Possible Head Gasket Leak?

[dhoch]

Hey everyone, asking for some help again here - with all the experience here, I figure someone will be able to point me in the right direction on this. I'm more of an electronics guy with DIY projects, so engines are well outside of my area of expertise.

This past Monday (8/31) after driving home from work on the highway, I parked my NSX and noticed some white smoke coming out of the rear vent under the garnish - not a crazy amount, but definitely noticeable, as was the smell. I checked under the engine cover and noticed it was coming from the rear cylinder bank area, and it stopped completely after about 10 minutes. After letting the car sit for 30 minutes or so, I noticed a few drops of coolant under the car slightly towards the passenger side almost right under the cat (I assume the cat burning the coolant caused the smoke). I took some pictures of what I could find from above and underneath (should've done this in daylight instead of in the garage), and here are the spots where I found either a bit of coolant or sludge that I assume shouldn't be there. I also noticed some gunk around the oil pan seal, so it looks like I'm due for an oil pan gasket as well:






I bought this car (indirectly) from a Prime user a few months ago, and the list of maintenance performed within the last 2 years/5,000 miles includes machining the cylinder heads, replacing VTEC gaskets, and replacing the water pump, so I was hopeful that it was just bad hoses considering it's a higher mileage car. The thread for the car is available here for reference: http://www.nsxprime.com/forum/showt...ilver-Black-6-Speed-134-014-JH4NA2162VT000300
Unfortunately, I took the car out today (Friday, 9/4) for the first time since Monday, and after looking underneath again, I find some oil where I found the coolant last time... Pictures were taken outside this time. Hopefully these will suffice since I don't have the means to lift the car at the moment:









Since I have noticed this issue, the only indicator was the smell and smoke. I wouldn't say the smell was sweet like most say about burning coolant - it smelled more like oil. I haven't had any performance or cooling issues at all, and the car runs just as well as when I purchased it. The oil on the dipstick looks normal (fresh oil change when purchased in late May, driven about 2,000 miles since, most of which was highway from driving the car from Houston to SE Michigan), and the coolant reservoir is still at the max line. After finding this, I'm leaving the car parked until I can get someone to look at it. I got in touch with Mike Michalik over at Suburban Honda, but he said they're not too fond of people bringing in their NSXes anymore, so if I can't get this taken care of by Mike, I'd like some recommendations on where to go for service.

From the research I've done, it seems like this is a sign of a head gasket problem, but I have no history of the hoses or valve cover gaskets being replaced, so between that and my lack of knowledge on this, I can't say for sure. Hopefully someone can make a diagnosis from the information I've provided here, but I'll try to get more info as needed to find the issue until I can get someone who knows what they're doing to look at it. Also, if it is the head gasket(s), I'd really appreciate a list of while-you're-in-there things to get done on the car. Thanks in advance for any advice on this!

 

[Bram]

I would ask the Guys in the MI region, there are some really good people in this area and they are quite knowledgeable about the NSX and where you can get some good advise.

Bram

 

[Old Guy]

I suggest the following tests. The first is a pressure test on the cooling system. If the cooling system will not hold pressure then you absolutely have to find the source of the problem before doing more driving around. The problem can be big (head gasket) or smaller (hose problem or gasket problem that is not the head gasket). Do a combustion products reagent test - indicators that you add to the coolant sample which change color if there are combustion products in the coolant indicating a breach of the head gasket from the cylinder into the cooling jacket. Finally, a UV dye in the coolant test which makes it easier to spot the location of external coolant leaks. This is easier to do if the outside of the engine is relatively clean.

If you don't have, or have access to the pressure tester or the UV light you may want to farm this out to a dealership or NSX specialist. The combustion products reagent test should be easy to do. This is one kit, there are others that I think are less expensive

https://www.amazon.ca/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76

Good luck, hope its not the head gasket.

 

[goldNSX]

Too much everywhere. I'd suggest to rinse the oil off completely, drive a short distance and inspect again.

