[DeTomaso] Update - cause of death - blown engine

Tomas Gunnarsson guson at home.se
Mon Jan 11 08:19:19 EST 2010 

I understand that Göran. Will mentions a torque that is 50% higher than stock and assuming that the bolt size is unchanged this alarms me. If the bolt quality was upgraded from 8.8 to 12.9 it would make sense but I hope that the stock bolts are not made from "coathanger steel". Let's await Will's response.

Tomas

----- Original Message ----- 
From: <hemipanter at hemipanter.se>
To: "Tomas Gunnarsson" <guson at home.se>
Cc: "'De Tomaso List'" <detomaso at realbig.com>
Sent: Monday, January 11, 2010 1:28 PM
Subject: Re: [DeTomaso] Update - cause of death - blown engine


> There are rodbolt Tq that are quite high, my own is 80 fp for example.
> Many aluminium rods has higher Tq recomendations, but also rod bolts
> designed for it.
> Goran
> 
>> Will,
>>
>> Did you torque the bolts until you had whatever strech you wanted or did
>> you torque to your decided figure, then measure the strech just for
>> verification (without adjusting torque)? I'm also wondering if you simply
>> over-torqued the bolts so that they went into plastic deformation. I just
>> checked my Tom Monroe rebuild book and it says 40-45 ftlbs for std engines
>> and 45-50 for Boss and HO. Where does the 67 ftlbs come from?
>>
>> Tomas
>>
>> ----- Original Message -----
>> From: "Will Kooiman" <wkooiman at earthlink.net>
>> To: "'De Tomaso List'" <detomaso at realbig.com>
>> Sent: Monday, January 11, 2010 5:40 AM
>> Subject: Re: [DeTomaso] Update - cause of death - blown engine
>>
>>
>>> The bummer is I know I torqued the rods.  I even used a rod stretch
>>> gauge to
>>> measure the stretch - just for grins.  I can't explain, however, why it
>>> only
>>> took 40-50 lb/ft to loosen the bolts.
>>>
>>> Also - I'm definitely not a professional, but I've put together several
>>> engines - maybe 10 or 15.  This is the first time anything like this has
>>> happened.
>>>
>>> I'm going to put the next one together too, but this time I'm going to
>>> make
>>> damn sure the torque is correct on all of the critical bolts.
>>>
>>> I'm also going to buy a better torque wrench - probably snap-on.
>>>
>>> -----Original Message-----
>>> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com]
>>> On
>>> Behalf Of Asa Jay Laughton
>>> Sent: Sunday, January 10, 2010 9:23 PM
>>> To: 'De Tomaso List'
>>> Subject: Re: [DeTomaso] Update - cause of death - blown engine
>>>
>>> wow
>>>
>>>
>>>
>>>
>>> Asa Jay
>>>
>>> Asa Jay Laughton, MSgt, USAFR, Retired
>>>
>>> & Shelley Marie
>>> Spokane, WA
>>>
>>> 1971 Mach I Mustang  [ASA JAY]
>>> 1973 Pantera L 5533  [ASASCAT]
>>>
>>> ******************************
>>> http://www.asajay.com
>>> http://www.teampanteraracing.com
>>>
>>>
>>>
>>>
>>> Will Kooiman wrote:
>>>> I pulled my engine today.  I haven't taken it completely apart, but I
>>> pulled
>>>> the pan.
>>>>
>>>>
>>>>
>>>> The official cause of death is:      The #4 rod cap came off.  It
>>>> appears
>>>> that the rod bolts were not properly torqued.
>>>>
>>>>
>>>>
>>>> Here's what I found inside the pan:
>>>>
>>>>
>>>>
>>>> The #4 rod cap was not attached to the crank.  A rod bolt was in the
>>>> pan.
>>>> I'm sure the other rod bolt is in the pan somewhere, but I haven't
>>>> found
>>> it
>>>> (haven't looked through the sludge).
>>>>
>>>>
>>>>
>>>> The #4 rod cap was in one piece in the pan.  It was flattened out.
