New NSX owner but head gasket issue already!

FlyboyShooter

FlyboyShooter

Registered Member
Joined
14 May 2024
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13
Location
Regina, SK
Good Day all!

I’ve recently come into trust/possession of my grandfathers old 2000 NSX-T. I’m in Canada but it’s a US one that spent its first 20 years in Phoenix. It has 85000 miles on it now and did great driving out to me for the first month or so but seems to have developed what my local Honda dealership diagnosed as an external head gasket coolant leak. Is this a common issue that is out there? I’m not too confident in the local Honda dealer or Acura that’s about 60 miles away and am probably going to go with Science of Speed gaskets if this is indeed the case, by a performance shop that specializes in Japanese cars. Any big gotchas out there? Anything that should be done while in there? It was dealer serviced only in the past and just had a timing belt done. The dealership also quoted replacing the water pump (at $900 Cdn for the part). Any chance those maintenance/trunk covers are still available? OEM or aftermarket? I’d wanted to do most of the work on this car myself but this is a big project that I’m not in a position to do myself ATM. Thanks all! I’m in love with this car even with this hiccup early on!
 
There are actual techs out there that i'm sure will better answer you, but if it JUST had the timing belt done (the water pump is usually done at the same time), perhaps you simply have air in your cooling system(?). Are you seeing coolant on the garage floor? I'm sure others will ask how you were alerted to this. Head gaskets don't just fail for no reason so simply replacing a gasket will likely not suffice. Will cross my fingers for you that your Honda dealership mis-diagnosed your issue, but this list WILL help you thru it.
 
If it's a head gasket you should see coolant in the oil. Check it with the dip stick, and also have it changed and inspect the drained oil. If it has coolant in it you'll get a nasty goo that looks like a chocolate milk shake. It should also be blowing white smoke.

For the gaskets I tend to go OEM. It seems that the only things that have failed on my car were for the most part after market parts. My mechanic won't even install anything but OEM for gaskets on all Hondas and Acuras, which I take as good advice based on years of working on these cars.

Hope this helps and fingers crossed that's not what it is!
 
I have a 2000 with similar mileage. Head gasket failure is not a common issue on cars that remain naturally aspirated, even with the earlier C30 engine. However, if the engine ever suffered a significant overheating event such as might occur if a major cooling hose failed that changes everything. All aluminum heads on either an iron or aluminum block have a high probability of developing a head gasket failure if you suffer a coolant dump. I had a 1987 745T turbo Volvo (iron block and aluminum head) which had a coolant dump when the retaining screw for the block heater rusted out allowing the block heater to drop out dumping pretty much all the coolant by the time I got the car pulled over to a safe place where I could stop. We installed a new block heater and refilled with coolant and it seemed fine; but, perhaps like you it developed a very slow external weep after a couple of months. The weep was slow enough that we needed a UV tracer dye to spot it.

I would review the basis for the diagnosis. If you confirm that it is a coolant leak from the head - block interface then you are probably dealing with a head gasket replacement. The big 'if' may be do you do both head gaskets? If you knew that there was an overheating event in the past then I would be planning to replace both head gaskets even if you do not have an as yet confirmed leak on the other head. The other big 'if' is does the head require resurfacing and does the block require resurfacing. According to the service manual you can remove the cylinder heads without removing the engine from the car (that is what the SM says). Resurfacing the block clearly requires removal of the complete engine. If only the heads require resurfacing or no resurfacing is required then the repair may be a lot less money. I could not find anything in the SM that explicitly says that resurfacing is required when replacing a failed head gasket.

If you elect to resurface I might be more concerned about the machine shop that does the work than who does the engine R&R. Depending on where you live, Prime member @Bram or other members may be able to advise on dealerships or other service providers who are NSX knowledgeable.

On a 2000 model year I would be inclined to stick with the original OEM head gaskets. The SOS gaskets are MLS and I know on the C30 engines the surfaces definitely need to be resurfaced for use with the MLS gasket. I don't know whether that applies to MLS with the C32. If the head is undamaged then it might be possible to do a straight up head gasket replacement with out resurfacing on the C32. If you have the work done at a dealership they may not provide any warranty if you use a non OEM gasket.

