Head Gasket Failure

[pralognan]

Thank you for your detailed response.Head gasket leaks can be intermittent depending on load and temperature.Did you ever do a leak-down test? This is better than a compression test for this type of problem.The sequential failure of hoses,aluminium pipes and radiator over a period of many months is consistent with over pressure caused by a head gasket leak gradually getting worse.

[goldnsx]

pralognan throws in an interesting point here. Did you also use a chemical headgasket test kit? https://www.youtube.com/watch?v=CHp5E7XnbXo If the headgasket is only acting up under high load (pedal to the metal) then it's hard to find a leak even with this kit.
My guess is too that your car
- either had the wrong coolant in it for some time
- or the coolant got contaminated by combustion gases

I guess the short hot red needle period only finally gave the headgasket the rest of his life.

One thing about the cooling system of the NSX is interesting and has been observed not only in my car.
In short:
- coolant level was at max in the bottle with a cold engine
- German Autobahn fun at 15 deg C outside temp, pedal to the metal
- got home an recognised a higher level in the coolant bottle when cold (maybe 2 cm) and even higher when warmed up (maybe 5 cm higher)
- was very worried about the headgasket
- had some very tiny bubbles in the coolant in the bottle
- went to the mechanic
- used the fluid test kit above for 10 minutes or so at idle, nothing, headgasket seemed to be ok
- over the next drives the coolant level in the bottle went back to where it should be
- this was 8-10 years ago and before CTSC
- no such observation again, well, no German Autobahn since then too
- I had observed a similar occurance in a car that has been on the track, also no headgasket failure and has been good since then

The headgasket material of the NA1 is organic and prone to fail in the longrun. I'm about to do the TB/WP job next winter but am guessing if I should wait until my headgasket fails too...

[UnhuZ]

Hi,

pralognan:
i understand what you say, but the sequence can also be caused by repairing one thing, bring the pressure back up,
so the next weakest thing fails, and so on. I'm more inclined to this, you will see why below (headgasket test)

And yes, this happened for a long period of 3 years.

Thomas:
Yeap, i used that one, bought in UK. Not from Napa, and the box is the same but with different printed stuff,
but the elements inside are exactly the same.

Answering your 2 points:

- a friend and me went to Germany back in Sep 2004 and bought it from the first owner. It was always mantained
in the same Honda Dealer (actually where we picked it up). We got to Portugal and 2 Honda mechanics changed the
timing belt. They used Honda Coolant. In my friend 1 year ownership, the coolant was never touched again. I bought
the car from him in Sep 2005. The coolant was never touched until 2010, when i drained it all and put new Honda
Coolant back in. Then early in 2011 the coolant level started to go down and then i found the Hoses under the car
to be leaking from the ropes... and with this the saga i described above begin.
While chasing the leaks, i was using a cheap coolant, because Honda Coolant is a lot expensive to trash while figuring
out what is leaking. I made sure that this was aluminium compatible.

- I used the headgasket tester when the coolant level started go back down again after i changed all the Hoses, this
in early 2011. It didn't change to green, it stayed blue. When i tested it after that red temp event, like within a week
or 2, which was a long time after the Hose change, it turned green. At this time, the coolant was still clear, as new.

Those level variantios you experienced, i never did in my NSX... and i drove it like i stole it for, both in top speed and
in twisted mountain roads. Never was above max... it always moved whithin the max-min limits.

Now, with everything new, but the aluminium pipes, and with MLS headgaskets, let's see if i will have missing coolant
again !!

Nuno