Coolant system help

Hi again all!
So.... my radiator top hose blew up. My 1996 ja22w is on the side of the road about 3 miles away. I will take pictures next time i see her. My plan A is to buy a universal hose install it, top off fluids, limp it home, and wait for replacement parts before driving again. My wife was driving when the hose blew and she said she was going up a hill and it lost power so she pulled over. 
my questions:
does anyone know the diameter of the stock upper hose so I can grab the right size universal hose?
can anyone reccomend a site for the actual replacement parts?
Is there anything I should be cautious of when refilling coolant and limping home?
Why could my hose have blown in the first place? Was it just old or should I be concerned the same thing will happen with the new hose?
AND FINALLY, what are the odds that the engine is totally wrecked right now?

Thanks for reading! 

I don't know the hose size for Gen 2 but the engine will be ok if you shut it off as soon as the hose went.  They can just go due to age and if this is the original, it's not surprising.  The top hose usually leaks first because it gets far more heat than the bottom one.

Assuming it's like the Gen 3, you won't get any air locks as long as you fill slowly.  Ensure the heater control is turned to full hot (most cars these days don't have a heater control valve and just direct the cabin air accordingly, but it's best to be safe).

I'm hoping she pulled over as soon as it went, but she did say the engine was loosing power. I'm hoping she didn't not notice the hose and drive until it started to seize. Thanks for the reply and I will update asap

If it was losing power, that's not good.  Maybe take out the spark plugs and see how freely it turns over from the crank pulley, before trying to start it?

The temperature gauge (which is probably very non-linear anyway) wouldn't have shown a problem if the water dropped enough to uncover the sensor.  Hopefully, being the top hose, the head would have stayed full, although the coolant would have boiled in an instant.

I pedaled my butt out to the car, grabbed the blown hose and found a close enough replacement. The engine turns over freely, but I haven't tried to start it yet. On my way back to the jimny now. Pray for me!

Welp, new hose is on and coolant is re-filled. It turns over, but doesn't start. I'm on the side of the road still so I think I'm going to have to call for a tow. There is one symbol on the dash when I turn it over but I can't remember if it is usually on when the engine is being started:

That is a catalyst warning light, either it is on fire (you'd notice) or not working (the car wouldn't know until the engine is running).

Probably it goes out when the engine starts.

No idea why it won't start though, check you didn't disturb any wires when you changed the hose.


Overheating could have warped the head, and lost compression, but I wouldn't expect the water to fill up if it were that bad.

Sounds promising.  Is there fuel and a spark?

Well I just pulled the plugs and all three came out with coolant on them. I'm hoping it's just an absolutely wrecked head gasket and I'm hoping the heads aren't warped. Either way I'm not set up to do the job myself. It will be in the shop on Friday but I may get a start on ordering parts because she's my daily driver. I'll be spending the day scouring the internet. 

Good diagnosis there.  There's a reasonable chance it will need a skim (and the block too) but that's best practice after any HGF.  It must have been driven miles without coolant.

I had been thinking about this before I saw the latest posts (they confirmed what I was thinking)

Either the hose was old and just let go or more likely the cylinder head gasket went,this would cause a loss of power, cause the engine to over heat and loss of coolant. It would also pressurise the coolant system and it was probably a combination of over heating and pressure in the coolant system that caused the top pipe to fail.

I haven’t had a head gasket go on a Jimny, but have on other engines and always had the head skimmed. If not when you put the new gasket in it might fail prematurely and you don’t really want to do the job twice. You can check a head with a piece of plate glass and feeler gauges, but it’s a bit time consuming and you need to know the tolerance. Expect to pay about £50 to £100 depending on how flat it is and how much needs to be removed and replaced.

If the head hasn’t been skimmed before, it’s usually a straight forward job for the right garage or motor engineering firm.

Thank you for the advice and the information. I appreciate you and everyone who took the time to help me. I'm in puerto rico so I'm hoping the shop I'm going to is capable of doing the job. If not I will likely have to send the head somewhere to be skimmed which means more money and more time. I absolutely agree that this I'd a job I would rather do once and do right. I've been told countless times that I have the only JDM jimny people have seen on the island so there's no way I'm letting this story end with a broken jimny. I'm just hoping now that I don't have to sell her once all is said and done to recoup my losses. I will send updates as I get them!