Hi all,
Seriously pissed off as have confirmed today my head gaskets have failed. Only just got the car ready for the summer fully forged engine only just run in.
On Wednesday had it mapped for methanol & it ran slightly hot, parked it up to cool down & just put it down to being driven hard while mapping.

Since then whenever it's driven hard on boost it spews all it's coolant out the expansion tube. I'm worried about doing the gaskets as it was all Skimmed on the build which included a CDB ARP studs & Cometic gaskets,what's to stop it going again. It's only done 2500 miles & running 440 BHP, there is no way it should have blown.
Do & rebuild again or break the money pit? It's already cost a fortune to build it to this spec & I can't afford failures like this every 2500 miles.

 

are you sure its not an airlock?

 

What's on her spec wise,interested in parts
On a serious note I had some cometic MLS gaskets fail after roughly the same mileage on a forged build and then went to genuine suabru MLS type and fine ever since[4k on theses]

 

It's not an air lock, Iv messed around draining & refilling for hours since Wednesday it's fine until allowed to boost then it spews half it's coolant out the expansion tube.
The spec is good 6 speed Simtec FMIC RCM 400 plus the usual goodies.
I thought Cometic were the best? Perhaps I was misinformed.

 

sorry to hear this mate, i have read a few things about cometic gaskets failing, maybe changing to a different make will help

 

They are good but didn't work on mine,I very nearly broke my motor over the failure and if it wasn't for the fact I build them myself I would have due to the massive cost.

 

Seems I'm not alone, anyone else know of premature failure of cometics? What's best then for my spec Subaru or Cosworth & do I switch to Cosworth studs too? The worrying thing is will my bottom end fail next as Iv often heard happening after HG failure & as I'm running 1.6 mm gaskets dare I risk another skim or are my heads now scrap too. I love my car but perhaps it's time to throw in the towel.

 

If she has gone bad enough to blow a lot of coolant out on boost then there is a fair chance the heads are warped also and I wouldn't personally want to skim again but only a deck height check will tell you whether the heads have a skimable amount left in them.
Mine didn't go that bad but I did buy some reworked heads off Mick from API to put on mine at that point.

Either way I think it will be an expensive build for you mate

 

If I can get some used heads what's this likely to cost me?

 

Can you build it yourself Rich?

 

Yes I can. Just worried it may do it again or the bottom end fail next. Is Cosworth gaskets & studs the best?

 

Well some sti heads will be around 3-400,then the cosworth studs and gaskets will be around the same along with new seals/cambelt so I'd say you wouldn't get out of it under a grand I'm afraid by the time you have the new heads slightly skimmed to level those's as well.

To top that off you will require a map tweak to check the knock levels are ok etc

 

I had an issue with 1 set of cosworth gaskets, they didnt last 3000 miles on mine even with the heads & block face skimmed, stripped it fitted another set of cosworth gaskets and it's been no issue since

 

iv never known a block to be skimmed after hg failure. on any car?

 

Sorry to hear about your luck fella, itys about as bad as mine......but I have some V3 sti heads/cams for sale from the car im breaking.

 

How much?

 

i think need more info?

what compression ratio is engine?

id be more inclined to look at ARP studs or improper torque sequence. anything over 400bhp use cosworth high tensile studs or RCM 14mm ones

 

£270

 

We've never had a head gasket subsequently fail on any Subaru engine. I can only put that down to very careful preparation and working out the CR by trial assembly.
Cosworth don't make a 1.6mm gasket. We run the basic ARP studs up to 500 bhp plus.
It's possible to work your original heads to open up the chambers. Personally, I'd strip the motor then check the condition of the surfaces and CR before you do anything else.

 

Well mine required the deck to be skimmed after HG failure, I wasn't going to get it done but then I thought about it; if the head can warp then why not the cylinder block as well?

I had mine checked by Advanced Automotives in Bristol, and they confirmed that the head and the deck were warped. If I had just had the head skimmed then I would have been looking at another HG failure very quickly after the rebuild.

 

Don't know CR ratio after measuring head height my engine builder recommended using the 1.6 mm gaskets.
The torque setting was as per ARP instructions in the correct sequence using a calibrated snap on digital torque wrench.

 

Alan, what do you charge to do the gaskets & set up the compression ratio?

 

Thanks for the offer,I'll see if I can use mine first.

 

My block halves & heads were skimmed this is what worries me about doing it again. A CDB with ARP studs & cometics ought to be good for 500 BHP.

 

Have always used stock Subaru MLS gaskets in all my engines, including my current which I will be running up to 700bhp + , no failures to date,, if your heads were skimmed as well as the block its seriously odd! was the correct tightening sequence and torque settings applied on the ARP's ?

 

Did you get your heads pressure tested?, may even be a hairline crack somewhere?

 

Yes it was torques up using the instructions in the box which were confirmed as being correct by my engine builder. Im thinking this is odd too,perhaps.there is an underlying reason for this,or perhaps Cometic gaskets are crap. I don't think many tuners use them. Think gen Suburu or Cosworth if I can find the will to do it again.

 

Heads were pressure tested & were fine. Before the gaskets blew it went through two mapping sessions & a power run on the rollers. I would have thought any cracks would have become apparent sooner. It was the last mapping session it had for methanol which killed it,but it was built to handle the power it's been mapped for & then some.

 

It does make a big difference what surface finish was achieved on the block & head face, was it milled or ground ?, some machine shop finishes are not compatable with MLS gaskets, as 99% of their work is for fibre gaskets.

 

Perhaps that's the problem,looked OK to me,but who am I to question those who are supposed to know better. All I know is my car is not usable after spending a fortune on it,& I don't know if I can afford or justify the cost of doing it again especially if it's going to happen again in another 2000 miles.