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Blown engine details

To: buick-rover-v8@autox.team.net, mgb-v8@autox.team.net
Subject: Blown engine details
From: "" <james_nazarian@excite.com>
Date: Sun, 15 Dec 2002 17:24:11 -0500 (EST)
Reply-to: "" <james_nazarian@excite.com>
Sender: owner-mgb-v8@autox.team.net
 Now that I am rested, here are the details of my engine failure.  
Unfortunately, my hopes of a recoverable situation were thuroughly dashed.  The 
engine was balanced as evidenced from the markings of 1-4 L and R on each rod 
and piston.  I think that the rods were originally of an H beam design with a 
ridge or bar around the entire beam and small end; my rods were H beam in shape 
and clearly showed that the small ends and the beam had been ground, what leads 
me to beleive that there was another ridge around them was that about 3/4 inch 
of this bar was left on each side of the rods where the big ends tapered into 
the beam.  It was the #3 rod that broke, the small end was still in the piston, 
and I know this to be the source of the failure because one peice of the H that 
was left exposed by the failure was the same darkened color as the whole inside 
of the block (almost black).  So I know that the rod was cracked for a very 
long time, if not from the factory.  The engine had 1100 miles on it since the 
rebuild from the PO.  My feeling is that when they removed the extra ridge from 
around the rod, in an effort to lighten them, the remaining rod was no longer 
strong enough to hold the crack together. So the rod snapped at the top of its 
stroke, because there was no indication of impact damage to the bottom of the 
piston which was sitting at the top of the bore.  About 1/3 of the skirt was 
missing from the #3 piston, including half of the wrist pin bearing surface on 
one side.  Either the rod broke and the action caused the fracture of the 
piston, or the piston broke, cocked in the bore and caused the rod to break.  I 
think it was the first one because there was no damage to the #3 sleeve. The 
rod removed a chunk of the block, on the passenger side, under the engine mount 
of about 25 square inches, gutted the pan on that side,crushed and tore the 
motor mount (stock olds mount), and opened up the galley from pickup to oil 
pump and broke open the water jacket; on the other side it punched straight 
through the block about 5 times and punced straight through the pan about 8 
times. The #3 rod swung through the #4 sleeve about two inches up, and cracked 
and holed the piston on both sides, in line with the damage to the sleeve.  It 
also hit the cam;  the cam broke between the #2 intake lobe and the 2nd 
bearing, this first section consisting of the front of the cam and the first 4 
lobes walked out, the timing chain started to eat the cam gear and all four 
spokes of the cam gear cracked.  The second bearing and the next two lobes (#3 
cyl) broke and were forced up in the journal about 40 degrees, the #3 exh lobe 
was the only one showing significant damage, was in line with the broken rod, 
and was forced up tells me that this was the point of impact.  The #3 rod was 
curved about 30 deg presumably from this impact. The next two lobes, for #4 
cyl, were in the pan, however the big end cap of the #4 rod showd significant 
signs of damage from impacting this.  It bent the bolt hole around one of the 
rod bolts and I had to hammer the rod apart from this damage, the crank shows a 
few small dings from the same impact, the remainder of the cam, from the 3rd 
bearing back (4cyls worth) was intact.  What I think happened was that the #3 
rod hit the cam made the rear most break (at 3rd bearing) which left a bent cam 
connected to the timing gear.  The bent, spinning cam then impacted the #4 rod 
cap causing the other fractures, forced the cam to angle up,  cracked the 
timing gear, and broke out the lifter guides for the #3 int and exh and the #4 
exh. One of those pushrods was severely bent, but I found them all in the pan 
so I don't know which one.  The #4 exh rocker broke where the valve arm joins 
the rockershaft bearing surface. I think that when all of this happened the #7 
intake was open and the valve colided with the piston, because this was the 
worst bent rod of all, I think this is what caused the back halft of the cam to 
stop turning.  I saw no visual indications that any of the pistons had collided 
with any of the valves, everything looked decent and without telling scratches 
or dents. One of the lifters from the #3/4 area was shattered and about 1/3 of 
them were chipped around thier cam surface.  Most of the valve train and block  
parts were found in the oil pan, along with the remains of the coolant and the 
oil.  I also found some magnetic parts that were probably from the #3 rod, 
since about 1/2 inch of it is unacounted for. The bearings from #3/4 big ends 
look perfect as does the rest of the bottom end except #3 and #4's parts. That 
leaves me in need of an entire engine as even the heads are suspect if enough 
force made it up there to break a rocker arm.  The valley pan gasket was 
severly dented up around #3/4 but the intake showed no signs of being hit. 
Basically I think my only useable parts are the flywheel, pulleys, front cover, 
intake, exhaust, and valve covers.  Oh well. AND THE MORAL OF THE STORY IS.... 
you really ought to magniflux old parts, especially if you are going to try and 
lighten a stock part.  It looks like the rod was cracked from new but it was 
probably the loss of so much strengthening material that caused it to let go.  
Unfortunately the motor was built about a dozen years ago, buy a guy that was 
into these motors in Medina, OH.  My dad traded him an old Oliver tractor for 
the motor and trans, so no chance of reimbursement or anything there. Whew!!! I 
think that about covers it.James Nazarian71 B tourer71 BGTV8 with ventilated 
block and 4 piece cam85 Dodge Ram with bad gas mileage

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