Blown Neo head gasket - Next steps?

[V28VX37]

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!

[hy_rpm]

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

[V28VX37]

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...

[AngryRB]

Check the Head isn't warped...

 

[KiwiRS4T]

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.

[V28VX37]

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?

[hy_rpm]

You can get cheap alloy replacement off ebay
Better to replace that and see how you go cheaper option for now and will need it
Look at it as a upgrade for the track

[Scott Black]

Radiators normally have three parts the top and bottom tanks and the core. The plastic tanks and held in by the core clamping over them with a rubber seal under them. Not a diy job though

[Dose Pipe Sutututu]

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

[V28VX37]

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?

[GTSBoy]

Oil water heat exchanger failure is a possibility.

[V28VX37]

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.

[Scott Black]

They normally get a rotten fish sort of smell if you run it without coolant for a while

[V28VX37]

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.

[GTSBoy]

Gasket well gone.

[V28VX37]

8 minutes ago, GTSBoy said:

Gasket well gone.

Thanks man, at least that's a given then. I'll get onto the replacement.

[Watermouse]

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

[Scott Black]

Have you also done a leakdown test on the motor?

[Dose Pipe Sutututu]

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.

[V28VX37]

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..