I replaced my heater core hoses a few years back with the rubber non braided type. I thought that was it for another 10 years or so but i got a big surprise when i heard a hissing noise

and then tons of steam inside the car.

This night really sucked. It took me 2 hours to travel 30 miles. It completely drained my radiator and i only had a lunch box with a dr pepper and 2 ice packs. You can't imagine how expensive a tow is at midnight in hawaii. So i improvised. First the dr pepper went in then i poked holes in the ice packs. Its semi liquid but helped a little. 2 mph in the emergency lane and i finally reached a little shopping center and drained some stinky koi pond water.

Anyways, fortunately i live in a place that is warm enough to not need a heater so i just bypassed the heater core altogether. I was reading a few threads in the past about looping to bypass the heater

and how bad it was for the coolant temps in the cylinders in the back of the head. So i plugged everything off.

The lesson learned here was to replace the heater core hoses with

the braided type that last 30+ years.

I think mine are OEM, but not certain of that. They are braided though. I know the Nissan dealer here has to source them from the states. At least the hoses are easy to replace or temporally block off.

Heaters can be a problem. They are easily neglected because they are hard to get to. Different story when replacing the heater valve which worries me some.

Chas

I had this exact problem happen to me Sun. morning at a show I don't think I did it correctly. I cut the hose going into the firewall and connected it to the rear of the cylinder head. now that I look at what you did. I think I'm going to plug the holes like you did. on my way home it stayed pretty hot. I hope I didn't do any damage

I'm going through the same thing. My heater valve is leaking onto the passenger's floor board so I looped the 2 connections with a short piece of hose instead of plugging them. It does run hotter on the gauge but feeling around the engine I don't think it's too hot for any damage. My local Nissan parts guy ordered one yesterday and I hope to get it today. I've found some Gates pre formed heater hoses that I can work into that tight spot next to the tunnel. I won't be shooting fire crackers this weekend, eating and drinking too much for sure though. I'll put some pictures and part numbers up when I'm done.