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Location:
Newcastle
Registered:
September 2003
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7mgte keep blowing HG, any help???
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Sat, 07 May 2005 06:32
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hi b & g,
this is a third headgasket ( stock) retorqed properly to 78lbs that`s been blown running no more than 16psi.
Now this time i`m going for metal one, so i need to know which is the best one.
Questions:
1. how thick MHG i should get
2. what torque should apply
3. been told that mhg want fix problem as 7mgte are weak between 5-6 cyl(gap is too small) and it will keep blowing under high boost!
Cheers
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Location:
Thornleigh sydney
Registered:
January 2005
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Re: 7mgte keep blowing HG, any help???
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Sat, 07 May 2005 06:40
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to fit a MHG...
u need to have the head and block skimmed....the standard finish on the head and block is not smooth enought to completley seal a MHG,
until u do this...run less boost!
blake
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Sat, 07 May 2005 15:42
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it's a super powerful, top of the class engine that has been running at its max, or it's an improper install - preparation and/or technique. how long between the 3 BHG's??
the surface of the block, head, bolt head & washer, and the condition of the threads on the block and bolts.
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retorqed properly to 78lbs
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what does this mean - step by step????
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Location:
Lost in the K hole
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Sat, 07 May 2005 17:03
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a) theres nothing special about the #5 -#6 cyl wall gap... that excuse is pretty lame. bore spacing is equal, and though minimal, should be adequate for 99% of build ups
b) a MHG will fix the problem if:
- the head and block are surfaced PROPERLY
- theres not too much corrosion in the block/head water galleries
- you use Hylomar on the MHG
c) NEW stock head bolts should be torqued to 72ft/lbs only, with proper lube, not oil, not dry, in recently threaded block threads
d) if going ARP fasteners, follow thier guidlines, dont guess
e) thickness should be exactly the same as the HG coming out (1.2mm ??)
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Location:
melb
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Sun, 08 May 2005 11:13
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ed u said 72 ftlbs torque.....vs 78 ftlbs - thats not a huge difference, I doubt half the torque wrenches out there would still be reading that accurately.
is the 7m that sensitive to correct torque?
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Location:
Lost in the K hole
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Sun, 08 May 2005 16:09
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| chrisss wrote on Sun, 08 May 2005 21:13 |
is the 7m that sensitive to correct torque?
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no, but the bolts might be 
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Location:
Newcastle
Registered:
September 2003
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Re: 7mgte keep blowing HG, any help???
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Mon, 09 May 2005 07:43
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Thanx guys for advice.
By the way i have standard studs and head has been shaved.
Not sure about block, cos i`ve bought this engine not long ago.
Engine by itself had 85000kms and will check block for detorations.
any other advice ( a heard some people apply between 90-100 Nm)???
How much is this in lbs?
Any other advices?
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Location:
Melbourne
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Mon, 09 May 2005 10:04
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| Mr.TRIM wrote on Mon, 09 May 2005 17:43 |
Thanx guys for advice.
By the way i have standard studs
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Standard studs you meen bolts?
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Location:
Redbank Plains,near Ipswi...
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Mon, 09 May 2005 12:05
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you may have a soft head. this is common on overheated engines. any engine shop can test it. surface finish is critical as several people have said. your chance of getting a good enough block finish when its sitting in the engine bay, is very small, bordering on stuff-all. I have never seen any metal gasket maker recommend a spray like hylomar. the gaskets have a teflon coating from factory. the 7m does not have studs, it has bolts. toss them away and use new ones torqued to correct value, nothing more.
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Location:
On your mum!
Registered:
May 2002
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Re: 7mgte keep blowing HG, any help???
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Mon, 09 May 2005 12:19
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| Quote: |
any other advice ( a heard some people apply between 90-100 Nm)???
How much is this in lbs?
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66.4 to 73.8 ft/lbs.
try typing "conversion table" into google and you will come up with many sites that can convert just about anything that you can think of.
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