This is not a thread on how I'm having a problem. It's how I solved a particular problem. At least, it's what worked for me. I tried searching for similar threads, and it seems like it's a common problem with the Gen 4 Prii. I looked through the posts where people were having hood latch issues, and some posts touched on this. I've had two Gen 4 Prius Primes. Both of them I got used to, and both of them had the same problem: when I pulled the hood release lever inside the car, the hood wouldn't pop up. I could hear it trying, but it just didn't make it. I've also had a Gen 2 and a Gen 3; neither of these had the problem. The same fix might work for those. They use either the same or a similar mechanism, but I'm posting this in the Gen 4 forums because that's where it showed up for me. What's the problem Nothing was actually broken; it was just that the mechanism that pops up the hood was weak. If it wasn't too cold outside, the hood would sometimes pop up so I could get into the engine compartment, but mostly I had to stick something into the gap or have a helper. This got annoying, and I didn't want to have this kind of problem when I was on a long trip. What didn't work: I opened the hood and duplicated what happened when the hood was closed. Pulling the release activated the hood release mechanism properly. (The cable between the lever and the release mechanism worked properly, even when I closed the actual hood.) I tried spraying some lubricant into the hood latch mechanism, but this didn't seem to do anything. Maybe for 5 minutes after I sprayed it and worked the mechanism over for a while, but it didn't really work - or last. I looked for body damage that would have changed the way the hood release worked. There was a little (both of my Primes were used), but nothing really to keep the hood releases from working properly. I tried giving the hood stops a little adjustment. DO NOT DO THIS. The main reason is that it risks warping your $350 aluminum hood (not including painting, which could easily double or triple that $350). Aluminum hoods really can't be bent back into shape like steel hoods. It's theoretically possible if the hood isn't bent more than a slight amount. I asked my guy at the body shop. He tried to tweak an aluminum hood before. He said not only no but hell no. Even if adjusting the hood stops worked, it would make the hood gap inconsistent between the middle and the sides. There's a much better solution. I tried opening up the holes in the hood latch mechanism with a file (or the bracket where it mounts. There are three bolts, and I forget which ones have the nuts welded to the hood latch mechanism or the radiator support bracket), I kept my tweaks subtle, making only a slight change, but I didn't see any results at all. (It also does something similar to adjusting the hood stops.) I also jacked up the front end and found where there had been some scrapes on the underside of the front end. I pulled off the lower radiator support and gave it a little tweak, but that didn't seem to do anything either. (It's also a bit like adjusting the hood stops. I suppose if someone really crashed into a curb with the front end, this could be different for your car.) What ended up being the fix was to replace the largest of the three springs in the hood latch mechanism (90506-14085 for my 2017 Prime; make sure you get the right part for your Prius, though). This part cost less than $5 from my local Toyota dealer. The best argument for not simply adjusting the hood stops is that it's using a $350 hood as a helper to boost a worn-out $5 spring. It doesn't really work either. I measured the spring in the relaxed, the hood unlatched, and the normal hood closed position. When it's fully closed, the coil part of the spring is stretched to over 300% of its totally relaxed position. Over time, that seems to be just too much for the spring, especially when the spring is overstretched 99.9% of the time. I did work some new grease into the mechanism when replacing the spring. It's a good idea to make sure that wasn't the problem. I also tried to come up with a different spring arrangement that could handle the stretch for the long run, even using a dual spring setup (using smaller diameter wires so the springs had more coils. It turned out to be pretty much impossible to do with the current hood latch design. I guess spending $5 every few years won't be so bad. Of course, this is what worked for my car. There are also other possibilities, and some of them are covered under the other threads which talk about broken release cables, front end damage... As they say, your mileage may vary.
