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Just finished coolant hose replacement DIY

14 April 2009
Ottawa, Ontario, Canada
I know this has been discussed previously on Prime, but I thought I would provide some feedback / insight into my adventures of replacing all 22 coolant hoses on my 1991 NSX in case anyone is considering doing this job in the near future. The car had the originals and thus were over 20 years old. I figured I'd better change them out before something bad happens.

One thing I should point out is that before doing this job, I called around some local shops to see how much they would charge to replace the hoses. Most were reluctant to do this kind of work, making me suspicious of the quality of work. As such, I decided to do it myself.

I ordered the kit from Dali along with a new alternator and A/C belt. The entire procedure took me 2 full days to complete - a bit longer than most here on Prime, but I wanted to take my time and make sure I was doing a good job. I was quite bruised, sore and cut up from doing the work, especially my back and leg muscles - must have been all the bending and contortionist positions I executed.

All in all, the job wasn't too difficult technically, but extremely time consuming. A lot of patience is required to do this kind of work and I can understand why a shop would charge $1,500 - $2,000. For those of you looking to do it yourself, if you have the time and patience, then go for it. The manual is detailed enough to pinpoint all the hoses that need replacing, along with the draining and bleeding procedures involved. Otherwise, if you're not comfortable, then bring it to a shop to get done. I consider myself a novice mechanic and was able to do this, so for those of you on the fence, it is entirely possible. Just bring time and patience, and the right tools, with you.

Some interesting tidbits from doing this work:

[FONT=Courier, Monospaced] - The most important tools for doing this job include a razor sharp cutting knife and various sized pliers (especially 12” long vise grips and angled needle nose pliers)[/FONT]
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- I’d say only 3 of the 22 coolant hoses came off by themselves. The
rest had to be cut off with a knife.

[FONT=Courier, Monospaced] [/FONT]
[FONT=Courier, Monospaced]- I was surprised at how good a shape the original hoses were in. I did hear some crunching noises while taking some of them off, but most did not. These hoses are of very high quality for sure.[/FONT]
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[FONT=Courier, Monospaced] - Putting the hoses on was a pain. These hoses go on extremely tight. KY jelly came to the rescue here – I knew there were other uses for KY other than…….
[FONT=Courier, Monospaced]
[FONT=Courier, Monospaced] - I couldn’t believe how much coolant these cars hold. I thought I
had thoroughly drained the system, but always found residual coolant
in the hoses, which made for a messy job. Also, I never realized how sweet coolant tastes!!
[FONT=Courier, Monospaced]
- The clamps Honda uses on the hoses work really well, but are
potentially dangerous. I had one let go on the vise grip and snapped
onto my finger, which is now purple.
[FONT=Courier, Monospaced]
- I would say the most difficult hoses to get to were the 3 under the
car and 2 going to the oil cooler. Patience is required to get to the hoses on the oil cooler, and I followed the advice here on Prime to remove the cooler entirely and do one hose at a time. Many thanks!!

After finishing the job, it was time to fill the system up with
coolant. I followed the bleeding procedure in the manual and tried
the “raise the rear of the car” trick advertised here on Prime.
Raising the rear didn’t work for me as it “screwed up” the bleeding
procedure, so I dropped it and did it via the manual. When I started
the engine, I noticed the temperature gauge began to climb past the
halfway mark and saw steam and bubbling from the expansion tank. I
figured there was still air in the system somewhere, so I shot it off,
bled the system again and started it up. This time no problem. Took if
for a drive and all was fine.

So far so good. I haven’t noticed any leaks and am keeping my fingers
crossed that none will happen.

Hope this helps those considering doing this job. I'll try posting pics here of my work.

Car on stands being drained of coolant:

2012 NSX Events - 30.jpg

Draining coolant from middle pipes:

2012 NSX Events - 32.jpg

Draining coolant from front and rear engine banks:

2012 NSX Events - 33.jpg

Middle hose removal (these were tough):

2012 NSX Events - 34.jpg

Another shot of the middle:

2012 NSX Events - 36.jpg

Front hose removal. The small hoses going into the heater core were a bit tricky too:

2012 NSX Events - 37.jpg

Another shot of the front, carefully cutting the hose and peeling it away with pliers:

2012 NSX Events - 40.jpg

Attacking the hoses in the engine bay. I found removing the air filter box and expansion tanks were a must, but I was able to get away with not removing the throttle body :

2012 NSX Events - 41.jpg

2012 NSX Events - 42.jpg

2012 NSX Events - 45.jpg

Time to tackle all the small little hoses around the throttle body. Time consuming and tedious, but doable:

2012 NSX Events - 43.jpg

2012 NSX Events - 44.jpg

2012 NSX Events - 46.jpg

New hoses installed in the engine bay:

2012 NSX Events - 47.jpg

Now the oil cooler. I found the trickiest part was getting at the top bolt of the CV joint shield (not shown). Otherwise, these hoses weren't too bad:

