Up on Jackstands this week - things to inspect while she's in the air?

[MikeNSX92]

Hi All,

I continue to go through my recently acquired '92 NSX. I bought the car from a good friend who owned the car for 27+ years. She has 153K miles on her now, and has some track miles, so I currently have her sitting on jack stands in the garage:



My main projects were:

1. Swap out new brakes all around. The rotors were pretty grooved, and had race pads on it without backing plates or clips, so it was rattle-city. I have the brakes all done now. OEM compound pads (Raybestos ceramic) since this will be a street car going forward (maybe an AutoX or two). Coated rotors from Dynamic Friction look great and were dirt cheap on Rock Auto. Will see if they suck or not.
2. Check the shocks/suspension for issues. The Koni adjustable shocks look good, no signs of leaking or anything so I am going to keep them for now. Same with the aftermarket swaybar(s). Has stock springs, those look fine. Before I removed the wheels I did a lot of tug and pull on the wheels. Don't feel any play from the bushings or ball joints.
3. The factory 16/17 wheels are off getting powder coated in the factory color, should have them back tomorrow.
4. New Falken Azenis RT660 tires in stock size front and rear
5. Changed the transmission fluid. Went with Honda white cap MTF. Easy change. Shifted fine before I just didn't know how old the fluid was.
6. Swap the fuel filter
7. Changed the ignition switch since I had some bad behavior last week on start-up that sounded like the common switch failure. Will clean the old switch and save for a spare. That was an easy swap. My only screw up was I didn't realize I needed to have the key clicked to the "ON" position to swap the switch. First time it was in the "OFF" position and the key wouldn't turn. Lesson learned.
8. Buff the whole car. I am 6'4" so it was much easier to wax in an elevated position! Turned out great!

What else should I check out while she's up in the air? Underside of the engine looks great. Only issue I see is a little oil seepage from the pan, just above the exhaust. Not dripping anything on the garage floor so I will keep an eye on it and probably change that gasket when I do future timing belt, etc.

Speaking of timing belt, the current belt was changed probably 10 years ago, but only a few K miles. I know it's a time or mileage recommended change interval. I used to say timing belts on the Honda was "cheap insurance" but it ain't so cheap these days, LOL.

Thanks,

-- Mike

 

[Old Guy]

When was the coolant last replaced? Honda says 5 year life on their type 2 premix.

If you plan to do the timing belt then water pump replacement at the same time might be a good idea if the pump is original. Include a new tensioner with the belt replacement. If the mileage on the TB is low and it has not been exposed to high temperatures with track duty then this can probably be lower priority (>5 year old coolant versus 10 year old TB - I would pick the coolant first)

Replacement of the coolant hoses is not a bad idea if they are original. That said, I just did the coolant hoses on my 2000 and they all looked to be in very good condition.

On a 1992, inspecting / cleaning the electronic idle control valve would be a good preventative measure. Cleaning the throttle body would also be a good idea.

If you need to comply with emission standards checking to make sure the EGR is functional (the ports are clean) would be good. Easier to get at when other stuff is already out of the way.

If you tend to paranoia you might want to inspect the retaining screws on the intake air bypass butterflys. They have been known to loosen and drop out. Reported to be more of an issue on early cars; but, none seem immune.

How are the boots on the half shafts - any splits or signs of grease loss? Even if the boots look good the grease is now 31 years old and you might want to give consideration about a future clean and repack.

On a 1992 I have to believe that the main EFI relay has already been replaced. That said, if the relay was replaced > 15 years ago you might want to think about having a spare on hand. 10 - 15 years seems to be about the time that solder fractures start to materialize (although my 2000 made it to 20 years).

Spark plugs?

Probably lots of other stuff if you are desperate for things to do.

 

[Honcho]

Looks like you already did a great job on the work you listed. Once again, the above list from Old Guy is fantastic. I would only add at your mileage, the EACV, FITV, throttle body and intake manifold are probably badly gunked up. On the NSX, this issue manifests as poor idling, rough starting, failure to start, hunting idle, and random shutdowns while idling. It's a when not if problem on the OBD-I cars. Unfortunately, all this stuff needs to come off for a proper cleaning.

For the same reason, it's likely your EGR passages are totally blocked. The EGR lift sensor on the NSX is dumb- it just looks to see if the EGR valve itself is opening- it has no way to know if there is actually any exhaust flow going into the intake. The EGR ports in the intake manifold are tiny- about 5mm wide. After about 100,000 miles, they become clogged with a combination of exhaust soot and gooey oil blowby from the PCV system. So, the car toots along thinking everything is hunky-dory, but it's actually running lean because it's compensating for exhaust gas that is not in the mixture. It's a bi$ch to clean- the best way is to find a machine shop with an ultrasonic hot tank and pay them $50 to let your intake soak in there for a few hours. It comes out sparkling and you're good for another 100,000 miles.

I'd recommend a full cleaning, which means taking off the intake manifold and throttle body. On the throttle body, you'll need to remove the idle screw and clean the idle air passage, which is the one that gets gunked up.

Doing this will save you a TON of headaches.

 

[MikeNSX92]

Thanks all for the feedback! Coolant and 23 (I think that is the right number) of hoses were all changed about 2 years ago so that has been checked off the list. The half shafts and boots look really good, surprisingly. They are original according to the PO. The PVC and TB/Intake cleaning is probably long overdue. Will add that to my list for sure. I saw the kit that removes the butterfly valves. The dyno graph doesn't appear to show a loss of low end torque either, so seems like a no-brainer for $150 in parts. I'll order and do that when I clean the intake.

I just picked up the wheels and tires from powder coat. Oh man, they turned out AWESOME! They are just a touch darker than stock. They didn't have an exact match of the factory color in powder coat, so they asked if I wanted slightly lighter or slightly darker. I went darker and love the look.