why me old lord? Oh well I can still dance!

[Niel Hoback]

please let an old guy ramble. your motor runs on after shut off when its hot because there is enough hot carbon in the cylinders to fire any fuel it can suck in. if the throttle plate shuts tight enough and there are no vaccuum leaks, such as open vaccuum ports, missing or broken vaccuum lines loose carb mount, manifold leaks egr system, or any other way for air to get in the cylinder, it will not be able to run. thats why it wont do it when its cold, because the carbon is not hot enought to fire.

if you dont find any vaccuum leaks, make certain that nothing is keeping the throttle open, ie; choke linkage, fast idle cam, or as i once found, a dried up dead mouse.

try not to resort to running colder as you will only cause more carbon build-up and your gas mileage will be worse than it is now.

thank you for your time, and remember my signature.

[Niel Hoback]

this and the previous post were typed while holding one hand in the air, and i'm too lazy use the shift key.

[JIPJOBXX]

Thanks for all the info the old man!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[greg g]

I agree with Niel, most of the dieseling was due to carbon hotspots and an air leak somwhere. most likely faulth vacuum lines related to the emmissions system. If the emmissions system stuff is missing, I would bet there is an open vacuum port somewhere allowing air in after the throttle plate . Tim mentioned doing the water trick. you said it was pretty clean, however even a bit of carbon can start to glow and stay hot aafter shut down. If you don't want to do the water thing try a can of SEA FOAM and a tank or two of really expensive high test gas with lots of detergents in it like the Shell Hydrogen stuff.

http://www.seafoamsales.com/motor-treatment/index.html

[JIPJOBXX]

Finally found my Vaumm gages yesterday and tested the engine for vacuum and its running a steady plus 20 to 22 psi. Now my question is that I have no Idea what one of those vacuum line does or what the item it attaches does? This item is located on the passengers side on the wheel wheel. It has one large air hose leading down to the inlet hose of the carburetor plus a whole lot of wire in some type of plastic box that's seems to be operated somehow in conjunction with that vacuum line. Any idea's? I got to get a repair manual! Other than that the car seems to be running fine Oh yes I reset the timming but have not reinstalled the thermostat probably will do that today. I'm going to backtrack for a second here that mysterious box that attached to the firewall the bellow that attaches to the vacuum line seems to be leaking as when I plug up that line than the vacumm line held at a steady reading.

[JIPJOBXX]

One more thing the electrical choke on the carburetor does not seem to be working (Damn) so even with the new linkage I built from a 8-32 screw I cannot get the butterfly choke vlv to close down. Now if I do this by hand and choke it the car runs terrible. The engine starts right up with no problem not even using the choke so high ho, high ho its the pain in the butt I go!!!!!!!!!!!!!!!!!!!!!!

[Don Coatney]

I am not familur with vacuum readings listed in "plus" pounds per square inch.

[JIPJOBXX]

Well I kind of got oust that expression from when I worked down at the shipyard during testing procedures on SSTG's. Kind of stuck in my head.

SSTG's=Ships Service Turbo Generator's

[paulmusiclover]

Is Seafoam sold in stores or only online? (just thought I'd ask, I'll check my local stores when I go in there next time.)

[greg g]

most auto supplies have it locally.

[Plymouthy Adams]

not sure if the chain is in your area but I noticed my local Advance has Seafoam on the shelf..

Edited September 13, 2009 by Tim Adams

[JIPJOBXX]

Well I finally found out what the problem was about the car die sling and that was a leaking bellow as I might call it. I stated here before who ever owned this little truck in the past removed all most all of the environmental control stuff and so most everything has a hose missing or not hooked up. So that Item which I do not know what it does has a vacumm hose attached to it but it does not seem to serve a purpose? So I attached my vacumm gage to the hose that lead over to that Item and noticed right away that the vacumm was at a steady range. So I reinstalled the thermostat and guess what no dieseling. So as far as I can figure that bellow attachment must have a leak in it and that was causing the carburetor to get to much air. So my truck is up and running and I thank all the people here for there many suggestions. I think we all learned a little bit about what causes dieseling and in my case it was a hidden problem.