You can source the OEM replacement parts at a much much lower cost from Amayama.com than through Acura Canada. Check with whoever is doing the service work about parts sourcing. Acura Canada does not maintain an inventory of very many NSX parts so all the parts tend to be special order from Japan. As such, even some of the dealerships are OK with you providing the parts; but, it is on you to make sure that all the parts are there and are the correct part number. My experience has been that if the part is in stock in Japan Amayama will have it on my my doorstep much faster than Acura Canada even if they mark it critical back order.
 
Before you spend $10,000+ to do the head gasket, you should do a block gas test on the coolant. You can also pay a mechanic to do it if you don't want to DIY. You can buy the kit from Amazon. This tests for combustion gases in the coolant and is the definitive way to confirm a head gasket rupture. If your fluid looks like this (blue), your car is ok:

20230318_162427.jpg

If it turns yellow or green, the gasket is leaking.

I find it very hard to believe the NA2 head gasket is blown. It is a 3-layer steel gasket and pretty much indestructible unless you put like a 25psi turbo on there or something. Considering it had the TB/WP done the MUCH more likely cause is that the tech did a sloppy job, since there are many ways to cause a coolant leak during that service that don't involve removing the heads. In all of these cases, the coolant will seek the lowest point and flow down the head gasket seams and then down the engine block. It will appear that the coolant is leaking from the gasket, but it's not.

My best guess is that he probably screwed up on the water pump install.
 
Welcome to Prime! Hope it's not as bad as they say. I agree a water pump lasting less than a year seems incredible; it should have been changed with the timing belt.

Throw your location in your profile so we can see where in Canada you are with respect to recommending service locations - it's a pretty big place. I agree that a lot of dealers no longer have staff qualified to work on the NA1 & NA2, and unfortunately, Acura Canada can't afford to stock parts for such a rare car. I suspect they're using the American Honda and/or a Japanese supplier as well - I get parts way faster from Japan than from my local Acura dealer.
 
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Honcho said:
Before you spend $10,000+ to do the head gasket, you should do a block gas test on the coolant. You can also pay a mechanic to do it if you don't want to DIY. You can buy the kit from Amazon. This tests for combustion gases in the coolant and is the definitive way to confirm a head gasket rupture. If your fluid looks like this (blue), your car is ok:

View attachment 193375

If it turns yellow or green, the gasket is leaking.

I find it very hard to believe the NA2 head gasket is blown. It is a 3-layer steel gasket and pretty much indestructible unless you put like a 25psi turbo on there or something. Considering it had the TB/WP done the MUCH more likely cause is that the tech did a sloppy job, since there are many ways to cause a coolant leak during that service that don't involve removing the heads. In all of these cases, the coolant will seek the lowest point and flow down the head gasket seams and then down the engine block. It will appear that the coolant is leaking from the gasket, but it's not.

My best guess is that he probably screwed up on the water pump install.
Click to expand...
You can actually rent these from autozone or o'reilleys if they have them up in canada, only thing you end up paying for is the solution which is a couple of dollars..
 
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SK! Another NSX in @Old Guy 's neck of the woods (Large woods, I know.) with the same year NSX!
 
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Old Guy said:
I have a 2000 with similar mileage. Head gasket failure is not a common issue on cars that remain naturally aspirated, even with the earlier C30 engine. However, if the engine ever suffered a significant overheating event such as might occur if a major cooling hose failed that changes everything. All aluminum heads on either an iron or aluminum block have a high probability of developing a head gasket failure if you suffer a coolant dump. I had a 1987 745T turbo Volvo (iron block and aluminum head) which had a coolant dump when the retaining screw for the block heater rusted out allowing the block heater to drop out dumping pretty much all the coolant by the time I got the car pulled over to a safe place where I could stop. We installed a new block heater and refilled with coolant and it seemed fine; but, perhaps like you it developed a very slow external weep after a couple of months. The weep was slow enough that we needed a UV tracer dye to spot it.

