Why You Should Replace Your Head Gasket

[scam75]

Well after deciding not to rush out and replace my HG after the last debate on the subject it finally gave way on Tuesday night. In a cruel twist of fate my turbo imploded at exactly the same time. You couldn't write it! It's a real strange one with the turbo, Al and me could only surmise that it has threw a wobbler (it did happen at 5.5k revs at full beans), spat out a bit of impeller and then sucked it back in before distributing it all over the place. The cold side impellers have chewed themselves flat! Fortunately only very minimal scoring on 2 bores so got off light. That was just bad luck, however the HG going was my own fault for not attending sooner. Fortunately my failure was a sealing ring causing oil to flood into the bores, no water was lost and it didn't overheat. Anyway, here is the HG:

Argh!

 

[TTM]

How many miles on the headgasket?

 

[Diver944]

Bad luck []

Or you could look on the bright side and say that at least your bores weren't trashed by the resultant debris. Are you going to replace the turbocharger with another standard one or go a bit more exotic?

 

[PSH]

failed in the usual place No. 4 I see, there is a remedy to help avoid this, a steam release system. You can buy a kit cheaply from Lindsey's but to be honest it's nothing special and you can easily make up a kit yourself. I'll be doing this to my head once I get to that stage, having had two gaskets fail in exactly the same place one of which was fairly new, the result of not keeping an eye on the AFR..

Pete

 

[Copperman05]

Some pretty bad luck, feel for you, what mileage is the engine? Was considering doing the HG on my S2 next year, whilst perhaps less vulnerable on a n/a engine replacing a HG at 125,000 miles or 25 years cant be considered a bad move for piece of mind. Perhaps Barry was right all along (as usual).


Edd

 

[scam75]

Don't know how many miles, wasn't original, definite signs of non porsche workmanship in places! Over 13 years old though as I contacted previous owner who had it 10 years and he didn't have the head off in his time. I've had it 3 years.

Was thinking long and hard about exoticising the turbo but have decided on a freshly rebuilt K26/8. i am not planning (!) any more power upgrades and instead hope to run a fairly bullet proof 310 ish bhp with 18psi on my current set-up. Re-conned turbo and head refresh should see me ok for this. Also going to use a standard HG so don't want to push much further along the boost scale.

I will be installing 55lb injectors though which I have recently acquired so my poor old standard ones aren't running full tilt all the time.

Cheers

Stuart

 

[scam75]

ORIGINAL: Copperman05

Some pretty bad luck, feel for you, what mileage is the engine? Was considering doing the HG on my S2 next year, whilst perhaps less vulnerable on a n/a engine replacing a HG at 125,000 miles or 25 years cant be considered a bad move for piece of mind. Perhaps Barry was right all along (as usual).


Edd

Hi Edd

Thanks. Currently 116k miles and that was not the original gasket. I am sure I read the 3L lump is more vulnerable to overheating around no. 4 cylinder for some reason? Definately worth doing in my opinion. It does appear that Barry was indeed right and I too decided to leave it last year because all seemed fine and was running well. A standard HG seems good for 10-12 years it would seem then you are trusting blind faith!

Stuart

 

[PSH]

Stuart, regarding getting the turbo re-conned try talking to Chris at Universal turbo's, he's done mine in the past and will be doing it again this time around too. Great service and he'll send a courier to you to collect your turbo.

Pete

 

[scam75]

Thanks Pete.

Al has got somewhere in Glasgow he trusts. £360 all in.

Cheers

Stuart

 

[sulzeruk]

It looks like the nut securing the compressor impellor has unwound slightly and then fallen into the impellor causing the damage. The intercooler will be chucked as there is small bits of shrapnel everywhere. The guy who does the turbos is very good with a 1 day turnaround if you get it in sharp in the morning or he has the bits in stock.
The gasket really is bad, I am surprised it lasted so long. If your head gasket hasn't been changed in the last 10 years, get it done people!!!!
The valves are in dire need of a decoke as the exhausts have a fair bit of baked on carbon on them. It will get a skim to flatten it and clean the face as there is some corrosion on it as well. The guides will be changed with new stem seals and the valaves will be cut and the faces done.
Will be interesting to see the dyno figures after the rebuild.
Alasdair

 

[PSH]

ORIGINAL: sulzeruk

It looks like the nut securing the compressor impellor has unwound slightly and then fallen into the impellor causing the damage. The intercooler will be chucked as there is small bits of shrapnel everywhere. The guy who does the turbos is very good with a 1 day turnaround if you get it in sharp in the morning or he has the bits in stock.
The gasket really is bad, I am surprised it lasted so long. If your head gasket hasn't been changed in the last 10 years, get it done people!!!!
The valves are in dire need of a decoke as the exhausts have a fair bit of baked on carbon on them. It will get a skim to flatten it and clean the face as there is some corrosion on it as well. The guides will be changed with new stem seals and the valaves will be cut and the faces done.
Will be interesting to see the dyno figures after the rebuild.
Alasdair

Rather than change the impeller like for like why not upgrade to a ball bearing design, would make a difference although admittedly wouldn't be cheap. iirc when I enquired about this upgrade on mine the quote was £1150 instead of £350 for a standard rebuild. Mind you if this fails it means a new impeller again instead of just a new bearing and seal. I only mention this as you need an impeller anyway.

