cooling system

creeker

creeker

Registered Member
Joined
25 July 2015
Messages
57
Location
Stony Creek, Ct.
As a new owner of the NSX, I quickly discovered how remarkably hot it gets when the engine is shut down (I did find a thread explaining the heat sink effect) and it refreshed my memories of much hand-wringing over the incredibly hot temps that occurred in my Callaway twin turbo Alfa TGV6, which I always parked with the hood slightly open to relieve the heat. Is there any benefit from replacing the stock radiator with an aluminum Koyo or similar (as I did in the Callaway), and when should the hoses be replaced? My car has 51k miles on it. I realize those changes won't address the heat sink issue - I imagine Porsche Boxters and Caymans must have the same issue, if it is an issue. Anyway, I leave the car outside for a bit before garaging it - it's amazing how warm the garage gets otherwise.
 
What temp is showing on your gage when you shut the car down?
My NSX temp had never gone beyond halfway no matter how I've driven it.
 
Tight quarters in engine compartment but I've never had a problem under all conditions and I have tracked the car at VIR once though I was driving more in the mode of smooth and learning track vs. all out (but I was giving her a workout). As for the hoses I am told by two highly respected NSX gurus that Honda hoses are excellent and last a long time. Mine are being done as I write this -- /94 with 49,000 miles. No evidence of any serious hose degradation as far as I know but it is certainly time. I will let the experts chime in on this thread but IMHO for a street driven car that does relatively low miles per annum I'd feel safe renewing the hoses every 2nd TB/WP change which in the case of my /94 makes it every 12 years. FWIW since my car is driven for the most part gently and doesn't see a lot of miles, I intend to go (with the blessing of my two NSX guru techs) 7-8 years on the TB/WP. I believe the NA2 cars have a longer TB/WP interval -- 7 years if I recall correctly.

Best,
Jeff
 
Thanks for the responses - my car also shows temps slightly below halfway, so operating temperatures are not so much a concern as those that develop after the car is shut down and the radiator stops cooling the engine (again, I blame this on my Callaway paranoia), so I wondered if an upgrade to the cooling system might have some residual benefit after shutdown by allowing the car to run cooler. I'm glad to hear the hoses are durable - the other thread I found on this topic was not so reassuring. I look at all those rubber hoses in the NSX engine compartment and start to fret. We went to all sorts of very trick (for the time) high temp hoses in the Callaway because the under hood temps were so extreme.
 
The NSX hoses are just as durable as any other hose, but the increased heat in the engine compartment leads to faster degradation. Most NSX experts know of at least one lost engine due to a blown hose (typically one of the 2 large ones running off the water jacket into the rear firewall or the oil cooler ones). The NSX heads are aluminum and will twist quickly after a significant coolant loss event. For this reason, the expert recommendation is to replace the hoses (including the expansion tank- it is a consumable!) with every timing belt job. Similarly, the radiator is a consumable item and should be replaced when it is old. Dented, bug-encrusted fins reduce cooling efficiency and the glue between the plastic tanks and rad core can become brittle and crack with age, causing slow leaks. I replaced my 20-year old rad with a Koyo and never looked back. It held up to 100F track days at high altitude in thin air with no overheating.
 
I have basically the same car as you Creeker, and haven't changed any hoses yet. It has 16000 miles on it. I think some of the hoses are more likely than others to fail. The small ones under the oil cooler and one larger one in the front compartment, I recall seeing discussions about on here. As long as you keep the coolant changed and occasionally drive the car the way it's meant to be driven, and keep an eye on things, I personally, am not terribly worried. If I was able to make the trip to NSXPO with the car, I probably wouldn't be comfortable doing it, without doing the hoses.
After a decent drive, I often open the glass and sometimes the roof holder to let things cool down. I seem to recall it mentioned before that propping up the holder with the roof in it for long periods of time isn't recommended. Leaving the car outside for awhile is a good idea too, except when it could rain at any time.:cool:
 
Thanks, Honcho - that is precisely my concern and the reason for my inquiry about this. I think I will be pursuing some of those pre-issue remedies. I am amazed your 16k mile car, in beautiful Nova Scotia (wonderful trip there last summer) and I did the same as you just tonight, opening the glass before garaging it. I appreciate the insights.
 
Here's what I do ,I use my car every weekend when I come home Iopen the engine compartment to allow it to cool down.It is not that hot when Ipark it but temps rise as it sits, I shoot the valve covers and alternator with a Fluke infra red thermal gun and you would not believe how temps rise. The alt is at 150 degrees ,ten minutes later it's at 165, which makes sense ,no cooling air passing over . I changed my hoses after 13 years (97-2010) not one hose showed any degradation ,I cut each hose open ,no signs of cracking. In reference to our temp gauge ,does it not seem strange that everyone posts that their cars run right below the half mark , does everyone's car run at the same temp ? Ihave 5 Hondas and all cars temp gauges always are in the same range ,winter or summer . Here's why ,our temp gauges are buffered ,meaning in a certain range the temp can increase up or down with little or no movement on the gauge ,once it exceeds that temp it will move . Drive the car with a quality scanner and monitor the coolant sensor ,you'll see what I mean . I seen my cars go from 185-204 no gauge movement . if it starts to exceed like 215 that gauge takes off .
 
creeker said:
Thanks, Honcho - that is precisely my concern and the reason for my inquiry about this. I think I will be pursuing some of those pre-issue remedies. I am amazed your 16k mile car, in beautiful Nova Scotia (wonderful trip there last summer) and I did the same as you just tonight, opening the glass before garaging it. I appreciate the insights.
Click to expand...

