Jeepney cross country trip

bizshop said:

Back home finally. The shop put in a 26" wide radiator that gave more cooling capacity. Helped quite a bit. The rest of the ride went pretty smooth. Had to shim the outside of the starter more. The overheating remains a problem - At 2200 rpm with the overdrive I figure I am going between 60 and 65, and the temperature holds around 215-220 degrees. However in traffic, at a stop light, or going up a hill the temp climbs on up. I've gotten as high as 250 again before I realize it and slow way down going up a hill. I'm right in there with the semis crawling up the big hills.

I just had a possible brainstorm - I have been using Herm's overdrive on my sbc 350 and TH350 rig, with the dana 18 transfer case. I need to get the shims to allow to it go back to direct, so it has been in overdrive constantly. Would this cause the overheating? My thinking is that with the lower rpm, the water pump isn't turning as fast and not circulating water as well. 60 mph before would be 3500 rpm, now it is around 2400 rpm - that would be about 30% less rpm - would that equate to quite a bit lower waterflow?

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Interesting... (I've got a 283/ M465/D-18w/od so very similar) I also used to run warm (220+)--but I never overheated (boiled over). 16lb thermostat on a 3 core radiator. The SBC was designed to cruise on the highway at 2400rpm--the water pump should be doing fine with that. Do you have the oem pulleys on the engine? You could try swapping a smaller pulley on the water pump to increase the rpm of the pump. Only cost you a pulley and a belt to try... Can also get a cheap IR thermometer 'gun' and see what the temps really are on the heads, intake, various spots on the radiator and "see" what's happening...

Never have overheated bad enough to boil over either, but 250 degree temps at times are scary. I've read so many things online that say temps should not be over 205, and 260 can cause damage to engine. I will look for smaller pulley on water pump and/or larger on crank, to increase waterpump rpm. I do have an IR gun, I'll check my temps.

I have seen chevys overheat because of a high flow performance waterpump without a matching radiator. The water flowed so fast through the radiator it did not cool down. Also chevys need flow through the heater hoses or they can overheat in hot weather. Had a customers summertime roadster with no heater that would boil over with the heater outlets plugged. Ran a bypass hose and no more overheating. I have also had bad waterpumps before, poor rebuilds with to much clearance internally, standard pumps with a reverse flow impeller installed, old pumps with impellers rusted away or loose on the shaft.
Do you have a mechanical fan or just an electric? If mechanical do you have a shroud? If mechanical is it a factory style or a worthless flex fan with blades 1" wide at the tips? Do you have a bad fan clutch? Is there a large gap between the radiator and the core support letting air bypass the radiator?
Lastly what temp gauge are you using, perhaps it is reading high?

If my engine gets past 210 I get off the road. My problem was keeping too much heat in the engine compartment, so I cut a hole and put on a scoop. And my fans were producing to low CFM. This is what I bought to install in their place from DERALE.

Right now the fans I have are producing about 800 CFM. These produce 4,000 CFM.

Try running separate trans and oil coolers with fans, and mechanical temp gage. When my under hood temps got higher my elec gage would spike, and the mechanical I added as a check would show less than a 10 degree rise, still less than 210. I put in a 29" two row radiator by trimming off the back of the passenger side headlight bucket. I drove Houston to Ft Worth and back in 96 degree weather at 70/75 mph with a/c on no problem.

Replacement radiator: brass or aluminum? Aluminum with two 1" tubes cool significantly better than a 4 row brass versions of the same size. Good for about a 15 degree drop in overall maximum temp.

Water pump: I've never had one pump too much water and remain unconvinced that a high flow pump will cool less than a stock pump, everything else being equal. I have had very good results with Flowkooler 1880's on sbc's. Again, good for a 10 to 15 degree potential temp drop. On my 3B, which it sees a lot of time in the rocks, I run a smaller than stock pump pulley that speeds the pump up about 15%.

Fan: Maybe old school, but you can't move more air with anything compared to a GOOD, LARGE, RIGID mechanical fan. My preference are 7 blade, 19". It costs you some efficiency (power robber) but if you want to really move air, it's hard to beat.

Fan shroud: Mechanical or electrical fans, neither will give you the cooling potential of a given radiator if you are not moving air through the entire core area. A well fit shroud is the most important thing you can do, especially for low speed crawling.

Engine bay air flow: as previously mentioned, you need to be able to exhaust cooling air from the engine bay. Nothing will help the cooling if there isn't any place for the air pulled through the radiator to exit.

Last, coolant additives. The water wetter's DO WORK. They will not cure systemic problems but are good for about a 5 degree temp drop just by pouring them in the radiator.