Head Gasket Failure

[UnhuZ]

Hi,

Thomas and pralognan, the sequence of failures was:

1 - Coolant level was dropping in the tank, slowly but steady.

2 - At first glance, i didn't see any leaks in any part of the circuit

3 - after a short while, i was able to get the car on a lift and remove the black plastic covering the hoses
under the car. Found coolant green residues on the upside of that cover and saw that it was getting out by
the ropes on both edges of both big hoses under the car.

4 - Replaced all hoses, 6 Big ones with Venair, the rest OEM Honda and a new OEM tank

5 - Coolant level kept going down, slower, but surely.

6 - Discovered leaks on one of the big aluminium pipes that go from under the car and over the fuel tank.
Replaced with a pressure tested used one.

7 - Coolant level stabilized and slowly got down again. This time was one of the big alumium pipes that go
from under the car to the front, the driver side thicker one. Again, replaced with a pressure tested used one.

8 - Coolant level was stable for some time, like 3 or 4 months, and then it start to go down faster than ever
before. This was when my OEM radiator failed... it was leaking bad...


as i needed to daily drive the car, i checked the tank level right before every time i started the car... i never
let the tank get empty, and always had an eye on the temp needle.

If it started to go up, a quick blip on the throtle and it came immediatly down, which only happened when
stopped at a light and such.

In one of the drives, for the first time i found myself in a stop and go traffic and to avoid being hit by an
asshole on a bike, i didn't look to the temp for like 2 or 3 minutes, and when i looked, it was up there in the
red, with a blip, it came immediatly back down one trace below the middle. This was what killed my head
gasket.

Up to this point, the coolant was always clean just like the one in the jug, but after this, the coolant color
got darker and some time later it suddenly became brownish, this was when the oil started to get in the
coolant and right when i stopped the car for good.

So, pralognan, i don't think that the first thing was the head gasket failure, just because of this:
(but i can well be dead wrong)

Prior to that red temp event, the compression test was always 200-210 in all 6 cylinders.

Right after that high temp event, i made another test within a couple of days after and 5 cylinders were
still at 200-210 and one on the front bank was just going up to 185.
And it took more time for this to get to 185 than the others to 200-210.

additional things i checked:

- no coolant in the oil. Oil is still crystal clean today. Dark brown color as i use Sikolene Titan Race Pro S.
- no significative oil level drop. As always, from 3/4 down to 1/4 in each oil change, i.e. each 7500kms.

I discussed both with Kaz and with Larry B if i should change bearings and piston rings in this major refresh.

Things in favour of NOT to do it:
- The oil consumption doesn't justify it.
- The compression tests show good compression.
- My worries on mistakes torquing back the crank and rod screws/bolts and everything then go KABOOOM !

So, with the above, they both said that it wasn't necessary as the block is apparentely with good health.
BTW, it now has 220.000kms

Man... i think i never wrote a post this long.. loool

Thanks,
Nuno

[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