ralph cerbone said:
Here's what I do ,I use my car every weekend when I come home Iopen the engine compartment to allow it to cool down.It is not that hot when Ipark it but temps rise as it sits, I shoot the valve covers and alternator with a Fluke infra red thermal gun and you would not believe how temps rise. The alt is at 150 degrees ,ten minutes later it's at 165, which makes sense ,no cooling air passing over . I changed my hoses after 13 years (97-2010) not one hose showed any degradation ,I cut each hose open ,no signs of cracking. In reference to our temp gauge ,does it not seem strange that everyone posts that their cars run right below the half mark , does everyone's car run at the same temp ? Ihave 5 Hondas and all cars temp gauges always are in the same range ,winter or summer . Here's why ,our temp gauges are buffered ,meaning in a certain range the temp can increase up or down with little or no movement on the gauge ,once it exceeds that temp it will move . Drive the car with a quality scanner and monitor the coolant sensor ,you'll see what I mean . I seen my cars go from 185-204 no gauge movement . if it starts to exceed like 215 that gauge takes off .
Click to expand...

What is funny is on NSX track days, you'll see all the NSXs lined up in the pit area with their engine hatches open in between sessions. I always did it. Hot air rises, so... :D Larry can tell you a few stories about blown head gaskets and bent heads- all due to blown coolant hoses.
 
Very interesting - thanks for the information. It is funny that all NSXs run at the same temp, at least on the gauge.
 
Ihope no one misconstrues what I posted , Ihave always been proactive on maintenance , maintenance means replace before broken , once it fails it's called repair . I was just posting my experience and Honcho ,yes I know hot air rises .
 
That's great - thanks so much; I looked at SoS and found only the silicone hoses, but didn't enter hoses in a search.
 
I thought to put a timer on the engine compartment fan to run for 5 minutes after you turn the ignition off. What do you think?
 
After 16 years of ownership, and working on them as long, I have never seen that fan go on! The factory eliminated it, I recall in 1995;).....
 
Last edited:
Like [MENTION=18194]Honcho[/MENTION] mentions I will open the rear hatch between sessions at track...but I don't worry about it in context of regular driving. Don't think the heat is a big deal, but you generate a lot more on the track without a lot of opportunity for it to dissipate.

I just replaced the 23 hoses on my 1991 with 60k miles. Still on original radiator. Some of the hoses were showing signs of age - when you pulled on them REALLY hard you could hear the nylon or whatever is in them cracking. Not as bad as I've seen them come off other cars (where you could hear cracking if you twisted them in your hands), but makes me very glad they are all now new.

Another item that will degrade with age/heat is the OEM coolant tank. When yours yellows, have it replaced before it cracks/leaks. UV exposure (mesh or no engine cover) will significantly speed this up.

I'm not sure a 2003 would need hoses yet (might also depend on mileage). The condition of coolant bottle might correlate (if it is yellowed significantly, replace tank AND hoses?).

I used the SOS kit. Makes it easy to order.

These help...
http://www.autozone.com/greases-and...ngle-use-pouch-radiator-hose-lube/374056_0_0/ (2 of these TINY packets)
http://amzn.com/B000F5JM0O (wonderful, just wonderful tool)
http://amzn.com/B00A7EQF8A (great for breaking loose small hoses, risk of pipe scratches on larger)
http://amzn.com/B0002SRH5G (I can't imagine filling/bleeding system without)
http://www.homedepot.com/p/Husky-6-5-in-Long-Nose-Locking-Pliers-96493/

Or just pay someone to do it.
 
Last edited:
Thanks very much for the useful information. I do plan on following that plan; my coolant tank is somewhat yellowed - I have no clue how much coolant is in it without using a stick - so I've bought one of those beautiful aluminum tanks with a view tube, as well as an aluminum radiator. Hoses are next.
 
I picked up my car last weekend after replacement of all 23 hoses and the tank (car is a /94 with 49,000 miles -- tank not yellowed but replaced anyhow). None of the hoses were in bad shape which leads me to conclude that indeed Honda hoses are very high quality and in my opinion replacement with every TB/WP job is a bit of overkill for a street driven car that is treated with respect. Unless the miles are really being piled on I'm comfortable with changing the hoses every second TB/WP job. Regarding the comments on temperature gauge my tech told me same as Ralph mentioned -- buffered and doesn't move until temp rises above a certain level. I keep on top of all maintenance items and probably over maintain to a degree but in 6+ years of ownership of this exotic but shockingly reliable car I have come to the conclusion that it is so well engineered/bolted together that one should drive, enjoy and not worry too much about it -- try that with a 21 year old Porsche -- no thanks.
 
I'm sure you - and others - are correct in their appraisal of the quality of NSX hoses; really, they would have to be in an application like that, in - as you said - such a well-engineered car. My car has 51k miles on it, so I'm think if I do this now, it pretty much will keep the car happy for a very long time - beyond my ownership.
 

Similar threads

Wild Turkey
Electrical: Radio display not dimming, buttons not illuminating when headlights on
Replies
9
Views
1K
Wild Turkey
Wild Turkey
Heineken
Radio Head Unit (EU 1991) Repair
Replies
14
Views
2K
docnsx
D
N
1992 NSX coupe White/Black 5-Speed 51000 JH4NA115XNT000806
Replies
22
Views
13K
nice_tan
N
Valhalla
Forced Induction Aerocharger Twin Turbo System
Replies
4
Views
3K
Valhalla
Valhalla
Honcho
Tire Decisions 16/17
Replies
6
Views
3K
Honcho
Honcho
Back
Top