I would review the basis for the diagnosis. If you confirm that it is a coolant leak from the head - block interface then you are probably dealing with a head gasket replacement. The big 'if' may be do you do both head gaskets? If you knew that there was an overheating event in the past then I would be planning to replace both head gaskets even if you do not have an as yet confirmed leak on the other head. The other big 'if' is does the head require resurfacing and does the block require resurfacing. According to the service manual you can remove the cylinder heads without removing the engine from the car (that is what the SM says). Resurfacing the block clearly requires removal of the complete engine. If only the heads require resurfacing or no resurfacing is required then the repair may be a lot less money. I could not find anything in the SM that explicitly says that resurfacing is required when replacing a failed head gasket.

If you elect to resurface I might be more concerned about the machine shop that does the work than who does the engine R&R. Depending on where you live, Prime member @Bram or other members may be able to advise on dealerships or other service providers who are NSX knowledgeable.

On a 2000 model year I would be inclined to stick with the original OEM head gaskets. The SOS gaskets are MLS and I know on the C30 engines the surfaces definitely need to be resurfaced for use with the MLS gasket. I don't know whether that applies to MLS with the C32. If the head is undamaged then it might be possible to do a straight up head gasket replacement with out resurfacing on the C32. If you have the work done at a dealership they may not provide any warranty if you use a non OEM gasket.

You can source the OEM replacement parts at a much much lower cost from Amayama.com than through Acura Canada. Check with whoever is doing the service work about parts sourcing. Acura Canada does not maintain an inventory of very many NSX parts so all the parts tend to be special order from Japan. As such, even some of the dealerships are OK with you providing the parts; but, it is on you to make sure that all the parts are there and are the correct part number. My experience has been that if the part is in stock in Japan Amayama will have it on my my doorstep much faster than Acura Canada even if they mark it critical back order.
Click to expand...
Any recommendations for someone to take another look at this in SK? I have one positive recommendation from a friend about a Chris at performance plus in Saskatoon but haven’t contacted him yet.
 
FlyboyShooter said:
Any recommendations for someone to take another look at this in SK? I have one positive recommendation from a friend about a Chris at performance plus in Saskatoon but haven’t contacted him yet
Click to expand...
I responded to your PM

Who did the diagnosis of the head gasket failure and how? Since you mentioned external leak, I assume that this was not diagnosed by checking for combustion gasses in the coolant or checking for coolant in the oil. Was a cooling system pressure test done? Do you have obvious significant loss of coolant? If not, have you cleaned the block / head area and then added a UV dye to confirm that you are actually losing coolant at the head-block interface? You might be losing coolant; but, it may be from some other location. I raise all of this because:
1. since the car was family owned I presume that they would have revealed something like a coolant dump while the engine was running
2. absent #1 or some other over heating incident the C32 does not have a chronic head gasket problem and if there was a coolant dump, in the reported cases the head gasket fails immediately or fairly quickly after the event
3. you want to be absolutely sure that it is a head gasket failure because head removal is going to be expensive.

If the water pump was replaced or disturbed at the same time as the recent timing belt service I would side with Honcho that this may be a more likely source for the coolant leak.
 
Old Guy said:
I responded to your PM

Who did the diagnosis of the head gasket failure and how? Since you mentioned external leak, I assume that this was not diagnosed by checking for combustion gasses in the coolant or checking for coolant in the oil. Was a cooling system pressure test done? Do you have obvious significant loss of coolant? If not, have you cleaned the block / head area and then added a UV dye to confirm that you are actually losing coolant at the head-block interface? You might be losing coolant; but, it may be from some other location. I raise all of this because:
1. since the car was family owned I presume that they would have revealed something like a coolant dump while the engine was running
2. absent #1 or some other over heating incident the C32 does not have a chronic head gasket problem and if there was a coolant dump, in the reported cases the head gasket fails immediately or fairly quickly after the event
3. you want to be absolutely sure that it is a head gasket failure because head removal is going to be expensive.