 

[Jerry@Mobile]

Heads

You mentioned that the head(s) were machined. Why? Was the engine overheated? Was the block decked to match the heads? Jerry

 

[Honcho]

I suggest the following tests. The first is a pressure test on the cooling system. If the cooling system will not hold pressure then you absolutely have to find the source of the problem before doing more driving around. The problem can be big (head gasket) or smaller (hose problem or gasket problem that is not the head gasket). Do a combustion products reagent test - indicators that you add to the coolant sample which change color if there are combustion products in the coolant indicating a breach of the head gasket from the cylinder into the cooling jacket. Finally, a UV dye in the coolant test which makes it easier to spot the location of external coolant leaks. This is easier to do if the outside of the engine is relatively clean.

If you don't have, or have access to the pressure tester or the UV light you may want to farm this out to a dealership or NSX specialist. The combustion products reagent test should be easy to do. This is one kit, there are others that I think are less expensive

https://www.amazon.ca/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76

Good luck, hope its not the head gasket.

Too much everywhere. I'd suggest to rinse the oil off completely, drive a short distance and inspect again.

You mentioned that the head(s) were machined. Why? Was the engine overheated? Was the block decked to match the heads? Jerry

I would add to all of the above excellent advice that you really should do a block gas test. It's not that expensive and will tell you very quickly and definitively if you have a head gasket issue. A bad HG might explain the problems you are having, but it looks like your car has a nearly new HG. Much more likely is an improperly installed o-ring or other gasket and/or coolant hose. The C32B has so many little seals and hoses that it is quite easy for even an experienced tech to make a mistake during reassembly- especially is they are not taking their time. One small bolt not torqued correctly or one hose clamp not positioned juuust right and now you've got a leak.

That said, it's a bit concerning that this car had the heads resurfaced. That is NOT a normal part of an engine out service- even a full refresh service like [MENTION=25737]Kaz-kzukNA1[/MENTION] does. This is usually done after the heads have warped from an overheat/loss of coolant event.

 

[dhoch]

I'm not sure why the previous owner had the heads machined - I'm trying to get a hold of him and find that out now. In the mean time, I'll perform the tests suggested here and report back with the results when I'm finished.

EDIT: The previous owner said there was a coolant leak that resulted from one of the engine bolts de-threading. His tech (Carl McClellan) re-threaded with a new one and took the engine apart to make sure there was no internal damage (no warping of the heads). He replaced some gaskets and seals as well.

I'll give Carl a call and see if he can offer any more info.

 

[dhoch]

UPDATE: The car leaked oil pretty noticeably this morning from a cold start. It made a puddle about 6 inches in diameter after idling for 30 seconds and left a thin trail as I pulled it out of the climate controlled storage facility I keep it in. After it warmed up, it did not leak at all, which sounds like a problem with a seal to me. After shutting it off at home and starting it again, the leak was gone, and any more drops of oil I found were residual from the initial loss of oil earlier. The burning smell still persists, and it's definitely a burning oil smell (burning on the cat) rather than coolant.

I have reason to believe it's not a head gasket issue - the combustion leak test was good (test fluid stayed dark blue), and the oil and coolant are still clean. The coolant pressure tester I received doesn't have the proper fitting for the car, so I have to wait for that to arrive to test it, but the coolant is still at the max line. I was able to get underneath the car on a lift in the storage facility and clean it up some, and it looks like most, if not all, of the oil is coming from the corners of the oil pan gasket and making everything else underneath messy when the car is moving. The worst offender is the corner closest to the cat where I noticed the burning vapor and smell:





The rear side of the gasket looks squished out pretty badly as well:


My guess is that the oil leaking from the gasket splashed up into the areas pictured here and in my first post. The only other place I saw any sign of oil was this tiny drop next to where the rear header is bolted on:


I did find couple tiny specks of coolant on the worst corner of the oil pan gasket, but after cleaning it up and observing the leak further, only oil and no coolant came through. Then, I looked a bit in front and found this wiring harness conduit (I think?) directly below the coolant reservoir with coolant in the grooves:


