[DeTomaso] Update - cause of death - blown engine

[Will Kooiman]

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.