New NSX owner but head gasket issue already!
- Thread starter FlyboyShooter
- Start date
From my old hot rod days, you could always pull the spark plugs to see if any of them appear to be steam cleaned. If the engine was overheated, do not force any plug out. In addition to sending out the coolant for analysis, you could send out an oil sample as well. Google is your friend for analysis labs. I also have a 2000 with 82K miles. Good luck. Jerry
Well. Oil looked good but coolant exhaust gas check on the other hand…that seems to look contaminated to me. Closer to green maybe than yellow like the test was saying but definitely not unchanged blue. Taking the car to Acura tomorrow for a second opinion on if it’s head gasket but could it be anything else? Couldn’t visually see a leak myself but I only ran the car a bit to get the coolant temp up for the test and I don’t have a lift.
Did you make absolutely sure you did not suck up any coolant?
R&R'ing a head gasket on the NSX is no small feat. Dealer may not be up to this task if required.
R&R'ing a head gasket on the NSX is no small feat. Dealer may not be up to this task if required.
You typically need to drop the level in the expansion tank prior to the test to make room. If by chance you suck up a little coolant into the tester you get that murky green color. Edit - to be clear I think what you want to be doing is sniffing the various gasses above the coolant level in the bottle. If you want to know what failed looks like put some fresh reagent into the tester and then go to the tail pipe with the tester and with a running engine give the tester bulb a few squeezes so that it sniffs some exhaust gas. That will give you the bright yellow color.
That said, passing this test is not definitive since the original diagnosis was failed head gasket with an external leak. That needs to be pressurize the coolant system with UV dye and look for the external leak.
That said, passing this test is not definitive since the original diagnosis was failed head gasket with an external leak. That needs to be pressurize the coolant system with UV dye and look for the external leak.
Last edited:
Agree with everyone- you probably sucked up some coolant droplets/vapor. If there was combustion gas, it would be bright yellow. You can run the test again, but I suspect you're alright.
To confirm the external leak, you need to wash/rinse off the area around the head gasket seams on the engine block. Dry thoroughly and then drive the car on the highway for about 30 minutes. Put it back in the air and see if there are any wet spots around the gasket seams. I still find it hard to believe a NA2 MLS gasket is leaking- those things are pretty much indestructible on a NA car. I've seen plenty of NA1 gaskets weeping, but never a NA2.
To confirm the external leak, you need to wash/rinse off the area around the head gasket seams on the engine block. Dry thoroughly and then drive the car on the highway for about 30 minutes. Put it back in the air and see if there are any wet spots around the gasket seams. I still find it hard to believe a NA2 MLS gasket is leaking- those things are pretty much indestructible on a NA car. I've seen plenty of NA1 gaskets weeping, but never a NA2.
Does seem like it’s seeping at the gasket sadly. Any idea what that little hex plug is and if it’s loose could it be from there? Grasping at straws hoping it’s not the gasket still I know (it’s on the lift at the dealership).
So it doesn’t look wet in the above picture but with some extra pressure it seems like the the pipe/fitting that goes to the two blocks and contains the thermostat in the middle is getting wet and might be the culprit. I found an old thread that had a the picture of the assembly and seems like there are o-rings there. Maybe a point of failure that’s less work than a whole head gasket replacement.
Yes- there is an O-ring. Many shops replace the thermostat when they do the TB/WP and it's easy to pinch the O-ring if you're moving too fast.
I recommend some serious due diligence before breaking open the engine.
Get out the bore scope and get a 100% confirmation for external leakage at the gasket.
Doubtful the dealership is up for the diagnosis or the job.
Clean the engine to a high degree using pressure washer or dry ice or whatever to make the leak source stand out.
It would be worth it to ship the car or fly out a tech. Too bad Larry isn't still doing this work.
The NSX head gasket is extremely difficult to get right.
Get out the bore scope and get a 100% confirmation for external leakage at the gasket.
Doubtful the dealership is up for the diagnosis or the job.
Clean the engine to a high degree using pressure washer or dry ice or whatever to make the leak source stand out.
It would be worth it to ship the car or fly out a tech. Too bad Larry isn't still doing this work.
The NSX head gasket is extremely difficult to get right.
First off, if it is getting wet around the thermostat housing you should perversely be happy. A much cheaper and easier fix than a head gasket repair.
Small; but, important detail. Not the 'two blocks' but the 'two heads'. The thermostat housing connects to the opening circled in red on the rear head (similar port on the front head). The connection of the housing to the two heads and the water pipe that connects to the pump on the other side of the engine are sealed with O rings.
All of this is above the head gasket level so a leak there can drain down and mimic a leak from other spots. To me nothing appears wet so I can provide no wisdom on the source of the leak.
The fact that the tech at Dilawri is looking above the head gasket level is an encouraging sign. Dilawri's sole NSX tech is methodical. I remember having a coolant flush done by them about 6 years ago. The service department called and said come pick up the car, it will be ready in 20 minutes. When I got there they said oops, still bleeding, here is a loaner car and we will call when it is ready, about 2 hours later. Better to pay extra up front for a methodical diagnosis than jump to the 'its the head gasket' diagnosis.
For some inexplicable reason, the factory service manual specifies that the complete thermostat housing be removed in order to service the thermostat. I am not aware of anybody who has ever done that; but, if some service tech went 'by the book' and removed the thermostat housing to service the thermostat then those three O rings need to be replaced during servicing in addition to the sealing ring on the thermostat itself noted by Honcho. If they did not install new O rings or damaged the new O rings during the install that could be the source of the leak.
Hoping it is a much cheaper O ring replacement that fixes this.
Small; but, important detail. Not the 'two blocks' but the 'two heads'. The thermostat housing connects to the opening circled in red on the rear head (similar port on the front head). The connection of the housing to the two heads and the water pipe that connects to the pump on the other side of the engine are sealed with O rings.
All of this is above the head gasket level so a leak there can drain down and mimic a leak from other spots. To me nothing appears wet so I can provide no wisdom on the source of the leak.
The fact that the tech at Dilawri is looking above the head gasket level is an encouraging sign. Dilawri's sole NSX tech is methodical. I remember having a coolant flush done by them about 6 years ago. The service department called and said come pick up the car, it will be ready in 20 minutes. When I got there they said oops, still bleeding, here is a loaner car and we will call when it is ready, about 2 hours later. Better to pay extra up front for a methodical diagnosis than jump to the 'its the head gasket' diagnosis.
For some inexplicable reason, the factory service manual specifies that the complete thermostat housing be removed in order to service the thermostat. I am not aware of anybody who has ever done that; but, if some service tech went 'by the book' and removed the thermostat housing to service the thermostat then those three O rings need to be replaced during servicing in addition to the sealing ring on the thermostat itself noted by Honcho. If they did not install new O rings or damaged the new O rings during the install that could be the source of the leak.
Hoping it is a much cheaper O ring replacement that fixes this.