2012 NSX Events - 48.jpg

2012 NSX Events - 49.jpg

Everything put back together:

2012 NSX Events - 51.jpg

2012 NSX Events - 52.jpg

Finally, all the old hoses, belts and figure 8 gasket:

2012 NSX Events - 57.jpg

I have to thank Prime and all the users that contribute to this community for their information, advice and guidance. Prime is an invaluable resource!!
Thank you for this beautiful story and for pictures, you have not replaced the thermostat (in the throttle body)? ... I hope your aches and pains are healed and you do not drink too much fluid cooling ... now you can go walk to the North Pole in a swimsuit: Sourire: ... thank you again for this good report: Sourire:
Thanks for the write up and great pics. How long did it take you? Where did you buy your hose kit?
Took me 2 days working from 9-5. Longer than most here, but like I said I took my time.

I got the kit from Dali racing, whom by the way I thought provided great service and were very responsive to my emails.
Took me 2 days working from 9-5. Longer than most here, but like I said I took my time.

I got the kit from Dali racing, whom by the way I thought provided great service and were very responsive to my emails.

Other than the figure '8' gasket for the oil cooler, any additional parts required?

Did you also change the thermostat? I imagine it is fairly easy to get to while changing all the hoses?
I too have just done the hoses and thermostat. It is a frustrating job to be sure, but once done, you've done some serious mechanical work on your NSX. It makes taking on other jobs less intimidating. I highly recommend doing it yourself.
Most were reluctant to do this kind of work, making me suspicious of the quality of work. As such, I decided to do it myself.
Good choice. It doesn't take an arm or a leg to do it, just plenty of time. It was a three day job for me, maybe 10 hours.

Did you change the o-rings of the radiator plugs too?

Nice OEM car BTW.
Long term updates? There is someone asking for input on the OBX.

- - - Updated - - -

While silicone radiator hoses are great because they are capable of carrying much higher temperature fluids (max 350°F/177°C) than a standard EPDM rubber radiator hose (max 257°F/125°C), they are really only ideal for race cars.

Here's a fun fact: silicone's water permeation rate is 15 times greater than EPDM rubber. What does that mean to you? It means with the daily heat cycling of a street driven car, that you will lose water from your cooling system over time. According to a Gates Corporation report, "Testing by Gates engineers shows that a Class 8 truck, operating at a temperature of 210°F with a two shift per day driving cycle, would lose nearly five gallons of water each year if it was equipped with silicone hose." FYI, Gates makes both rubber and silicone coolant hoses so hold off on the forum bullshit line of, "Well of course Gates made that report. They sell rubber hoses!"

Silicone hoses are porous. That's why you do not use silicone for fuel and oil. It's also why you shouldn't use silicone radiator hoses on a street car. I use silicone radiator hoses for race cars or occasionally driven cars that are regularly maintained, but on street cars I use standard EPDM rubber hoses. On top of that, I prefer factory hoses from the dealership rather than the aftermarket hoses that are never molded quite right.

There's the tip of the day. Now if you already have silicone radiator hoses on your street car just make sure you check your water level regularly. If you don't want to worry about loosing an engine because you didn't want to listen to me then get yourself some new factory rubber hoses and check the water level occasionally.

Why did I go with Silicone Hoses:

1. I plan on getting Classic Car insurance for the NSX which would limit my miles to 3000/year. No work commute. Just a weekend warrior fun car and one for car shows.
2. My car makes almost double the power and is capable (with the right forced induction solution) of making more, so I was more interested in coolant hoses that can handle greater heat
3. It looks dam sexy

- - - Updated - - -

oops i replied in the wrong thread.

Do a search and you will find a comprehensive list of the hoses needed. The Dali & SOS kits saves you time because you order only one part (vs approximately 22) plus you get an instruction sheet on what hose goes where.

Purchased separately from www.oemacuraparts.com they are about $50 less expensive, but you are on your own. However, the diagram in their on-line parts book is a good aid.

I purchased a set of hoses last month, mostly because of concerns about when Acura might stop supplying them. It will be part of my "Happy 20th Birthday" gift to my NSX next year. (My existing hoses are in excellent shape, no dry rot, no gummy spots, so there's no immediate need to change them.)
Great write up, Larry B also has a detailed write up in the DIY issue of NSX Driver.
His write up includes part numbers and the "lube" he uses. (at work right now, will edit post later with info)
Great write up, Larry B also has a detailed write up in the DIY issue of NSX Driver.
His write up includes part numbers and the "lube" he uses. (at work right now, will edit post later with info)

Interesting. Could you provide me with an URL?

-edit- Lot of good info here. Thanks Shawn for pointing me to it!
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For what it's worth I was just quoted 4 hours at my dealer as part of a full engine out timing belt service.
Replacing everything listed here
on my 1993 at present.

Started thinking about the radiator... When have you guys been changing them out?

John at Acura of Augusta shipped everything listed on the site listed above to my door for $376 in Maryland