Wanna see what a spun crank bearing looks like?


(The Jag Man) #1

A bit off topic as the car in question is a 1972 Pontiac GTO. This has suffered through a lack of maintenance most of its life and has 95,000 miles on the clock. We were testing out a new exhaust system and did a U-turn and then laid into the gas pedal only to hear a horrible bang, bang bang… limped home hoping we would not shoot a piston through the block. I know we should have had it towed, etc. Note the pictures of the upper and lower bearing spinning right over itself and the fact that many other bearings are as thin as razor blades. Forum discussion for these cars indicates the need not to accelerate through hard curves as the oil pickup will suck air if the sump is low at any time. More than likely this happened many times in the cars long life. Looking at about $4,000 with a days worth of dyno break in and reassembly of the engine. Wife isn’t happy…

Gerard
Loveland, Colorado


(Paul Breen pay palled it) #2

That’s grim. Hard to sugar coat that as an opportunity. Paul


(tony) #3

given the state of those bearings, Gerard was very fortunate to not have a totally destroyed engine, which could have happened at any time, so I guess you just have to look at it as a rebuild that was due

my highly responsive digital OP gauge shows that Jag I6 also drop oil pressure on steep slopes, the OP on my worn 420G engine would drop to as low as 4psi at hot idle on a steep slope, maybe even zero. The rebuilt one I replaced it with has never been below 18psi


(1958 Mark I) #4

Where was that great photo of the car taken?


(The Jag Man) #5

Rocky mountain national park in Colorado:

https://www.nps.gov/romo/index.htm

Gerard


(Paul M. Novak) #6

Gerard,
I got a partially disassembled Jaguar VII 3.4L XK engine with spun crankshaft bearings several years ago. It looked much like yours.

The owner was down on his luck and forced to move so he was selling a bunch of Jaguar MK VII parts stored in his garage that he accumulated over the years while he owned the car. He got a replacement engine installed, drove it for years afterwards, but eventually sold it. I bought a bunch of assorted parts from him as spares for my MK VIII restoration project, including the disassembled engine. Boy, I had no idea how heavy a crankshaft was until I tried picking it up. :wink:

Paul


(Paul Wigton) #7

Lucky it didnt stack…:frowning:


(The Jag Man) #8

You mean like one of those all you can eat pancake deals at IHOP!!!

Those on the other side of the pond prolly don’t know about our International House of Pancakes never ending American, lets eat too much deals for only $5.00.

Gerard


(The Jag Man) #9

Those cranks are HEAVY indeed, yet fragile if you drop them and they crack $$$$$$$$$$$$$$$$$$$$$$

Gerard


(Paul Wigton) #10

If that’s a cast crank–easy to tell–I’d seriously think about getting a forged one.


(The Jag Man) #11

I will put that on your credit car…

Don’t forget this engine lasted 95,000 miles with minimal care. Special parts will just run my bill higher unless your generosity kicks in for the goodies!!

Gerard