ot i need a web site or mechanic familiar with peterbilt 330

im doing another ot due to shear desperation i have searched the web for a site for big trucks like this tractor forun with no luck and im about to run a dozer over the bosses truck and he wont like me if i do that, heres the deal we have a 2004 peterbilt 330 series tandem axle dump, it has the little 8.3 cummins in it, last january the fan clutch broke a shaft and the fan flew off the engine we had to replace it, the fan, the radiator and the fan shroud, since then the truck will overheat when loaded, BUT only on the hiway, it wont do it in a town or unloaded anywhere, the radiator is clean inside and out, the innercooler is clean, no debris blocking the airflow, as is the a/c condensor this thing has spent a month in the nearest dealer [ 200 miles away] for this problem and no help, they replaced the main computer and and some thermo thingy they fryed, [ i dont know anything else to do, the fan turns the correct direction,it is full of water, no bubbles in the water doesnt use water or oil, sorry for the long ot, but im about to tear my hair out, oh, the new radiator is exactly the same as the old one all parts came from peterbilt

Absolutely sure it is the correct fan and clutch...sounds like when it needs maximum airflow there isn't enough. Fans in housings have critical clearances to achieve maximum airflow. Any turbine device is a good example of this. Could the fan clutch be slipping under load? Good luck and when you locate the problem let us know.
Andy

I was just about to ask you if you checked to see if the fan clutch was air on or air off, but that would show up in the city and not in the country if the fan wasn't running. Jim

thats what in down too andy with the fan clutch in manuel lock, there isnt much "suck" in front of the grill,peterbilt swears this is the correct fan and clutch its special for the 8.3 its a horton, but a regular horton like for a big cummins wont fit, there has to be a reason though the truck ran fine before the fan clutch broke, im about to try a old school truckers fix from the 1950's , mount a small tank filled with water, a 12 volt fuel pump and some copper tubing with 1/64th holes in it and run it between the innercooler and the radiator, when the heat comes up i can mist the radiator with cooler water to cool it down, boss aint going to like that fix though

should have added the fan clutch isnt slipping, either at the clutch itself or the belt on the clutch weve checked that, the fan is swinging right in the middle of the shroud now if we turned it around it would be between the engine and shroud plus covering the fan clutch itself i know the old one didnt do that, and the blades do "bite" in the correct direction too

I was a Cummins mechanic back in the 1980s so I dont know if any of these suggestions is your problem.I probably worked on a 8.3 but my memory is not so good about it.Seems like there is a float or a ball with a spring on it or some kind of valve in the Radiator.That can give you lots of trouble with overheating and what it did on the newer motors was made like a overflow tank inside the radiator.Seems like it was on the first air to air trucks.Im sure that was on big cam 4 855 trucks.You should get a break down view of your radiator if there is one and see if maybe that is something causing your trouble.The reason I say that is this,somewhere there is a switch to make the fan come on when the water gets hot.If you had something like that in your radiator,and Im not saying you do,if it was stuck and the water was actually heating up where the water temp sensor was but not where the fan switch was.I have driven quite a few trucks that would get hot on a big hill and the way the mechanics fixed it was put a manual switch on the fan.All the driver has to do is turn the switch on for real hot weather,pulling a long hill,whatever is not kicking the fan on soon enough is maybe complicated or expensive and a switch is cheaper,I dont know and cant remember right now what the deal was.I seem to remember a wiring harness you could buy just for that purpose to hook up a fan switch.I could be wrong and I never was a parts man anyway.

Other things that caused me trouble on a Cummins was when they switched to a low flow cooling system they switched to 2 thermostats for that weird radiator I was talking about.If somebody replaced the dual thermostats if you have them,there is a piece of brass like a pipe that fits up into the thermostat housing.I think it comes on the thermostat.If you pull the old thermostat out and that piece doesnt come with it,then put a new one in,that thermostat wont ever close completely with that in there.Hope this helped.I dont even know if that stuff is on a 8.3 Cummins or not.Also there is a seal that goes around the thermostat up inside of the housing.If you replace the thermostat you should replace the seal.If that seal doesnt seal its the same as the thermostat being stuck open.I seem to remember a 8.3 has dual thermostats.If it has air to air,dual thermostats and a radiator with a built in overflow tank,Maybe this stuff could help.I know N14 Cummins motors have all of that stuff and more,but thats the newest Cummins owned an 1998 N 14.Other than that those switches that turn the fan on come in different temperatures.If you replaced that,and put the wrong one on,or if it had another one that was damaged and nobody caught it,could maybe be your trouble.I hope you tell me how you fix it,I would like to know.I worked on and owned Kenworths but very few Peterbuilts.However the truck with the weird radiator was a Peterbuilt and so was the truck with the thermostat jammed in wrong and stuck open was also a Peterbuilt.I dont remember if this was only on Peterbuilt trucks or not.Somehow I think everybody had a version of that weird radiator,and all Cummins motors went to low flow water system and 2 thermostats I think, and Peterbuilt was the only truck I ever drove where it caused a problem.Sorry thats about the best I can do for you with what I can remember.Some other big truck mechanics are on here sometimes and maybe they will know more.

thedieselgarage.com There is a MD and HD truck section there.

As a general rule, heating at low speeds is air flow related as fan is needed to generate flow to cool. Heating at highway speeds is water flow related as the fan isn't as critical at 60mph. So, I would look at pump,radiator, piping and hoses. Is it possible that a hose is partially obstructed or collapsing under hi flow/suction?

If it's overtemping on the hiway, have you checked the thermostat(S)? It may be helpful to carry a temp gun (infrared temp reading)with you and check for hot spots when driving and it o temps

DOES THE FAN PULL A SHOP RAG UP TO THE GRILL WHEN THE FAN IS ENGAGED(LOCKED IN)?EVEN AT ENGINE IDLE?IT SHOULD SUCK RIGHT UP TO THE GRILL.IF NOT ,IT IS AN AIR FLOW PROBLEM ,MAYBE SOMETHING BETWEEN THE RADIATOR AND CHARGE AIR COOLER AND A/C CONDENSOR.I'VE SEEN WHERE YOU COULD SHINE A LIGHT THRU ALL 3,AND THERE WAS BLOCKAGE.I GUARENTEE IF THE RAG TEST FAILS,IT WILL OVERHEAT.I BELIEVE THIS IS MORE LIKELY YOUR PROBLEM,UNLESS WHOEVER INSTALLED THE RADIATOR LEFT A RAG OR SOMETHING UP IN 1 OF THE HOSES(I'VE SEEN THAT BEFORE ,TOO!)BUT I BELIEVE IT WOULD OVERHEAT IN TOWN TOO OR AT LOW SPEEDS, LIGHT LOADS,IF THAT WAS THE PROBLEM.ALSO DOES THE FAN LOCK IN SOLID :NO SLIPPAGE.USUALLY YOU CAN TURN KEY ON,ENGINE OFF,AND UNPLUG FAN SOLENOID TO LOCK IN THE FAN. LET US KNOW,GOOD LUCK,MARK