Interesting event this weekend.  Coming back from a quick trip to the store (just < 1 mile).  Realize there is no heat as the mrs is complaining.  Look at temp gauge and it is a little higher than normal...and rising.  Cold air is blowing.  Keep cruising home and a block away I see some steam start to come out from under the hood and smell hot coolant.  I figure something blew out (hose, etc.).  Coast in the last block to the house, get the hood up and see the air bleed screw is broken (top is cracked).

 

The air bleed screw might have been weak, as I thought it seemed a little soft when I buttoned up my engine reinstall some months ago, but the car has been driven daily many times since then and no problem.  Temp gauge on the dash is always at the same spot when warm, hot air blew fine.

 

Yesterday I decided to throw in a new OEM thermostat I had (old t-stat was factory size- nice and beefy).  As I went to fire it up I saw CEL (P0115 and P0125).  Did some searching and came up with engine coolant temperature sensor.    

 

Fired it up and saw a small coolant leak.  Determined that the upper radiator hose blew out, but it didn't split the hose or pop a slightly loose hose clamp...it blew out the plastic at the lip where the upper hose was connected to the radiator (a small ring of plastic was inside the upper hose, corresponding to where the hose clamp was secured).

 

I was able to dremel off a small plastic stop nub on the stub on the radiator so I could get the hose on there another cm or so, and then clamp it down.  I replaced the ECTS and cleared the codes.  Figured out that the air bleed screw is M10 x 1.25 threads and stuck a bolt in there).  Coolant added, fired up and after some burping, heat is again working.

 

Any thoughts on why the pressure built up and blew out the upper radiator connection?  I'm thinking it was a bad thermostat and the lack of circulation built up pressure there.  Something else?

 

 

Age. I've had mine do that. I figured out wad just old, since it was the original radiator.

Year?

Model?

Year?

Model?

In the sig line...

'95 LS EJ22 4EAT.

 

Cooling fins are in decent shape, but I don't have a good idea of how old the radiator is generally.

Sometimes folks over tighten the hose clamp and crack the plastic.