Coolant Leak

[Steveycaz]

Thought I'd take the NSX in to work this morning. Coolant leak changed my mind:(. I'm assuming its coolant; it's green and tastes funny!

Anyone technically minded want to offer some advice? A rubber cap on one of the pipes next to the blower unit has a nice neat hole in the top and it spews coolant out at a generous rate. can I replace the rubber cap? How do i refill the coolant? What do I use?

Offending rubber cap thingy:
3055

[Steveycaz]

Had a leaf through the workshop manual. Looks like it is a bleed cap that's blown. Local honda dealer want to pressure test it for other leaks then recharge it. Looking at the manual it doesn't look like something I can do myself without a hoist or a pit (need to get under the car to drain, bleeed and recharge properly). Not happy paying for transport to Winchester (10 miles) so tempted to bung up the bleed valve with something, top it up with antifreeze and drive the 10 miles to Winchester watching the temp guage. Does this sound too risky?

[simonprelude]

Do you have AA / RAC cover ??
They would flat bed it to the Garage for you.

I wouldn't risk it, even with the small distance and the weather.

[Steveycaz]

Hi Simon. Not got Home Start! Got a mate with a trailer for his race car though - could give that a go.

[NSX 2000]

Hi Simon. Not got Home Start! Got a mate with a trailer for his race car though - could give that a go.
I would push it down the road then call them with the following story, "you've set off to do some xmas shopping when you saw steam/smoke from the bonnet, you've pulled over to investigate and found some pipe or another leaking" Hence you don't need home start as the car will start but you don't fancy driving any further just in case of damage.
Any how that's what I would do.
HTH
Paul.

[simonprelude]

I think homestart is within 2 miles of home :(

[AR]

Had a leaf through the workshop manual. Looks like it is a bleed cap that's blown. Local honda dealer want to pressure test it for other leaks then recharge it. Looking at the manual it doesn't look like something I can do myself without a hoist or a pit (need to get under the car to drain, bleeed and recharge properly). Not happy paying for transport to Winchester (10 miles) so tempted to bung up the bleed valve with something, top it up with antifreeze and drive the 10 miles to Winchester watching the temp guage. Does this sound too risky?

Can't you buy the black cap from them and then drive the car there?

Cheers,

AR

[Steveycaz]

Can't you buy the black cap from them and then drive the car there?

Ah the clever answer. Good idea Ary. The garage is saying that there may be another problem and the burst cap is just the symptom. Its not an urgent job as I don't usually drive it much over winter - but I will weigh up these options and let you know how I get on.

thanks chaps!

[goldnsx]

Interesting to see that this heater bleeding small cap bursted. I would not have expected that.

Depending on how much coolant the car lost get a new cap, it's an ultra easy DIY.

Just the symptom? Could be but it's not very logical to me. Why? There have been other hose failure reported on older cars and it was always a different hose. There is not very much pressure to the heater lines.

If there is too much pressure in the system most likely the coolant cap is not working properly (easy check) or the bad way: the head gaskets are blowing blowing air into the cooling system. But this is more than hypothetical. :)

[nigel]

Sounds like your thermostat has gone off and it's allowing the system to build to much pressure, thus the weakest link in the system is the plastic cap. Just a thought. A new thermostat should be only be a few quid at the local parts store as it's a part that doesn't necessarily have to be a Honda part. Do get a new gasket though. The thermostat is not a hard job just get in your manual for the bleeding procedures. Mix the anit-freeze at 50 / 50 with distilled water. Also, you don't want to trap air in the system. If the thermostat has gone off, how old are the rest of your hoses. They may go next, espicially the one in the engine bay by the coolant tank and they are a pain in the bollicks to replace, There are 22 total to replace and they do fit tight.

Cheers
nigel

[NSXGB]

Sounds like your thermostat has gone off and it's allowing the system to build to much pressure, thus the weakest link in the system is the plastic cap. Just a thought.


The thermostat does not have any effect on system pressure. The weakest point should be the pressure cap, it's there to relieve pressure before anywhere else does....
Hopefully it's just a piece of plastic that's deteriorated with age as no other symptoms have been mentioned.