>>>>
>>>>
>>>>
>>>> I found the #4 rod bearing.  It is still in a half circle.  I haven't
>>>> examined it very much.  It was getting dark, and I had to do chores.
>>>>
>>>>
>>>>
>>>> The #8 rod is broken in half.  The cap is still on the crank.  I
>>> previously
>>>> thought it was the #4 rod that was broken.  I couldn't tell for sure
>>> because
>>>> I was looking down the #4 bore -- which had the #4 piston lodged
>>>> sideways
>>> in
>>>> it.
>>>>
>>>>
>>>>
>>>> The #8 piston has the pin broken out of the piston.  At first I thought
>>> the
>>>> piston came apart to cause the destruction, but it looks like the crank
>>>> counterweights cut it off after the rod broke and the piston dropped
>>>> into
>>>> the crank.  The counterweights have some debris on the leading edge to
>>>> support this theory.
>>>>
>>>>
>>>>
>>>> The #4 main cap (between #3/7 and #4/8) is cracked at the base.
>>>>
>>>>
>>>>
>>>> The #4 cylinder is cracked.  I think this happened when the #4 piston
>>>> went
>>>> sideways.  I don't know about #8.  I haven't removed the driver's
>>>> cylinder
>>>> head.
>>>>
>>>>
>>>>
>>>> The #4 rod journal is gouged slightly on one side.  It looks like it
>>>> got
>>> hit
>>>> after the rod came off.  If the bearing had spun, it would have cut
>>> grooves
>>>> along the entire circumference.  I think the crank is going to be
>>> reusable.
>>>>
>>>>
>>>>
>>>> I just bought a new torque wrench -- in case my old wrench was
>>>> inaccurate.
>>> I
>>>> checked the #8 rod.  It was only torqued to 40 lb/ft.  It is supposed
>>>> to
>>> be
>>>> torqued to 67.  I checked a few of the other rods, and they were in the
>>>> 40-50 range too.
>>>>
>>>>
>>>>
>>>> I checked a couple of the inner mains (ARP studs).  They were around
>>>> 120
>>>> lb/ft.
>>>>
>>>>
>>>>
>>>> I don't think the torque wrench is bad, otherwise the mains would be
>>>> off
>>>> too.  The inner head bolts were correct too.  The outer head bolts have
>>>> always lost torque due to the excessive heat compressing the aluminum.
>>>>
>>>>
>>>>
>>>> I'm guessing that either
>>>>
>>>>
>>>>
>>>> a)       I set the torque wrench incorrectly when I did the rods or
>>>>
>>>> b)       I didn't use the proper procedure to torque the rods or
>>>>
>>>> c)       Both.
>>>>
>>>>
>>>>
>>>> I did not torque it, loosen it, torque it, loosen it, torque it.  I
>>>> used
>>> the
>>>> grey moly grease that came with the rods on the threads and under the
>>>> bolt
>>>> heads.  I snugged them up with a ratchet, and then I torqued them to
>>>> about
>>>> 35 (don't remember -- I usually go about ½ of the final torque), and
>>>> then
>>> I
>>>> torqued them to 67.  I measured the bolt length before and after they
>>>> were
>>>> torqued.  I didn't write it down, but I'm pretty sure they stretched
>>> 0.004".
>>>>
>>>>
>>>>
>>>> The block is probably reusable with a sleeve, a new #4 main, and a line
>>>> bore.  It will probably cost more than it's worth, though. The crank
>>>> might
>>>> be reusable.  The #4 and #8 pistons are obviously trash as are the #4
>>>> and
>>> #8
>>>> rods.  Everything else looks like it's in good shape.
>>>>
>>>>
>>>>
>>>> I'll do pictures eventually.  It's going to be at least 2 weeks,
>>>> though.
>>> I
>>>> have a lot of non-car-stuff going on -- going out of town next weekend.
>>>>
>>>>
>>>>
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