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Location:
Brisbane
Registered:
June 2003
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How long is my 7M going to last?
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Thu, 21 July 2005 10:56
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I'm curious as to know how long people tend to think my 7MGE will last before blowing another head gasket.
Heres the story:
I rebuilt it 18000km ago. New head, block surfaced, genuine HG, torqued down to 73ftlbs. I have since pulled it down again to discover no tension was lost.
it runs coolant and is regularly serviced...
Any ideas on whether or not the hg will go again, and how long if it will? Anyone hear anything from USA forums about repeat 7M problems?
thanks
Blake
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: How long is my 7M going to last?
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Thu, 21 July 2005 11:02
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If it's repaired properly and torqued down properly, there is no reason it should be any more prone to failure than any other engine provided you keep it healthy.
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Location:
Brisbane
Registered:
June 2003
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Location:
Edmonton, AB
Registered:
June 2005
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Re: How long is my 7M going to last?
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Thu, 21 July 2005 20:52
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I would agree... it's not liable to happen again.
Generally don't re-use old head bolts. Get new ones. I learned the hard way...
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Location:
Brisbane
Registered:
October 2004
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Re: How long is my 7M going to last?
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Thu, 21 July 2005 23:10
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When do you normally see the first blown HG on a 7MGE? My m8 has a grandpa-driven one with 178000km on it with good servicing and no probs...
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Location:
Brisbane
Registered:
May 2002
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Re: How long is my 7M going to last?
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Thu, 21 July 2005 23:41
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A 7M is a ticking bomb. Good maintenance will help a lot, but there are plenty of stories of well-maintained 7M's that still pop a gasket for no apparent reason.
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Location:
tas
Registered:
June 2002
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Re: How long is my 7M going to last?
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Fri, 22 July 2005 00:07
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Stock boost, 68ft-pounds headbolt tension, has proven very reliable for me over the past near 3 years i've had the 7m supra.
Have Run Toyota red coolant, always let it cool down after a drive and i really don't see it cuasing any problems. (recheck the headbolts every 6-12monts to see if they have come loose, so far have not budged)
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Location:
Adelaide, SA
Registered:
May 2002
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Re: How long is my 7M going to last?
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Fri, 22 July 2005 07:32
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Sean (MS-75) wrote a good post about the alloy used in 7m heads and the possibilty of it softening under heat (such as when the head is cooked the first time) leading to repeated failures of HG's. It's an interesting theory, be interesting to see if annealing the head would harden it and offer some improvement.
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Location:
Melbourne
Registered:
May 2002
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Re: How long is my 7M going to last?
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Fri, 22 July 2005 10:52
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| lumpy wrote on Fri, 22 July 2005 17:32 |
Sean (MS-75) wrote a good post about the alloy used in 7m heads and the possibilty of it softening under heat (such as when the head is cooked the first time) leading to repeated failures of HG's. It's an interesting theory, be interesting to see if annealing the head would harden it and offer some improvement.
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a mate of mine (IJ) has had several 7m heads tested all come back as grade 0 (soft as) on the exhaust side  he went and got a new casting from toyota!
anyway try here! http://www.deathclock.com/
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Location:
tas
Registered:
June 2002
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Re: How long is my 7M going to last?
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Fri, 22 July 2005 13:12
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Ah yes that is so fucking true about alloy heads once they've overheated!! the alloy becomes too soft. I have seen the effects of this just recently with a mercedes diesel! fan clipped the bottom radiator hose, lost all the coolant over heated big time! Head was bent like a banana, machine shop had a test tool for determining if the metal was too soft, and it was just under the threshold (no good), Regardless we put the head back on the motor (machined flat again) And once the engine got to operating temp and put under abit of load, the head would warp in no time ruining the new headgasket, and letting coolant and exuast move to nearby cylinders,
disaster! but we did not care too much as we had another engine.
So i'd be weary about using a head that's been a victim of a BHG (or more to the point overheated.)
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Location:
Brisbane
Registered:
June 2003
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Re: How long is my 7M going to last?
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Fri, 22 July 2005 13:17
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oh ok
well im glad the 7m in my ma70 has a ex mx83 head not done that many kms!
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Location:
Sydney
Registered:
June 2005
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Re: How long is my 7M going to last?
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Sat, 23 July 2005 00:14
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I personally think that if you use ARP Head Bolts (72 lb i think) and a metal headgasket the issue won't happen again.
Other things are to use Toyota Coolent (Red Stuff) and regular maintenance of the coolent system.
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Location:
Brisbane
Registered:
June 2003
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Re: How long is my 7M going to last?
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Sat, 23 July 2005 07:53
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i rebuilt the thing 18km ago with std bolts torqued down to 73ftlbs and they didnt loose tension after 10,000km.
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Location:
QLD
Registered:
October 2004
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 04:11
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i was told that apart of the problem is that the 7m's block are bored.
or something like that
pls correct me if im wrong
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Location:
Brisbane
Registered:
June 2003
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 06:19
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| MX73_drifter wrote on Sun, 24 July 2005 14:11 |
i was told that apart of the problem is that the 7m's block are bored.
or something like that
pls correct me if im wrong
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youd be referring to the very tight gaps between bores and water jackets.
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Location:
QLD
Registered:
October 2004
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 06:58
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| Quote: |
youd be referring to the very tight gaps between bores and water jackets.
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yeh thats what i was reffering to
my mate said something i thought was quite stupid (i didn't tell him he's dumb) but yea he said 5mge's and 7m's use the same block. he said the 7m is just a 5mge block bored to 3litres.
is this true
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Location:
Brisbane
Registered:
June 2003
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 07:17
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| MX73_drifter wrote on Sun, 24 July 2005 16:58 |
| Quote: |
youd be referring to the very tight gaps between bores and water jackets.
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yeh thats what i was reffering to
my mate said something i thought was quite stupid (i didn't tell him he's dumb) but yea he said 5mge's and 7m's use the same block. he said the 7m is just a 5mge block bored to 3litres.
is this true
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theres lots of "m" motors
m, 2m, 4m, 5m3, 5mge, 6mge, 7mge, 7mgte.
They are all based on the same block just the same as fords 4.0L motors are all based off the 250x flow block.
boring and stroking was the difference
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Location:
QLD
Registered:
October 2004
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 07:38
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thanx so they use the same block just bored out
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Location:
tas
Registered:
June 2002
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 09:35
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I doubt it, While the blocks would be simular they are not the same blocks simply bored out etc. Many changes and improvements would of taken place with every new generation of the M series. (and every other family of engine for that matter.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: How long is my 7M going to last?
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Sun, 24 July 2005 10:59
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Likewise the Ford blocks - there have been many changes since 1963, even though they do still use the same bore spacing today.
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: How long is my 7M going to last?
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Mon, 25 July 2005 07:06
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a 7M is a STROKED 5M, not a bored 5M
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