NSX broke down while driving

I experienced a breakdown while driving home from work. Noticed a light squeaking / nocking noise while stopping. Seemed to only happen when the clutch pedal was pushed in. While on the hiway the noise was not heard and car drove normally. After exiting and sitting at a red light the noise was louder. The engine died after letting off the gas in 2nd gear. I restarted the can and the noise seemed to go away in in 3rd. Rounding my block the car made a louder noise and died. I coasted into my Garage.


How should I go about diagnosing this? The oil was changed less that 100 miles ago and is right on the mark. I reached out to Larry B and he seems to think it’s the transmission. The trans is not in the snap ring range.

any thoughts? I might want to check the obvious stuff before towing the car to the shop.

thanks!

Check the clutch hydraulics. First the level in the reservoir.

The reservoir looks a bit low. Also the fluid looks dirty.

It should be still enough to operate the clutch. But maybe the clutch hydraulic is faulty. While idling and clutch pedal fully pressed, are you able to select gears?

How does your timing belt and pulley shield look?

Formula 170 said:

After exiting and sitting at a red light the noise was louder.

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At a red light, are you a press the clutch in rather than shift into neutral person? If so, that contributes to accelerated wear in the throw out bearing. Based upon your comment 'Seemed to only happen when the clutch pedal was pushed in' and 'sitting at a red light the noise was louder' that would be consistent with a worn throw out bearing since that is normally the only time the throw out bearing is doing anything.

The engine died after letting off the gas in 2nd gear. I restarted the can and the noise seemed to go away in in 3rd. Rounding my block the car made a louder noise and died.

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The above does not exactly line up with a throw out bearing problem unless the throw out bearing entered some kind of catastrophic failure. Typically , throw out bearings give you some early warning.

Did the transmission become difficult to shift with the engine running? If so, that might be the clutch failing to release completely and could be related to the hydraulics (you definitely have a low reservoir). Check for signs of leakage at the master cylinder and the slave cylinder. If you sit at a red light with the pedal pressed in, a partially released clutch is going to make noise; but, would also typically be accompanied by the fragrance of toasted clutch. If the noise persists with the engine running, the clutch pedal pressed in and the transmission in neutral; but, goes away when you release the clutch I am more inclined to think that something is up with the non hydraulic part of the release mechanism.

I have heard of the case of the clutch damper springs failing on original dual disc clutches. This results in noise when attempting to disengage the clutch and usually the inability to disengage the clutch. With the clutch engaged and the car in gear the car drives more or less normally.

With the car parked / engine off, can you shift the transmission into 1 through 5. First may be initially difficult to get into. If you can shift the transmission at rest it is less likely that you have a transmission problem.

The reality is that the only item that can be addressed without removal of the transmission and the clutch is the clutch hydraulics. If the hydraulics are not obviously leaking and the pedal free play is correct then it is off to the repair shop.

The brake master cylinder is leaking on the brake booster. I was able to move the shifter through all 5 gears and reverse with clutch in and out (though somewhat difficult when out).
Haven’t started the car because last time I did the engine dies immediately.

If it’s the transmission is it normal to rebuild or just replace with good condition used one?

Lastly does anyone know of a good mechanic in the New York area? Larry B worked on the car 7 years ago but he’s now retired.

I wouldn't point at the gearbox too early. Or did the shift lever move strangly in 1st/2nd while driving?

Good point of checking the timing belt pulley shield if in place. The engine could also stall if a bad clutch is dragging even fully pressed in. A broken spring of a clutch disc has happened here and there.

I think you might have a problem with the clutch or hydraulics. Leaking clutch master? Best to change the complete hydraulics to rule it out completely.

just curious why would the transmission cause the engine to stop? unless it is stuck in gear and unable to disengage, the motor should start and run ok.

agree if you could coast home the car can't be in gear...

Formula 170 said:

The brake master cylinder is leaking on the brake booster. I was able to move the shifter through all 5 gears and reverse with clutch in and out (though somewhat difficult when out).

If it’s the transmission is it normal to rebuild or just replace with good condition used one?

