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DIY Coolant pipe change by first timer, lessons learned...

Joined
10 April 2009
Messages
164
Location
Somewhere north of Toronto...
Did a LOT of searching and while NSX prime has a lot of threads on swapping out the coolant pipes (preventatively or post-blow-out) I thought I'd add a couple key lessons I learned after my first time. Of course I'm not responsible if you screw this up, these are just some tips I discovered along the way I wish I'd known. I've only ever done a couple pipies on a non-mid-engine car before and while the NSX is significantly harder to do than say a Subaru, I DID manage to do it in a single car garage, on my own. It took me about 8hrs of total work time. The engine bay was by far the more time consuming area to work in simply because I was so cautious in taking things apart. After this, bleeding the system properly consumed the second most amount of time- once you figure it out though it's easy and what seems like a complicated system is very elegantly designed. Doing it again, I think I could do the whole shabang in about 5-6 hours, but that's always the way with this stuff.

First, I ordered the full pipe kit from Dali Racing. Great, included all the pipes I needed at a fair price, but did not include the crush washers for the two drain plugs under the car. I re-used my old ones and they are holding because nobody up here in Canada has the stupid things in stock, however I will be picking up some fresh ones and swapping them on to be safe. Order new crush washers for these two bolts when you order your pipes! There are two to replace and the part number is 90471-580-000 (8mm crush washer)

My car is a 92 and I don't think the pipes had been done, so of course removing pipes with that kind of age is a... challenge. Due to the location of some of the pipes the old 'push the hose into the fitting' method does not really work to break the seal. I wound up cutting the vast majority of pipes off the fittings and if you're good with a blade I would recommend this because it saves so much time/hassle. However you have to be VERY careful when doing this not to cut into the fitting. Use a very sharp blade (both hands!), and cut lightly lengthwise down the pipe where it meets the nozzle, you don't want to go the whole way through the rubber in the area it is over the fitting because you don't want to scar the fitting. Once the blade is beyond the fitting and just on the hose area, push it the whole way through the hose. Now stick your finger in there and slowly pry it apart, peeling it back over the nozzle. If it's not peeling you probably haven't cut far enough in to the rubber over the nozzle area, so again carefully use the blade until it goes. If you DO manage to cut into the nozzle a tiny bit (you should only have scored it very lightly anyways) you can use some VERY VERY fine sand paper and smooth that area out, but remember it's aluminum and easy to create a flat spot even with sandpaper very quickly. Just take your time and go slow.

I read in numerous threads about using Silicone spray to help get the new pipes onto the fittings. I cannot recommend this stuff enough. I found it up here in Canada at Canadian Tire, it's very common stuff and it really made the job 10x easier than without it. Do buy this. DO NOT use anything petroleum based (ie. WD-40), as it will eat away at the hose.

Bleeding the car seemed daunting after reading the service manual PDF (which if you don't have it, you need it, go download it here on prime it's absolutely priceless). However, the only thing I found missing from the 'method' explained in the manual was that you REALLY DO need to elevate the rear of the car. I put mine about 1ft up on jackstands at the rear jackpoints and it helped fix the airbubble issue I was having. With the car flat (as I assume an Acura tech would do it?) I was getting an airbubble in the rad and in the heater core, even with the core opened. Jacking the rear of the car up completely fixed this issue. I repeated the bleed procedure twice, yes you get coolant on the engine/floor/spare tire bracket - but it's easy to clean up so just do it.

While taking apart the engine bay (coolant tank, fuse box, intake box, throttle body) to get the three main pipes was not that hard I DID have problems with the throttle cable on the throttle body. I did not want to loosen the throttle cable, and did not want to kink/bend it either. I found the easiest way to get the throttle cable off the throttle body linkage was to remove the TB with the cable attached, flip it upside down to relieve the tension on the cable, then just remove the cable (it's a bit odd if you've never done a door lock cable or throttle cable before, but look closely and you'll see how it slides out of the notch on the inside of the linkage and then the cable end comes out of the linkage.) Putting the cable back on, I managed to do it with the throttle body bolted back in place, but I needed a second set of hands holding the throttle open so I could get enough slack in the cable line. Just take your time and study the way the cable has to wrap the linkage so you ensure you don't kink/stretch/bend the line and you will be fine. This procedure will be different for TBW cares I assume, so I cannot speak to those.

