7MGTE - Should I get the block decked?

[doobs]

Ey all,

As I am a victim of the grand ole 7M BHG, I have decided to replace my head gasket (amongst other things), with a metal one. I have just got the head back from being surfaced and checked out, and its all sweet and smooth.

Now for the block, I asked at the head shop whether I should get the block decked, he said its up too me, but some fine emery cloth on a flat file should do the trick... I really don’t want to pull the guts out of the block, as that would mean I'm gonna spend a shit load of money on it... but I will, if its warranted.

Surely many other victims have been down this road, your opinions/thoughts would help me greatly. Also he took 8 thou off the head, so what size metal gasket should I be looking for?

Thanx fellas, any help is greatly appreciated.

[TA-022]

visually inspect block. if looks fine then light sand back.

for the 8 thou remark ... 8 thou off means add 8 thou at least to std head gasket thickness.

make sure to use hylomar or similar on gasket when fitting head... top and bottom of gasket.

note: make sure head bolts are oiiled on re-assembly. (newies off course... re-use is a big no-no)

[hamgatan]

8 thou off... a 1.2mm job should do the trick fine..

[doobs]

Thanx fellas, I will post up some pics of the block when I clean it up. +1 rep each

[RyleyMA61]

as far as i have read, if you are going to get a metal headgasket, you want the block to be very very flat and smooth, i've been told a mirror finish is required...

also get aftermarket head bolts/studs, torqued right with proper 'wearing in' periods between retorques... i can give you more details if you need it.,

i had a hks metal gasket and it blew as well.... due to not replacing head bolts, not proper wearing in procedure and a bit of dust/dirt between gasket and head.

my current stock gasket w/ aftermarket bolts etc has lasted through all conditions for well over a year now...

good luck mate!

[ed]

what headgasket ate you using? if laminated steel - id be machining the block

[ed]

bah, too slow

[EldarO]

I just had BHG, i had the head reco'd with a standard gasket put back in and torqued up to around 75 ft/lbs.

the car went back in after 1000k's to have everything checked over, the studs retorqueds, and some other shit that cost me money.

Apparantly with the MHG you need everything dead smooth, dead flat, in order to get the proper seal, because the head gasket wont "squish" like a standard one would, so you need it flat.

Id say check out the cost, if its not too much, get it done for peice of mind.

i have to say, no relevance to your question, but my 7M, with 111k or so on it, after the head reco, and new engine mounts, is simply the smoothest running engine ive ever seen, ive had it next to a 2002 porsche boxter, and the boxter was a fair bit more noisy, and i dont know whether it was a bit of a wild cam or something, but it was *just* a bit more rockey-rolly at idle.

i was suprised, and it whacked a smile on my face

Eldar.O.

[JetspeedCamry]

Sorry for the off topic, but whats the benefit of a MHG?

[mullett]

Metal head gasket can handle more pressure, but really I wouldn't bother unless you need to. To inspect the block, get a good straight edge and feeler gauges. Put the straight edge at an angle across the block, and see the thickest feeler you can run under it, the move the straight edge around until you've checked all the basic surfaces. Don't use emery on a file, get a big oilstone and use that lightly over the whole surface. Some abrasion on the surface actually helps the gasket bite in and seal better, so don't be afraid.

RM

Edit: Oh, and make sure that your straight edge is longer than the block, and of good quality

[1200det]

Almost a mirror finish is how you want it , both surfaces

[30psi 4agte]

RYLEY: What do you mean by proper wearing in proceedure ? I also use a HKS gasket ( 2mm) and have blown one ( loong story but it was totally torched along with the head )
I usually re-torque/ keep an eye on the head gasket due to the boost i run. However i have only done this because i am a fussy Bast@rd not cause the gasket instructions told me to! I have questioned many people about re-torquing the gasket and no one seems to no what the go is! ( even the place i get the gaskets from)
Was there something that came with your gasket telling you to re-torque at diff stages i.e every 1000 km or something like that?

DOOBS
Get them pics up so we can see what we are dealing with!!
Its is best/ideal to have the block decked BUT you dont always have too depending on how bad the surface is!

[doobs]

Will get them pics up after work tonight.

Cheers fellas

[Cressida91GLX]

If MHG will sit properly it can last a long time. But for that you have to have mirror clean finish on head and block. But seeing the history of 7M, I won't be bothered spending too much money if you are not going for a proper re-build of the engine. While it is out also make sure that you get your radiator cleaned, and place a new water pump + thermostat. Done it properly will cost too much though but will be worth the money spent.

[RyleyMA61]

mr 4agte-

my 'wearing in' prodecure was simply decided by my mechanic- he'd built a 500hp 7mgte so i figured i was in safe hands.

When i first got the headgasket done, I was to only drive 500kms, with no boost at all. Then off for a retorque. Then another 500kms with only little squirts of boost, and a then another retorque. Then I was good to go- Once it's tightened now it should be right for a long time. Whether this procedure would change for a metal headgasket I'm not sure, but it seemed to work very well. It's not absolutely necessary, but I figure with the 7M it's nice to take proper precautions