When an engine is run with Diesel Fuel in the oil the most damage will be found near always on the Main Bearings, this is the result of the mass weight of the rotating group on a bearing without the oil film to float the Crankshaft, the balance shaft that spins x2 the speed of the Crank would also show an amount of damage, if the pistons have not picked up on the skirt and left marks on the lower liner wall you might be lucky with this section of the engine, but I know you will find the Main Bearings to show more damage than the Big Ends, its always best to check the oil level before starting not at night after the days work as any increase over night from fuel is spotted easily. tctractors

This is a photo of a partly dismantled 17A engine.
The big ends can be a challenge through the side covers but the mains would be impossible.

Forgive my ignorance but what exactly are the big ends?

Hi, dependzic.
Depends very much on the particular piece of equipment being referred to. In this particular case where we are talking about engines, it is the bottom end of the connecting rod between piston and crankshaft where it attaches to and pivots on the crankshaft - hopefully, with minimal friction.

"Big end" 'cos the other end, the end which attaches to the piston and which some of you 'top-siders' seem to call 'the wrist' is somewhat smaller.

Now if we were talking about women - - - - - nah, let's not go there.

Just my 0.02.

Thanks Deas--i was thinking it was the fore and aft main bearings on the crankshaft--was way off!!----Yes we have wrist pins up here!!!

It is common for the Main Bearings to spin and damage the cylinder block when they are allowed to run in Diesel Fuel - E/Oil mix, the only way to tackle this repair is Sump plate removal, to remove the rod caps through the side windows can be a struggle plus the plates are well hidden behind things, the cap numbers are always placed towards the windows and the nuts have split pins. tctractors

"tctractors" wrote:

It is common for the Main Bearings to spin and damage the cylinder block when they are allowed to run in Diesel Fuel - E/Oil mix, the only way to tackle this repair is Sump plate removal, to remove the rod caps through the side windows can be a struggle plus the plates are well hidden behind things, the cap numbers are always placed towards the windows and the nuts have split pins. tctractors

What damage to the cylinder block maybe possible?

On the plus side, main bearings receive lubrication prior to rods.

"Neil" wrote:

The surface of the shell cavity in the block (and the main bearing cap) can be damaged when the shells spin.

Is the shell cavity in the block replaceable or if it is damaged does that make the block unusable? I assume the main bearing caps are replaceable. If the main bearing shells did spin would this require the block to be line bored?