If the water pump was replaced or disturbed at the same time as the recent timing belt service I would side with Honcho that this may be a more likely source for the coolant leak.
Click to expand...
Honda in my area did the diagnosis. They did a cooling system pressure test for sure, but I’m unsure what else. There was a significant loss of coolant. I had noticed a slower drip earlier in the day and had a friend look and we noted that I would need to keep an eye on it but what got me to take it in was on that very hot day I had just driven on the highway and upon stopping, the smell and obvious trail of fluid behind the car got me to look under and see coolant in a steady stream coming from below the engine area. Prior to this, I had only noted slower dripping. The stream did dissipate as the engine cooled/once it was turned off. I’m trying to track down a more detailed service history as at the moment I only have a summary page from the dealership in Arizona where it came from to see if the water pump was in fact done with the timing belt. I would also think that at 80000 miles, if the water pump was not done and was disturbed when the timing belt was done or done poorly than that would make sense.
 
Since the car failed the coolant pressure test you have a confirmed issue. As you have no doubt discovered, seeing anything on the NSX engine when it is in the car is exceedingly difficult without starting to remove things. To see a UV dye leak at the head gasket area requires that the car be up on a hoist (for leaks on the outside of the engine) or have the intake manifold removed for leaks on the inside of the Vee.

The 2000 NSX has 21 coolant hoses (I replaced mine last year). Where that steady stream is coming from may provide some guidance. There are a lot of hoses on the drivers' side of the car (throttle body and thermostat housing) and there are connections to the oil cooler on the oil filter pedestal on the right side of the car. There are no direct hose connections to the water pump so it would be a pump base gasket leak or a failed water pump shaft seal if the pump is the problem. The pump is normally not disturbed during a timing belt replacement. The oil filter pedestal gets moved during a timing belt service. If the leak is on the right side of the engine I might be inclined to jack the car up and take the right rear wheel off and check the hose connections at the pedestal to see if the hoses have developed a split of perhaps they were not completely seated after the TB work or the cooler has developed a leak. If you purchase or can borrow a cooling system pressure tester, putting the system under pressure may make the source of the leak more obvious and if it is one of the many small hoses 'up top' or on the oil filter pedestal this may be fixable without a trip to the dealership. There are two large hoses and one not so large hose located at the firewall that connect the engine to the rest of the car. A split on these hoses is unlikely as they tend to be catastrophic rather than gradual; but, it might be possible that they have developed a leak at the pipe connections.

The reason I mention this is that with moderate wrenching skills the hose replacement on the thermostat, throttle body and oil filter pedestal range from quite easy to moderately difficult; but, doable at home. Check these for sources of leaks and if it is one of those you may be able to do the repair yourself and save yourself a trip to the dealership. If it is not it is probably best to have the car flat bedded to the Acura Dealership in Regina. If this is a hose leak, be aware that any work that involves coolant loss of more than a liter or so probably requires that you go through the process of bleeding the cooling system which is a non trivial exercise.

I have attached the pdf file that I created for my hose replacement project which provides all the part numbers and shows the location of all the cooling system hoses. In the NSX Prime Library you will find a link to a .pdf copy of the 1991 service manual. This is useful and 90% accurate; but, there are significant changes between 1991 and 2000 and a 1997 service manual with the 2000 update is the best source for repair information. These may help you in determining the source of the leak.
 

Attachments

Hoping it's just a coolant leak from a busted hose. I say learn to diagnose it on your own. This is probably a great opportunity for you to gain experience to learn the car, as a bad H/G will be considerably more expensive to fix than just replacing/fixing all the coolant hoses/radiator, etc. Definitely download a copy of the FSM and lookup the cooling system section. You will feel tremendous satisfaction after having fixed it yourself, just make sure you have the right tools/ torque wrenches for the job.

Here's a very good video on the process of gaining access and removing all the coolant hoses.. advance the video to minute 10:56..
 
Life is much easier if you have access to a garage lift as opposed to jack stands.

