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***STICKY*** - Timing Belt & Transmission Rebuild Thread (2005 NSX 6MT)

Then install. I just use a jack until that corner of the car lifts off the axle stand to simulate the ride height. I see people have the car on the ground on all 4 wheels, drive back and forth 3 times, sing a rain dance, yada yada yada; you do what you’re comfortable with and what you believe in for tightening bushings.

Then take a break to teach your toddler how to tighten lug nuts. I was in the process of tightening the suspension bolts hence why I’m holding the torque wrench.



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Now button up the shifter cables



This was a bit of a faff so I used a mirror to see the cotter pin/clip hole


I used the same technique as before to tighten the crank pulley up. Breaker bar on a milk crate. It worked perfect.



Now onto the home stretch. Boomerang, catalytic converters, parking brakes.



I tried to clean up the supports as best I could


Plug in the ECU stuff

Engine beauty items

I replaced my battery negative cable as the rubber has perished. Fun fact you can’t just buy the rubber piece.


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Here is a quick video of the stepper motor working. I was always curious to see if the butterfly opened fully without the car running. Turns out it does.

Install the airbox and then came the moment of truth:

Long story short it started with no issues however ran very rough. No check engine lights or anything and temperature was very stable. More on what I found later.

Cold start:

Up to temperature:

Got the seal of approval. Note she really wanted to drive it :) .
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While the engine was idling I ran through all of the gears to get the fluid circulating throughout the transmission. The filter picked up a lot of little bits but overall no major issues.




The transmission hole


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I also changed the oil again, then dropped the car back on its wheels after tightening the axle nuts. Now came the worrying part about why it was running so rough. Of course everything ran through my mind with the immediate conclusion being that I messed up the timing. Reading the forums they said to check the compression to make sure as well as check the intake manifold readings.

I started with the intake manifold. Everything checked out perfect.

It’s the green line. In the middle there I blipped the throttle.

On the exhaust side lots of water came out but nothing out of the ordinary

Notice the green intake manifold line. It’s fairly constant which is good.
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Next up was the compression check.





Good news is all numbers checked out. So I assumed no issues with the timing.


I buttoned everything up and took it out for some test drives.
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Note I raised the car up since I was scraping on everything before and I ended up lifting the front way too high. I lowered it a few drives.


At this point something still didn’t feel right. I parked it and went in for the night.

The next morning when I went to start the car it had a hard time starting. It cranked for a long time before firing up and then “stumbled” into life. At this point that means fuel related.

Sure enough, the middle injector on the rear bank was leaking!!! Great success. Knowing the problem is way better than wondering what a problem could be.


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I replaced these seals with new but I’m not sure if they were the proper ones. 4 out of the 6 were ripped. I doubt Honda would make such a mistake so I’m going to say maybe I didn’t lube them up enough when installing.



Never throw out any of the old stuff until the car is fully up and running. I found the old injector seals and put them back in. I’ll order new ones again and change it at the start of next season.

..nothing like doing a job twice…my favourite



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Button everything up again and now it’s running as it should.

I drove out the rest of the season with no issues. Got it aligned, went for a few cruises, went to a few car shows; just normal stuff. I wish my wife would allow a forward facing car seat.



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Fun fact, turns out that 17 years of stop and go traffic is the limit of the NSX radiator fan motor. It completely melted down. I really wish it didn’t take the shroud and blade with it though. What can ya do…..






I ordered a new shroud, blade, and motor.
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Are people seeing all the pictures or are they stuck on the code? For me only a few sporadic pictures show up. I can confirm that all links work as I post in another forum and all pictures show up proper. Seems like the new forum format might have something to do with it???
Many stuck on the code with me :(
Are people seeing all the pictures or are they stuck on the code? For me only a few sporadic pictures show up. I can confirm that all links work as I post in another forum and all pictures show up proper. Seems like the new forum format might have something to do with it???
yep bad links..
yep bad links..

It's not bad links. See side-by-side screenshot of the same post below (if it works haha). Every single picture works on the other forum; the problem is with this forum. Maybe there are too many pictures for a single sheet? The other forum has fewer posts per page so there are more total pages but fewer posts in each.


Maybe Bram has a firewall along the boarder...🥶🤡
I changed out the radiator fan, fan blade, and shroud due to the meltdown from a little while ago. Refer to the radiator pictures in post number #237 for background.

I have a KOYO radiator which I bought because I had a euro plate on the front of my car and I wanted extra cooling (euro plate obstructed much of the air damn). I don’t know if it’s just my KOYO radiator in particular (maybe it’s a knock-off) but the mounting tabs are way too long and I had a massive air gap all the way around. When the fan was running you could feel the draft “short circuiting” through the gaps instead of pulling through the fins. This may have been a cause as to the failure of the fan motor since I suspect it was free wheeling a lot more than it liked. I always had temperature creep in stop/go traffic and just chalked it up to the mid engine. But now that I replaced everything, made the mounting tab modifications, the idle temperatures are solid. To clarify by temperature creep I mean on the HKS readout; the factory temperature gauge didn’t even wiggle after it got to operating temperature (even with the air gap). But having said that the fan motor was on a lot with the air gap so still good to do this if you have an aftermarket radiator with gap.

I actually did this last year but just didn’t get around to posting it until now (the dead of winter).

In the image below you can see the air gap between the shroud and the radiator. It doesn’t look big but is a solid 1 cm in places on the top and bottom; the sides were better.
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Get the radiator out of the car. I suppose this modification can be done in the car but those little aluminum shavings get everywhere so not wise. And you can nick one of the many things nearby.



I just used an angle grinder to shave down the tabs. Essentially you have to go all the way down to the welds of the tabs (note I said the welds of the tabs and NOT the welds of the radiator end tanks).



I used a bolt like this to clean the threads out.



There is still plenty of meat left for the bolts to hold tight. I had to file the OEM bolts just ever so slightly on the ends. You could also just use a small washer but I didn’t want to do that.

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All 4 tabs complete.





I had to put the radiator in first before the shroud. I don’t know if I just have tiny little girl hands but there was no way I can get that lower little radiator hose on without the leverage needed without the shroud in. Really happy you can get the shroud in after the fact.

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New fan shroud, blade, and motor. New from Amayama was cheaper than used North America parts believe it or not. So since I could wait the 2 months it took to get here it made sense for me to go this route.




Finished product. No more gap.

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I took apart the old motor to see what went wrong. There are 2 little bearings in there and the one on the backside of this picture was seized solid (the blade side).


The bearings read Thailand NMB 6082 ?608Z?


This guy here was seized

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Looks like I'm still having issues with pictures not showing up. When I click on the 3 vertical dots of the forum post in the top right corner, then click on the "Toggle BB code", all of the pictures show up. I don't know how to keep that permanently on (?or off?).
You might have better luck uploading the photos directly to the forum. It's what I do, since the hosted links are sporadic in functionality, depending on the host server and all the issues that come with it. There are two ways:

If you're just adding one photo, the "add picture" button works well. You just drag and drop you photo into the box.

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If you have several photos to add to the post, you can use the "Attach files" button at the bottom of the new post area. This will upload a batch of photos (the max is 20 per post). You can then click on the attachments to add them to your post by clicking "full image".

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