MHG versus standard (7m-gte)

[Wildsupra]

ok now i know everyone is going to say you have to use a metal head gasket if your going to build a 7M properly.

HOWEVER i like to be different and do the opposite to the norm and try different theries.

Nows heres my theory
The problem with the 7M headgaskets blowing is caused by the bolt spacings/positions then made futher worse with incorrect torque settings.
The problem is that there is not enough pressure clamping down "between cylinders and water gallories"??? Causing the alloy head to slightly come away from the gasket or warp and then leak.

If this is the case then wouldnt it be worse on a MHG because there is no real sponge affect when tightening compared to composite gasket?? Surely the only way to ensure the seal would be to stop the head from lifting/warping at all and remaining completely sealed against the MHG at all times. How could i possibly achieve this for certain?

I blew 2 head gasket on my last 7M then on the 3rd one i used a special paste/goo (which ive never seen since) and that gasket NEVER blew. Even after CONSTANTLY driving it with the temp gauge of the dial. I drove it for half an hour with steam pissing out the bonnet just to get home. Turned out my radiator was blocked causing the over heating.

Should i go stocko gasket and try find this magical paste/goo shit again? Or can people assure me MHG will survive?? Trying to avoid Decking the block if possible.

Please no noobs guessing on this one, hopefully some technically minded peeps may be able to help here.

Cheers
Matty

[TheStitt]

if your not going to deck the block, id be looking for the goo again

[Wildsupra]

if i MHG then i will definatly deck the head and block. but depends wot people think about the whole idea.

Cheers
Matty

[Jasper]

I blew 2 head gasket on my last 7M then on the 3rd one i used a special paste/goo (which ive never seen since) and that gasket NEVER blew. Even after CONSTANTLY driving it with the temp gauge of the dial. I drove it for half an hour with steam pissing out the bonnet just to get home. Turned out my radiator was blocked causing the over heating.

Hi Matty,

Is the motor you are talking about the one I bought from you (years ago now) after you did the 1J conversion, which had that custom head gasket in it?

I have blown my share of 7Ms and figured out how to get them to last. Use a stock gasket tighten to 80ftlbs and cold retorque after 500kms of not thrashing it. The last one I did like this did not blow, even though it detonated enough to smash the rings and ringlands out of some of the pistons.

[Wildsupra]

wow funny how the world works, yeah man you got it

I just went to my grans place where i still got stuff stored, and i found my majical paste

looks like i'l be going stocko with my majic paste again

Which gasket did it have in it when you opened it?? was it that copper one?? They were awesome gaskets!!! however the guy who did that for me sold all his equipment and no longer makes em

When you re torque them, do you back them off first, like just crack em back then re torque to 80ftlbs or do you just try going from where it is?

Next question which you may know, is the 7m-ge gasket the same as the 7m-gte one? cos i have a new one sitting here but not sure if i should use it or not.

Cheers
Matty

[Jasper]

It had a non-stock gasket in it, which looked crap (sorry!) I don't think I still have it, but the gasket didn't was badly out of shape around most of the bores. IMHO a stock gasket is better, though you did say you had well and truely cooked it...

I slapped a new gasket into that old NA 7M, and thrashed it, running 18psi on my Turbo A gear. May have even gone up to 21psi at one stage. It made a shitload of power, but always used a bit of oil, and ended up spinning big ends because I was slack checking the level. I still have it in my 7M graveyard...

[amichie]

ok now i know everyone is going to say you have to use a metal head gasket if your going to build a 7M properly.

HOWEVER i like to be different and do the opposite to the norm and try different theries.

Nows heres my theory
The problem with the 7M headgaskets blowing is caused by the bolt spacings/positions then made futher worse with incorrect torque settings.
The problem is that there is not enough pressure clamping down "between cylinders and water gallories"??? Causing the alloy head to slightly come away from the gasket or warp and then leak.

If this is the case then wouldnt it be worse on a MHG because there is no real sponge affect when tightening compared to composite gasket?? Surely the only way to ensure the seal would be to stop the head from lifting/warping at all and remaining completely sealed against the MHG at all times. How could i possibly achieve this for certain?