I also noticed the main coolant hoses have some white residue on them (not sure if this is normal):


One smaller hose in particular also looks worse for wear:


All of this makes me think it is separate issues with the oil and coolant. I'm trying to get the car looked at, but Suburban Honda, Troy, and Ann Arbor told me they won't take them in anymore, and the tech at Jeffrey Acura is out for a month for surgery starting yesterday, so I'm out of dealership options. I'm storing the car over the winter, so if I can't get it taken care of by mid-October, I'll probably just tackle this in the spring unless anyone knows of another place in SE Michigan that can look at it. I picked up some UV dyes for each system to pinpoint the locations of the leaks, but I probably won't be driving the car again until I take it to a tech. But hey, maybe the dye will make the tech's life easier.

Sorry if this is a mouthful - just trying to be thorough and give enough info to see if someone can recognize this problem from prior experience. Replacing the oil pan gasket, coolant hoses, and probably the coolant reservoir tank are the first things on my list, but if anyone has any other suggestions on what's going on here, let me know. Thanks for all the great advice so far!

 

[dhoch]

After a long awaited update, it is indeed the head gasket. The repair to the threads was done poorly, and the repaired threads failed, so there was no clamping force on one corner of the head. Brian at Source 1 is taking care of it for me, and while my wallet isn't happy about it, I'm glad it's in good hands and will be done correctly this time. Thanks Prime!

 

[Honcho]

After a long awaited update, it is indeed the head gasket. The repair to the threads was done poorly, and the repaired threads failed, so there was no clamping force on one corner of the head. Brian at Source 1 is taking care of it for me, and while my wallet isn't happy about it, I'm glad it's in good hands and will be done correctly this time. Thanks Prime!

Sorry to hear- was it a helicoil or time-sert that failed?

 

[goldNSX]

Sorry to hear about the hassle with unprofessional work. Hope it will be fixed 100% this time.

 

[Old Guy]

That is a bitter pill for a new owner. Not how you want to start off the ownership experience.

What final diagnostic test was used to confirm the leak, coolant pressure test, UV dye in the coolant? Do you know whether the original bolt threading failure was repaired with a Timesert or equivalent or just a clean up of the threads? Since the 2018 repair was engine out that should make the correct installation of an insert easier. The original failure is interesting because it has to be pretty uncommon for a head bolt to fail at 134,000 miles without some sort of precipitating event. I notice from the link you provided to the vehicles for-sale post that it had the water pump replaced with the TB in Jan 2018 and I am wondering if the cooling system didn't get completely purged leading to a possible bubble. Having the head bolt failure become apparent 1600 miles after the water pump was repaired may be a coincidence; but, it is a suspicious coincidence.

What is also concerning is what is almost equivalent to outright refusal by the dealerships to deal with the car. That does not bode well for NSX owners in the future if they don't have facilities or skills to do their own maintenance. It would also give me concern if I was considering 2nd generation ownership. With a service manual owner maintenance on the first gen is feasible. I don't think I would want to be attempting diagnostics on an NC1. Around here there used to be a group of Ferrari owners who organized a transporter to have their Ferraris hauled 750 km to Calgary for their regularly scheduled maintenance. Made for a really expensive oil change!

 

[dhoch]

Sorry to hear- was it a helicoil or time-sert that failed?

They said it doesn't seem like either of these were used... They're not sure what it is exactly, but they said it seems very soft and not suitable for the repair. They also let me know that generic bolts were used in place of the OEM ones, the cam plugs were fully covered in Hondabond, and there are metal shavings stuck in some sludge around the engine mounts, so it sounds like I'm lucky that the car isn't in worse shape considering all that...

What final diagnostic test was used to confirm the leak, coolant pressure test, UV dye in the coolant? Do you know whether the original bolt threading failure was repaired with a Timesert or equivalent or just a clean up of the threads?

