Jump to content
SAU Community

Recommended Posts

Blown Neo head gasket - Next steps?

Ok so I am 95% certain I have blown the head gasket in my Neo.

Symptoms:

  • The engine is pushing coolant into the overflow bottle when pushed even moderately. I tried it out at Sandown today with an eye on the temps at all times and returned back to the pits whenever it hit over 90C -> overflow is at max or beyond. I added a second overflow bottle for the day too.
  • Coolant in the overflow bottle not clean/clear, it's bubbly/foamy after a run, and also there's occasionally 'floaties' (black sediment) on the surface. Doesn't smell the best either; not quite like combustion gases but not like clean coolant either.
  • I also noticed that the exhaust is popping on more than usual on gear changes, running rich perhaps? Also it doesn't feel like it's hitting/holding boost quite as well as normal (not that I pushed it a 100% but still). Unsure if this is related.

What's weird is that I had a tee kay test done earlier this week and it came back all clear. Comp test was 155,155,155,140,146,150 so not top of class but within the 10% tolerance.

The back story is that I had a small coolant leak at Sandown last time two months ago -> lost coolant and pressure -> temps shot up to 125. What I'm not 100% sure about is whether that's the root cause. The engine is currently at 153,000 kms and it's been running ~20psi for the past 20,000 kms, with about half a dozen track days on it.

Now, to the questions.

I know that I'm up for a head gasket and head studs at a minimum, plus probably a head skim. Some would recommend a head reco too.

  1. With the studs, I'm guessing ARP over OEM?
  2. With the gasket, OEM should do with stock bottom end at up to low-300 kw's, no? From what I understand it's a bit more forgiving to an uneven surface than a metal one.
  3. Where in Melbourne should I go for some quotes, who knows this stuff well? What should I expect to pay?

Also, some other options:

  • An alternative to all that work is just buying another Neo, which can probably be had for say 2k? Lots of labour to change it over though, plus the condition would be anyone's guess. Or just go crazy and buy someone else's 24/30...
  • What else might I look at doing when the head is off? Built bottom end would be nice but gets pricey very quickly. Also poncams would be cool but I'm not sure how much they add without any other mods.

Anyway all I really want is a track ready ~300rwkw @ 98 car that is reliable...

Thanks guys! Also big hat tip to Bill and Greg for troubleshooting this with me at Sandown today!

Link to comment
https://www.sau.com.au/forums/topic/467066-blown-neo-head-gasket-next-steps/
Share on other sites

If your not going to go crazy with the boost levels
Stock headbolts will be fine unless you plan on running more than 22psi closer to 25psi

Would get away with a head skim and genuine headgasket unless it was blowing smoke or burning oil i wouldnt bother getting the head serviced
Expensive job especially on a 6cyl
You can usually tell by the spark plugs
The cylinders that are blown will be very clean
You cant always tell using the tk tester but if the cooling system is bled proberly and not blocked shouldnt push coolant
Another way to test is with a pressure tester connected and running the car the pressure should be steady

  • Like 2
14 minutes ago, hy_rpm said:

If your not going to go crazy with the boost levels
Stock headbolts will be fine unless you plan on running more than 22psi closer to 25psi

Would get away with a head skim and genuine headgasket unless it was blowing smoke or burning oil i wouldnt bother getting the head serviced
Expensive job especially on a 6cyl
You can usually tell by the spark plugs
The cylinders that are blown will be very clean
You cant always tell using the tk tester but if the cooling system is bled proberly and not blocked shouldnt push coolant
Another way to test is with a pressure tester connected and running the car the pressure should be steady

Thanks mate. Not blowing smoke or burning oil, although there was some oil residue on the #2 plug when the guys checked it earlier this week.

The system has been bled multiple times and seems to behave itself on idle, it's just under load when it starts pushing coolant.

Is there any chance a blocked radiator or hose somewhere could cause symptoms like these? I'd hate to get the head gasket done and not have the issue fixed...

Have you got a new radiator cap? Have you had a new radiator? Go to a radiator shop and get a pressure test then get them to take the top tank off and clean out the radiator or recore as necessary. You're going to feel really silly if you replace the engine and nothing changes.

  • Like 2
11 hours ago, AngryRB said:

Check the Head isn't warped...

Yeah will do – silly question but I assume there's no way to check without pulling it off? 

11 hours ago, KiwiRS4T said:

Have you got a new radiator cap? Have you had a new radiator? Go to a radiator shop and get a pressure test then get them to take the top tank off and clean out the radiator or recore as necessary. You're going to feel really silly if you replace the engine and nothing changes.

Yes brand new Tridon cap put in on Friday. It's got the original radiator still, it passes the pressure test fine. What's a good replacement worth? When you say 'top tank', are there multiple parts to the rad?

I would go ARP non 2000 studs if the head is coming off. Good clamp is good for keeping thr head and block together. Never know, one day you might have the urge to push out 350kw+ lol

2 hours ago, Dose Pipe Sutututu said:

I would go ARP non 2000 studs if the head is coming off. Good clamp is good for keeping thr head and block together. Never know, one day you might have the urge to push out 350kw+ lol

Yeah there's a good chance haha :)

I'm currently thinking:

  1. Replace radiator and hoses & see how it goes
  2. If still no good remove & skim head (no reco), re-install with OEM gasket and ARP studs

The thing that concerns me is the bad smell & sediment in the coolant, that doesn't feel like a radiator-only issue. Unless there's a blockage somewhere and the pressure is pushing the crud collected over the 150k around?

5 minutes ago, GTSBoy said:

Oil water heat exchanger failure is a possibility.

Hmm it's been changed early this year as the original one was leaking. However, I think the 'new' one is second hand too so you never know.

Because of the pressure differential (oil 2-6bar vs. coolant ~1bar) I'm guessing it'd mix oil into the water rather than the other way around? I'm not seeing any loss of oil at the moment.

Here's what the overflow looks like after a drive, it does smell like exhaust and there's dark gray matter near the bubbles. It pushed about an inch from the radiator into the overflow during the drive.

29974945431_72d82856bc_c.jpg

8 hours ago, Dose Pipe Sutututu said:

I would go ARP non 2000 studs if the head is coming off. Good clamp is good for keeping thr head and block together. Never know, one day you might have the urge to push out 350kw+ lol

Hey, could you give me a heads up on why go non 2000 studs?

Thanks

  • Like 1
4 hours ago, Watermouse said:

Hey, could you give me a heads up on why go non 2000 studs?

Thanks

because budget conscious track build and they're fine... ARP 2000 for big power and boost.

Since the head is coming off, might as well do value stem seals and also basic performance valve springs... RB25DET is prone to valve float once it gets some heat into it.. sometimes noticeable on the dyno after many pulls usually only noticed on the track.

  • Like 2
9 hours ago, Scott Black said:

Have you also done a leakdown test on the motor?

Nope, just a comp test and the tee kay. Should I get a leakdown done, what's the benefit?

Also I just checked yesterday on cold start that the car is not blowing any smoke just at least that's good..

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
    • I'm not going to recommend an EBC pad. I don't like them. Just about anything else would suit me better. I've been using Intima pads for a while now.
×
×
  • Create New...