Oil cooler lines on 1996 993 passenger side super hot

[ralphedo]

The passenger side door threshold that covers the oil cooler lines radiates a lot of heat to the passengers leg. Is this normal or did somebody fail to reinstall insulation ?? Is there a recommended way to fix this or do I have an engine thermostat problem in the oil cooler system. The engine temp is fine.

[Junkseller]

That’s a pretty common issue on air-cooled 911s (especially 964s and 993s), since the oil cooler lines run right under the passenger-side rocker and door threshold. When the car’s fully up to temp, those oil lines can be carrying oil at 220°F+ — and that radiant heat bleeds straight into the cabin sidewall.

Here are the best ways to mitigate it on your 1997 Porsche 993:

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1. Add Heat Shielding
• Use a reflective heat barrier (e.g., DEI Reflect-A-Gold, Thermo-Tec aluminized mat, or similar) on the inside of the rocker panel/threshold trim.
• Stick it to the floor pan and side of the tunnel near the oil lines to reflect radiant heat.
• You can also wrap the oil lines themselves with heat sleeve insulation (fiberglass/aluminized sleeves designed for fluid lines).

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2. Upgrade Interior Insulation
• Remove the threshold trim and carpet on the passenger side, then add a layer of high-temp closed-cell insulation or dynamat extreme with a heat barrier layer.
• Porsche didn’t put much insulation in that area, so upgrading it will significantly cut cabin heat soak.

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3. Check Airflow Around Oil Lines
• Ensure there’s no underbody shielding or debris restricting airflow around the oil lines. Air movement helps keep them cooler.
• Some owners fabricate a thin aluminum heat shield between the oil lines and body, with a small air gap to deflect radiant heat.

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4. Condition of Oil Lines
• Old, dirty, or oil-soaked insulation on the lines (if fitted by a prior owner) can actually trap heat. Make sure the lines are clean and bare if you plan to apply new shielding.