That video kind of skipped lightly over the bleeding process. I think there must have been a gap in the video where that miracle occurred. I vacuum filled my system and followed Kaz's method for bleeding and it still took me 3 heat cycles until I had no bubbles at the heater bleed valve.

If the purpose was to provide useful information, a really useful piece of information would be to absolutely note the orientation of the paint dots on the big hoses which determines how the hoses are connected on the car (towards engine versus towards the rad). The 3 hoses at the firewall look pretty symmetrical; but, they aren't. I recall there was one owner who could not get the hoses to fit and ultimately it was because he did not have the paint dots lined up correctly.
 
You're right.. that video I posted skipped a big part of the process, it's not a DIY video, just show the basics.
Best to follow the FSM, it's the best way to ensure one's doing it correctly step by step.
And I agree, vacuum filling the system is the absolute best way to completely rid all air pockets.
 
JDMGoat said:
And I agree, vacuum filling the system is the absolute best way to completely rid all air pockets.
Click to expand...
I would not go so far as to say that.

I purchased the vacuum refill tool on the basis of a couple of enthusiastic posts about 6-7 years ago with the hope that it would reduce or eliminate the bleeding process on the NSX because bleeding hassles were a fairly well discussed issue. I have a fairly big ass 2 stage air compressor so was properly equipped to use the tool. Subsequent to my purchase of the tool Kaz posted that the consumer level single stage vacuum refill tools did not cut it and would not eliminate the need for extensive bleeding. My experience reenforced his observations. On the NSX the vacuum refill tool was good for two things:
- pulling and holding a vacuum prior to filling was a nice confirmation that everything was buttoned up tight (I hadn't made a major goof)
- a convenient way to fill the cooling system and avoid spillage while pouring into the coolant tank from the coolant mix jug.

My experience was that even with the vacuum refill tool I still had to go through a rather extensive effort to bleed the car. I recently used it on a vintage Volvo with a conventional front engine arrangement and it worked well; but that car has never been a chore to bleed anyway. As such, I do not advocate for the vacuum refill tool as a miracle tool for the NSX.

I guess the video is OK if you view it as a puff piece and not as a serious guide to doing the coolant hose change out.
 
Old Guy said:
I would not go so far as to say that.

I purchased the vacuum refill tool on the basis of a couple of enthusiastic posts about 6-7 years ago with the hope that it would reduce or eliminate the bleeding process on the NSX because bleeding hassles were a fairly well discussed issue. I have a fairly big ass 2 stage air compressor so was properly equipped to use the tool. Subsequent to my purchase of the tool Kaz posted that the consumer level single stage vacuum refill tools did not cut it and would not eliminate the need for extensive bleeding. My experience reenforced his observations. On the NSX the vacuum refill tool was good for two things:
- pulling and holding a vacuum prior to filling was a nice confirmation that everything was buttoned up tight (I hadn't made a major goof)
- a convenient way to fill the cooling system and avoid spillage while pouring into the coolant tank from the coolant mix jug.

My experience was that even with the vacuum refill tool I still had to go through a rather extensive effort to bleed the car. I recently used it on a vintage Volvo with a conventional front engine arrangement and it worked well; but that car has never been a chore to bleed anyway. As such, I do not advocate for the vacuum refill tool as a miracle tool for the NSX.

I guess the video is OK if you view it as a puff piece and not as a serious guide to doing the coolant hose change out.
Click to expand...
+1 @Big McLargeHuge and I also used the consumer vacuum tool on the Zero and it left a ton of air- it's really meant for front-engine cars with very short coolant loops. I think doing the FSM procedure and following Kaz's advice to run about 1L of coolant through each bleeder is the way to go. I also think even a slight elevation of the rear of the car (like 1 notch difference on jack stands) can help the air bubbles migrate from under the center tunnel to the engine-side bleeders.
 
Interesting.. I’d have thought vacuum filling the system in an NSX would work the same as other cars. I spoke from reference of my three Subarus and a Chrysler Pacifica minivan where the tool really helped, particularly on the horizontal layout of the Subie boxer motors which air pockets tends to be a very common issue leading to engine overheating.
Seems probable that on the NSX mid engine location, far from the radiator and many coolant hoses, especially the long ones, can attribute to leaving air pockets in several places throughout. There’s much I need to learn yet on this car.
 