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The brake MC leaking out the back on the brake booster is a separate problem that you need to fix; but, does not affect clutch operation. You need to check for leaks in the clutch hydraulic system.

Its not particularly surprising that it is harder to shift with the clutch engaged. The fact that you can shift into the gears is a good thing and suggests that the problem is likely not inside the transmission (no guarantee).

Most Acura dealerships would rather do a replacement because they don't have the experience doing a rebuild. Good luck finding a used transmission in good condition.

Yes, I’m stumped.

Guess the next stop is Friendly Acura in Middletown. I usually don’t like to pay dealer prices but with Larry B retired and no one else trusted close, its my best option.

I’ll keep you guys updated.

It is a 90s Honda, with distributorless ign. The first thing is look for fault codes, check the fuel pump, ignition switch and (a bit of a long shot) the main relay. Did Larry B say why he thought transmission? I would think that unless it is stuck in gear and you stop, the engine shouldn’t stall.
The loud noise is troubling. Hopefully a backfire. Maybe a linkage popping?

Update. Took the NSX to GT Japanese Automotive in Edison. This shop came recommended from other NSX owners. The verdict is a spun rod bearing. They recommend replacing the engine. I put the car in storage while I research my options.

Is it better to rebuild or get a new (used) engine?

Well I have been there.....I decided on being patient and waiting for a used long block to show up on prime, and pounced when a good one showed up...sadly I have not seen many for sale recently.

Yes there were a few listed in Prime awhile back but they are gone now. Looks like I’m in for a wait.


Question, how much is a 91 with 137k and a bad motor worth? Keeping all options on the table...
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Depends on getting the right buyer at the right price. Now days there are so many potential owners with real mechanical skills and no fear. If you love the car and want another option think about doing the turbo K swap.....just a thought.

Can't you source a used engine from Japan?

Listing a car with a broken engine....make it a parts car. Your car looks great get a replacement engine .

Bram

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can’t see me selling her as a parts car. Too much work and time invested in 10 years. The car is stored in an enclosed garage and can stay there indefinitely. One thing on my side is time.

Wonderful....keep it going.

love the interior

Bram

J or K swap engines are an option, what you save on the engine, you spend on the labor of the swap.

A spun bearing is rebuildable, I believe. Does require pulling the engine and pretty much a full teardown and reassembly with machine shop work involved. But as long as the block and crank are usable, it should be doable.

That kind of damage sucks, man. Good luck and keep the car.

Miner said:

J or K swap engines are an option, what you save on the engine, you spend on the labor of the swap.

A spun bearing is rebuildable, I believe. Does require pulling the engine and pretty much a full teardown and reassembly with machine shop work involved. But as long as the block and crank are usable, it should be doable.

That kind of damage sucks, man. Good luck and keep the car.

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I agree with Miner. A spun rod bearing means the rod and possibly the piston need to be changed. Nothing wrong with the engine block or crank there. If it's a spun main bearing, the crank might need to be machined, which is expensive. But, replacing the crank should solve the problem. Replacing the entire engine seems like a very expensive way to solve your problem, but perhaps there is more damage than we realize. On the NSX, spinning a bearing is quite rare and usually occurs during sustained hard right turns, due to oil starvation. From your description, it sounds like you were just driving around town? That means you lost oil pressure at the bearings some other way- maybe a clog or obstruction in the oil passage? If I were you I'd have the short block torn down, hot tanked, vapor blasted and replace the damaged parts. Reassemble and you're good for another 200k miles at least. At 137k you're probably also due for LMAs and valve seals. Good time to take care of it.

I can tell your car is special to you- I think you should fix it and keep it.

Spun bearings often wreck the crank journal, and if a main spins it can kill the block too, just depends on how lucky you are really.

I would try to rebuild if possible, just make sure you send it somewhere that does NSX work like HQ engineering or SoS as machinists seem to have issues with NSX blocks if they aren't familiar with them.

Replacing the stock motor is expensive. Your car looks clean it would make a nice base for a J swap / turbo build. I'm local and might be interested in it for the right price if you decide to sell, I would J swap it. Lots of the R&D is already done and available in a kit.