Oil cooled vs non-oil cooled pistons.

[madsam]

I always hear that the 855-250 cumins in these trucks don't have oil cooled pistons. Does anyone have a pic of a oil cooled piston vs non-oil cooled?

I assume the oil cooled has holes in it that oil runs through the head of the piston. Does it have different rods for the extra oil? I would assume the oil would need to be cooled well, so having an extra oil cooler or a bigger oil cooler might be needed. Do any of the diesel guys have any info on this?

 

[No.2Diesel]

I'm probably not 100% correct here but:

I think when any engine (gas or diesel) is referred to as having oil cooled pistons it means:

That there are nozzles pointing upward below the cylinders that spray oil at the underside of the pistons to keep temperatures down.

I'm sure there are other methods to do the same thing though.



Here's a pic

 

[madsam]

Aaa. I have seen a rod that had holes to spray the bottom of the piston. I think it was a slant 6 dodge. But I thought it was to oil the cylinder wall for lubrication. If that is the case, are the pistons different or just an oil sprayer?

If it is just an oil squirter, It seems that you could mod that in easily.. If that is the case?

 

[Capt.Marion]

Excellent question, I've always wondered about this myself...

 

[timntrucks]

im interested to see if someone comes up with more infor ill be watching Tim

 

[WillWagner]

A piston cooled 855 has plastic, or, depending on how old it is, metal nozzles inserted into the block on the oil cooler side of the engine, apx 1/2 way up the length of the block from the pan rail. Sorry, I've been here a bit and still can't post a pic like cranetruck!

 

[madsam]

Thanks. This is good info. Is there a pic of the inside of the block on an oil cooled 855?

One question. What is a "boss"?

 

[madsam]

This is a link I found. Are we sure there is no oil running through the piston head?

http://www.marinediesels.info/2_stroke_engine_parts/piston.htm

 

[madsam]

Here are some other pics.

 

[WillWagner]

The rods are also drilled in the 855.

 

[Gamagoat1]

But the drilled passage in the rod provides lube for the rings, wrist pin and piston, not cooling, like the nozzles Will refers to.

 

[madsam]

Sorry for my ignorance, but what is the "boss"?

 

[Pinkie]

Boss is the nub or nipple that is there but there is no hole drilled.