Decisions, Decisions

- J
- JRE
  
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posted
16 years ago

Fri, Jun 8, 2007 11:04 PM

Our 1995 850 seems to have broken a rod today at 114K miles. The piston doesn't move when the crank does but the other 4 cylinders move and have good compression. I was able to move the piston by tapping firmly on it.

Anyone seen this before and know the chances of salvaging this block and crank? I assume the crankcase is full of junk resulting from the failure that would have to be cleaned out to rebuild the bottom end, and that the crank requires measurement for bending and magnaflux for crack detection.

Or...to save the car is it better to just find a used engine?

Or...maybe for the price of an engine and the work of a swap it's better to just get another beater? (This isn't the primary car.)

JRE

- M
- Michael Pardee
  
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posted
16 years ago

Sat, Jun 9, 2007 1:02 AM

I get goosebumps thinking about trying to restore an engine that has thrown a rod. Occasionally the rod will have had a flaw but more often there was a reason the rod broke. Oil starvation tops the list. A look at the crank bearings (especially on the broken rod) will tell a lot, but if it were mine I'd put my efforts and resources into a good used engine. After all, any engine is likely to be better than the one you have!

Mike

- J
- James Sweet
  
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posted
16 years ago

Sat, Jun 9, 2007 1:55 AM

Usually when a rod breaks some pretty serious damage is done. In this case though you're likely gonna have to get another engine anyway so you may as well open it up and get a good look at things. 850s have been around long enough by now that engines can be found cheaply in U-pull yards, albeit in generally unknown condition.

- R
- Roadie
  
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posted
16 years ago

Mon, Jun 11, 2007 4:41 PM

If it separated at one of two locations and the chances are very good that the loose end of the connecting rod did a lot of damage while banging around. You might have a salvagable block but the piston may have hit the valves. Apparently the timing belt is intact which is good. If you want to put in a fair number of hours and salvage this car you could look for a donor vehicle with running engine.

Alternatively you could buy either a short block, long block or turnkey engine but options 1 and 1 would require quite a bit of work. All three choices can get into some serious $$$, so one question would be whether you are going to rebuild the car for long term use. If not I would just shop around for another comparable car.