jv9999

I bought a '90 C4 cheap with what I thought was a thrown rod, but it turns out it was broken. The bearing surface is good, the piston is good (minus a chip from said rod), no valve hits, no bent push rods, no signs of water, just twisted and broken.
Any thoughts on what might have caused this? I've seen many broken engines, but this one has me scratching my head. It's a 60K car and other than the rod, the engine is clean with almost no wear.

Anyone got a good used L98 piston and rod? :-)

bill mcdonald

No idea. Hard to tell but the rod looks like it is starting to bend as well?

I had a single 90 piston and rod sitting around for years. threw it away about a year ago man.

bjankuski

Injector leaked down and filled the cylinder with fuel and when the car was started it hydraulic locked and snapped the rod. My guess.

PatternDayTrader

Agreed.
​​​​​​​You could also add that water ingestion from driving thru a somwhat deep puddle coukd do the same thing.

jv9999

I hadn't thought of the injector. That does seem most likely. Thanks!

ghoastrider1

remove the rod. Cut the piston in half, about where the pin goes thru it. They make great ashtrays for smoker gearhead types. I have several out in my garage

FostersPerformance

I have a full set of rods and pistons from my 88...If you really need one, PM me..

Joe C

kind of curious - what cylinder? was it 7 or 8, or ???

jv9999

#2 oddly enough

C409

..... Hydro-lock ... Nitrous backfire ... or a heavy dose of starting fluid with the distributor 180 or so out ... if the engine was running when that rod broke , it would have ventilated the block and oil pan .....