philshannon (205.188.196.59)
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Votes: 0 (Vote!) | | Posted on Sunday, October 07, 2001 - 12:38 pm: | |
I figure this subject title will get everyones curiosity. On my first trip in PD4104-3832 from St George Utah to Grand Jct Colorado, we experienced overheating. After the first 55 miles of which 75% was uphill I decided to change the thermostast. I didnt overheat until the next grade. This went on for the entire 13 hour trip which should have taken 8 hours. Several times durring the voyage we had to pull over and spray the radiator with water using a hudson sprayer. I really ran the bus easy, never letting the temp get over 200 degrees before pulling over. We finally nursed it into Grand Jct and set up for the week.
I had already replaced the water pump during the first year that the bus was in C-Check. (Heavy Maintenance for all you non-aviation types) The temperature gage and sending unit were verified as accurate using a digital temperature sensing test box prior to the trip. The radiator fluid, all 78 quarts were fresh and clean.
The only remaining possibility was the radiator itself. While in GJT I removed the radiator and too it to a reputable radiator shop. They called me the next day and told me to come down right away to see somthing they'd never seen before. I hopped in the car and headed for the radiator shop.
They took me into the back and showed me the radiator. The top tank cover was removed, and to my astonishment, the top of the radiator core was level with several inches of clean pea gravel. The pea gravel was large enough to remain on top of the radiator and not go down the tubes of the core. Great I said, get that stuff out of there and let's rod out out my radiator and put here back together.
The top of the tank needed some aluminum welding to fill in some corroded cavities, that was outshopped to a welding shop just down the road. Other than that the core was in good shape, the tubes were virtually clean, the radiator was reassembled and reinstalled.
I was thrilled to finally figure out the "overheating on a grade only" mystery. The pea gravel had effectively reduced the surface area of the radiator by restricting flow down to that of a much smaller radiator. The radiator could maintain system parameters as long as the diesel was not under load. I have an 8% grade 3 miles from my house and every time I'd take the bus to town and back it would get up to arround 195 degrees after that grade. I figured that an 8% grade is rare out in the real world and that living in St George wher the temperature is rarely below 100 degrees during the summer, that this was to be expected.
The reality is, that my return trip back from GJT to SGU was uneventful, the temperature never, and I mean never, got above 185 degrees on any of the passes and the outside air temp was hovering near 90 degrees. So for all you Busnuts out there with a 4104, with a DD6-71 with a 4 speed spicer, you should never overheat on the hottest day cutting through the passes within the western united states if your cooling system is up to specifications. Good news huh?
Now for my usaul question for the old guys, what the hell is pea gravel doing in my radiator? As stupid as this sounds I just gotta ask, is this some old WWII trick or something? Myself, I suspect that when old 4104-3832 was sitting derelict in Las Vegas for the the last 10 years of its life, I think the kids with the BB guns decided it would be fun to put gravel in the radiator.
Ideas?
Best,
Phil Shannon |
mel la plante (208.181.100.83)
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Votes: 0 (Vote!) | | Posted on Tuesday, October 09, 2001 - 2:35 pm: | |
hi Phil , you are right on thinking that it was kids I had the same thing with some buses that I had stored in the back field. I went to look at them one day and some NICE kids had broken all the glass and put gravel in the rads and fuel tanks.so much for the local rug rats. great choice of units mine is a 4104 and I have on desire to change to any thing else,how ever I will put a 4 valve head on next rebuild. in a gmc you can sleep at nite as you do not hear it rust 24 hours a day. good luck mel... |