Pete

 

[sulzeruk]

Pete, the £360 includes a new impellor and cassette in the price. Can't get them done anywhere cheaper I think than that!
Alasdair

 

[PSH]

ORIGINAL: sulzeruk

Pete, the £360 includes a new impellor and cassette in the price. Can't get them done anywhere cheaper I think than that!
Alasdair

Hi Alasdair

I wasn't doubting the price, was just mentioning that if Stuart wanted a more efficient turbo why not improve his with a roller bearing, I agree £360 is good as my last rebuild at £350 was some years ago now. I'm sure your guy could give him a quote for such an impeller/bearing too.

Pete

 

[George Elliott]

Alasdair, will you bother correcting the cam timing?

It will get a skim to flatten it and clean the face as there is some corrosion on it as well.

I think there are a lot of engines with compromised timing following skimming, and if it did not overheat then its flat ! Plus the Compression is affected. The corrosion you refer to - if its like the cyl head face, then....well maybe.

Stuart, sorry to hear of scoring, I had exactly the same failure on a previous car, but luckily no bore damage or turbo failure. Victor Reinz gasket, but I replaced it with a Cometic from Promax, and while I did not learn of the Steam vent kit Pete refers to until later, I'd say its a good idea. Even if you consider how difficult these engines are to bleed the coolant it makes sense.

Would it be possible the gasket failure at high revs drew in coolant water and shoved it back out into the hot manifold and the steam / exhaust gas combination burst the turbine as the wastegate could not release the excessive gas flow?? There is a connection I believe, there is no way the turbo and head gasket failed at the same moment by coincidence.

Good luck with the repairs
george
944t

 

[Frenchy]

Mike Moore has done the coolant mod on his Turbo, basically a hole drilled and tapped at the back of the head where an air pocket can occur a Festo right angled fitting fitted and a 6mm push in solid pipe back to the expansion tank again using a Festo fitting.

 

[scam75]

Hi George

Not sure about the corrosion Al mentions, don't think I paid much attention at that point, was too busy looking at that gasket!! I would be tempted to avoid skimming it myself unless absolutely necessary, but then that's not from experience, simply what I have read.

I was planning to use another Victor Reinz gasket, purely because I have one already purchased for a rainy day (which it now is!), and know it should be good for another 10 years by which time another head refresh would probably be in order anyway.

What are the benefits of the cometic gasket?

Lastly, your point about the sequence of events sounds plausible. Without doubt one failure triggered the other and judging by that gasket and the faultless way the turbo behaved previously my money is on the gasket going first. Pretty miserable luck taking the turbo with it!

Cheers

Stuart

 

[scam75]

ORIGINAL: Frenchy

Mike Moore has done the coolant mod on his Turbo, basically a hole drilled and tapped at the back of the head where an air pocket can occur a Festo right angled fitting fitted and a 6mm push in solid pipe back to the expansion tank again using a Festo fitting.

Steam vent kit seems a good idea.

Pete - How does it prevent gasket failure at number 4 cylinder?

Stuart

 

[PSH]

ORIGINAL: scam75



What are the benefits of the cometic gasket?



Stuart

It's a multi-layer steel construction that as far as a gasket is concerned is nye on bullet proof, I'm also told that it's reusable although I don't think that I would try this myself. However the one that I have taken off of my car still looks as good as the day that I put it on some years ago so perhaps it is reusable which is a shame as it's too small for my car now.

Pete

 

[George Elliott]

Stuart,
there are others with more scientific reasons for the cometic than me, I guess I was quite shocked at the corroded mess which I removed and vowed not to put another back in. The Cometic will not corode in the same way.

The cometic is likely to be stronger,- will stand more cylinder pressure due to its construction, however that cuts 2 ways because the CHG is also a fuse in some respects.

If you want 300bhp with high torque, the cometic is less likely to fail, but if you have a VicR turbo CHG to the new design (there are 2) (but the new one dates from the 90's) so you will have it - double check the part numbers with OPC for latest revision maybe? then I'd say you will be OK.

Others may shed a lot more light on your question than me.....

George
944t

 

[Frenchy]

Turbo S has a cometic, Scam apperently you can get an air pocket at the back of no 4 causing overheating.
I up at Mikes tomorrow to finally try and liberate the turbo from the car to sort out some snapped studs...........Grrrrr !
I must remember to take my camera and i will get some pics, a simple mod !