David Harris
Expedition Leader
I picked up a nearly new radiator for an 80's Range Rover. This doesn't have provision for the oil or transmission coolers in the side tanks. I would like to install this in my 1992 Range Rover with an external trans cooler. As far as the oil cooler I am planning to install an external one too, eventually. For the winter I was thinking of just blocking the oil cooler ports in the timing cover, and was interested in whether this was feasible/safe or not.
I thought I'd offer up what I've learned:
3.5-3.9 Pre-serpentine to 1993
There is a gallery running from the oil pump discharge to the filter inlet. When the cooler line fitting on the outlet side is threaded into the housing, it blocks this gallery, thereby forcing the oil to flow through the cooler first. However, when the cooler line fitting is removed, and a normal plug fitted in its place, the gallery passage is open and the oil can flow directly from the oil pump discharge to the filter, as if there were no cooler. The same thing happens if you just remove the cooler adapter plate and connect the filter adapter directly to the oil pump. An important note on the pre-serpentine system, is that when the cooler is fitted and the gallery passage is closed by the fitting, if anything blocks the oil cooler or lines, the engine will be starved of oil. There is no way for the oil to bypass the cooler because the gallery is plugged.
1993-02 Interim Serpentine, GEMS and Bosch
These covers have a bypass valve assembly (not to be confused with the pressure relief valve) which forces the oil to flow through the oil cooler under normal circumstances. However, should the oil cooler or lines become blocked, the increased pressure will force the valve open and allow the oil to flow directly to the oil filter, thus bypassing the cooler. So, with these one can block off the cooler ports safely and the oil will just go through the filter. An improvement over the earlier design. You could also just remove the bypass valve hardware permanently if you were not going to run a cooler.
03-04 Bosch
On these trucks, the timing cover has the cooler line ports, but it is not machined for the bypass valve. So, if one were to fit a cooler, there would be nothing to force the oil through the lines, so very little would reach the cooler. To make the cooler work correctly on this type of cover, it would have to be machined for the bypass valve, or the oil gallery passage from the oil pump to the filter can be plugged somehow to force the oil through the cooler as on the pre-serpentine engines. However, as with the pre-serpentine, if you do this then the engine would be starved of oil if the cooler or lines should be restricted.
If anything doesn't make sense, or is wrong, let me know.
David
I thought I'd offer up what I've learned:
3.5-3.9 Pre-serpentine to 1993
There is a gallery running from the oil pump discharge to the filter inlet. When the cooler line fitting on the outlet side is threaded into the housing, it blocks this gallery, thereby forcing the oil to flow through the cooler first. However, when the cooler line fitting is removed, and a normal plug fitted in its place, the gallery passage is open and the oil can flow directly from the oil pump discharge to the filter, as if there were no cooler. The same thing happens if you just remove the cooler adapter plate and connect the filter adapter directly to the oil pump. An important note on the pre-serpentine system, is that when the cooler is fitted and the gallery passage is closed by the fitting, if anything blocks the oil cooler or lines, the engine will be starved of oil. There is no way for the oil to bypass the cooler because the gallery is plugged.
1993-02 Interim Serpentine, GEMS and Bosch
These covers have a bypass valve assembly (not to be confused with the pressure relief valve) which forces the oil to flow through the oil cooler under normal circumstances. However, should the oil cooler or lines become blocked, the increased pressure will force the valve open and allow the oil to flow directly to the oil filter, thus bypassing the cooler. So, with these one can block off the cooler ports safely and the oil will just go through the filter. An improvement over the earlier design. You could also just remove the bypass valve hardware permanently if you were not going to run a cooler.
03-04 Bosch
On these trucks, the timing cover has the cooler line ports, but it is not machined for the bypass valve. So, if one were to fit a cooler, there would be nothing to force the oil through the lines, so very little would reach the cooler. To make the cooler work correctly on this type of cover, it would have to be machined for the bypass valve, or the oil gallery passage from the oil pump to the filter can be plugged somehow to force the oil through the cooler as on the pre-serpentine engines. However, as with the pre-serpentine, if you do this then the engine would be starved of oil if the cooler or lines should be restricted.
If anything doesn't make sense, or is wrong, let me know.
David
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