From the looks of things, it would be easy to swap over as it's high up in the system and as it's the actual bleed nipple, couldn't be better placed...

[goldnsx]

The thermostat is not a pressure regulator, it's a temperature regulator. Your argument would only hold if you got higher temperature and therefore higher pressure than normal (tendency to overheat). But still then the pressure cap should relieve the overpressure (above 1.1 bar) and the hoses should still do their job. If the engines temp is normal I'd NOT change the thermostat.
The cap is not the weak point, that's why I'm astonished hearing about a failure. There are much better hoses to burst: engines, radiator and oil cooler hoses, most of them suffer heat and vibrations.
What is more likely that the bleeding cap was damaged in some way in the past during the coolant-refilling-job.

Good luck!

[NSXGB]

The thermostat is not a pressure regulator, it's a temperature regulator. Your argument would only hold if you got higher temperature and therefore higher pressure than normal (tendency to overheat). But still then the pressure cap should relieve the overpressure (above 1.1 bar) and the hoses should still do their job. If the engines temp is normal I'd NOT change the thermostat.
The cap is not the weak point, that's why I'm astonished hearing about a failure. There are much better hoses to burst: engines, radiator and oil cooler hoses, most of them suffer heat and vibrations.
What is more likely that the bleeding cap was damaged in some way in the past during the coolant-refilling-job.

Good luck!

I think that's what I just said? :think:

Apart from the fact that the coolant cap should be the weakest point....in a healthy system....

[goldnsx]

I think that's what I just said? :think:

You've posted your message while I was still writting mine. ;) I was too lazy to delete mine.

[Steveycaz]

Thanks everyone - the bleed nipple cap is definately damaged and I'm just wondering whether I bashed it when I was removing the spare tyre holder some time back :cantlook:.

A good couple of litres of coolant have gone so it will need draining, recharging and pressure testing properly to give me piece of mind that its all pucker. Given that the drains are underneath the car I'm not going to DIY it.

Question is; Honda dealer or any reputable workshop?

[NSXGB]

Question is; Honda dealer or any reputable workshop? Yesterday 10:29 AM

I would say that if you are not getting a rubber stamp in your book for it, go somewhere that charges reasonable rates...:)

[Kevin]

I would just fill it back up with coolant mix, following correct procedure. Once you've started it and the system's warmed up it will pressurised enough. I don't see any reason to be taking it anywhere. Just like I don't see any need to be draining it either.

[TheSebringOne]

On this subject of replacing/topping up the coolant, which one do we require from Honda? Is there one specific to the NSX? or can the brands from Halfords do the job?

[gsuds]

NO - please don't buy Honda coolant - really no need! But worth getting a good quality generic one (Comma / Halfords / whatever's "Taste the Difference" range).

Agree topping up easy enough - just do the bleed points in correct sequence per the workshop manual. I did it myself after replacing rad. If you're not confident then really any garage could do it....

[Kevin]

As it's already lost coolant and it's at home, you're going to have to fill it anyway before taking it somewhere else.

[goldnsx]

NO - please don't buy Honda coolant - really no need!

Why not? It's not expensive here around. :unsure: And you sleep better taking the Genuine stuff. ;)

[NSXGB]

What's the capacity and mixture required?

I was charged for 3 x 5 litre bottles of a/f in my last Honda service @£15 per bottle.....

[Lankstarr]

I'd refill, pop the new cap on and watch it for half an hour whilst idling. How long did it take to pour out as it is? Maybe wait that long then another 10 mins before going for a little drive and rechecking. If it's fine after that and you want peace of mind then go see your stealer for a check... I would for the sake of 50 - 100 quid to stop me from worrying that I was losing juice every time I drove it. Then again, if you keep an eye on it and take it to work and back one morning it should be fine if it survives the 30 mile trip.

Talking about coolant thermostats. I had mine replaced last year at a cost of £70 fitted from Honda. IF your car takes a lot more than 5 mins to warm up in this weather then I'd recommend getting it replaced.

Good luck mate!

