Head gasket let go at #4
Turbo Mini Forums

Howdy all,

No sooner have I got back on the road, I blow up! I went down to the Crewe's Missiles Rolling Road a week ago. All was going reasonably well, though the clutch started slipping but had managed 97bhp @ 3,500rpm.

Adjusted teh clutch and gave it another spin up on the rollers (you might just want to skip to the last 20 seconds)
http://www.youtube.com/watch?v=oWQSsfaFQM0

Rolled it out. Calmed down a bit. Popped it in gear and rolled it forward; no crunching/ grinding. Popped it out of gear and turned it over, chucking fuel out of the side (i.e. head gasket) at #4. Popped out the spark plug and checked it wasn't full of water and/or oil. All "OK". Wasn't overly hot at the time (though did then warm up after it came away from the rollers/ fan). AA turned up a few hours later and it even fired up, albeit on 3 cylinders.

After the video, you'd have thought it was something mechanical giving up in a big way. Without the video, everything points to the head gasket, albeit in a peculiar area.

Needless to say, the head came off at the weekend;





If you can see the piston it's got no carbon build up. #3 is similar, #1 & #2 have a "normal" amount of build up (pics are still on my camera unfortunately, otherwise I'd add them). The head's similar (in tems of 1 & 2 build up/ 3 & 4 cleanliness). Could that cleanliness be attributed to it running (briefly) with the head gasket blown out? Wouldn;t have through that'd clean #3 too. It's a standard alloy inlet manifold, not sure why the fuelling would be different across the engine?

Couple of suggestions that it might've been hot (understandable with it being #4 that let go) but I'm not running an insane engine, and it wasn't overly hot coming off the rollers. I still need to check the thermostat's working mind you.

I'm already considering myself bloody lucky that, after the initial blow-up, it does only seem to be the head gasket - the video suggested something far more severe. The question now remains whether it was a failure of the head gasket alone, or something else caused the gasket to blow. Any thoughts appreciated!

Cheers, Pottsy

Engine spec.:
1,293cc
35mm/29mm valves
Benross head
Hif 44
1.3 full roller rockers
Avonbar phase 2 cam
Knifed/ bladed crank
Accralite forged pistons
Hybrid T3 turbo (I'm still not sure what "hybrid" means?! Well, I know what [i]hybrid[/] means, just not sure how this T3 differs to a std T3?) at about 12psi
Ford RS Turbo intercooler
4 core rad & mechanical fan
Megajolt

Advert for 11 stud right there.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Ah - that's been said too! I'm going to have a word with a mate that runs an engineering firm...

Mine did the same not long ago. I've since knocked back a few degs of ignition timing.

What boost / ign adv are you using?

In the 13's at last!.. Just

It was at 12psi. Ignition's on Megajolt - came as it is, was runng fine so I wasn;t worried while it was finishing running in. Now I'm starting to run it in anger I planned to check the timing properly but struggling to get my laptop to work with the serial adaptor driver

Once rebuilt I'll be taking it straight back to AB Garage to have it set up on the RR - they're fully clued up on MJ though so I can start there and adjust it as needs be.

Are you still on a 9 stud head? http://www.turbominis.co.uk/photo/1777/

Im still on 9 studs with 150bhp

Id say u culda just had a dodgy gasket. Wat was it torqued too?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Quality video if I do say so myself I shit myself when it let go!

one day boost will be mine!

What's with the gasket in the top left of the final photo ???

It looks as if it has started to distort there too, as if it wasn't clamped properly at that point.

Any photos of the head (upside down) ???

Schrödinger's cat - so which one am I ???

I didn't build it, bought it with 600 miles on it. All the nuts were tight as I disassembled it but of course that doesn't necessarily mean it was properly torqued. Have head photos too, yes, but I can't get them loaded till tomorrow evening.

I'm "hoping" for dodgy gasket of course, the only other inkling that something might be amiss is the cleanliness of the pistons in 3 & 4. Maybe head pics will help?!

Hopefully it wasent torqued down.

Clean the faces pop a new gasket on and away u go.

Do u have a wideband?


Just watchd the vid, ouch!

Edited by eden7842 on 30th Apr, 2012.

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

pop goes the weezle

I'm still using 9 studs. 20odd psi.

Check ign timing on the MJ and check its accurate with a gun.

What CR is this?

In the 13's at last!.. Just

What would cause those random sparks to appear? Could hear a popping noise like a steam train but also something like a forign object trapped in the OS wheel area. Your trigger wheel hasnt slipped has it? Saying that you said it restarted so possible not.

sparks were probably burning head gasket as it made a bid for freedom and i assume the noise would be combustion/compression from the gap.

Fingers crossed for ya mate it was just a badly torqued up head or weakness in gasket

My small bore turbo project http://www.turbominis.co.uk/forums/index.php?p=vt&tid=473901

Mine had sparks too. Bits of molten gasket flying out.

In the 13's at last!.. Just

Nice! Hope you get it sorted.

The damage may have been done on the. Rolling road

fit a new gasket and torque the head to 55 ft pounds. With a calibrated wrench....

Have the car set up on the rolling road pronto! Check the Max advance on the megajolt and the fueling must never go lean under boost. Does the rolling road Guy understand! Turbo fueling and Max ignition advance under boost

Keep us posted

Edited by BENROSS on 1st May, 2012.

cant help but wonder if the 2 holes for 11 studs was not there would the head gasket have still gone?

nice nut rack

Edited by Brett on 1st May, 2012.

Yes i moved to the darkside

Instagram @jdm_brett

You been on those sites again Colin.....lmao

lol, no post is safe from finding a tenuous link to some boobs! (.Y.)

Cheers for the tips Benross. I'm calling at a mate's tomorrow (he owns an engineering firm) to have my torque wrench set on his analyser. Also have a word with him about machining the head/ block for 11 stud; does anyone have a pattern/ drawing of where the holes go? Closest thing I could find on a search was the depth of the hole in to the block at the thermostat end http://www.turbominis.co.uk/forums/index.php?p=vt&tid=378543 For the time being I'll put it back together as a 9 stud - properly torqued of course! See how things go - as has been said, people are coping well enough with 9 stud and decent amounts of power.

Following that I'll be straight back to the rolling road we used on the day - AB Garage near (ish) Chester. I think Gr4h4m uses (or has used) them. They're fully up to speed on MJ, and I'll check they know what they're doing with forced induction too, I'd be amazed if they weren't.

Back to the engine though, the couple of pics I said I'd grab of the bores and head so you can see the "cleanliness" of cylinders 3 & 4 compared to 1 & 2. Checked the inlet/exhaust gasket to see if there was a break/split causing a leak in to 3 & 4 but nothing untoward. I'll pay close attention to the fit up of the manifolds as I put it back together though, could be that the shared studs were only tightening on the exhaust manifold perhaps. We'll see...





Shall keep you posted!

Edited by Pottsy on 2nd May, 2012.

That is strange how much cleaner those two cylinders are.

My small bore turbo project http://www.turbominis.co.uk/forums/index.php?p=vt&tid=473901

Use a headgasket as a template, it will become clear where they need to be drilled.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Yep AB are well upto speed on MJ. Get Ade to check the the MJ is correct.

AB are very good. They have kept my evil sc setup from destroying my 40+ year old engine!

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!