I first found the leak from it dripping on the cat and burning. I had some pig mats underneath it for a while in the place I store it, and there was oil with a few drops of coolant directly underneath the problem area. I did also put UV dye in both the oil and coolant. I wasn't able to get a coolant pressure test done, but I did a combustion leak test with the blue fluid, and it passed with no problems. Between that and the car running fine, I was shocked to find out that this is the problem. I was extremely careful and drove the car gently for the few miles I drove it after finding the leak, so that may have helped prevent some damage.

Brian couldn't even really describe the original repair method - all he knows is it's not a Heli-Coil or a Timesert, and it's very soft for that kind of repair. They were able to get some of the bolts out with a 1/4" ratchet with little effort, and the threads came right out with the bolts.

What is also concerning is what is almost equivalent to outright refusal by the dealerships to deal with the car. That does not bode well for NSX owners in the future if they don't have facilities or skills to do their own maintenance.

I was able to get a hold of Jeffrey Acura a few months ago, and they were willing to look at the car. Their suggestion that it was a head gasket leak was correct, but they only have 1 person who works on NSXes, and the repair would be both expensive and take a long time to get completed. For those in SE Michigan, Jeffrey Acura in Roseville is an option if you're in a pinch, but it seems like Source 1 is the place to go for now and worth the ~250 mile trip.

 

[dhoch]

Sorry to hear- was it a helicoil or time-sert that failed?

They said it doesn't seem like either of these were used... They're not sure what it is exactly, but they said it seems very soft and not suitable for the repair. However, Carl claims he put Timeserts in for the repair. They also let me know that generic bolts were used in place of the OEM ones, which Carl claims is not true because he only uses dealer parts. Unless it earns me some sort of compensation for the repair, I'm not really interested in the he-said-she-said on this.

What final diagnostic test was used to confirm the leak, coolant pressure test, UV dye in the coolant? Do you know whether the original bolt threading failure was repaired with a Timesert or equivalent or just a clean up of the threads?

I first found the leak from it dripping on the cat and burning. I had some pig mats underneath it for a while in the place I store it, and there was oil with a few drops of coolant directly underneath the problem area. I did also put UV dye in both the oil and coolant. I wasn't able to get a coolant pressure test done, but I did a combustion leak test with the blue fluid, and it passed with no problems. Between that and the car running fine, I was shocked to find out that this is the problem. I was extremely careful and drove the car gently for the few miles I drove it after finding the leak, so that may have helped prevent some damage.

Carl claims they're Timeserts, but Brian couldn't accurately describe the original repair method - all he knows is it's not a Heli-Coil or a Timesert, and it's very soft for that kind of repair. They were able to get some of the bolts out with a 1/4" ratchet with little effort, and the threads came right out with the bolts, which shouldn’t happen with Timeserts from my understanding unless a considerable amount of Loctite was used.

What is also concerning is what is almost equivalent to outright refusal by the dealerships to deal with the car. That does not bode well for NSX owners in the future if they don't have facilities or skills to do their own maintenance.

Jeffrey Acura was willing to look at the car, and they told me that the leak was from the head gasket, but they only have 1 person who works on NSXes, and the repair would be both expensive and take a long time to complete because of their backlog. For those in SE Michigan, Jeffrey Acura is an option if you're in a pinch, but it seems like Source 1 is the place to go for now and worth the ~250 mile trip.

Other things to note are that the cam plugs were fully covered in Hondabond, and there are metal shavings stuck in some sludge around the engine mounts, so it sounds like I'm lucky that the car isn't in worse shape considering all that... Another interesting thing is that Brian told me (with pictures) the knock sensor was loose and laying near the engine, but I’ve never had a check engine light since I owned the car, so I find this one interesting, to say the least.

 

[nis350]

So sorry about the terrible situation. Hope you'll get your car back soon.

After a long awaited update, it is indeed the head gasket. The repair to the threads was done poorly, and the repaired threads failed, so there was no clamping force on one corner of the head. Brian at Source 1 is taking care of it for me, and while my wallet isn't happy about it, I'm glad it's in good hands and will be done correctly this time. Thanks Prime!