I've got a 90 740 turbo with heat issues. I replaced the water pump (fins electrolysised off the volvo reman.), the upper hose (old one was bloated), and had the radiator rodded and repaired. I even bought the 20$/gallon volvo coolant, hoping I would not need any more for a long time.

The upper rad. hose was an autozone cut-to-fit job. The problem is that the radiator and the thermostat housing metal pipes are not the same size. The radiator is a good 3-4 mm smaller in diameter. The radiator actually appears to be aftermarket (made in Mexico mean anything?), so maybe that's the problem. Does anyone know what the deal is with this? While at a used volvo dealer, I saw that it looked like (from the 2 inch picture) the hose was belled out at one end.

Additionally, today I ran the A/C a ton (not enough to get the aux fan on, but it works + I just resoldered the relay). When I parked, I noticed that there was a dribbling puddle of very green Volvo coolant from the opposite side of my mis-fitted hose. 1) maybe the sensor for the AUX fan is not working. There are two listed on FCP groton, screw-in and push-in, but I'm not sure which I have.
2) I think the leak came from the feed-tube from the top, small nipple of the rad. to the fill-tank. There is no clamp on the end attached to the radiator, I see no markings on it, and the routing seems.. wrong. It was routed under the turbo-intercooler hose, but I moved to around the airbox. I didn't really want to add any more heat to the incoming air. Might a spring clamp to match the tank side fix this end?

Maybe my difficulties with cooling are contributing to my crappy 20mpg. Tomorrow, I'll try to calc the expected difference in mileage between the high (mine) and low differentials and account for the non-locking torque converter I have sucking off 10% of my work.

Thanks in advance,
Will
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1990 740 Turbo, on its way to stock specs, maybe beyond