Temps climbing in 318
I think that fan shroud isn't doing you any favors because the air is missing a big part of where the hottest coolant is.
I would also recommend a different shroud. The one you have is not any good (don't mean to sound harsh, but just to the point). It's not letting the fan do its job. :eye:
The only opening in the back of the shroud should be where the fan goes. The purpose of a shroud is to make a "nozzle" to direct the air to the fan, so it can pull air through the radiator. With the openings that I have circled, you are not letting the fan pull the air through the radiator. The whole back side of the shroud needs to be covered and the only opening is to be around the fan with just enough clearance so the fan doesn't hit the shroud. Your shroud does not let that happen.
Your position of the fan in the shroud looks ok to me. This is called FOOS (and not Chip Foose), it is an acronym for Fan Out Of Shroud. The shroud should cover about 50% of the depth of the fan give or take approx 15% so the fan can draw the air through the radiator. The fan being too far inside or outside the shroud will hurt the ability of the fan to pull the air through the radiator.
The shroud's biggest benefit is when you are not moving or going very fast. I would find a better shroud.
Now in this case, I don't believe that the shroud is causing your overheating problems, but I took a closer look at it when Trailbeast mentioned it. He has a good point that the shroud is not adequate.
Usually overheating problems are when you are not moving fast or at all, you have the opposite problem. At highway speeds you get "ram air" effect through the radiator from the car moving and the fan is not necessary - that's when the clutch fans disengage.
Have you tried to spray the radiator with a hose when it's hot to see if it helps cool it down? When the car is hot/overheating, spray the radiator with a garden hose or car wash hose and see if the temp comes down. That will indicate if your radiator is the bottleneck/weakest link in your cooling system. It sounds like your radiator does not have the capacity to cool your engine (maybe clogged etc).
Keep in mind when looking at new radiators, area before depth. You get more benefit from adding area than you do depth, if you have the space for it. The thicker the fins/rows are, the more resistance to air flow it has. Thicker is not always better to a degree. I wouldn't go more than 3 row. If you have more area to increase the radiator size, then that will give you more cooling capacity without restricting airflow. You would be better going from a 18" radiator to a 22" radiator if you have the room, than adding more rows to a 18" radiator (this is just for example to prove the point and not implying that you have an 18" radiator).
I agree that your problem is due to not enough capacity for the radiator. But also recommend getting you shroud improved also. You want the whole package to be correct.
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