I blew 2 head gasket on my last 7M then on the 3rd one i used a special paste/goo (which ive never seen since) and that gasket NEVER blew. Even after CONSTANTLY driving it with the temp gauge of the dial. I drove it for half an hour with steam pissing out the bonnet just to get home. Turned out my radiator was blocked causing the over heating.

Should i go stocko gasket and try find this magical paste/goo shit again? Or can people assure me MHG will survive?? Trying to avoid Decking the block if possible.

Please no noobs guessing on this one, hopefully some technically minded peeps may be able to help here.

Cheers
Matty

Was the goo called 3-BOND by any chance??

[Jasper]

And all 7M headgaskets are the same.

With the retorque, you just need to make sure that the bolt moves, so the dynamic coeffiecient of friction is at play rather than the static...

Set the torque wrench to tighten in the correct order. If the torque wrench clicks before the bolt turns, you will have to back it off a little (only a little!) and retorque if the bolt turns first up you won't need to back it off.

You should get at least 60 degrees more advancement of of each bolt, just torquing them down to the same as the were before the engine was run. Monotorque gaskets included!

[TheStitt]

Hi Matty,

Is the motor you are talking about the one I bought from you (years ago now) after you did the 1J conversion, which had that custom head gasket in it?

I have blown my share of 7Ms and figured out how to get them to last. Use a stock gasket tighten to 80ftlbs and cold retorque after 500kms of not thrashing it. The last one I did like this did not blow, even though it detonated enough to smash the rings and ringlands out of some of the pistons.

I did that and it didn't work, the block needed a deck, you should of seen how much material came off it when the metal h/g went on.

So i beleive there is a point when not even the factory head gasket will flex enough

Also if you still want to go factoy h/g get the 2nd gen one from toyota

I can't get my hands on the part number right now but will post if ppl want it

[Wildsupra]

I did that and it didn't work, the block needed a deck, you should of seen how much material came off it when the metal h/g went on.

So i beleive there is a point when not even the factory head gasket will flex enough

Also if you still want to go factoy h/g get the 2nd gen one from toyota

I can't get my hands on the part number right now but will post if ppl want it

there is more than 1 gasket??
did they come up with a better design or something??

A part number would be great if thats the case.
I do have a 7m-ge sitting here but yeah.....

I'l be measuring the block for flatness, if need be it will be decked anyway, but if it measures up pretty nice then it wont be now.

Matty

[Bored?]

Here's a lesson I learned the hard way:
Trying to save money by using a standard gasket will probably cost more time and money in the long run. The little bit extra time and money it costs to deck the block and head and buy a metal head gasket and ARP studs is a lot less than it will cost you to replace a standard gasket a second time if it fails again.

[Wildsupra]

i see what your saying, however im not sure i trust a mhg fully.

Spoken to a few people just before and i'm not sure i wanna go down that road.

Ive had success with this goo before. its good for 200degrees C and 300psi

Think i'l give it a go.

Cheers
Matty

[ma61turbo]

I've been running an HKS MHG for a number of years now and as far as I can tell, it's bulletproof. I've recently been having overheating issues which are now pretty much sorted and overheated the car, or had it running way hotter than it should have, on multiple occasions. The MHG just takes everything in its stride. First time I cooked my 7m about a year after it was put into the car the HG went. It was torqued up higher than factory spec(can't remember what I used now), but just couldn't cope.

As long as the MHG is put in the way it's supposed to be it will be far more reliable than a standard gasket + goo. I would expect that anyone having issues with a MHG hasn't had it put in properly.

[EldarO]

there is more than 1 gasket??
did they come up with a better design or something??

A part number would be great if thats the case.
I do have a 7m-ge sitting here but yeah.....

I'l be measuring the block for flatness, if need be it will be decked anyway, but if it measures up pretty nice then it wont be now.

Matty

toyota have revised the gaskets twice now (to my knowledge), the first was obviously released from factory, the second, from memory was released mid-late nineties, and the latest one, the second revision, around january 2006.

ive got my old gasket that i took out, and replaced with a 2nd revision, if you want to compare (even though its blown and shit) minor differences at best, but theres more metal on the 2nd revision, looks pretty beefy.

Eldar.O.

[ma61turbo]

Interesting to hear they made a second revision, I was only aware of the one.