Sequence of the water pump shaft failure

[Bob Dunahugh]

Was just about to get to the crest of a 1/4 mile climb in very high head w=
inds. Fan clutch had been engaged for about 5 miles. Speed was down to aro=
und 40 MPH in 3rd gear. Head winds at 45 MPH. RPM's were way down. The tran=
s shifted to second. Not a hard shift. About 5 seconds later. A loud bang. =
Pulled to the shoulder on I-40. Opened the floor hatch to find that the fan=
clutch was laying on the very broken fan shroud. I had just installed the =
water pump. Just before we started the trip as a preventative maintenance =
measure. Duralast from Auto Zone. Their best one. 1080 miles on it. There =
was an off ramp about a mile away. All down hill. Drove to the off ramp. Fo=
und an Auto Zone about 35 miles away that could have a water pump by 3:30=
. It was 12:30. Richard. A GMCer saw us, and stopped. He was on his way to =
Hal StClair's in Albuquerque NM. 70 Miles away. It's a one man job. Pulled=
the pump. Picked up the replacement pump. Installed it at the off ramp. Ha=
d the original GM fan with clutch with me. Hal called to see if I needed h=
elp. It was dark. So I told him I'd call in the AM. In the morning. We got =
on the road. Due to pulley damage. We just got to the next off ramp 8 miles=
away. Hal called. We needed the crank, and water pump pulleys that Hal had=
. And more new belts. So Hal, and his wife drove the 70 miles out to bring =
us some pulleys, and belts. He helped get the parts on. And off to his hous=
e. Then he wouldn't let me pay him. Fed us, and we staid for the night. Nex=
t morning off to Tucson. No issues to Tucson. Picked up a 403 fan shroud a=
t the rally. Jim K at Applied will have a proper roller bearing water pump =
here by Tuesday. Tom Pryor will have the electrical plug here Tuesday. Ins=
tall the Benz fan, and another water pump Wednesday. The Benz fan didn't ca=
use this. Me not getting the proper water pump from Jim K at Applied GMC to=
start with DID. We can't thank the StClair's enough. Bob, and Linda Duna=
hugh

 

[Jim Hupy]

Many years ago when the Toyota Celica sports car first was introduced, a
friend had one and drove the snot out of it. Eventually, he had a steering
shaft on the drivers side of the car fail. As he was not too far from my
house, they towed the car to my garage and we proceeded to take the left
side apart and recovered the broken shaft. It clearly had a piece of ball
bearing included in the steel shaft which was about the diameter of my
thumb. 20 mm or so. When he took the part back to Toyota to get a new one,
the parts guy called the service writer over, and soon there were several
technicians there too looking at the broken shaft. The dealership kept the
broken shaft, and sent it up the chain. I heard nothing further about the
broken shaft, but I have always remembered that incident. It made me really
curious about failures on shafts. That shaft was fully machined, not forged
like most American stuff is. I have seen alternator shafts, power steering
pump shafts, A/C compressor clutch shafts, water pump shafts broken through
the years, and often times they break on an intersection of a step up or
step down. Many of them are not radiused where the transition happens. I
suspect that the sharp transitions are a stress point, and the radius
spreads out that stress. Sounds like that is what you had. Poorly
manufactured or poor heat treatment, or inclusions of foreign material in
the steels. Many are made from reclaimed scrap these days. Only x-rays by
experts will determine exact causes. Install the roller bearing pump, and
find something else to worry about on the way home. What I would do. Sorry
to have missed seeing all of you at the Tuscon Rally.
Jim Hupy
Salem, Or
78 GMC Royale 403

> Was just about to get to the crest of a 1/4 mile climb in very high head
> winds. Fan clutch had been engaged for about 5 miles. Speed was down to
> around 40 MPH in 3rd gear. Head winds at 45 MPH. RPM's were way down. The
> trans shifted to second. Not a hard shift. About 5 seconds later. A loud
> bang. Pulled to the shoulder on I-40. Opened the floor hatch to find that
> the fan clutch was laying on the very broken fan shroud. I had just
> installed the water pump. Just before we started the trip as a
> preventative maintenance measure. Duralast from Auto Zone. Their best one.
> 1080 miles on it. There was an off ramp about a mile away. All down hill.
> Drove to the off ramp. Found an Auto Zone about 35 miles away that could
> have a water pump by 3:30. It was 12:30. Richard. A GMCer saw us, and
> stopped. He was on his way to Hal StClair's in Albuquerque NM. 70 Miles
> away. It's a one man job. Pulled the pump. Picked up the replacement pump.
> Installed it at the off ramp. Had the original GM fan with clutch with me.
> Hal called to see if I needed help. It was dark. So I told him I'd call in
> the AM. In the morning. We got on the road. Due to pulley damage. We just
> got to the next off ramp 8 miles away. Hal called. We needed the crank, and
> water pump pulleys that Hal had. And more new belts. So Hal, and his wife
> drove the 70 miles out to bring us some pulleys, and belts. He helped get
> the parts on. And off to his house. Then he wouldn't let me pay him. Fed
> us, and we staid for the night. Next morning off to Tucson. No issues to
> Tucson. Picked up a 403 fan shroud at the rally. Jim K at Applied will
> have a proper roller bearing water pump here by Tuesday. Tom Pryor will
> have the electrical plug here Tuesday. Install the Benz fan, and another
> water pump Wednesday. The Benz fan didn't cause this. Me not getting the
> proper water pump from Jim K at Applied GMC to start with DID. We can't
> thank the StClair's enough. Bob, and Linda Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[johnny]

One of my VWs broke a reground crankshaft and inspection showed a lack of radiusing at the failure point - rear of the #2 rod throw. The grinder gave
me all new parts including case halves.

As to Hal and his gracious wife, their hospitality is unbelievable! In the hill country around here they'd be referred to as Real Good People.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased