Today we had about 100F in Texas. Running loaded, the 855 was getting warm over 60 and up hills. That's classic radiator insufficiency symptoms. I was dreading finding a radiator for this ole 1984 truck. Got home and pulled out this nifty 90° squirter the LS dealer gave me with my little 55hp tractor. AMAZING how much dirt came out of my radiator fins. Had to hose down my carport after I was done. Red East Texas dirt ... the worst kind. I think tomorrow she'll run cooler.
I LIKE that tool, easy enough to make one if you can't find one.
Yep, bend some copper tubing in a vice and JB Weld it onto a nozzle...
dry feedlot.
Welp, a few hot days running later, it's clear that cleaning out the mud definitely helped. But she still climbs up a bit in heat on hills. In the old days, I'd take a radiator out to get rodded, dipped, resoldered. Haven't seen a radiator shop in years. There used to be a couple good ones in any decent small city. I am saving a brass IH 7.3 IDI radiator out on a fence in case I find one. Now I need one for my 855 also. Guess I'll call around. Radiators are aluminum with plastic tanks these days. The one in my 99 F550 is still running fine on that original. But rebuilds are not a thing with aluminum radiators, afaik.
It is normal for it to heat up somewhat on a hard pull. As long as it stays below the allowable max, whatever that might be.
As long as she isn't touching 220, stop worrying about it. Proper coolant with a working cap to maintain at least 8 psi will raise the boiling point to about 240°F.
205* to 210* and that all depends on how good the block deck surface is.
OK guys, thanks. This is my first Cummins. I owned a 14 liter V6 Mercedes rolloff tipper in France and had cooling issues with it. That makes me a little gun shy as it were. Its radiator was aluminum. Cleaning fins did not help.
The thermostat starts to open below its official set point, so if it is a 180 degree thermostat the engine will run like 172 most of the time at light load, cold days etc. When you really get it working on a warm day the stat will be fully open and the temperature drop from radiator to outside air will be doing the regulating. The hotter the water gets, the greater the difference between the water and the outside air, and the easier the heat flows from one to the other. At some point the fan comes on. I don't remember if you talked about that in another place. Is it air or viscous? It should sound like an airplane when the engine is at high RPM and be very noticeable when on vs off. Another item is the temperature gauge, how do you know it is telling the truth.
Since this is an 84, and somebody that drove it along the way didn't use distilled water to top it up. Have you flushed the cooling system? l like to drain it hot after it's been working, fill it with rainwater once it's not hot, and work it another hour, drain some into a clean white bucket, and repeat until you don't get any more sediment, or at least you're comfortable with the amount of sediment. Then refill with 50/50, or 40% antifreeze. The antifreeze is thicker and has less heat capacity than the water, straight water will keep it cooler, but antifreeze will give you a little more room before it boils so more cooling capacity there like BV said.
what is the gauge reading?
I'll take a pic Monday. Quarries are closed today.
Well, how do you not remember if it was reading 180, or 220?
It's a fair question. I'm 6'5" and keep the air seat up near the top of its travel. So the hood of the instrument panel masks the top of the gauge, but I can see the needle and I'm familiar with the range it's in and when it creeps up. If I lean down to look closer, then I'm looking thru the top part of my glasses, which are for seeing down the road, not up close. So it's blurry. Finally, I messed up my neck in hapkido years ago so it won't lean back like you young guys. Somebody should invent upside down bifocals for working under trucks and seeing well up close thru the top part of the glasses. But of course I could not wear them to drive and see that darn gauge. It would be great when under a truck working on things.
I'm guessing that it was probably running just fine. It would have to bury the needle to be running at 220. When you look at it, I'm betting you're going to guess it was between 205 and 210.
Does it have a air clutch fan hub? if so many of those the sending unit {Index brand} was set at 205* before fan would engage.
Actually, prescription bifocals with a top lens have been around a long time. Just ask for them next time you get glasses. OTC type top lens? I have no idea if they exist.
I took a pic too, but yours is much better. Yes, it was around 205 at the highest. So I guess I was worrying for nothing. It was 100F and I was hauling up a 2 minute hill. Thanks guys. Anybody have a pic of an air clutch fan hub, so I can compare it to what I have? I'm going to the optometrist soon with that tip. Thanks for that info!
It would be a Horton 790000 series fan hub.
It's a classic thermal fan clutch. I have not heard it roaring yet.
A tired viscus hub. Viscus hubs were very common years back, many fleets bought/spec'ed with viscus fan hubs to cut costs. Probably original and probably shot.
We're familiar with that type of fan clutch. We'll give it a good check. Thanks for the tip.
I have been fighting a similar overheating problem on the 8.3L Cummins in my '97 L8000. It only happens on warm days, pulling hard on passes, etc. Over time, I've been through and replaced a lot of components (water pump and thermostats needed done, anyway), the latest being the viscous clutch. The one that was on there appeared okay, passed a couple of the tests, but after a nervous two days finding a replacement, new one acts different - need to have a day with a hard pull to see for sure if it did any good. You pic looks a lot like my application, I hope you have better luck finding one, at least an inexpensive one. Parts stores and KitMaster were no help with the Cummins part #, which was 59921. Finally found one out in OR, (gulp) $475 ground shipped. Radiator is the final component, and same problem here .. nobody boils/rods the old ones out, gotta travel at least an hour to a shop elsewhere. A new, inferior, plastic/aluminum one in horizontal configuration is stratospheric in price. One hint, beg, borrow or buy the air hammer style clutch nut removal tool to take the thing off. I soaked the assembly point in PB for a day before attempting with a pry bar, air hammer/chisel and big crescent wrench - it did not go well. After a couple more attempts and some pretty inventive language, a buddy of mine who works at a shop loaned me his kit, 1 7/8" flange size fit, and it was off in 30 seconds. I'll never tackle that project again without one.