my mechanic and i have a theory that suggests that the rods are bending from failed head gaskets. it goes like this: the gasket fails, and leaks water or oil or both into the cylinder when the car is shut down, and if enough gets in the cylinder, specifically more than 1.6 cubic inches, upon startup the rod bends. the engine still runs but may have an occasional miss, and eventually will oval out the cylinder and cause excessive oil consumption.

i believe this theory but unfortunately dont know how to prevent it because i dont know how to detect an early failure of the head gasket. it seems a little too much to just replace head gaskets at random.

we have replaced my head gasket but i still dont know if any rods are bent because i was not aware of the possibility and didnt do a compression test before we tore it down and didnt measure the distance from the top of the piston to the top of the block while the head was off. i have since done a lot of reading on this web site and know a lot more than i did a month ago.

my 90 350 is in the shop at present getting a compression test. i have an occasional miss and am using too much oil.

one idea i have is to install a higher rear end gear to reduce engine speed on the highway. the 300d's which dont seem to bend their rods very often have a 2.65 gear and the 350's have a 2.87. this doesnt seem very significant but i know that the chevy 6.2 diesels from the eighties tended to break main bearing webs in trucks with 4.10 rear ends and didnt much if equipped with a 3.73. another idea is to convert to a five speed stick which would be a lot more expensive and i am not sure about parts compatablility.

in the mean time i would watch like a hawk for any sign of a head gasket failure and replace it at any sign. if that is the case i would also do a compression test before tearing down and measure the piston to deck height and see if any come up short.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.