Fhooom.....
Turbo Mini Forums

Cylinder Head Gasket let go at the weekend on the M62 back from York....
Seems that running at speed in a power on/off situation where you are really pulling up hills can get things a little hot....(running a fairly low 10 psi top boost)

All went very gently with a slight missfire at full power, followed by a temperature increase (it runs flat happy at normal all day normally) so I pulled over and cooled it off. Pity really, the M3 dispatched earlier had such a pretty picture on his face...

Having the lump out to replace the std turbo gasket with something a bit tougher (and to check that I didnt cock up putting it in), so I have an important question or two:

1. Recommended Head gaskets and tricks for stopping blowbys

2. How do I fit undercrown cooling? (parts and places and drilling)?

3. Anything else to do when the block is out (besides do the diff and check the block, head, valves and rockers + the main bearings + clutch release bearing)

4. Best ways to get mayonaise off everything in sight.......

Edited by NeXTGen on 9th Mar, 2005.

Most people use the Payen BK 450 head gasket which is the proper Turbo item. You should have no trouble with this, especially running 10psi, they're an excellent gasket, as many have proved.
To help gasket reliability get the head/block surface ground to ensure they're completely flat. Also use some quality head studs/nuts and make sure they are torqued down correctly.

There a bit of info on undercrown jets here - or ask TurboDave, i think he was the first to use the Zetec jets.

If you're doing a full strip down then go through everything, and do a proper rebuild while it's out. Check crank end float, journals for size {regrind if needed}, fit new main & big end shells, new oil pump, check all gearbox tolerances, fit new bearings etc etc
It depends what condition things are in, what you can afford and how far you want to go ?

Petrol or thinners will remove most crap/grime.

Phil.

Edited by Turbo Phil on 10th Mar, 2005.

WWW.TURBO-MINI.COM

would also like to add phil

that nextTgen has been dogged before with head gasket problems for ages!

i would like to add is he running standard compression ratio
of the metro on 10psi of boost?

with NO intercooler its just on the threashold of detonation! and can easily bubble over to the dark side with poor fuel

(ie) 95 Ron unleaded

the missing he experienced on the motorway could well be detonation and he has not realised this!
once detonation starts its like a chain reaction and is self Perpetuating and takes only seconds to wipe a head gasket out.

i found this out twice over the years on my motor.
so a good indication is, if the gaskets gone between 2/3 bores then the above would most likley apply.

suggest intercooler fitment and de beaking of the combustion chamber,

this on a 1275 should get th C/R down to around 8:5:1
and prevent the above

i have made an assumption that its a 1275 standard metro engine with no intercooler:

there is NO head gasket or any meterial in the world would withstand detonation.

the job is to fix the problem at root cause.

worth thinking about!

Edited by BENROSS on 10th Mar, 2005.

unsercrown cooling jet pics info on www.miniwilliams.co.uk

Metro turbo weekend driver,Mini turbo in the making again!

heh- good point benross, but heres the wrap:
Previous probs were thought to be the head gaskett, turned out my oil was crap and too cold, and a few minor things!

Its been running like a rocket for about 5 months now!

Engine spec:
Avonbar Turbo head, sodium valves etc (yes, it is stamped with a T, and the chambers are mahoosive).
Omega 15cc turbo special pistons +20 thou
C/R 7.8:1 (done by biruette and possibly not spot on).
MED Wedged nitrited crossdrilled crank.
etc etc etc

Think i need to examine the block deck very closely...

TRUE

intercooled????????????????

make it happen buddy

Let you know when I've had the lump out of the mini - I've got to get the V12 out of the jag (bodywork scrap) before end of month so its going to be on hold a bit...

if i remember right

some of the EARLY Turbo heads were prone to cracking
as the face of the head to the water galleries were a lot thinner

leyland beefed them up later on

dont know which year though

i wonder if some one knows ?

hope you have not got one of these

What headgasket have i got? I used the one avonbar sent me, its like a black rubbery silicone thing!!!

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

silicone head gasket.....

Sounds like the BK 450 to me.

Phil.

WWW.TURBO-MINI.COM

last time the gasket was blown!

was ther any visable signes of it BLOWN????

if not and its gone this time

its a safe bet the heads cracked!

let us know just a thought! TGEN

Got it, had the head off, and its DEFINATELY the gasket. Head and block are pristine in EVERY way

Cylinder 1, (next to radiator), fire ring has gone next to the waterway between 1 and 2 towards the back of the block. I would post photos I f i knew how!

Gasket is badged:LVB 100830 and was from Avonbar.
I have an AF470 and an AF460 (copper) as spares in the garage, but whats the difference between this 470 and the AF450? - cant just be looks alone?

Dave - any experience?

If your sure both the head and block surface are true, the clean up the head and inspect for any cracks. I use a 500W lamp over head, and carefully examine the head.

If this is OK, then how about your head studs and nuts, If their older than your gran then perhaps they don't wanna hold the torque anymore.

One final thing to check is your torque wrench, if its been abused at some time then perhaps its not reading correctly.

Best of luck with it :)

Had it on an engineering bench and went over it with a dial gauge on an overhead mount.... Also straightedge and feelers. Flat as a pancake. same with the block!

The head studs are brand new minispares race grade ones, but i checked them over for marks anyway. The block is countersunk, so i dont suspect that. The torque wrench.... now thats a funny one, because it a "Halfords Professional" (i was in a hurry) and I had to take one back because it stopped working.

It does look rather like the fire ring might have been pinched to an edge just below the stud, and this would then fail catastropically.

Buying a decent "recommended" wrench today....
Ed

Well my "bk 450" has taken 9 psi for a long time now and its happy :) definately using them in future

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

Got it all back together, with the proper turbo part, running 10 psi, lets see...!
I'd put money on the torquw wrench as the old gaskett was flat as a pancake on one side but not on the other..

NEXTGEN:

a lot of people make the MISTAKE NOT re torqueing the head down correctley

after it has been brought up to normal operating temp for the first time

say after 10 to 15 mins running,

this causes a lot of head gasket problems with cast heads

i hope you have not fallen in this trap! buddy

Oh!!! and dont forget to do the valve clearences after

ben, have i gotta re torque my head up then? i thought i did but couldnt find anything in the haynes, its 50ftlbs on turbo's yeah?? thats what i did mine to,and 24 on the rockers

I heard this wasnt the case Ben....

Some people say do, some say dont...

iain, dan

with the experience i have had trust me buddy

SADLY this is where most people go wrong!

retorque the head and stuff what the others says

suppose i will now get ripped to bits but its
AS SIMPLE AS THAT!

50 foot pounds to 12 psi
and on a highley boosted motor say 16+ psi

55 foot pounds

OH! in the right sequence............. of course

remember "ENGINE HOT NORMAL OPERATING TEMP"

dan re....check the valve clearences after

i know its a pain in the thruster but............

do it right and THATS IT!

Thats what its all about having FUN

building, modding, repairing, running and doing it right!

Edited by BENROSS on 18th Mar, 2005.

cheers buddy

i do this anyway ben as its what ive been taught. saying that ive done some without re-torquing and they've been fine.

Have a good quality torque wrench though that i can get calibrated at work so that does help a great deal.

I've always retorqued the head after heating up and cooling it off a couple of times. It's always worked for me.

What I don't understand is the advice on torquing up the head nuts more when more boost is being used.

If a head gasket is supposed to be compressed by X%, becase this is where it works the best and is designed for, then compressing it even more will ruin it.

Why not torque it up more on a lower boosted engine as well?? This surely is better after the advice given....