Why Bar it Over Every Month...in Winter

[spartonboat1]

Part II of conversation with my old diesel tech (see the new impeller post).

Since boats on the hard, during the Mich winters sit for 6 months, (fingers at ready, Nov, Dec, etc. to Apr). He says I should bar-over the DD's every month or so, (about a 1/4 to 1/2 turn) so that the crank does not sit in a single position and burrow down on the bearings and through the oil film. He says over the long haul, the effect of the crank pressure on the bearings over a 6 month period will affect the running oil pressure.

So has anyone heard of this effect and the need for barring over every month or so, during the winter or other down time. I know these old-time techs are aware of interesting stuff and I am curious about this. About time I registered on Diesel.com I guess.

 

[Trojan]

There is no pressure in the motor after it sets for 1 hour. The amount of pressure on the bearings is far greater when running. But there is very little pressure at all inside the engine when the engine is not running. The ring friction pressure is enough to support the piston and rod when the engine is off. My 6-71 DD sat for 3.5 years with zero rotation and started like it was never turned off. Any pressure left inside the piston and cylinder area is dissipated through the ring end gaps. Only 2 pistons will have pressure after the engine is turned off and soon is dissipated. Don't believe it. It's another zoomer story. The only reason to bar a stored engine is to keep the moisture out of the open cylinder preventing any rust. But there is so much lube inside the diesel that rust will not form.

BILL

 

[jim rosenthal]

Bill is right on this, I agree. On the other hand, it's an interesting exercise regimen...

 

[rsmith]

In aircraft engines and I asume any engine it would be true for it is not recomended to "pull it thru" or turn it over because you are wiping the oil film off the parts because you have metal to metal contact when the engine oil system is not pressurized. And then can form rust.

 

[krush]

Good intentions with seemingly wise logic that is proven wrong by common sense.

He's saying the bearing is going get squished by the crank sitting on it? Bearings are soft, but not that soft!

 

[Trojan]

Cintered bronze used in rod bearings is quite hard. I designed many machines that manufactured bronze, Babbitt, lead and many other types of bearings. At rest there is zero load on the bearings.

BILL