JDMGoat said:
Interesting.. I’d have thought vacuum filling the system in an NSX would work the same as other cars. I spoke from reference of my three Subarus and a Chrysler Pacifica minivan where the tool really helped, particularly on the horizontal layout of the Subie boxer motors which air pockets tends to be a very common issue leading to engine overheating.
Seems probable that on the NSX mid engine location, far from the radiator and many coolant hoses, especially the long ones, can attribute to leaving air pockets in several places throughout. Seems there’s much I need to learn yet on this car.
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Yes, it's the hoses under the center tunnel that trap the air bubbles. You can see it happen in my thread here:

Honcho

Post in thread 'Honcho's Long Road to Imola Type-S Zero'

Engine Testing 3

Coolant bleed, thermostat, etc.

The Honda genuine thermostat arrived today and I installed it. I must have done a much better job during the previous Kaz bleeding cycle because even after draining the engine block, an OCEAN of coolant spilled out of the thermo cover. Anyway, with the Honda stat in place, it was time to do the bleeding sequence all over again.

Here is the drain from the heater return pipe in the engine bay firewall. This stream of bubbles never stopped- I assumed it was just air being pulled past the bleeder threads, but not sure. This is the...
  • Like

And the explanation:

Honcho

Post in thread 'Honcho's Long Road to Imola Type-S Zero'

Coolant...The Final Verdict

It was air trapped under the car after all.

After the new thermo switch, it boiled over again. 🔥

I put 12V to the fan at the pins and it spun perfectly.

Next, I swapped in my new fan control unit and the rad fan still did not come on.

So, new thermo switch, good fuse # 4, new FCU and healthy fan. That's literally the entire chain and yet the car was still overflowing the coolant.

My conclusion was that it had to be air. As shown in my crude diagram below, here is what was happening: an air bubble was trapped at the top of the...
  • Like

In order to purge all the air, you need to use a commercial 2-stage deep vacuum machine. It's better to just follow Kaz's procedure here:

Kaz-kzukNA1

Post in thread 'Honcho's Long Road to Imola Type-S Zero'

As I didn’t want disturbing your nice build thread, thought about not posting here.

However, you are happy for me to do so and other owners may re-visit your detailed thread in the future, going to add my experience here.

I wrote this for other owners when asked about how I bleed the cooling system years ago and it’s cut and paste of multiple messages from the past.

Very old info but should be still useful.


First, the basic.

The method in Workshop manual is OK but mainly written based on the theory.

The entire coolant capacity including the tank is about 16.5L for the C30A and about...
  • Like
 
Hmm, interesting. Since there's such distance from the radiator to the engine with long pipes in between, etc., I was wondering if anyone has ever tried filling up the cooling system partially with the car seating totally leveled till the radiator filler neck is full with coolant, and subsequently raising the car by the front only, a good, I don't know.. 10 degrees (this may be a bit too much) with the idea to get the pipes filled up and eventually up to the radiator again. Having the car elevated up front would naturally get rid of the air, it'd be like filling up a pipe at an angle.. Just a theory..

Man.. and I thought burping the systemin a Subie was difficult.. Ha! Thank you for all the info and links btw.
 
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JDMGoat said:
Hmm, interesting. Since there's such distance from the radiator to the engine with long pipes in between, etc., I was wondering if anyone has ever tried filling up the cooling system partially with the car seating totally leveled till the radiator filler neck is full with coolant, and subsequently raising the car by the front only, a good, I don't know.. 10 degrees (this may be a bit too much) with the idea to get the pipes filled up and eventually up to the radiator again. Having the car elevated up front would naturally get rid of the air, it'd be like filling up a pipe at an angle.. Just a theory..

Man.. and I thought burping the systemin a Subie was difficult.. Ha! Thank you for all the info and links btw.
Click to expand...
There's no radiator filler neck on the NSX. ;)
 

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