Any other pearls of wisdom that I remember that I didn't find covered in other threads on prime I'll add into this post, but I would encourage anyone willing to put up with some down time on their NSX to do this themselves and save a $1500-2000 mechanic visit. It's not 'hard' so much as time consuming. There's very little chance for you to do anything bad other than scrape a knuckle and get some coolant on the floor. Take your time, go slow and enjoy!
 
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My trick is to get some decent multiple size plyers and grab the rubber thats connected to the pipe/pipes and turn it you only have to turn it half an inch to break the seal. with this method it will save you a finger. as I tried the cutting method first because its hard to get into some of those tight spots and after the blade slides off the pipe there goes parts of your finger or arm what ever the blade takes with it. LOL trust me

as for sliding the new pipes on everyone has some old motor oil laying around, greese the inner lip of the new hose and it slides on with ease.

before you slide it one make damn well sure the hose clamps are in the right postion, and turned to the point you can get a good grip on them with some plyers to crimp them for installation.

good write up def.

after doing it to my 2004 I decided that I would just pay someone to do it. but if I had to I would get down there and do it.
 
as for sliding the new pipes on everyone has some old motor oil laying around, greese the inner lip of the new hose and it slides on with ease.

That would be a VERY BAD idea. Never use petroleum products on rubber hoses. Have you ever seen a rubber hose that has had oil dripping on it? It destroys the rubber. Always use silicone spray or o-ring silicone grease.

Regards,
LarryB
 
My trick is to get some decent multiple size plyers and grab the rubber thats connected to the pipe/pipes and turn it you only have to turn it half an inch to break the seal. with this method it will save you a finger. as I tried the cutting method first because its hard to get into some of those tight spots and after the blade slides off the pipe there goes parts of your finger or arm what ever the blade takes with it. LOL trust me

as for sliding the new pipes on everyone has some old motor oil laying around, greese the inner lip of the new hose and it slides on with ease.

before you slide it one make damn well sure the hose clamps are in the right postion, and turned to the point you can get a good grip on them with some plyers to crimp them for installation.

good write up def.

after doing it to my 2004 I decided that I would just pay someone to do it. but if I had to I would get down there and do it.

I understand the urge to use pliers on those hoses but I was scared to because the fittings are surprisingly soft aluminum. You (well, I) could easily bend/dimple/crush a fitting (big or small) simply by pulling that hard on a hose even at a slight angle. Your car is an 04 so I doubt the hoses are that fused on, but mine being a 1992 were so solidly attached I'm sure I would have bent a fitting or even broken a bracket that the aluminum hardlines are connected to if I had given in a used pliers and a lot of pulling/pushing/twisting. I had no troubles reaching any of the hoses with a knife, but I agree some of them are definitely tougher to get to than others - just use an exacto knife vs. a carpet knife. Again - lots of very very light cuts. If you're cutting hard enough to lose a finger, you're cutting way way waaaay too hard!

Just my $0.02
 
In order to remove the hoses easily, a heat gun can be very effective;).

I also use a x-acto knife, NEW blade each time. By the time you get to hose 22 the knife is dull:).

Regards,
LarryB
 
For removing the small diameter hoses, I've got a set of hose removal pliers from Harbor Freight that are very handy. They are shaped to fit specific hose diameters so they don't squash the metal fitting underneath the hose.

They worked wonders on my 'vette when I had to remove and replace a hard to reach piece of fuel line.

Again, as others above have said - use silicon spray or silicon grease on anything rubber, including coolant hoses, to help them slip back on easily. Petroleum eats rubber; silicon helps preserve it.
 
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