Prior to starting a summer of engine work on my 250 SL, JonnyB and I carefully placed masking tape on the hood mounting brackets before we removed it, and we used those marks when we installed it. But after installation, the front of the hood (on the battery side) was nearly a quarter inch too high. Then we were REALLY surprised to find that the culprit was the crack shown in the first picture below.
It turns out that the crack was caused by a mistake I made. I’m writing this post so no-one else makes the same mistake. Here’s what happened:
The hood spring slides into the plastic guide shown in the second picture below.
Prior to installation, I prepared as much as I could. This included installing the guide and tightening it until it was snug. Then, so the hood strap wouldn’t be in our way, I rolled it up and wrapped it with masking tape. Unfortunately I had slid the guide nearly all the way toward the hood. With the hood on the hinges, the spring settled into the bottom of the guide, but without the strap attached we didn’t know the hood was open too far.
The third picture below shows what happens when the hood opens too far. Since the axis of the hinge is close to the point where the hood hits the radiator mounting rail, a small amount of pressure on the top of the hood places tremendous stress at the hinge. With the guide too far forward and no strap, the force from the spring was too great and the aluminum just ripped.
Here’s what I learned:
1) If you don’t want to end up with a cracked hood, make sure that, with your hood open, there is clearance between the radiator mounting rail and the hood. Also make sure that your strap will protect the hood from hitting the radiator rail.
2) If your hood opens too far, slide the plastic guide toward the rear of the car.
3) If you end up with a crack like this, a skilled welder can fix it without damaging the paint on the hood. Hjeltness Restorations in Escondido did a great job fixing mine.