L*

[TheSebringOne]

I prefer to use Honda's own for peace of mind, does anyone know whether the same stuff goes in all Hondas? I have a nearly full tub from my old Prelude, will this do or is there a special one for the NSX? Was the Prelude not a Alu block like the NSX? :)

[simonprelude]

It depends on which Prelude.

[goldnsx]

What's the capacity and mixture required?

I was charged for 3 x 5 litre bottles of a/f in my last Honda service @£15 per bottle.....

I refilled about 14-15 (!) litre. Mixture is 50/50. Please ask your dealer if it's premixed or not. If not use destilled water, not normal.

I had to refill it 4 times while running at idle and was wondering if my head gasket was blown because it always seemed to drink that much coolant. ;) I've correctly bleeded the coolant lines.

£3 per litre is at the higher margin.

[jaytip]

Honda coolant in the UK is pre mixed.Just open the cap and pour it in.

[nigel]

I was just thinking the thermostat might be stuck closed and thus allowing the system to build pressure and because the plastic cap was damaged or old it broke before the system reached relief pressure of the radiator cap.
You don't have to use Honda coolant and i'll be much cheaper to mix it 50/50 yourself.

Cheers
nigel

[Steveycaz]

Is that 15 litres of coolant solution or concentrate?

As I am topping up I'd rather go for Honda stuff (manual says not to mix different makes and I'm naive enough to believe them!).

I am going to brave it and do it myself now! I hope the bleed bolts are all easily accessible.

[goldnsx]

Is that 15 litres of coolant solution or concentrate?

As I am topping up I'd rather go for Honda stuff (manual says not to mix different makes and I'm naive enough to believe them!).

I am going to brave it and do it myself now! I hope the bleed bolts are all easily accessible.

15 liters solution.

The middle bleed bolts are behind the plastic cover of the mid tunnel. The engine drain screws are a little pain to get to.

[Steveycaz]

15 liters solution.

The middle bleed bolts are behind the plastic cover of the mid tunnel. The engine drain screws are a little pain to get to.

I don't intend draining the system down - just topping it up. According to the manual it looks like two bleed points in the front compartment and 2 in the engine bay but I'm not sure how obstructed they are. Are you sure the middle bleed bolts aren't actually more drain points? If I need to get under the car I won't be doing it myself!

[gsuds]

No, you don't need to get under car to top up - just the 4 bleed screws.

G

[Greybloke]

This thread suddenly became interesting as I too found a small green puddle under the front o/s this morning:angry:

I checked levels, started her up and warmed to see if there was an obvious source. All appeared OK so I ran her to work and kept a very close eye on everything!

Ive since covered about 200 miles, with no obvious problems? Maybe it was just cat pee:laugh:

[TheSebringOne]

The same shape as yours minus the ironing board & the Maser lights! Its in a blue tub if thats helps! :D

[goldnsx]

I don't intend draining the system down - just topping it up. According to the manual it looks like two bleed points in the front compartment and 2 in the engine bay but I'm not sure how obstructed they are. Are you sure the middle bleed bolts aren't actually more drain points? If I need to get under the car I won't be doing it myself!

Sorry, I meant the middle DRAIN screws. There are no middle bleeding screws. Have a look in the manual it clearly stats where they are.

[NSXGB]

Sorry, I meant the middle DRAIN screws. There are no middle bleeding screws. Have a look in the manual it clearly stats where they are.

The bleed screws will always be at the highest points of the system, 'cause that's where the air bubbles go to. Therefore you won't have to go under the car.

[Steveycaz]

Right! Parts arrived from Belgium today (£4.66) and I've bought Honda Type 2 coolant (which is Blue interestingly?) - £13 per 5 litre solution. Should have the car up and running again on Saturday - ready to put it back under the cover until Spring!

[TheSebringOne]

Honda's anti freeze now blue? When my had a leak from the expansion tank recently, it was green and I had the whole system changed at Honda 2-3 years ago. Is it possible to top up my through the expansion tank with a bit of blue, even though its mainly green ( both supplied by HUK)? :dunno:

[Steveycaz]

All done now:pleased:

Took about one hour. Thermo bleed bolt is a little tricky to get to, but apart from that no problem.

Took it for a blast to check it all out. Big smiles again!